九州大学 研究者情報
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渡邉 康一(わたなべ こういち) データ更新日:2020.07.03



主な研究テーマ
熱と風を同時利用し発電するウインドソーラータワーに関する研究
キーワード:ハイブリッド発電、ウインドソーラータワー
2017.10.
レンズ風車の高性能化に関する研究
キーワード:レンズ風車、集風構造体、出力増加
2017.10.
高精度風況予測手法の開発に関する研究
キーワード:風況予測、数値計算手法
2017.10.
研究業績
主要原著論文
1. Koichi Watanabe, Sho Fukutomi, Yuji Ohya, Takanori Uchida, An Ignored Wind Generates More Electricity
A Solar Updraft Tower to a Wind Solar Tower, International Journal of Photoenergy, 10.1155/2020/4065359, 2020, 2020.01, [URL], A solar updraft tower is one of the wind power generation plants which utilizes solar energy. The purpose of this study was to ascertain whether the tower was also able to utilize crosswind energy. Wind tunnel experiments and numerical simulations were conducted simulating the crosswind. The results showed that suctioned updraft speed in the tower was proportional to the crosswind speed, and its conversion rate depended on the tower configuration. A diffuser-shaped tower with a vortex generator achieved to produce the updraft whose speed exceeded the crosswind speed. It was due to the low pressure created by the vortex atop the tower and to the diffuser effect. The crosswind utilization enables the simple power generation device to generate electricity during the night, and the hybrid utilization of renewable energies contributes to the increasing wind energy market..
2. Koichi Watanabe, Yuji Ohya, Takanori Uchida, Power output enhancement of a ducted wind turbine by stabilizing vortices around the duct, Energies, 10.3390/en12163171, 12, 16, 2019.08, [URL], A brimmed-diffuser augmented turbine (called a wind lens turbine: WLT) actively uses vortices around the brim to enhance its power output. However, the vortices are usually unstable and asymmetric. This study attempted to stabilize the vortices to enhance the power output of a WLT. Then, we investigated new approaches using vortex stabilization plates and polygonal brims in wind tunnel experiments and numerical simulations. Both approaches achieved a 1.5-3.8% increase in power output compared with a standard WLT. Our numerical simulations revealed a periodicity existing in a fluctuating vortex structure on the circular brim. Importantly, vortex stabilization plates and polygonal brims must be the same periodic scale to suppress the vortex fluctuation and stabilize the vortices effectively. In addition, a larger brim tended to enhance the stabilizing effects. We believe that this discovery provides an easy way to increase the power output of existing wind turbines. It is particularly important in light of advances in wind energy technology and the increasing wind energy market..
3. Ohya Yuji, Koichi Watanabe, A new approach toward power output enhancement using multirotor systems with shrouded wind turbines, Journal of Energy Resources Technology, Transactions of the ASME, 10.1115/1.4042235, 141, 5, 2019.05, [URL], A multirotor system (MRS) is defined as containing more than one rotor in a single structure. MRSs have a great potential as a wind turbine system, saving mass and cost, and showing scale ability. The shrouded wind turbine with brimmed diffuser-augmented wind turbines (B-DAWT) has demonstrated power augmentation for a given turbine diameter and wind speed by a factor of about 2-5 compared with a bare wind turbine. In the present research, B-DAWTs are used in a multirotor system. The power output performance of MRSs using two and three B-DAWTs in a variety of configurations has been investigated in the previous works. In the present study, the aerodynamics of an MRS with five B-DAWTs, spaced in close vicinity in the same vertical plane normal to a uniform flow, has been analyzed. Power output increases of up to 21% in average for a five-rotor MRS configuration are achieved in comparison to that for the stand-alone configuration. Thus, when B-DAWTs are employed as the unit of a MRS, the total power output is remarkably increased. As the number of units for an MRS is increased from two to five, the increase in power output becomes larger and larger. This is because that the gap flows between B-DAWTs in a MRS are accelerated and cause lowered pressure regions due to vortex interaction behind the brimmed diffusers. Thus, a MRS with more B-DAWTs can draw more wind into turbines showing higher power output..
4. Koichi Watanabe, Yuji Ohya, Multirotor Systems Using Three Shrouded Wind Turbines for Power Output Increase, Journal of Energy Resources Technology, Transactions of the ASME, 10.1115/1.4042971, 141, 5, 2019.05, [URL], Brimmed-diffuser augmented wind turbines (B-DAWTs) can significantly increase the performance of the rotor. Multirotor systems (MRSs) have a lot of merits such as significant saving mass and overall cost of the wind turbine system. In the present research, B-DAWTs are studied in a MRS. In wind tunnel experiments, the power output and aerodynamics of three B-DAWTs placed in close vicinity have been investigated. The results show a significant increase of up to 12% in total power output of the MRS with B-DAWTs compared to the sum of the stand-alone (SA) same turbines. The accelerated gap flows between B-DAWTs in a MRS cause lowered pressure regions due to vortex interaction behind the brimmed diffusers and draw more wind into turbines..
5. 渡邉康一、宗像秋生、大屋裕二, つば付きディフューザ風車を用いたマルチロータ型風車システムの発電出力・抗力特性, 日本風力エネルギー学会論文集, Vol.41, No.124, pp.25-32, 2018.02.
6. 渡邉康一、松本恵実、NweThander、烏谷隆、大屋裕二, 直線翼垂直軸型風車の出力を向上させる周辺付加物の形状検討, 日本風力エネルギー学会論文集, Vol.41, No.1, pp.1-8, 2017.05.
7. Koichi Watanabe, Yuji Ohya, Takanori Uchida, Tomoyuki Nagai, Numerical Prediction and Field Verification Test of Wind-Power Generation Potential in Nearshore Area Using a Moored Floating Platform, Journal of Flow Control, Measurement & Visualization, DOI:10.4236/jfcmv.2017.52002, Vol.5, No.2, pp.21-35, 2017.04.
8. Yuji Ohya, Jumpei Miyazaki, Uli Goeltenbott, Koichi Watanabe, Power Augmentation of Shrouded Wind Turbines in a Multi-Rotor System, The American Society of Mechanical Engineers, Journal of Energy Resources Technology, DOI:10.1115/1.4035754, Vol.139, Issue5, 051202, 2017.02.
9. Yuji Ohya, Takashi Karasudani, Tomoyuki Nagai, Koichi Watanabe, Wind Lens Technology and Its Application to Wind and Water Turbine and Beyond, Journal of Renewable Energy and Environmental Sustainability, DOI:10.1051/rees/2016022 , Vol.2, 2, 2017.01.
10. Yuji Ohya, Masaki Wataka, Koichi Watanabe, Takanori Uchida, Laboratory Experiment and Numerical Analysis of a New Type of Solar Tower Efficiently Generating a Thermal Updraft, Energies, DOI:10.3390/en9121077 , Vol.9, Issue12, 1077, 2016.12.
11. Koichi Watanabe, Shuhei Takahashi, Yuji Ohya, Application of a Diffuser Structure to Vertical-Axis Wind Turbines, Energies, DOI:10.3390/en9060406, Vol.9, Issue6, 406, 2016.05.
12. 渡邉康一、大屋裕二、烏谷隆, 直線翼垂直軸型風車への風レンズの適用, 九州大学応用力学研究所所報, DOI:10.15017/1660015, No.149, pp.36-41, 2015.09.
主要学会発表等
1. @大屋 裕二、@烏谷 隆、@内田 孝紀、@渡邉 康一, つば付きディフューザ風車を用いたマルチロータシステム の野外実験 ー その2 乱れ特性の影響, 第41回 風力エネルギー利用シンポジウム, 2019.12.
2. @渡邉康一、大屋裕二、@HalawaAmr, 熱と風が同時に与えられたときのウインドソーラータワーの創風性能, 第41回 風力エネルギー利用シンポジウム, 2019.12.
3. #藤松 拓弥、@内田 孝紀、@渡邉 康一、@大屋 裕二、@松島 啓二、@髙田 青, 2基風車配置における後流の相互干渉に関する研究, 日本航空宇宙学会西部支部講演会 2019, 2019.11.
4. #齋藤 望、@内田 孝紀、@渡邉 康一、@大屋 裕二、@松島 啓二、@髙田 青, 地表付近の風況予測精度向上のための孤立峰を用いた風洞実験および数値流体シミュレーション, 日本航空宇宙学会西部支部講演会 2019, 2019.11.
5. @渡邉康一、大屋裕二、@HalawaAmr、@内田孝紀, ウインドソーラータワー内部に発生する熱上昇風の数値計算, 第33回 数値流体力学シンポジウム, 2019.11.
6. #斎藤望、@内田孝紀、@渡邉康一、@大屋裕二、@松島啓二、@高田青, 複雑地形上の風況予測精度向上のための孤立峰を用いた風洞実験および数値シミュレーション, 流体力学会年会 2019, 2019.09.
7. #藤松拓弥、@内田孝紀、@渡邉康一、@大屋裕二、@松島啓二、@高田青, 複数風車配置における後流の相互干渉に関する研究, 流体力学会年会 2019, 2019.09.
8. @渡邉康一、@大屋裕二, ウインドソーラータワーの様々なタワー縦横比におけるエネルギー変換効率, 流体力学会年会 2019, 2019.09.
9. Koichi Watanabe, Yuji Ohya, Energy conversion efficiency of a wind solar tower, Wind Energy Science Conference 2019 (WESC2019) , 2019.06, A wind solar tower (called WST) is one of wind-power generation plants. WST is composed of four parts; a transparent thermal collector on the ground, a tall tower at the center of the collector, a vortex-generation plate on the top of the tower, and a wind turbine inside the tower. The tower utilizes an updraft generated in the tower to rotate its turbine. Two mechanisms below exist for generating the updraft;
i) Solar energy warms the air inside the collector. Then the warm air rises in the tower with its buoyancy.
ii) Wind energy generates a vortex above the tower. The low pressure of the vortex sucks up the air inside the tower.
Although the first mechanism has already used in a traditional solar tower, the second one is our new idea. Generally, renewable-energy power plants are expected to increase their outputs per unit area. WST has a chance of becoming the most powerful device, due to its advantage over the hybrid utilization of renewable energies. Then we have tried to optimize the tower shape for the further enhancement of its power output.
Our previous study showed that a diffuser-shaped tower with a semi-open angle of 4° was efficient. The diffuser-shaped tower demonstrated about 4-5 times power output as large as a cylindrical tower. Recently, we conducted some experiments using towers in several varieties of aspect ratios (AR = h/D). We supplied heat energy to the towers in laboratory experiments and wind energy to them in wind tunnel experiments respectively. In the case of heat utilization, the tower with larger aspect ratio tended to show the high heat energy conversion efficiency (=ηH). Similarly, in the case of wind utilization, the tower with a larger aspect ratio increased the wind energy conversion efficiency (=ηW). However, the tower with the vortex-generation plate achieved high ηW regardless of its aspect ratio. This result suggests that wind energy enables us to gain a large power output with a low tower. The low tower will be built at relatively low cost and contribute to the growth of renewables..
10. Koichi Watanabe, Yuji Ohya, Power output enhancement of a ducted wind turbine with various shapes of brim, Wind Energy Science Conference 2019 (WESC2019) , 2019.06, A brimmed-diffuser augmented turbine (called Wind Lens Turbine: WLT) utilizes vortices around the brim actively to enhance its power output. However, the vortices are usually unstable and asymmetric. This study attempted to stabilize the vortices and enhance the power output of WLT. Polygonal brims were investigated in wind tunnel experiments and numerical simulations. As a result, ideas achieved 2% increase of the power output compared with standard (round) WLTs. The numerical simulation unveiled a periodicity existed in the fluctuating vortex structure on a circular brim. Polygonal brims with the same periodic scale were able to suppress the vortex fluctuation and stabilize the vortices effectively. Besides, the larger brim tended to encourage the stabilizing effects..
11. Yuji Ohya, Koichi Watanabe, Multi-rotor systems in staggered arrangements using diffuser augmented wind turbines, Wind Energy Science Conference 2019 (WESC2019), 2019.06, Multi-rotor systems(MRSs) are defined as single structures containing more than one rotor. For more power output of MRSs, we examined staggered arrangements of MRSs with brimmed-diffuser augmented turbines (Wind Lens Turbine (WLT)). When the central turbine on staggered arrangement was moved in upwind direction, the output increase was close to a single unit’s value, while the total output of MRS did not change a lot. The changes on the individual power output increases were thought to be due to flow pattern changes of accelerated gap-flows among them. The results showed that staggered arrangements have a potential to make flows around the turbines more effective for their power output..
12. 渡邉康一、河原信太郎、大屋裕二, 上空風によるウインドソーラータワーの集風性能にタワー縦横比が与える影響, 第25回 風工学シンポジウム, 2018.12.
13. 渡邉康一、大屋裕二, 太陽熱と風力を同時利用するウインドソーラータワーの性能, 第40回 風力エネルギー利用シンポジウム, 2018.12.
14. 大屋裕二、烏谷隆、渡邉康一, つば付きディフューザ風車を用いたマルチロータシステムの野外実験, 第40回 風力エネルギー利用シンポジウム, 2018.12.
15. 村上大河、内田孝紀、渡邉康一、大屋裕二, スタッガード配置による複数の集風体付き風車の性能向上に関する研究, 第40回 風力エネルギー利用シンポジウム, 2018.12.
16. Taiga Murakami, Takanori Uchida, Koichi Watanabe, Yuji Ohya, Researches on the efficiency of multi wind turbines with brimmed diffuser on the staggered arrangement, 10th Kyushu Univ.-KAIST Symposium on Aerospace Engineering, 2018.12.
17. Koichi Watanabe, Takanori Uchida, Yuji Ohya, Wind solar tower harnessing wind energy and solar energy, The 29th International Symposium on Transport Phenomena (ISTP29), 2018.11, Wind Solar Tower is a new power-generating device using renewable energies. A similar conventional device known as a solar chimney has utilized the solar energy alone. Besides, its generation efficiency was very low. Therefore, we largely improved the generation efficiency by arranging the shape of the tower from the cylinder type to the diffuser type. At the same time, we attached a vortex generation plate on the tower. The plate enabled the tower to utilize not only solar energy but also wind energy. The simultaneous utilization of renewable energies with one device is notable discovery. We tried the optimization of the tower shape by laboratory experiments (including wind tunnel ones) and numerical analysis. As a result, we found that the diffuser tower with 4° is the optimal shape, and we succeeded in wind-converging whose speed inside of the tower was faster than upper-wind speed, using the vortex generator. Numerical analysis contributed significantly to clarify the mechanisms. Eventually, we demonstrated the simultaneous utilization of the renewable energies in field experiments..
18. 村上大河、内田孝紀、渡邉康一、大屋裕二, スタッガード配置による複数の集風体付き風車の性能向上に関する研究, 日本航空宇宙学会西部支部講演会 2018, 2018.11.
19. Koichi Watanabe, Yuji Ohya, Effective utilization of wind energies by wind solar tower, Grand Renewable Energy 2018 International Conference and Exhibition (GRE2018), 2018.06.
20. Yuji Ohya, Koichi Watanabe, A new wind turbine system using multiple rotors with brimmed diffusers (Multi-Lens Turbine), Grand Renewable Energy 2018 International Conference and Exhibition (GRE2018), 2018.06.
21. 渡邉康一、大屋裕二、綿加正樹, ウインドソーラータワーが創風する熱上昇風の構造に関する研究, 第39回 風力エネルギー利用シンポジウム, 2017.12.
22. 森山喬史、渡邉康一、大屋裕二、内田孝紀, 複数のつば付きディフューザ風車を用いたクラスタシステムの開発, 第39回 風力エネルギー利用シンポジウム, 2017.12.
23. 河原信太郎、内田孝紀、渡邉康一、大屋裕二, ウインドソーラータワーの発電性能向上に関する研究, 日本航空宇宙学会西部支部講演会 2017, 2017.11.
24. 森山喬史、内田孝紀、渡邉康一、大屋裕二, 複数の集風体付き風車を有するクラスタシステムの開発, 日本航空宇宙学会西部支部講演会 2017, 2017.11.
25. 井上諒、内田孝紀、大屋裕二、渡邉康一, 複雑地形における地表付近の風況予測精度向上に関する研究, 日本航空宇宙学会西部支部講演会 2017, 2017.11.
26. Yuji Ohya, Koichi Watanabe, Multi-Rotor System Using Brimmed-Diffuser Wind Turbines for Power Output Increase, 15th International Energy Conversion Engineering Conference, AIAA Propulsion and Energy Forum, 2017.07.
27. Koichi Watanabe, Yuji Ohya, A Wind Solar Tower Harnessing Sunshine and Wind Energies, Wind Energy Science Conference 2017 (WESC2017), 2017.06, In 1989, a pilot plant of a solar chimney was erected in Manzanares, Spain, to evaluate the feasibility of the solar tower as a new source of renewable energies. Since then, the solar tower was discussed in the press and academic research, but no commercial plant succeeded the development. A reason for this could be very low efficiency, i.e., very low power output compared with other renewable energy production systems. However, a solar tower that can generate electricity in a simple structure, and enables easy and less costly maintenance, has considerable advantages. A solar tower consists mainly of three components. The collector area is a glass roof, above ground with increasing height towards the center. Attached to the center of the collector is a vertical tower inside which a wind turbine is mounted at the lower entry into the tower. When solar radiation heats the ground through the glass roof, the uprising warm air is guided to the center into the tower.
To improve the efficiency in power production for a solar tower, we focused on the shape of the tower and modified the structure from a conventional cylindrical type to a diffuser-type tower. This modification is considered to combine two mechanisms. Firstly, the mechanism to “Generate Wind” which becomes effective when solar thermal energy is available, and secondly the mechanism to “Converge Wind” which becomes effective when wind passes the top end of the diffuser even when solar thermal energy is not available. For a new power generation system using both of wind and solar energies, we named “Wind Solar Tower (WST)”. By combining these two independent concepts which complement one and another, a profitable energy availability power generation system is expected, that is capable of a larger power generation compared to the original solar tower prototype and much larger capacity factor.
As a result of fluid dynamic shape optimization, a diffuser-shaped tower shows an increase in the updraft speed of a scaled model. A remarkable improvement in the power output of the internal wind turbine as much as 4-5 times compared to the cylindrical tower is obtained (Fig.1). Based on the two kinds of laboratory experiments, we are now making a field experiment using a prototype of WST with 10m tower height (Fig.2). We have elucidated that the thermal updraft speed is proportional to the root of tower height and temperature difference between the collector inside and the ambient aloft. In the present research, we propose a new renewable energy device that can harness both sunshine and wind energies. It is now showing a high potentiality, reaching 50 times in power output compared to the Manzanares. Furthermore, almost similar amount of power output by wind aloft over the tower is expected depending on wind condition of the site..
28. Yuji Ohya, Akio Munakata, Koichi Watanabe, Power Output Performance of Clustered, Diffuser Augmented Wind Turbines - Multi Rotor System Using Wind-Lens Turbines -, Wind Energy Science Conference 2017 (WESC2017), 2017.06.
29. 渡邉康一、福富翔、大屋裕二, 上空風によって効果的に集風するウインドソーラータワーの形状に関する研究, 平成29年度 日本風工学会 年次研究発表会, 2017.05.
30. 渡邉康一、福富翔、烏谷隆、大屋裕二, 上空風によって発生するウインドソーラータワー内部の上昇風に関する研究, 第38回 風力エネルギー利用シンポジウム, 2016.12.
31. 宗像秋生、ウリゴルテンボット、渡邉康一、烏谷隆、大屋裕二, つば付きディフューザ風車を用いたマルチロータシステムにおける発電出力・抗力特性, 第38回 風力エネルギー利用シンポジウム, 2016.12.
32. 渡邉康一、大屋裕二、烏谷隆, 垂直軸型風車の駆動原理の解明と集風装置の適用による高出力化, 第21回 風工学シンポジウム, 2010.12.
33. Shuhei Takahashi, Yuji Ohya, Takashi Karasudani, Koichi Watanabe, Numerical and Experimental Studies of Airfoils Suitable for Vertical Axis Wind Turbines and an Application of Wind-Energy Collecting Structure for Higher Performance, The Fourth International Symposium on Computational Wind Engineering (CWE2006), 2006.07.
34. 渡邉康一、高橋周平、大屋裕二、烏谷隆、渡辺公彦, 垂直軸型風車の駆動メカニズムの解明と2次元風レンズ体(集風装置)の適用, 平成17年度 日本風工学会 年次研究発表会, 2005.04.
35. 渡邉康一、大屋裕二、烏谷隆、渡辺公彦, 直線翼垂直軸型風車への2次元風レンズ体(集風装置)の適用, 第26回 風力エネルギー利用シンポジウム, 2004.11.
36. 渡邉康一、大屋裕二、烏谷隆、渡辺公彦, 集風構造体の垂直軸型風車への適用, 日本航空宇宙学会西部支部講演会 2004, 2004.10.
37. 渡邉康一、大屋裕二、烏谷隆、久米宏明, つば付きディフューザ風車の開発と周辺流解析, 流体力学会年会 2004, 2004.08.
38. Koichi Watanabe, Yuji Ohya, Takashi Karasudani, Kimihiko Watanabe, Development of a Wind Turbine Generating High Output Power, The 5th Korea/Japan Joint Workshop on Aeronautics and Astronautics, 2004.07.
学会活動
所属学会名
日本風力エネルギー学会
日本風工学会
日本流体力学会
日本航空宇宙学会
研究資金
科学研究費補助金の採択状況(文部科学省、日本学術振興会)
2018年度~2020年度, 基盤研究(C), 代表, シングルからマルチロータシステムの採用による風車システムの発電・構造性能の強化.

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