|渡邉 聡（わたなべ さとし）||データ更新日：2021.05.28|
教授 ／ 工学研究院 機械工学部門 流体工学
|1.||Yohei Tanaka, Takahiro Kitabata, Satoshi Watanabe, Satoru Ohashi, Akira Sakata, Yasushi Matsunaga, Evaluation of Suction Performance of Inducer with Splitter Blade, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2021.14.1.13, 14, 1, 13-24, 2021.01.|
|2.||T. Takamine, S. Nakano, S. Watanabe, H. Watanabe, Influence of axial rotor offset on residual axial thrust characteristics of a centrifugal pump at low flow rates, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2020.13.4.655, 13, 4, 655-667, 2020.10.|
|3.||田中 陽平，森井 達也，渡邉 聡，大橋 聡，坂田 彬，松永 易, 小径吸込み管への接続によるインデューサ付きターボポンプのキャビテーションサージ抑制効果, ターボ機械, 10.11458/tsj.48.10_577, 48, 10, 577-586, 2020.10.|
|4.||Yohei Tanaka, Satoshi Watanabe, Satoru Ohashi, Yasushi Matsunaga, Numerical Investigation of Suction Performance of Inducer with Splitter Blade, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2020.13.4.750, 13, 4, 743-749, 2020.12.|
|5.||De ZHANG, Yusuke KATAYAMA, Satoshi WATANABE, Shin-Ichi TSUDA, Akinori FURUKAWA, Performance prediction model of contra-rotating axial flow pump with separate rotational speed of front and rear rotors and its application for energy saving operation, Journal of Fluid Science and Technology, https://doi.org/10.1299/jfst.2020jfst0015, 2020.07.|
|6.||De Zhang, Yusuke Katayama, Satoshi Watanabe, Shin Ichi Tsuda, Akinori Furukawa, Numerical study on loss mechanism in rear rotor of contra-rotating axial flow pump, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2020.13.1.241, 13, 1, 241-252, 2020.01, [URL], It is known that higher efficiency can be achieved with reduced specific speed design of rear rotor in contra-rotating axial flow pump. To investigate the mechanism of increased efficiency with the reduced specific speed of rear rotor, three models with different specific-speed rear rotors are designed with the conventional method, and the flow fields are simulated by unsteady RANS simulation. To analyze the loss generation mechanism, two loss evaluation methods based on the entropy production rate and the material-derivative of rothalpy are employed. It is found that, although the both methods qualitatively estimate the total loss through the rear rotor, the derivative of rothalpy can give much better quantitative prediction of the losses. Two distinct flow features are observed in the rear rotor, the corner separation at the hub corner of blades and the tip leakage vortex, both of which are responsible for the loss generation. With the evaluation of local loss generation based on the material derivative of rothalpy, the loss contribution of corner separation is found to be very small compared with that due to the tip leakage vortex. The tip leakage vortex structure in high specific speed rear rotor shows the strong interaction with the leading edge of adjacent blade, which seems to strengthen the blockage effect in the tip region. This is relieved in the lower specific speed rear rotor, resulting in the achievement of higher efficiency with it..|
|7.||渡邉聡，辻本良信, 二次元翼列を用いた理論解析に基づくキャビテーションサージ発生条件の再検討, ターボ機械, 47, 11, 686-694, 2019.11, 液体燃料ロケットエンジン用インデューサなどの高速ポンプでは，キャビテーションの発生により，旋回キャビテーションやキャビテーションサージなどの不安定現象がしばしば問題となる．これらの不安定現象は，キャビティの体積の応答特性であるマスフローゲインファクタM（入口流量の低下に対する体積の増加）とキャビテーションコンプライアンスK（入口圧力の低下に対する体積の増加）を用いてモデル化されることが多く，その発生原因が正のマスフローゲインファクタ（M>0）にあることが過去の研究により示されていた．しかしながら，準静的に考えた場合M>0は必然であり，限られた吸込み圧力でキャビテーションがかなり発達した条件でのみ発生する実験事実との乖離があった．
|8.||松下大介，岩本渉，渡邉聡，津田信一，菊川裕規，古川明徳, 傾斜側溝の浅水流におけるポータブルダリウス水車の水力性能に関する考察, ターボ機械, 47, 10, 589-596, 2019.10.|
|9.||Tatsuya Morii, Yohei Tanaka, Satoshi Watanabe, Satoru Ohashi, Yasushi Matsunaga, Suction performance and cavitation instabilities of turbopumps with three different inducer design, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2019.12.2.128, 12, 2, 128-135, 2019.04, [URL], In the present study, the suction performance and the cavitation instabilities in turbo-pumps with three different inducers designed with different design incidence angle are experimentally investigated in the wide range of operating flow rate. Three inducers L with the lowest design incidence angle, M with the moderate one and H with the largest one are used in combination with identical main impeller. As a result, the total head of pump with inducer H is confirmed to be the largest especially at large flow rates, while the shaft power is almost the same, resulting in the best efficiency with the inducer H. The suction performance is the best with inducer H at large flow rates and is the best with inducer L at low flow rates. Two kinds of instabilities, the cavitating whirling vortex and the surges are mainly observed for the all both inducers, but they are limited at low flow rates. The occurrence ranges of these instabilities in terms of the operating flow rate is the widest with inducer H. However, those in terms of the shockless flow rate ratio is similar for the all three inducers: This fact can contribute to establish some guideline to the pump operation avoiding serious flow instabilities..|
|10.||Y. Suzuki, Y. Katayama, S. Watanabe, S. Tsuda, A. Furukawa, A study on performance prediction of Darrieus-type hydroturbine operated in open channels using CFD with actuator disk method, 29th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2018
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/240/4/042020, 240, 4, 2019.03, [URL], A performance of Darrieus-type hydroturbine is strongly influenced by the channel and flow condition. These flow conditions are different from place to place and also dependent upon the seasons, therefore it is difficult to study these influences only by experiments. On the other hand, numerical simulation can be adopted for various flow conditions. However, calculation costs are very expensive since fully unsteady simulation taking account of free surface of water should be conducted for this turbine as a cross-flow type. Then, in this paper, a simple numerical model is developed. In this model, instead of solving the complex flow field around the turbine, it is modeled by an actuator disk which imposes the total pressure difference consumed by the rotating turbine. Our previous study suggested that the head coefficient defined as the total pressure difference across the runner normalized by the dynamic pressure with area averaged flow velocity into the turbine seemed to well represent the specific performance of Darrieus-type hydroturbine. In this paper, the specific performance is determined from the experiment in one channel, and the corresponding total pressure change is locally applied to the actuator disk as a function of local inflow velocity. The predicted overall head coefficient, which is defined as the total pressure difference between far upstream and downstream normalized by area averaged velocity downstream of the turbine, is compared with experiment. As a result, when the flow velocity or depth decreases, the overall head coefficient increases. The proposed model can qualitatively reflect this influence of flow velocity and depth on the turbine performance in most cases, while quantitatively the predicted overall head coefficient is different from that in the experiments, indicating the necessity of further modification of the model for quantitative prediction..
|11.||T. Morii, Y. Tanaka, S. Watanabe, S. Ohashi, Y. Matsunaga, Experimental investigation on suction performance and cavitation instabilities of turbopumps with two different inducers, 29th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2018
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/240/3/032041, 240, 3, 2019.03, [URL], In the present study, the suction performance and the cavitation instabilities in turbo-pumps with two different inducers designed with different design incidence angle are experimentally investigated in the wide range of operating flow rate. Compared to the Inducer A, Inducer B is designed with larger incidence angle, therefore it has slightly larger inlet and outlet angles. The identical centrifugal impeller is used as a main impeller. As a result, the total head of pump with inducer B is confirmed to be larger than that with inducer B especially at large flow rates, while the shaft power is almost the same, resulting in the better efficiency with the inducer B. The suction performance is better with inducer B at large flow rates. Two kinds of instabilities, the cavitating whirling vortex and the surges are mainly observed for the both inducers, but they are limited at low flow rates. The occurrence ranges of these cavitation instabilities are wider with inducer B..
|12.||Yushin Ehara, Soichiro Kitamura, Wakana Tsuru, Satoshi Watanabe, Shin Ichi Tsuda, Unsteady forces and moments acting on a cantilevered rectangular hydrofoil with tip clearance in cavitating conditions, 29th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2018
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/240/6/062054, 240, 6, 2019.03, [URL], It is known that the lift and drag forces of hydrofoil increase then decrease with the decrease of cavitation number, i.e. the development of cavitation, in many cases. In our previous study, the measurement of lift and drag forces of cavitating Clark Y-11.7% hydrofoil was conducted under the assumption of two-dimensional flow, which showed the similar tendency to above common knowledge. However, since there was a tip clearance, the bending moment should present to some content due to the flow asymmetry. In the present study, by using hydrofoil supported by a cantilever equipped with totally 8 strain gauges, the lift and drag forces and their moments are separately measured. It is found that the time-averaged moments around midspan due to lift and drag forces change with the decrease of cavitation number as well as the lift and drag forces change. This means that the working points of lift and drag forces move in the spanwise direction, indicating the importance of the three-dimensionality of cavitation development including that due to tip clearance flow. Unsteady lift and drag forces and their moments also show the significant fluctuations due to periodic behaviour of cavitation instabilities..
|13.||北村宗一郎，江原悠眞，鶴若菜，渡邉聡，津田伸一，能見基彦, 境界層特性の異なる複数の迎角におけるClark Y翼形のキャビテーション発生下の揚抗力, ターボ機械, 46, 12, 715-722, 2018.12.|
|14.||D. Zhang, T. Tsuneda, Y. Katayama, Satoshi Watanabe, Shinichi Tsuda, A. Furukawa, Backflow vortex behaviours in contra-rotating axial flow pump at low flow rates, 2017 AWG-IAHR Symposium on Hydraulic Machinery and Systems
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/163/1/012036, 163, 1, 2018.07, [URL], Backflow usually exists at the inlet of rotors of many turbomachines at low flow rates. In counter-rotating rotors applied for the axial flow pump, such vortical structures are also able to form. In our previous researches, some broad-banded pressure fluctuations in low frequency range have been observed between front and rear rotors, but we have not yet been able to explain what causes such phenomenon. In this study, in order to find out the causes of low frequency components at low flow rates, unsteady numerical simulations for the whole front and rear rotors are conducted, and casing pressure is experimentally measured at the inlet and outlet of front rotor and the inlet of rear rotor. It is found that vortical structures exist between front and rear rotors at below 40% of design flow rate. These vortices seem to be the result of shear layer instability at the impingement location of the exiting flow from front rotor to the backflow of rear rotor. The behaviours of these backflow vortices and their interaction with front rotor contribute the low frequency components in pressure fluctuations observed at low flow rates..
|15.||Taiki Takamine, Daichi Furukawa, Satoshi Watanabe, Hiroyoshi Watanabe, Kazuyoshi Miyagawa, Experimental analysis of diffuser rotating stall in a three-stage centrifugal pump, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2018.11.1.077, 11, 1, 77-84, 2018.01, [URL], Rotating stall phenomenon limits the operation range of turbomacnines, therefore it is important to understand the crucial parameters of this phenomenon. In the present study, the diffuser rotating stall in a three-stage centrifugal pump was experimentally studied. Examined main parameter was an axial offset of rotor against the stationary part, which might be unavoidable due to accumulation of geometrical tolerances and assembling errors. The effect of leakage flow rate at the balance drum section employed as a thrust balancing device, which increases the thru-flow rate at the first and second stages diffusers. was also studied. The effect of rotor axial offset was clearly observed and, with the rotor axial offset to the suction side, the rotating stall appeared only at the third stage diffuser. By setting the balance flow rate set to zero, the onset range of rotating stall became wider m the first and second stage diffusers, which was well explained by the decrease of the thru-flow rate..|
|16.||Masashi Yasuda, Satoshi Watanabe, How to avoid severe incidents at hydropower plants, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2017.10.3.296, 10, 3, 296-306, 2017.07, [URL], Hydropower is now changing its role from the energy generator into the most powerful and reliable tool for stabilizing the electrical network, especially under the increase of intermittent power sources like wind-power and solar-power. Although the hydropower plants are the most robust generating facilities, they are not immune from unexpected severe incidents having long downtime, considerable restoration cost and sometimes fatalities. The present paper provides some study results about severe incidents in the conventional hydropower plants, mainly about the flood, fire and electromechanical troubles, except for the incidents of civil facilities. It also provides some possible scenarios which may lead some measures how to avoid such incidents. Finally, it provides some comprehensible recommendations to avoid severe incidents based on experiences..|
|17.||W. Tsuru, T. Konishi, S. Watanabe, S. Tsuda, Observation of Inception of Sheet Cavitation from Free Nuclei, Journal of Thermal Science, 10.1007/s11630-017-0933-8, 26, 3, 223-228, 2017.06.|
|18.||堤 啓介, 渡邉 聡, 早田 諒, 津田 伸一, 森 義英, 山口 健, ストール条件下における偏平形トルクコンバータのキャビテーション性能に関する研究, ターボ機械, 45, 6, 350-357, 2017.06.|
|19.||K. Tsutsumi, S. Watanabe, S. Tsuda, T. Yamaguchi, Cavitation simulation of automotive torque converter using a homogeneous cavitation model, EUROPEAN JOURNAL OF MECHANICS B-FLUIDS, 10.1016/j.euromechflu.2016.09.001, 61, 263-270, 2017.01.|
|20.||Taiki Takamine, Satoshi Watanabe, Daichi Furukawa, Hiroyoshi Watanabe, Kazuyoshi Miyagawa, Experimental investigation on diffuser rotating stall in a three-stage centrifugal pump, ASME 2017 Fluids Engineering Division Summer Meeting, FEDSM 2017
Keynotes; Advances in Numerical Modeling for Turbomachinery Flow Optimization; Fluid Machinery; Industrial and Environmental Applications of Fluid Mechanics; Pumping Machinery, 10.1115/FEDSM2017-69386, 2017.01, [URL], Rotating stall phenomenon frequently causes the troubles such as vibrations acting on the shaft system and reduces the reliability of turbomachines. In the present study, the diffuser rotating stall in a three-stage centrifugal pump was experimentally studied. Special emphasises were placed on the geometrical conditions; an axial offset of rotor against the stationary part, which might be unavoidable due to accumulation of geometrical tolerances and assembling errors., and the radial clearances of annular leakage paths which increases the thru-flow rate at the impellers and the first and second stage diffusers. As a result, with the rotor axial offset to the suction side, the rotating stall appeared only at the third stage diffuser, while with that to the discharge side, the rotating stall was more significant. By enlarging the leakage flow passages at the inter-stage bush and the balancing flow channel, the onset range of rotating stall became narrower in the first and second stage diffusers, which was well explained by the increase of the thru-flow rate. On the other hand, with the enlarged leakage passage at the liner ring, the onset range.
|21.||岩本 渉, 渡邉 聡, 津田 伸一, 松下 大介, 古川 明徳, 勾配を有する側溝に設置するポータブルダリウス水車の運転特性, ターボ機械, 44, 12, 746-752, 2016.12.|
|22.||Masashi Yasuda, Satoshi Watanabe, How to Avoid Severe Incidents at Pumped Storage Power Plants, 28th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2016
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/49/11/112002, 49, 11, 2016.12, [URL], Pumped storage is now increasing its importance as the most powerful and reliable tool for stabilizing the electrical network, especially under the increase of intermittent power sources like wind-power and solar-power. However, pumped storage power plants have generally more machinery troubles than the conventional hydropower plants and sometimes they encountered unexpected severe incidents having long-term outage and a considerable restoration cost. The present paper provides some study results about general tendencies of machinery troubles in pumped storage, some examples of severe incidents mainly about the electro-mechanical troubles but also about the flood and fire, and possible scenarios which may lead into a severe result. Finally, it provides lessons learned and some recommendations to avoid severe incidents based on experiences..
|23.||K. Nakashima, Satoshi Watanabe, D. Matsushita, Shinichi Tsuda, A. Furukawa, Performance Prediction of Darrieus-Type Hydroturbine with Inlet Nozzle Operated in Open Water Channels, 28th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2016
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/49/10/102011, 49, 10, 2016.12, [URL], Small hydropower is one of the renewable energies and is expected to be effectively used for local supply of electricity. We have developed Darrieus-type hydro-turbine systems, and among them, the Darrieus-turbine with a weir and a nozzle installed upstream of turbine is, so far, in success to obtain more output power by gathering all water into the turbine. However, there can several cases exist, in which installing the weir covering all the flow channel width is unrealistic, and in such cases, the turbine should be put alone in open channels without upstream weir. Since the output power is very small in such a utilization of small hydropower, it is important to derive more power for the cost reduction. In the present study, we parametrically investigate the preferable shape of the inlet nozzle for the Darrieus-type hydroturbine operated in an open flow channel. Experimental investigation is carried out in the open channel in our lab. Tested inlet nozzles are composed of two flat plates with the various nozzle converging angles and nozzle outlet (runner inlet) widths with the nozzle inlet width kept constant. As a result, the turbine with the nozzles having large converging angle and wide outlet width generates higher power. Two-dimensional unsteady numerical simulation is also carried out to qualitatively understand the flow mechanism leading to the better performance of turbine. Since the depth, the width and the flow rate in the real open flow channels are different from place to place and, in some cases from time to time, it is also important to predict the onsite performance of the hydroturbine from the lab experiment at planning stage. One-dimensional stream-tube model is developed for this purpose, in which the Darrieus-type hydroturbine with the inlet nozzle is considered as an actuator-disk modelled based on our experimental and numerical results..
|24.||松下 大介, 古川 明徳, 渡邉 聡, 堰止め式ダリウス形水車の開水路への設置と流量変動に伴う運転に関する一考察, ターボ機械, 43, 12, 721-729, 2015.12.|
|25.||Shinichi Tsuda, H. Hyodo, Satoshi Watanabe, Validation of Bubble Dynamics Equation for a Nano-scale Bubble via Molecular Dynamics Simulation, 9th International Symposium on Cavitation, CAV 2015
Journal of Physics: Conference Series, 10.1088/1742-6596/656/1/012039, 656, 1, 2015.12, [URL], For a validation of the application of conventional bubble dynamics to a nano-scale bubble behaviour, we simulated a nano-scale bubble collapsing or vibration by Molecular Dynamics (MD) method and compared the result with the solution of Rayleigh-Plesset (RP) equation and that of Confined RP (CRP) equation, whose boundary condition was corrected to be consistent with that of MD simulation. As a result, a good coincidence was obtained between MD, RP, and CRP in the case of one-component fluid. In addition, also a good correspondence was obtained particularly in the comparison between MD and CRP in the case of two-component fluid containing non-condensable gas. The present results indicate that conventional bubble dynamics equation can be applied even to a nano-scale tiny bubble..
|26.||山本 航平, 渡邉 聡, 石坂 公一, 津田 伸一, 古川 明徳, 障害板付設による３枚翼インデューサに生じるキャビテーションサージの抑制の検証, ターボ機械, 43, 7, 425-432, 2015.07.|
|27.||山田雅之, 大豆生田祐介, 渡邉 聡, 縦軸渦巻ポンプにおける気液二相流運転時の流体性能と励振力に関する研究, ターボ機械, 43, 4, 195-204, 2015.04.|
|28.||Y. Yamamoto, Satoshi Watanabe, Shinichi Tsuda, A simple cavitation model for unsteady simulation and its application to cavitating flow in two-dimensional convergent-divergent nozzle, International Symposium of Cavitation and Multiphase Flow, ISCM 2014
IOP Conference Series: Materials Science and Engineering, 10.1088/1757-899X/72/2/022009, 72, Forum 2, 2015.01, [URL], In this paper, a simple cavitation model is developed under the framework of homogeneousone-fluid model, in which the perfect mixture of liquid and vapor phases is assumed. In most of conventional models, the vapor phase is considered as a dispersed phase against the liquid phase as a continuous phase, while in the present model, two extreme conditions are considered: for low void fraction, dispersed vapor bubbles in continuous liquid phase, while for high void fraction, dispersed droplets in continuous vapor phase. The growth of bubbles and droplets are taken into account in the mass transfer between vapor and liquid phases, and are switched according to the local void fraction. The model is applied for the simulation of cavitating flow in a two-dimensional convergent-divergent nozzle, and the result is compared with that using a conventional model. To enhance the unsteadiness of cavitation due to the instability at the cavity interphase, the turbulent shear stress is modified depending upon the continuous phases in combination with the proposed cavitation model, which drastically reduces the turbulent viscosity for high void fraction region. As a result, the unsteadiness of cavitation observed in experiments is well reproduced..
|29.||Linlin Cao, Satoshi Watanabe, Akinori Furukawa, Dazhuan Wu, Numerical investigation of influence of rotor-rotor gap on performances of contra-rotating axial flow pump, ASME/JSME/KSME 2015 Joint Fluids Engineering Conference, AJKFluids 2015
Symposia, 10.1115/AJKFluids201533053, 1, 2015.01, [URL], As a high specific speed pump, the contra-rotating axial flow pump with two rotors rotating reversely has been proved with higher hydraulic and cavitation performances. However, while compared with the traditional rotor-stator combination, it suffers from more significant potential interactions between two rotating blade rows, and the gap between two rotors has to be kept large with accepting the small deterioration of head performance. In our previous studies, the different speed design was confirmed effective to weaken the blade rows interactions, and therefore indicated the possibility to pertinently reduce the gap between two rotors as well as improve the hydraulic performances of the contra-rotating axial flow pump. The present paper majorly discuss the possibility to further improve the hydraulic performances of contra-rotating axial flow pump by reducing the gap between two blade rows. The cases with original gap, increased gap and reduced gap were studied by the numerical approach. The internal flow structures between two blade rows were concentrated, and a simplified method for the pressure fluctuations investigation was applied. This study is supposed to offer more understanding about the internal flow properties and give more guidelines to determine the related parameters for contra-rotating rotor-rotor combination..
|30.||D. Matsushita, K. Tanaka, S. Watanabe, K. Okuma, A. Furukawa, Experimental and Numerical Investigations on Performances of Darriues-type Hydro Turbine with Inlet Nozzle, International Journal of Fluid Machinery and Systems, 7, 4, 151-159, 2014.12.|
|31.||L.-L. Cao, S. Watanabe, H. Honda, H. Yoshimura, A. Furukawa, Experimental Investigation of Blade-To-Blade Pressure Distribution in Contra-Rotating Axial Flow Pump, International Journal of Fluid Machinery and Systems, 7, 4, 130-141, 2014.11.|
|32.||Daisuke Matsushita, Kei Tanaka, Satoshi Watanabe, Kusuo OKuma, Akinori Furukawa, Experimental and numerical investigations on performances of Darriues-type hydro turbine with inlet nozzle, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2014.7.4.151, 7, 4, 151-159, 2014.01, [URL], Low head hydropower is one of realistic renewable energies. The Darrieus-type hydro turbine with an inlet nozzle is available for such low head conditions because of its simple structure with easy maintenance. Experimental and numerical studies are carried out in order to examine the effects of gap distances between the runner pitch circle and two edges of inlet nozzle on turbine performances. By selecting narrower gaps of left and right edges, the performance could be improved. From the results of two dimensional numerical simulations, the relation between the performance and flow behaviors around the Darrieus blade are discussed to obtain the guideline of appropriate inlet nozzle design..|
|33.||Linlin Cao, Hironori Honda, Hiroaki Yoshimura, Satoshi Watanabe, Akinori Furukawa, Experimental investigation of blade rows interactions in contrarotating axial flow pump, ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting, FEDSM 2014, Collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels
Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Multiscale Methods for Multiphase Flow; Noninvasive Measurements in Single and Multiphase Flows, 10.1115/FEDSM2014-21901, 2014.01, [URL], As a high specific speed pump, the contra-rotating axial flow pump with two rotors rotating reversely has been proved with higher hydraulic and cavitation performance, while in our previous researches, our prototype rotors designed with equal rotational speeds for both the front and the rear rotors was also confirmed with the strong potential interaction between two blade rows. In the present study, the experimental investigations were focused on the rotor-rotor interactions in the contra-rotating rotors under two rotational speed combinations, an equal speed and a different speed ones with the lower speed of rear rotor; the latter is determined aiming at relieved rotor-rotor interaction. As the major experimental approach, casing wall static pressure measurements were conducted at pressure taps covering from upstream to downstream of the both rotors, and the pressure fluctuation modes were investigated by the FFT analyses. By series of pressure taps with different peripheral locations prepared at several axial locations, the pressure fluctuation modes with frequencies non-synchronous to the BPF (blade passing frequency) components were recognized, and confirmed to be related to the rotor-rotor interaction on the basis of theoretical analyses on the rotor-stator interaction in conventional rotorstator types..
|34.||Linlin Cao, Satoshi Watanabe, Hironori Honda, Hiroaki Yoshimura, Akinori Furukawa, Experimental investigation of blade-to-blade pressure distribution in contra-rotating axial flow pump, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2014.7.4.130, 7, 4, 130-141, 2014.01, [URL], As a high specific speed pump, the contra-rotating axial flow pump with two rotors rotating reversely has been proved with higher hydraulic and cavitation performance, while in our previous researches, the potential interaction between two blade rows was distinctly observed for our prototype rotors designed with equal rotational speed for both front and rear rotors. Based on the theoretical and experimental evidences, a rotational speed optimization methodology was proposed and applied in the design of a new combination of contra-rotating rotors, primarily in expectation of the optimized blade pressure distributions as well as pertinently improved hydraulic performances including cavitation performance. In the present study, given one stationary and two rotating frames in the contra-rotating rotors case, a pressure measurement concept taking account of the revolutions of both front and rear rotors simultaneously was adopted. The casing wall pressure data sampled in time domain was successfully transferred into space domain, by which the ensemble averaged blade-to-blade pressure distributions at the blade tip of two contra-rotating rotors under different operation conditions were studied. It could be seen that the rotor pair with the optimized rotational speed combination as well as work division, shows more reasonable blade-to-blade pressure distribution and well weakened potential interaction. Moreover, combining the loading curves estimated by the measured casing wall pressure, the cavitation performance of the rotor pairs with new rotational speed combination were proved to be superior to those of the prototype pairs..|
|35.||D. Matsushita, R. Moriyama, K. Nakashima, Satoshi Watanabe, K. Okuma, A. Furukawa, Tentative study on performance of darriues-type hydroturbine operated in small open water channel, 27th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2014
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/22/6/062007, 22, 2014.01, [URL], The development of small hydropower is one of the realistic and preferable utilizations of renewable energy, but the extra-low head hydropower less than 2 m is almost undeveloped yet for some reasons. The authors have developed several types of Darrieus-type hydro-turbine system, and among them, the Darrieus-turbine with a wear and a nozzle installed upstream of turbine is so far in success to obtain more output power, i.e. more shaft torque, by gathering all water into the turbine. However, there can several cases exist, in which installing the wear covering all the flow channel width is unrealistic. Then, in the present study, the hydraulic performances of Darrieus-type hydro-turbine with the inlet nozzle is investigated, putting alone in a small open channel without upstream wear. In the experiment, the five-bladed Darrieus-type runner with the pitch-circle diameter of 300 mm and the blade span of 300 mm is vertically installed in the open channel with the width of 1,200 mm. The effectiveness of the shape of the inlet nozzle is also examined using two types of two-dimensional symmetric nozzle, the straight line nozzle (SL nozzle) with the converging angle of 45 degrees and the half diameter curved nozzle (HD nozzle) whose radius is a half diameter of runner pitch circle. Inlet and outlet nozzle widths are in common for the both nozzles, which are 540 mm and 240 mm respectively. All the experiments are carried out under the conditions with constant flow rate and downstream water level, and performances are evaluated by measured output torque and the measured head difference between the water levels upstream and downstream of the turbine. As a result, it is found that the output power is remarkably increased by installing the inlet nozzle, and the turbine with SL nozzle produces larger power than that with HD nozzle. However, the peak efficiency is deteriorated in both cases. The speed ratio defined by the rotor speed divided by the downstream water velocity at the peak efficiency is larger in both cases with the inlet nozzle, partly due to the increase of inflow velocity into the turbine. In order to understand the cause of the differences of power, i.e. torque characteristics of the turbine with SL and HD nozzles, twodimensional CFD simulation is carried out. It is found that the instantaneous torque variation is important for the overall turbine performances, indicating the possibility of further performance improvement through the optimization of nozzle geometry..
|36.||Satoshi Watanabe, Keisuke Enomoto, Yuya Yamamoto, Yoshinori Hara, Thermal and dissolved gas effects on cavitation in a 2-D convergent-divergent nozzle flow, ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting, FEDSM 2014, Collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels
Cavitation and Multiphase Flow; Fluid Measurements and Instrumentation; Microfluidics; Multiphase Flows: Work in Progress; Fluid-Particle Interactions in Turbulence, 10.1115/FEDSM2014-21902, 2014.01, [URL], It is well known that the thermal effect of cavitation suppresses the development of cavity with the decreased local temperature due to the latent heat of evaporation. In the present study, to obtain the fundamental knowledge of thermal effect of cavitation, an experimental study of cavitation in a simple convergent-divergent nozzle was carried out using hydrofluoro- ether (HFE) as a working fluid. HFE was expected to reveal the thermal effect at room temperature, which enabled us to simply neglect the heat flux between the test section and outside, and to roughly keep adiabatic conditions on nozzle wall surfaces. It was found that the cavitation in HFE was a foam-like sheet cavity, which was different from a film like cavity in cold water. The temperature depression, near the leading edge of cavitation, was confirmed especially in more developed cavitation cases, revealing the existence of thermal effect of cavitation. However, in lower velocity cases, the measured cavity length was apparently longer in HFE despite of the expected thermal effect. The measured pressures inside the cavity were found to be apparently larger than the vapor pressure, indicating the possible separation of dissolved air into the cavity. Then, the cavitation number based on the measured cavity pressure instead of vapor pressure was proposed, and by using the proposed cavitation number, the thermal effect was clearly confirmed in terms of the cavity development. Frequency characteristics of measured pressure fluctuations were qualitatively similar regardless of the species of working fluid..
|37.||S. Watanabe, W. Yamaoka, A. Furukawa, Unsteady lift and drag characteristics of cavitating Clark Y-11.7% hydrofoil, 27th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2014
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/22/5/052009, 22, 2014.01, [URL], Unsteady cavitating flow and lift/drag characteristics of a two-dimensional Clark Y- 11.7% hydrofoil are experimentally investigated in order to clarify the relation between the lift drop mechanism and the unsteady cavity behavior. Unsteady lift and drag forces are measured by strain gauges attached on the cantilever supporting the hydrofoil, assuming the negligible bending moment. In combination with the above force measurements, the cavitating flow is filmed from both top and side simultaneously using two high speed video cameras. It is clearly observed that, in larger attack angle conditions (4-10 degrees), the time-averaged lift coefficient slightly increases from that in the non-cavitating condition. After the slight increase, the lift gradually decreases then its steep decrease starts to occur. On the other hand, in a small attack angle case (2 degrees), little increase of the lift is observed, and just after that the sudden lift drop occurs. From the instantaneous frequency spectra of the lift, the followings are found; during the slight increase of the lift, the cavity is being a partial cavity in almost steady state, but during the subsequent gradual lift decrease, the partial cavity oscillates with cloud cavity shedding, in other word, the partial cavity oscillation occurs, whose frequency decreases with the growth of the cavity. During the sudden lift drop, the low frequency transitional cavity oscillation occurs, in which the cavity dramatically changes between partial and super cavities. The typical events of cavity behavior during the cavitation instabilities are found to be able to be related with the behavior of instantaneous lift force and pressure..
|38.||L. L. Cao, Satoshi Watanabe, T. Imanishi, H. Yoshimura, A. Furukawa, Blade rows interaction in contra-rotating axial flow pump designed with different rotational speed concept, 6th International Conference on Pumps and Fans with Compressors and Wind Turbines, ICPF 2013
IOP Conference Series: Materials Science and Engineering, 10.1088/1757-899X/52/2/022004, 52, TOPIC 2, 2013.12, [URL], The contra-rotating axial flow pump consisiting of counter-rotating tandem rotors has been expermentally confirmed with better performances than the conventional axial flow pump, but it is known to suffer from the significant potential interaction between the counter-rotating blade rows, which is responsible for the repetitive stresses and unfavourable to the reliable operation. Consequently, to improve the realiability of contra-rotating axial flow pump including the reduction of the blade rows interaction, a new type of rear rotor was designed in the previous study by the rotational speed optimization methodology with some additional considerations. In the present study, to understand the effectiveness of the new design method, instantaneous static pressure fluctuations on the casing wall under the design and off design conditions are investigated by means of experimental and numerical simulation methods. The Fourier analysis is employed to process the data obtained from experiments and numerical simulations, and the axial distribution of the Blade Passing Frequency (BPF) amplitude is obtained. The new rear rotor shows weakened BPF amplitude both upstream and downstream especially at the positions between the two blade rows in both CFD and EFD analyses, implying the reduced blade rows interaction with the new rear rotor..
|39.||S. Watanabe, Y. Uchinono, K. Ishizaka, A. Furukawa and J.-H. Kim, Suction Performance and Internal Flow of a 2-Bladed Helical Inducer with Inlet Asymmetric Plate, Journal of Thermal Science, 22, 5, 395-403, 2013.10.|
|40.||Kei Tanaka, Kotaro Hirowatari, Kai Shimokawa, Satoshi Watanabe, Daisuke Matsushita, Akinori Furukawa, A study on Darrieus-type hydroturbine toward utilization of extra-low head natural flow streams, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2013.6.3.152, 6, 3, 152-159, 2013.10, [URL], A two-dimensional Darrieus-type hydroturbine system, installed with a wear for flow streams such as small rivers and waterways, has been developed for hydropower utilization of extra-low head less than 2m. There are several problems such as flow rate change and flowing wastes to be solved for its practical use in natural flow streams. In the present study, at first, a design guideline in the case of overflow or bypass flow is shown by using simple flow model. Next, in order to avoid the unexpected obstacles flowing into the hydroturbine, an installation of waste screening system is examined. It is confirmed that the screen is effective with some amount of bypass flow rate, however the output power is remarkably deteriorated..|
|41.||S. Watanabe, Y. Uchinono, K. Ishizaka, A. Furukawa, J. H. Kim, Suction performance and internal flow of a 2-bladed helical inducer with inlet asymmetric plate, Journal of Thermal Science, 10.1007/s11630-013-0641-y, 22, 5, 395-403, 2013.10, [URL], It has been found in our past studies that the installation of asymmetric plate at the inlet of inducer is effective for the suppression of cavitation surge phenomenon. In the present study, the suction performance of 2-bladed helical inducer with an inlet asymmetric plate is experimentally investigated. It is observed that the suction performance in large flow rate conditions is not significantly influenced by the asymmetric plate, whereas the head of inducer with the asymmetric plate increases just before the head breakdown in partial flow conditions. To understand the mechanism of this additional head, the flow measurements and the numerical simulations are carried out. It is found that the circumferential component of absolute velocity at the exit of inducer slightly increases with the development of cavitation in both cases with and without the inlet asymmetric plate, indicating the increase of the theoretical head. The theoretical head increase with the inlet asymmetric plate is also confirmed by the unsteady numerical simulations, suggesting that the additional head is achieved through the increase of the theoretical head with the change of the exiting flow from the inducer associated with some amount of cavitation..|
|42.||K. Tanaka, K. Hirowatari, K. Shimokawa, S. Watanabe, D. Matsushita, A. Furukawa, A Study on Darrieus-type Hydroturbine toward Utilization of Extra-Low Head Natural Flow Streams, International Journal of Fluid Machinery and Systems, 6, 3, 152-159, 2013.09.|
|43.||Linlin Cao, Satoshi Watanabe, Toshiki Imanishi, Hiroaki Yoshimura, Akinori Furukawa, Experimental Analysis of Flow Structure in Contra-Rotating Axial Flow Pump Designed with Different Rotational Speed Concept, Journal of Thermal Science, 22, 4, 345-351, 2013.08.|
|44.||Linlin Cao, Satoshi Watanabe, Toshiki Imanishi, Hiroaki Yoshimura, Akinori Furukawa, Experimental analysis of flow structure in contra-rotating axial flow pump designed with different rotational speed concept, Journal of Thermal Science, 10.1007/s11630-013-0634-x, 22, 4, 345-351, 2013.08, [URL], As a high specific speed pump, the contra-rotating axial flow pump distinguishes itself in a rear rotor rotating in the opposite direction of the front rotor, which remarkably contributes to the energy conversion, the reduction of the pump size, better hydraulic and cavitation performances. However, with two rotors rotating reversely, the significant interaction between blade rows was observed in our prototype contra-rotating rotors, which highly affected the pump performance compared with the conventional axial flow pumps. Consequently, a new type of rear rotor was designed by the rotational speed optimization methodology with some additional considerations, aiming at better cavitation performance, the reduction of blade rows interaction and the secondary flow suppression. The new rear rotor showed a satisfactory performance at the design flow rate but an unfavorable positive slope of the head - flow rate curve in the partial flow rate range less than 40% of the design flow rate, which should be avoided for the reliability of pump-pipe systems. In the present research, to understand the internal flow field of new rear rotor and its relation to the performances at the partial flow rates, the velocity distributions at the inlets and outlets of the rotors are firstly investigated. Then, the boundary layer flows on rotor surfaces, which clearly reflect the secondary flow inside the rotors, are analyzed through the limiting streamline observations using the multi-color oil-film method. Finally, the unsteady numerical simulations are carried out to understand the complicated internal flow structures in the rotors..|
|45.||Kei Tanaka, Kotaro Hirowatari, Kai Shimokawa, Satoshi Watanabe, Daisuke Matsushita and Akinori Furukawa, A Study on Darrieus-type Hydroturbine toward Utilization of Extra-Low Head Natural Flow Streams, International Journal of Fluid Machinery and Systems, 6, 3, 152-159, 2013.07.|
|46.||渡邉 聡，末藤朴人，山岡 航，古川明徳, キャビテーション発生下のClark-Y 11.7%翼の揚抗力特性, ターボ機械, 41, 7, 440-446, 2013.07.|
|47.||Linlin Cao, Satoshi Watanabe, Simpei Momosaki, Toshiki Imanishi, Akinori Furukawa, Low Speed Design of Rear Rotor in Contra-Rotating Axial Flow Pump, International Journal of Fluid Machinery and Systems, 6, 2, 105-112, 2013.04.|
|48.||山田雅之，大豆生田祐介，渡邉 聡, セラミックス軸受の設計上の留意点と破壊メカニズムに関する実験的研究, ターボ機械, 41, 4, 226-232, 2013.04, 縦軸ポンプの信頼性向上の観点から，軸受潤滑水供給系を不要とするための無給水軸受の開発が望まれている．本研究では，短時間ドライ運転が可能で且つ，砂や異物が含まれるポンプの自己揚水を用いた潤滑でも長時間ドライ運転が可能なセラミックス軸受に着目し，剛支持および緩衝支持の二種類の軸受構造に基づいて，軸受隙間や片当りが軸受摺動特性に与える影響を実験的に明らかにし，軸受設計に際して留意すべき点を明らかにした．また，セラミックス軸受の破壊メカニズムについても調査し，構成材の熱膨張率の差に起因して発生する軸方向のクラックが破壊の起点となることを明らかにした．.|
|49.||Linlin Cao, Satoshi Watanabe, Simpei Momosaki, Toshiki Imanishi, Akinori Furukawa, Low speed design of rear rotor in contra-rotating axial flow pump, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2013.6.2.105, 6, 2, 105-112, 2013.02, [URL], The application of contra-rotating rotors for higher specific speed pump has been proposed in our studies, which is in principle effective for reducing the rotational speed and/or the pump size under the same specification of conventional axial flow pump. In the previous experiments of our prototype, the cavitation inception at the tip region of the rear rotor rather than that of the front rotor and the strong potential interaction from the suction surface of the rear rotor blade to the pressure surface of the front one were observed, indicating the possibility to further improve the pump performance by optimizing rotational speed combination between the two rotors. The present research aims at the design of rear rotor with lower rotational speed. Considering the fact that the incoming flow velocity defects at the tip region of the rear rotor, an integrated inflow model of 'forced vortex' and 'free vortex' is employed. The variation of maximum camber location from hub to tip as well as other related considerations are also taken into account for further performance improvement. The ideas cited above are separately or comprehensively applied in the design of three types of rear rotor, which are subsequently simulated in ANSYS CFX to evaluate the related pump performance and therefore the whole low speed design idea. Finally, the experimental validation is carried out on one type to offer further proofs for the availability of the whole design method..|
|50.||L. L. Cao, S. Watanabe, T. Imanishi, S. Momosaki, A. Furukawa, On high efficiency operation of contra-rotating axial flow pump with rotational speed control toward effective energy saving, 26th IAHR Symposium on Hydraulic Machinery and Systems
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/15/4/042027, 15, PART 4, 2012.12, [URL], For high specific speed pump with high performance operation, a contra-rotating axial flow pump has been proposed and the effectiveness of rotational speed control of front and rear rotors has been demonstrated experimentally. In the present paper, a prediction method of pump characteristics under the condition of optimized rotational speed control is proposed, based on consideration of flow mechanism in both front and rear rotors. The accuracy of prediction is examined for two combinations of front and rear rotors. Then, the amount of energy saving by application of rotational speed control method for the contra-rotating axial flow pump is demonstrated and an advantage of usage of contra-rotating pump is discussed..
|51.||A. Furukawa, Satoshi Watanabe, K. Okuma, Research on Darrieus-type hydraulic turbine for extra-low head hydropower utilization, 26th IAHR Symposium on Hydraulic Machinery and Systems
IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/15/1/012003, 15, PART 1, 2012.12, [URL], A Darrieus-type turbine has been investigated for extra-low head hydropower utilization. In the present paper, authors'research on Darrieus-type hydraulic turbine is briefly reviewed. The working principle of Darrieus turbine is explained with advantage of its simple structure, at first. Then the fluid-dynamic difference between rotating and linear motions of a blade in a uniform flow is clarified with guiding principle of high performance design of Darrieus turbine. Cavitation problem is also described. Next, effects of duct-casing, consisting of an intake, runner section and draft tube, are discussed and a simplified structure of Darrieus turbine is shown by installing the inlet nozzle. Finally, in the practical use, an adjustment of inlet nozzle section by lowering the inlet nozzle height is proposed when flow rate is varied temporally and seasonally..
|52.||Yoshiki Yoshida, Kengo Kikuta, Kazuki Niiyama, Satoshi Watanabe, Thermodynamic parameter on cavitation in space inducer, ASME 2012 Fluids Engineering Division Summer Meeting, FEDSM 2012 Collocated with the ASME 2012 Heat Transfer Summer Conf. and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and M, FEDSM 2012
ASME 2012 Fluids Engineering Division Summer Meeting Collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th Int. Conference on Nanochannels, Microchannels, and M, FEDSM 2, 10.1115/FEDSM2012-72212, 203-213, 2012.12, [URL], Cavitation is physically "a vaporization of liquid" which needs latent heat for phase change. A cavity grows in the liquid, so the latent heat of vaporization can only be supplied by the liquid surrounding the cavity. Thus, the liquid close to the interface region of the cavity is cooled down. In general, cryogenic liquids are very thermosensitive. For liquid hydrogen and oxygen used in rocket propulsion, the temperature in the cavity, i.e., the vapor pressure in the cavity, is lower than those of the liquid bulk. Thanks to this thermal effect, cavitation in cryogenic liquids is less developed than that in water at room temperature. This thermal effect on cavitation is beneficial in that it improves cavitation performance and alleviates cavitation instability in space inducers. In previous works, we investigated the relationship between the thermodynamic effect and the cavitation instabilities, e.g., rotating cavitation and cavitation surge, with a focus on the cavity length as an indication of cavitation. In the present work, first, aspects of cavitation in the inducer were observed by direct optical visualization in liquid nitrogen. Second, joint experiments in liquid nitrogen and cold water were conducted on a cavitaing inducer. In nitrogen experiments, operating conditions, i.e., rotational speed and liquid temperature, were varied to determine the cavitation scaling law. Through these experimental results, characteristic times, namely, the transit time for bubble growth and the characteristic thermal time introduced from the thermal property, were investigated as a cavitation thermodynamic parameter. It was found out that the adjustment of cavitation number has a good correlation with the ratio of the transit time and the characteristic thermal time..
|53.||Satoshi Watanabe, Ryosuke Otani, Shun Kunimoto, Yoshinori Hara, Akinori Furukawa, Takeshi Yamaguchi, Vibration characteristics due to cavitation in stator element of automotive torque converter at stall condition, ASME 2012 Fluids Engineering Division Summer Meeting, FEDSM 2012 Collocated with the ASME 2012 Heat Transfer Summer Conf. and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and M, FEDSM 2012
ASME 2012 Fluids Engineering Division Summer Meeting Collocated with the ASME 2012 Heat Transfer Summer Conf. and the ASME 2012 10th Int. Conf. on Nanochannels, Microchannels, and M, FEDSM 2012, 10.1115/FEDSM2012-72418, 1, 535-541, 2012.12, [URL], Cavitation behaviors in an automotive torque converter at pump speed of 600, 700 and 800 min-1 at the stall condition are investigated by means of the transparent model. At the same time, the influences of cavitation on mechanical vibration are studied. As a result, at the onset of cavitation, the longitudinal corner vortex cavitation is formed at the corner between outer wall and either suction or pressure surface of stator blades. After the further decrease of charge pressure, the cavitation bubbles are observed in the flow separation region formed at the leading edge on the suction surface of stator blades. Vibration spectrum peaks are found in the wide range of frequency, which increase with the development of cavitation but then decrease with its excessive development. Discussions are made for higher and lower frequency ranges separately to understand the relation between mechanical vibrations and cavitation..
|54.||Kai Shimokawa, Akinori Furukawa, Kusuo Okuma, Daisuke Matsushita, Satoshi Watanabe, Experimental study on simplification of Darrieus-type hydro turbine with inlet nozzle for extra-low head hydropower utilization, Renewable Energy, 10.1016/j.renene.2011.09.017, 41, 376-382, 2012.05, [URL], A ducted Darrieus-type hydro turbine has been proposed for utilization of extra-low head hydropower less than 2 m. In general, the low head hydro turbine system demands the simple structure to reduce the cost of power generation. The Darrieus-type hydro turbine is cross flow type and takes larger values of generated torque with higher efficiency on the upstream path of the Darrieus blades passing in one revolution. Based on this reason, when a narrow intake at the upstream of the runner, called as "inlet nozzle", is installed, the performance of Darrieus-type hydro turbine becomes higher than that without one. In addition, it is possible to remove the draft tube and side-walls of the runner casing keeping the turbine efficiency high. In the present paper, more simplified runner casing, composed of only the inlet nozzle and the small upper-casing, is proposed and the experimental results are shown..|
|55.||渡邉 聡，小西祐介，松成宏樹，古川明徳, 単独翼に生じるキャビテーション不安定現象の実験的研究, ターボ機械, 40, 4, 248-255, 2012.04, キャビテーションの発生は，ポンプ等の水力機械において，著しい性能低下や壊食，キャビティの成長・崩壊に伴う騒音，流体力学的不安定現象に伴う軸振動などの問題を引き起こす．本論文では，形状の大きく異なる二種類の二次元単独翼（平板翼およびClark-Y 11.7%翼）を対象に，キャビティの発生様相と供試翼上下流の圧力変動，キャビティ長変動の観点から，キャビテーション不安定現象の発生に至る流動状況を明らかにした．これらの知見は，現象の理解のみならず，キャビテーション流れ解析技術の高度化に対する検証データとしても有用である．.|
|56.||Satoshi WATANABE, Kai SHIMOKAWA, Akinori FURUKAWA, Kusuo OKUMA and Daisuke MATSUSHITA, Experimental Study on Adjustment of Inlet Nozzle Section to Flow Rate Variation for Darrieus-type Hydro-Turbine, Int. J. of Fluid Machinery and Systems, 5, 1, 30-37, 2012.03.|
|57.||Satoshi Watanabe, Kai Shimokawa, Akinori Furukawa, Kusuo Okuma, Daisuke Matsushita, Experimental study on adjustment of inlet nozzle section to flow rate variation for darrieus-type hydro-turbine, International Journal of Fluid Machinery and Systems, 10.5293/IJFMS.2012.5.1.030, 5, 1, 30-37, 2012.03, [URL], A two dimensional Darrieus-type turbine has been proposed for the hydropower utilization of extra-low head less than 2m. In a practical use of Darrieus-type hydro-turbine, head and flow rate may be varied temporally and seasonally. Considering that the cost advantage is required for the low head hydro turbine system, the Darrieus turbine should be operated with high efficiency in the wider range of flow rate possibly by using an additional device with simpler mechanism. In the present paper, an adjustment of inlet nozzle section by lowering the inlet nozzle height is proposed to obtain the preferable inlet velocity in low flow rate conditions. Effects of resulting spanwise partial inlet flow are investigated. Finally, an effective modification of inlet nozzle height over flow rate variation is shown..|
|58.||下川 海，廣渡光太朗，渡邉 聡，古川明徳，松下大介, ダリウス形水車のスパン方向部分流入が性能に及ぼす影響, ターボ機械, 39, 12, 753-761, 2011.12.|
|59.||下川 海，岩本俊介，大熊九州男，廣渡光太朗，渡邉 聡，古川明徳，松下大介, 低落差用ダリウス形水車の入口絞りが水車性能に与える影響と自己起動性, ターボ機械, 39, 6, 373-379, 2011.06.|
|60.||Satoshi WATANABE, Simpei MOMOSAKI, Satoshi USAMI and Akinori FURUKAWA, Internal Flow and Limiting Streamlines Observations of Contra-Rotating Axial Flow Pump at Partial Flow Rate, Int. J. of Fluid Machinery and Systems, 4, 2, 235-242, 2011.04.|
|61.||百崎晋平，宇佐見聡，渡邉聡，古川明徳，大熊九州男, 二重反転形軸流ポンプの回転数制御に関する実験的考察, ターボ機械, 39, 2, 119-125, 2011.02.|
|62.||宇佐見 聡，百崎晋平，渡邉 聡，古川明徳，大熊九州男, 二重反転形軸流ポンプの部分流量域における内部流れと限界流線観察, ターボ機械, 38巻7号，pp.436-443, 2010.07.|
|63.||Jun-Ho KIM, Takashi ATONO, Koichi ISHIZAKA, Satoshi WATANABE, Akinori FURUKAWA, Cavitation in Pump Inducer with Axi-asymmetrical Inlet Plate Observed by Multi-cameras, Int. J. of Fluid Machinery and Systems, Vol.3, No.2 pp.122-128, 2010.06.|
|64.||Satoshi WATANABE, Naoki INOUE, Koichi ISHIZAKA, Akinori FURUKAWA, Jun-Ho KIM, Internal Flow of a Two-Bladed Helical Inducer at an Extremely Low Flow Rate, Int. J. of Fluid Machinery and Systems, Vol.3, No.2 pp.129-136, 2010.06.|
|65.||松下大介，大熊九州男，渡邉 聡，岩本俊介，古川明徳，下川 海, 入口絞りを持つダリウス形水車の側壁開放化による性能変化, ターボ機械, 38巻5号，pp.313-319, 2010.05.|
|66.||松下大介，原 義則，渡邉 聡，古川明徳，松宮 輝, 複雑地形における風車性能評価のための数値サイトキャリブレーションの課題, ターボ機械, 38巻4号，pp.227-233, 2010.04.|
|67.||Akinori FURUKAWA, Satoshi WATANABE, Daisuke MATSUSHITA, Kusuo OKUMA, Development of Ducted Darrieus Turbine for Low-Head Hydropower Utilization, Current Applied Physics vol.10 Supplement2, pp.S128-S132, 2010.03.|
|68.||Jun-Ho KIM, Koichi ISHIZAKA, Satoshi WATANABE, Akinori FURUKAWA, Cavitation Surge Suppression of Pump Inducer with Axi-asymmetrical Inlet Plate, Int. J. of Fluid Machinery and Systems, Vol.3, No.1 pp.50-57, 2010.02.|
|69.||Daisuke MATSUSHITA, Hikaru MATSUMIYA, Yoshinori HARA, Satoshi WATANABE, Akinori FURUKAWA, Studies on Numerical Site Calibration over Complex Terrain for Wind Turbine, Science China, Technological Sciences, Vol.53, No.1, pp.8-12, 2010.01.|
|70.||Kai SHIMOKAWA, Akinori FURUKAWA, Kusuo OKUMA, Daisuke MATSUSHITA, Satoshi WATANABE, Side-wall Effect of Runner Casing on Performance of Darrieus-type Hydro Turbine with Inlet Nozzle for Extra-Low Head Utilization, Science China, Technological Sciences, Vol.53, No.1, pp.93-99, 2010.01.|
|71.||渡邉 聡，井上直樹，石坂公一，古川明徳，金 峻琥, 極低流量における平板ヘリカルインデューサの内部流れ, ターボ機械, 第37巻9号，pp.539-546, 2009.09.|
|72.||Naoki MATSUSHITA, Akinori FURUKAWA, Satoshi WATANABE, Kusuo OKUMA, Study on Design of Air-water Two-phase Flow Centrifugal Pump Based on Similarity Law, Int. J. of Fluid Machinery and Systems, Vol.2, No.21, pp.127-135, 2009.05.|
|73.||松下大介，大熊九州男，下川 海，渡邉 聡，古川明徳, 流入ノズル付きダリウス形水車の性能に及ぼす側壁隙間とランナ翼枚数の影響, ターボ機械, 第37巻4号，pp.237-243, 2009.04.|
|74.||金 峻琥，後野 隆，石坂公一，渡邉 聡，古川明徳, 非軸対称入口障害板付設によるポンプインデューサの脈動キャビテーション抑制, ターボ機械, 第37巻2号，pp.104-111, 2009.02.|
|75.||Jun-Ho KIM, Takashi ATONO, Koichi ISHIZAKA, Satoshi WATANABE, Akinori FURUKAWA, Rotating Behavior Observation of Cavitation in Inducer with Suction Axi-asymmetrical Plate, Journal of Fluids Science and Technology, Vol.3, No.6, pp.744-753, 2008.09.|
|76.||松下直樹，古川明徳，渡邉 聡，蓮井 智道，大熊九州男, 高気液混合比適用形二相流遠心ポンプの相似設計に関する考察, ターボ機械, 第36巻第8号，pp.499-506, 2008.08.|
|77.||後野 隆，金 峻琥，石坂公一，渡邉 聡，古川明徳, マルチカメラによる非軸対称入口障害板付きポンプインデューサのキャビテーション観察, ターボ機械, 第36巻第8号，pp.477-482, 2008.08.|
|78.||Satoshi WATANABE, Akinori FURUKAWA, Yoshiki YOSHIDA, Theoretical Analysis of Thermodynamic Effect of Cavitation in Cryogenic Inducer Using Singularity Method, International Journal of Rotating Machinery, Vol. 2008, Article ID 125678, 2008.06.|
|79.||Daisuke MATSUSHITA, Kusuo OKUMA, Satoshi WATANABE, Akinori FURUKAWA, Simplified Structure of Ducted Darrieus-type Hydro Turbine with Narrow Intake foe Extra-low Head hydropower Utilization, Journal of Fluids Science and Technology, Vol.3, No.3, pp.387-397, 2008.06.|
|80.||重光 亨，古川明徳，渡邉 聡，大熊九州男，福富純一郎, 二重反転形軸流ポンプの設計流量点流れのＬＤＶ計測, 日本機械学会論文集（B編）, 第74巻第741号，pp.1091-1097, 2008.05.|
|81.||渡邉 聡，山下修一，恒成雄介，大熊九州男，古川明徳, 二重反転形軸流ポンプの部分流量域における後段翼車周りのＬＤＶによる流れ計測, 日本機械学会論文集（B編）, 第74巻第740号，pp.550-555, 2008.04.|
|82.||Jun-Ho KIM, Masao ISHIZAKI, Naoki ENOMOTO, Koichi ISHIZAKA, Satoshi WATANABE, Akinori FURUKAWA, Suppression Effect of Upstream Installed Ring-shaped Obstacle Plate on Cavitation Surge in Pump Inducers, Journal of Fluids Science and Technology, Vol.3, No.1, pp.1-10, 2008.01.|
|83.||大熊九州男，松下大介，古川明徳, 渡邉 聡, 低落差水力利用ダリウス形ランナのピッチ円隙間が水車性能に及ぼす影響, ターボ機械, 35巻12号，pp.705〜711, 2007.12.|
|84.||Satoshi WATANABE, Tatsuya HIDAKA, Hironori HORIGUCHI, Akinori FURUKAWA, Yoshinobu TSUJIMOTO, Analysis of Thermodynamic Effects on Cavitation Instabilities, Transactions of ASME, Journal of Fluids Engineering, Vol.129, pp.1123〜1130, 2007.09.|
|85.||Mizuho MATSUBARA, Masao WATANABE, Satoshi WATANABE, Kozo KONISHI, Shohei YAMAGUCHI and Makoto HASHIZUME, Fluid Dynamic Study on Budd-Chiari Syndrome: Sensitivity Study of Vessel Reconstruction on Image-Based Simulation, Journal of Biomechanical Science and Engineering, Vol. 2, pp. 69-80, 2007.05.|
|86.||江口 崇，松原瑞浦，渡邉 聡，古川明徳, Ｙ字管内脈動流れのＰＩＶ計測と壁面せん断応力の評価, 日本機械学会論文集（B編）, 73巻728号，pp.965〜972, 2007.04.|
|87.||Satoshi WATANABE, Tatsuya HIDAKA, Hironori HORIGUCHI, Akinori FURUKAWA and Yoshinobu TSUJIMOTO, Steady Analysis of Thermodynamic Effect of Partial Cavitation Using Singularity Method, Transactions of ASME, Journal of Fluids Engineering, Vol.129, No.1, pp.121-127, 2007.02.|
|88.||Akinori FURUKAWA, Toru SHIGEMITSU, Satoshi WATANABE, Performance Test and Flow Measurement of Contra-Rotating Axial Flow Pump, Journal of Thermal Science, Vol.16, No.1, pp. 7-13, 2007.01.|
|89.||金 峻琥，石坂公一，石崎正雄，渡邉 聡，古川明徳, ポンプインデューサの入口上流に付設した軸対称障害板の脈動キャビテーション抑制効果, 日本機械学会論文集（B編）, 第72巻724号，pp.3043-3049, 2006.12.|
|90.||Akinori FURUKAWA, Tomoya TAKANO, Toru SHIGEMITSU, Kusuo OKUMA, Satoshi WATANABE, Blade Rows Interaction of Contra-Rotating Axial Flow Pump in Pressure Field on Casing Wall, JSME International Journal, Series B, Vol. 49, No. 3, pp. 670-677, 2006.08.|
|91.||古川明徳，高野倫矢，重光 亨，大熊九州男，渡邉 聡, 二重反転形軸流ポンプのケーシング壁面静圧計測と翼列間干渉, 日本機械学会論文集（B編）, 第71巻711号，pp.2710-2716, 2005.11.|
|92.||渡邉 聡，日高達哉，堀口祐憲，古川明徳，辻本良信, 熱力学的効果を考慮した翼列の部分キャビテーションの解析（第2報，旋回キャビテーションに対する線形解析）, 日本機械学会論文集（B編）, 第71巻709号，pp.2295-2302, 2005.09.|
|93.||古川明徳，重光 亨，高野倫矢，大熊九州男，渡邉 聡, 二重反転形軸流ポンプの気液二相流性能と後段翼車の回転数制御, 日本機械学会論文集（B編）, 第71巻708号，pp.2047-2052, 2005.08.|
|94.||松下直樹，大熊九州男，古川明徳，渡邉 聡, 遠心ポンプの気液二相流性能に及ぼす羽根車外径とディフューザ翼の影響, ターボ機械, 第33巻，第8号，pp.483-489, 2005.08.|
|95.||Toru SHIGEMITSU, Tomoya TAKANO, Akinori FURUKAWA, Kusuo OKUMA and Satoshi WATANABE, Pressure Measurement on Casing Wall and Blade Rows Interaction of Contra-Rotating Axial Flow Pump, Journal of Thermal Science, 10.1007/s11630-005-0025-z, 14, 2, 142-149, Vol.14, No.2, pp. 142-149, 2005.06.|
|96.||古川明徳，松下直樹，渡邉 聡，大下智史，大熊九州男, 気液二相流遠心ポンプの開発とその揚水特性, 日本機械学会論文集（B編）, 第71巻701号，pp.140-146, 2005.01.|
|97.||渡邉 聡，日高達哉，堀口祐憲，古川明徳，辻本良信, 熱力学的効果を考慮した翼列の部分キャビテーションの解析（第1報，特異点法による定常解析）, 日本機械学会論文集（B編）, 第71巻701号，pp.133-139, 2005.01.|
|98.||Hirokazu YAKUSHIJIN, Satoshi WATANABE, Hisasada TAKAHARA and Akinori FURUKAWA, Experimental Study of Stall Behavior in Radial Vaneless Diffuser of Centrifugal Pump, Memoirs of the Faculty of Engineering Kyushu University, Vol. 64, No.3, pp.185〜196, 2004.09.|
|99.||古川明徳，後野 隆，石坂公一，渡邉 聡, 平板ヘリカルインデューサの翼角と脈動キャビテーションに関する実験的研究, 日本機械学会論文集（B編）, 第70巻697号，pp.2325-2331, 2004.09.|
|100.||Akira FUJII, Seiji AZUMA, Yoshiki YOSHIDA, Yoshinobu TSUJIMOTO, Hironori HORIGUCHI and Satoshi WATANABE, Higher Order Rotating Cavitation in an Inducer, International Journal of Rotating Machinery, Vol. 10, No. 4, pp. 241-251, 2004.07.|
|101.||渡邉 聡，榎本直樹，石坂公一，古川明徳，金 崚琥, 極低流量で生じるインデューサの脈動キャビテーションの抑制, ターボ機械, 第32巻，第2号，pp.94-100, 2004.02.|
|102.||Takashi EGUCHI, Satoshi WATANABE, Hisasada TAKAKARA, Akinori FURUKAWA, Development of Pusatile Flow Experiment System and PIV Measurement in an Elastic Tube, Memoirs of the Faculty of Engineering Kyushu University, Vol.63, No.3, pp.161-172, 2003.09.|
|103.||大熊九州男，古川明徳，池田 満，松田優子，渡辺 聡, スタッガー翼配列をもつダリウス形ランナの水車特性に関する実験的研究, ターボ機械, 31巻9号，pp.554-561, 2003.09.|
|104.||Satoshi WATANABE and Christopher BRENNEN, Dynamics of Cavitating Propeller in a Water Tunnel, Transactions of ASME, Journal of Fluids Engineering, Vol. 125, No. 2, pp.283-292, 2003.03.|
|105.||重光 亨，古川明徳，大熊九州男，渡辺 聡, 二重反転軸流ポンプの後段翼車設計に関する実験的考察, ターボ機械, 30巻2号，pp.84-90, 2003.02.|
|106.||Akinori FURUKAWA, Koichi ISHIZAKA and Satoshi WATANABE, Flow Measurement in Helical Inducer and Estimate of Fluctuating Blade Force in Cavitation Surge Phenomena, JSME International Journal, 10.1299/jsmeb.45.672, 45, 3, 672-677, Vol.43，No.3，pp.672〜677, 2002.08.|
|107.||藤井 明，東 誠治，吉田義樹，辻本良信，堀口祐憲，渡邉 聡, インデューサに生じる高次の旋回キャビテーション, 日本機械学会論文集（B編）, 第68巻669号，pp.1466-1473, 2002.05.|
|108.||古川明徳，石坂公一，渡邉 聡, 低弦節比前翼をもつタンデム翼ヘリカルインデューサのキャビテーションサージ抑制効果, 日本機械学会論文集（B編）, 第67巻664号，pp.3005-3010, 2001.12.|
|109.||古川明徳，石坂公一，渡邉 聡, ヘリカルインデューサの翼長さと脈動キャビテーションに関する実験的研究, 日本機械学会論文集（B編）, 第67巻662号，pp.2425-2430, 2001.10.|
|110.||古川明徳，石坂公一，渡邉 聡, ヘリカルインデューサ内流れ計測とキャビテーションサージ状態における変動翼力の評価, 日本機械学会論文集（B編）, 第67巻662号，pp.2420-2425, 2001.10.|
|111.||Satoshi WATANABE，Yoshinobu TSUJIMOTO, Akinori FURUKAWA, Theoretical Analysis of Transitional and Partial Cavity Instabilities, Transactions of ASME, Journal of Fluids Engineering, 10.1115/1.1378295, 123, 3, 692-697, Vol.123, No.3, pp.692-697, 2001.09.|
|112.||古川明徳，曹 銀春，大熊九州男，眺野貴裕，渡邉 聡, 二重反転形軸流ポンプに関する実験的基礎研究, 日本機械学会論文集（B編）, 第67巻657号，pp.1184-1190, 2001.05.|
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