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Takanori Uchida Last modified date:2019.07.01



Graduate School


E-Mail
Homepage
http://www.riam.kyushu-u.ac.jp/windeng/
Introduction of my research .
Phone
092-583-7776
Fax
092-583-7779
Academic Degree
Dr. Eng
Field of Specialization
Wind engineering, Environmental fluid dynamics, CFD, EFD
Research
Research Interests
  • Development of the Non-Stationary and Non-Linear Wind Synopsis Simulator, RIAM-COMPACT
    keyword : LES, RIAM-COMPACT, Wind Energy Utilization, Atmospheric Environmental Assessment, Airflow over Complex Terrain and Buildings, Gas Diffusion, Bluff-Body Aerodyanmics
    2000.01.
  • Numerical Simulation and Wind Tunnel Experiment of Atmospheric Stratified Flows under Various Stabilities
    keyword : Atmospheric Stratified Flow, Atmospheric Boundary Layer, Numerical Simulation (DNS, LES), Wind Tunnel Experiment
    2000.01.
  • Basic Research on Numerical Simulation Method Based on Finite-Difference Method (FDM)
    keyword : Numerical Simulation Method, Finite-Difference Method (FDM), DNS, LES
    2000.01.
Academic Activities
Papers
1. Takanori Uchida, Numerical Investigation of Terrain-induced Turbulence in Complex Terrain by Large-eddy Simulation (LES) Technique, Energies, 10.3390/en11061530, 11(10), 2638, 15pages, 2018.10, [URL], In the present study, field observation wind data from the time of the wind turbine blade damage accident on Shiratakiyama Wind Farm were analyzed in detail. In parallel, high-resolution large-eddy simulation (LES) turbulence simulations were performed in order to examine the model’s ability to numerically reproduce terrain-induced turbulence (turbulence intensity) under strong wind conditions (8.0–9.0 m/s at wind turbine hub height). Since the wind velocity and time acquired from the numerical simulation are dimensionless, they are converted to full scale. As a consequence, both the standard deviation of the horizontal wind speed (m/s) and turbulence intensity evaluated from the field observation and simulated wind data are successfully in close agreement. To investigate the cause of the wind turbine blade damage accident on Shiratakiyama Wind Farm, a power spectral analysis was performed on the fluctuating components of the observed time series data of wind speed (1 s average values) for a 10 min period (total of 600 data) by using a fast Fourier transform (FFT). It was suggested that the terrain-induced turbulence which caused the wind turbine blade damage accident on Shiratakiyama Wind Farm was attributable to rapid wind speed and direction fluctuations which were caused by vortex shedding from Tenjogadake (elevation: 691.1 m) located upstream of the wind farm..
2. Takanori UCHIDA, Graham Li, Comparison of RANS and LES in the Prediction of Airflow Field over Steep Complex Terrain, Open Journal of Fluid Dynamics, 10.4236/ojfd.2018.83018, 08, 286-307, Article ID:87086,22 pages, 2018.09, The present study compared the prediction accuracy of the three CFD software packages for simulating airflow around a three-dimensional, isolated hill with a steep slope: 1) WindSim (turbulence model: RNG k-ε RANS), 2) Meteodyn WT (turbulence model: k-L RANS), which are the leading commercially available CFD software packages in the wind power industry and 3) RIAM-COMPACT (turbulence model: standard Smagorinsky LES), which has been developed by the lead author of the present paper. Distinct differences in the airflow patterns were identified in the vicinity of the isolated hill (especially downstream of the hill) between the RANS results and the LES results. No reverse flow region (vortex region) characterized by negative wind velocities was identified downstream of the isolated hill in the result from the simulation with WindSim (RNG k-ε RANS) and Meteodyn WT (k-L RANS). In the case of the simulation with RIAM-COMPACT natural terrain version (standard Smagorinsky LES), a reverse flow region (vortex region) characterized by negative wind velocities clearly forms. Next, an example of wind risk (terrain-induced turbulence) diagnostics was presented for a large-scale wind farm in China. The vertical profiles of the streamwise (x) wind velocity do not follow the so-called power law wind profile; a large velocity deficit can be seen between the hub center and the lower end of the swept area in the case of the LES calculation (RIAM-COMPACT)..
3. Takanori Uchida, Computational Investigation of the Causes of Wind Turbine Blade Damage at Japan's Wind Farm in Complex Terrain, Journal of Flow Control, Measurement & Visualization, 10.4236/jfcmv.2018.63013, 6, 3, 152-167, 2018.07, [URL], During the passage of Typhoon 0918 (Melor) over southern Honshu in Japan on 7 and 8 October 2009, strong winds with extremely high turbulence fluctuations were observed over Shirataki Mountain and the surrounding mountains in Shimonoseki, Yamaguchi Prefecture, Japan. These strong winds caused damage to wind turbine blades at the Shiratakiyama Wind Farm owned by Kinden Corporation. In order to investigate the causes of the blade damage, the airflow characteristics from the time of the incidences are first simulated in detail with the combined use of the WRF-ARW mesoscale meteorological model and the RIAM-COMPACT LES turbulence model (CFD model). Subsequently, in order to evaluate the wind pressure acting on the wind turbine blades, an airflow analysis is separately performed for the vicinity of the blades with the RANS turbulence model. Finally, the stress on the blades is investigated using the FEM with the RANS analysis results as the boundary conditions..
4. Takanori Uchida, Designed Wind Speed Evaluation Technique in Wind Turbine Installation Point by Using the Meteorological Model and CFD Model, Journal of Flow Control, Measurement & Visualization, 10.4236/jfcmv.2018.63014, 06, 03(2018), Article ID:85916,17 pages, 2018.07, It is highly important in Japan to choose a good site for wind turbines, becausethe spatial distribution of wind speed is quite complicated over steepcomplex terrain. We have been developing the unsteady numerical model called the RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, Computational Prediction of Airflow over Complex Terrain).The RIAM-COMPACT is based on the LES (Large-Eddy Simulation).The object domain of the RIAM-COMPACT is from several m to several km,and can predict the airflow and gas diffusion over complex terrain with highprecision. In the present paper, the design wind speed evaluation technique inwind turbine installation point by using the mesoscale meteorological modeland RIAM-COMPACT CFD model was proposed. The design wind speed tobe used for designing WTGs can be calculated by multiplying the ratio of the mean wind speed at the hub-height to the mean upper-air wind speed at the inflow boundary, i.e. , the fractional increase of the mean hub-height wind speed, by the reduction ratio, R. The fractional increase of the mean hub-height wind speed was evaluated using the CFD simulation results. This method was proposed as Approach 1 in the present paper. A value of 61.9 m/s was obtained for the final design wind speed, Uh, in Approach 1. In the evaluation procedure of the design wind speed in Approach 2, neither the above-mentioned reduction rate, R, nor an upper-air wind speed of 1.7 Vo, where Vo is the reference wind speed, was used. Instead, the value of the maximum wind speed which was obtained from the typhoon simulation for
each of the investigated wind directions was adopted. When the design wind speed was evaluated using the 50-year recurrence value, the design wind speed was 48.3 m/s. When a somewhat conservative safety factor was applied, that is, when the 100 year recurrence value was used instead, the design wind speed was 52.9 m/s..
5. Takanori Uchida, LES Investigation of Terrain-Induced Turbulence in Complex Terrain and Economic Effects of Wind Turbine Control, Energies, 10.3390/en11061530, 11(6), 1530, 15pages, 2018.06, [URL], In the present study, numerical wind simulation was conducted by reproducing the realistic topography near wind turbine sites with high spatial resolutions and using the Large-Eddy Simulation (LES) technique. The topography near wind turbine sites serves as the origin of the terrain-induced turbulence. The obtained numerical simulation results showed that the terrain-induced turbulence is generated at a small terrain feature located upstream of the wind turbine. The generated terrain-induced turbulence affects the wind turbine directly. The wind speed and wind direction at the wind turbine site are significantly changed with time. In the present study, a combination of the series of wind simulation results and on-site operation experience led to a decision to adopt an “automatic shutdown program”. Here, an “automatic shutdown program” means the automatic suspension of wind turbine operation based on the wind speed and wind direction meeting the conditions associated with significant effects of terrain-induced turbulence at a wind turbine site. The adoption of the “automatic shutdown program” has successfully led to a large reduction in the number of occurrences of wind turbine damage, thus, creating major positive economic effects..
6. Takanori Uchida, Computational Fluid Dynamics Approach to Predict the Actual Wind Speed over Complex Terrain, Energies, 10.3390/en11071694, 11(7), 1694, 13pages, 2018.06, [URL], This paper proposes a procedure for predicting the actual wind speed for flow over complex terrain with CFD. It converts a time-series of wind speed data acquired from field observations into a time-series data of actual scalar wind speed by using non-dimensional wind speed parameters, which are determined beforehand with the use of CFD output. The accuracy and reproducibility of the prediction procedure were investigated by simulating the flow with CFD with the use of high spatial resolution (5 m) surface elevation data for the Noma Wind Park in Kagoshima Prefecture, Japan. The errors of the predicted average monthly wind speeds relative to the observed values were less than approximately 20%..
7. Takanori Uchida, Computational Fluid Dynamics (CFD) Investigation of Wind Turbine Nacelle Separation Accident over Complex Terrain in Japan, Energies, 10.3390/en11061485, 11(6), 1485, 13pages, 2018.06, [URL], We have developed an unsteady and non-linear wind synopsis simulator called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, COMputational Prediction of Airflow over Complex Terrain) to simulate the airflow on a micro scale, i.e., a few tens of km or less. In RIAM-COMPACT, the large-eddy simulation (LES) has been adopted for turbulence modeling. LES is a technique in which the structures of relatively large eddies are directly simulated and smaller eddies are modeled using a sub-grid scale model. In the present study, we conducted numerical wind diagnoses for the Taikoyama Wind Farm nacelle separation accident in Japan. The simulation results suggest that all six wind turbines at Taikoyama Wind Farm are subject to significant influence from separated flow (terrain-induced turbulence) which is generated due to the topographic irregularities in the vicinity of the wind turbines. A proposal was also made on reconstruction of the wind farm..
8. Takanori UCHIDA, A New Proposal for Vertical Extrapolation of Offshore Wind Speed and an Assessment of Offshore Wind Energy Potential for the Hibikinada Area, Kitakyushu, Japan, Energy and Power Engineering, 10.4236/epe.2018.104011, 10, 04, 11pages, 2018.04, [URL], The author’s research group has been conducting research on applications of various meteorological Grid Point Value (GPV) data offered by the Japan Meteorological Agency (JMA) to the field of wind power generation. In particular, the group’s research has been focusing on the following areas: 1) the use of GPV data from the JMA Meso-Scale Model (MSM-S; horizontal resolution: 5 km) and the JMA Local Forecast Model (LFM-S; horizontal resolution: 2 km), and 2) examinations of the prediction accuracy of local wind assessment with the use of these data. In both the MSM-S and the LFM-S, grid points are fixed at 10 m above the sea (ground) surface. The purpose of the present study is to establish a method in which the values of the MSM-S and LFM-S wind speed data from the 10 m height are used as the reference wind speed and are, using a power law, vertically extrapolated to 80 to 90 m heights, typical hub-heights of offshore wind turbines. For this purpose, the present study examined time-averaged vertical profiles of wind speed over the ocean based on the MSM-S data and in-situ data in the Hibikinada area, Kitakyushu City, Fukuoka Prefecture, Japan. As a result, it was revealed that a strong wind shear existed close to the sea surface, between the 10 and 30 m heights. In order to address the above-mentioned wind shear, a two-step vertical extrapolation method was proposed in the present study. In this method, two values of N, specifically for low and high altitudes (below and above approximately 30 m, respectively), were calculated and used. The data were created for the five years between 2012 and 2016. Similarly to previous analyses, the analysis of the created data set indicated that the potential of offshore wind power generation in the Hibikinada area, Kitakyushu City is quite high..
9. Takanori UCHIDA, Large-Eddy Simulation and Wind Tunnel Experiment of Airflow over Bolund Hill, Open Journal of Fluid Dynamics, 10.4236/ojfd.2018.81003, 8, 30-43, 2018.03, [URL].
10. Takanori Uchida, Reproducibility of Complex Turbulent Flow Using Commercially-Available CFD Software
―Report 1: For the Case of a Three-Dimensional Isolated-Hill With Steep Slopes―, Reports of Research Institute for Applied Mechanics, Kyushu University, 150, 47-59, 2016.03.
11. Takanori Uchida, Reproducibility of Complex Turbulent Flow Using Commercially-Available CFD Software
―Report 2: For the Case of a Two-Dimensional Ridge With Steep Slopes―, Reports of Research Institute for Applied Mechanics, Kyushu University, 150, 67-70, 2016.03.
12. Takanori Uchida, Reproducibility of Complex Turbulent Flow Using Commercially-Available CFD Software
―Report 3: For the Case of a Three-dimensional Cube―, Reports of Research Institute for Applied Mechanics, Kyushu University, 150, 71-83, 2016.03.
13. Takanori Uchida, Fumihito Watanabe, Shin Mikami, Analysis of the Airflow Field around a Steep, Three-dimensional Isolated Hill with Commercially Available CFD Software, Reports of Research Institute for Applied Mechanics, Kyushu University, 149, 91-98, 2015.09.
14. Takanori Uchida, An Examination of the Taikoyama Wind Farm Nacelle Separation Accident Using a CFD Approach, Reports of Research Institute for Applied Mechanics, Kyushu University, 148.0, 15.0-24.0, 2015.03, Because a significant portion of the topography of Japan is characterized by steep, complex terrain, which results in a complex spatial distribution of wind speed, great care is necessary for selecting a site for the construction of wind turbines. We have developed a computational fluid dynamics (CFD) model for unsteady flow called Research Institute for Applied Mechanics, Kyushu University, COMputational Prediction of Airflow over Complex Terrain (RIAM-COMPACT®). The RIAM-COMPACT® CFD model is based on the large-eddy simulation (LES) technique. In this paper, a numerical wind simulation for the Taikoyama Wind Farm is performed using high-resolution terrain elevation data. The results suggest that all six wind turbines at the Taikoyama Wind Farm are subject to significant influence from separated flow (terrain-induced turbulence) which is generated due to the topographical irregularities in the vicinity of the wind turbines. A proposal has been also made on reconstruction of the wind farm..
15. Takanori Uchida, Validation Testing of the Prediction Accuracy of the Numerical Wind Synopsis Prediction Technique RIAM-COMPACT for the Case of the Bolund Experiment-Comparison against a Wind-Tunnel Experiment-, Reports of Research Institute for Applied Mechanics, Kyushu University, 147, 7-14, 2014.09.
16. Takanori UCHIDA, Takashi MARUYAMA, Tetsuya TAKEMI, Yuichiro OKU, Yuji OHYA and Graham Li , Proposal of Designed Wind Speed Evaluation Technique in WTG Installation Point by Using the Meteorological Model and CFD Model
, 九州大学応用力学研究所所報, 第141号, pp.1-12, 2011.10.
17. Takanori UCHIDA, Takashi MARUYAMA, Hirohiko ISHIKAWA, Masaru ZAKO and Akira DEGUCHI , Investigation of the Causes of Wind Turbine Blade Damage at Shiratakiyama Wind Farm in Japan-A Computer Simulation Based Approach-, 九州大学応用力学研究所所報, 第141号, pp.13-25, 2011.10.
18. 内田孝紀,大屋裕二, LES技術を用いたウインドファーム風況診断―熊本県阿蘇車帰風力発電所を例として―, 土木学会論文集A2(応用力学)Vol.67 特集号, 2011.09.
19. Takanori Uchida, Takashi Maruyama and Yuji Ohya, New Evaluation Technique for WTG Design Wind Speed using a CFD-model-based Unsteady Flow Simulation with Wind Direction Changes, Modelling and Simulation in Engineering, Volume 2011 (2011), 2011.03.
20. Takanori Uchida, Yuji Ohya and Kenichiro Sugitani, Comparisons Between The Wake Of A Wind Turbine Generator Operated At Optimal Tip Speed Ratio And The Wake Of A Stationary Disk, Modelling and Simulation in Engineering, Volume 2011 (2011), 2011.03.
21. Takanori Uchida and Yuji Ohya, Latest Developments in Numerical Wind Synopsis Prediction Using the RIAM-COMPACT® CFD Model—Design Wind Speed Evaluation and Wind Risk (Terrain-Induced Turbulence) Diagnostics in Japan, Energies, 4(3), pp.458-474, 2011.03.
22. Takanori UCHIDA, Yuji OHYA, Challenge to Huge Computation of Airflow around Urban Area by using RIAM-COMPACT® CFD Model, Proceedings of EAEP2010/The 4th International Symposium on the Asian Environmental Problems, pp.191-194, 2010.09.
23. Hirotaka HANO, Takanori UCHIDA, Yuji OHYA, Wake Structure Behind Wind Turbine Generator in Turbulent Boundary Layer, Proceedings of EAEP2010/The 4th International Symposium on the Asian Environmental Problems, pp.195-200, 2010.09.
24. Takanori Uchida and Yuji Ohya, Large-Eddy Simulation of Topography-Induced Turbulence around WTG by using the RIAM-COMPACT® CFD Model, Proceedings of RENEWABLE ENERGY 2010 (RE2010), 2010.06.
25. Takanori Uchida and Yuji Ohya, HIGH RESOLUTION LES OF TURBULENT AIRFLOW OVER COMPLEX TERRAIN, Proceedings of Seventh Asia-Pacific Conference on Wind Engineering (APCWE-VII), pp.405-408, 2009.11.
26. Tomohiro Hara, Yuji Ohya, Takanori Uchida, Ryohji Ohba, Wind-Tunnel and Numerical Simulations of the Coastal Thermal Internal Boundary Layer, Boundary-Layer Meteorology, Vol.130, pp.365-381, 2009.02.
27. Takanori Uchida, Yuji Ohya, The wind risk management in the wind farm by using the RIAM-COMPACT CFD code, Proceedings of China Wind Power 2008 & Global Wind Power 2008, 2008.10.
28. Takanori Uchida, Yuji Ohya, Numerical Simulation of Airflow around Urban Area by using the RIAM-COMPACT CFD Model, Proceedings of Sino-Japan International Symposium on The East Asian Environmental Problems (EAEP2008), pp.51-53, 2008.08.
29. Yuji Ohya, Takanori Uchida, Laboratory and numerical studies of the atmospheric stable boundary layers, Journal of Wind Engineering & Industrial Aerodynamics, Vol.96, pp.2150-2160, 2008.07.
30. Takanori Uchida and Yuji Ohya, Micro-siting Technique for Wind Turbine Generators by Using Large-Eddy Simulation, Journal of Wind Engineering & Industrial Aerodynamics, Vol.96, pp.2121-2138, 2008.07, 風力業界で未解決課題であった風車に対する風の乱れ(ウィンドリスク)に対して,NEDO技術開発機構の産業技術研究助成事業(若手研究グラント)に採択され,研究代表者として3年間の研究開発を実施した.本研究を通じ,先端的数値風況予測モデル「RIAM-COMPACT®(リアムコンパクト)」を駆使し,世界で初めてウィンドリスクの存在を視覚的に特定することに成功し,その力学的機構を解明した.一連の成果に対し,2010年科学技術分野の文部科学大臣表彰・若手科学者賞を受賞した..
31. T.Uchida and Y.Ohya, Verification of the Prediction Accuracy of Annual Energy Output at Noma Wind Park by the Non-Stationary and Non-Linear Wind Synopsis Simulator, RIAM-COMPACT, Journal of Fluid Science and Technology, Vol.3, No.3, pp.344-358, 2008.06.
32. Yuji Ohya, Reina Nakamura, Takanori Uchida, Intermittent Bursting of Turbulence in a Stable Boundary Layer with Low-Level Jet,Boundary-Layer Meteorology, Boundary-Layer Meteorology, vol.26, No.3, pp.349-363, 2008.01.
33. Takanori Uchida, High Resolution LES of Airflow over Complex Terrain, Proceedings of APCOM'07-EPMESC XI, 2007.12.
34. Takanori Uchida, Yuji Ohya, Diagnosis of Airflow Characteristics in Wind Farm by Using the Unsteady Numerical Model RIAM-COMPACT, Proceedings of Renewable Energy 2006, 2006.10.
35. T.Uchida and Y.Ohya, Application of LES Technique to Diagnosis of Wind Farm by Using High Resolution Elevation Data, JSME International Journal, 「Environmental Flows」, Series B, Vol.49, No.3, pp.567-575, 2006.09.
36. Takanori Uchida, Yuji Ohya, Numerical simulation of atmospheric flow over complex terrain, Journal of Industrial Aerodynamics, 10.1016/S0167-6105(99)00024-0, 81, 283-293, 1999.05, In order to develop an overall efficient and accurate method of simulating an unsteady three-dimensional atmospheric flow over topography, we examined two grid systems and corresponding variable arrangements: one is a body-fitted coordinate (BFC) grid system based on a collocated variable arrangement; the other is an orthogonal grid system based on a staggered variable arrangement. Using these codes, we calculated the wind system over topography such as an isolated hill and real complex terrain. Both codes remarkably removed the numerical difficulties such as the convergence of the SOR method in solving the pressure Poisson equation, resulting in numerical results with much higher accuracy. Despite the differences in the grid system and in variable arrangement, no significant differences in the flow pattern between the both numerical results were found. Compared with the previous studies, the numerical results obtained are very satisfactory in the sense that overall characteristic flows are successfully simulated irrespective of the simulation codes..
37. Takanori Uchida, Y. Ohya, A numerical study of stably stratified flows over a two-dimensional hill - Part I. Free-slip condition on the ground, Journal of Industrial Aerodynamics, 10.1016/S0167-6105(97)00096-2, 67-68, 493-506, 1997.01, Stably stratified flows over a two-dimensional hill in a channel of finite depth are analyzed numerically by using a newly-developed multi-directional finite-difference method at a Reynolds number Re = 2000. To simplify the phenomena occurring in the flow around the hill, the free-slip condition for the velocity is assumed on the ground, and the nonslip condition is imposed only on the hill surface. Attention is focused on the unsteadiness in the flow around the hill for the cases of K( = NH/πU) > 1 where N and U are the buoyancy frequency and free-stream velocity and H is the domain depth. The flow unsteadiness is discussed, being associated with shedding of the upstream advancing columnar disturbance..
Works, Software and Database
1. .
Presentations
1. Takanori Uchida, Micro-siting Technique for Wind Turbine Generator by Using Large-Eddy Simulation, International Workshop on Environmental Engineering 2019(IWEE2019), 2019.06.
Membership in Academic Society
  • Japan Society of Fluid Mechanics
  • Japan Association for Wind Engineering
  • Japan Society of Mechanical Engineers
  • Japan Wind Energy Association