The Experts below are selected from a list of 12888 Experts worldwide ranked by ideXlab platform
Rahul Goyal - One of the best experts on this subject based on the ideXlab platform.
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transient characteristics during the closure of guide Vanes in a pump turbine in pump mode
Renewable Energy, 2018Co-Authors: Deyou Li, Zheng-gui Li, Hongjie Wang, Torbjorn K Nielsen, Rahul GoyalAbstract:To achieve the flow mechanism during the closure of the guide Vanes in a pump-turbine in pump mode, a three-dimensional (3-D) incompressible simulation using the shear stress transition (SST) k-ω turbulence model was performed. The dynamic mesh method was adopted to simulate the closing process of the guide Vanes. Based on the validation of the steady experiments, the variation in performance characteristics (head, discharge, and torque), pressure, and velocity was presented, which shows dynamic instability at the end of the guide Vanes closing process. Numerical results confirm that the dynamic instabilities at the end of the closing process originated from severe fluctuations that occurred in the guide and stay Vanes. Detailed analyses of flow characteristics reveal that severe fluctuations occur due to vortices in the stay Vanes, and a high-pressure circular ring in the vaneless space and a low-pressure circular ring between the guide Vanes outlet and stay Vanes inlet were identified. During the closing process of the guide Vanes opening, the vortices appear in several passages initially, and then increasingly spread to all the passages. The position and rotating direction of the vortices vary with time. Using the Q-criterion method, the composition and evolution of vortex structures in stay Vanes were identified. These structures comprise streamwise vortices, horseshoe-shaped vortices, and spanwise vortices, which lead to severe pressure fluctuations.
Zheng-gui Li - One of the best experts on this subject based on the ideXlab platform.
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transient characteristics during the closure of guide Vanes in a pump turbine in pump mode
Renewable Energy, 2018Co-Authors: Deyou Li, Zheng-gui Li, Hongjie Wang, Torbjorn K Nielsen, Rahul GoyalAbstract:To achieve the flow mechanism during the closure of the guide Vanes in a pump-turbine in pump mode, a three-dimensional (3-D) incompressible simulation using the shear stress transition (SST) k-ω turbulence model was performed. The dynamic mesh method was adopted to simulate the closing process of the guide Vanes. Based on the validation of the steady experiments, the variation in performance characteristics (head, discharge, and torque), pressure, and velocity was presented, which shows dynamic instability at the end of the guide Vanes closing process. Numerical results confirm that the dynamic instabilities at the end of the closing process originated from severe fluctuations that occurred in the guide and stay Vanes. Detailed analyses of flow characteristics reveal that severe fluctuations occur due to vortices in the stay Vanes, and a high-pressure circular ring in the vaneless space and a low-pressure circular ring between the guide Vanes outlet and stay Vanes inlet were identified. During the closing process of the guide Vanes opening, the vortices appear in several passages initially, and then increasingly spread to all the passages. The position and rotating direction of the vortices vary with time. Using the Q-criterion method, the composition and evolution of vortex structures in stay Vanes were identified. These structures comprise streamwise vortices, horseshoe-shaped vortices, and spanwise vortices, which lead to severe pressure fluctuations.
Kenji Kaneko - One of the best experts on this subject based on the ideXlab platform.
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Effect of guide vane shape on the performance of a Wells turbine
Renewable Energy, 2001Co-Authors: S. Santhakumar, T.h. Kim, Kenji KanekoAbstract:A Wells turbine has inherent disadvantages: lower efficiency and poorer starting characteristics. Providing guide Vanes on either side of the rotor could be one of the most effective ways of improving its performance. Several papers have demonstrated the usefulness of 2D guide Vanes so far. In order to achieve further improvement in the performance of the Wells turbine, the effect of 3D guide Vanes has been investigated experimentally by testing a model under steady flow conditions. Then, the running and starting characteristics under irregular flow conditions have been obtained by a computer simulation using quasi-steady analysis. It is found that the running and starting characteristics of the Wells turbine with 3D guide Vanes are superior to those with 2D guide Vanes.
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Improvement of Wells Turbine Performance by Means of 3D Guide Vanes.
Transactions of the Japan Society of Mechanical Engineers Series B, 2000Co-Authors: Kenji Kaneko, T.h. Kim, Masahiro InoueAbstract:Performance of a Wells turbine was improved by equipping 2D guide Vanes before and behind a rotor. For further improvement, 3D guide Vanes have been proposed in this paper. The performance of the Wells turbine with 2D and 3D guide Vanes have been investigated experimentally by model testing under steady flow conditions. Then, the running and starting characteristics in irregular ocean waves have been obtained by a computer simulation. As a result, it is found that both of the running and starting characteristics of the Wells turbine with 3D guide Vanes are superior to those of the turbine with 2D guide Vanes.
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Performance of Wells Turbine with Guide Vanes for Wave Energy Conversion
Journal of Thermal Science, 1996Co-Authors: Kenji KanekoAbstract:In order to improve the performance of a Wells turbine, the effect of guide Vanes with various gaps between turbine rotor and guide vane has been clarified by model testing and numerical simulation. The results have been compared with those of the case without guide Vanes. It is found that the overall characteristics are considerably improved by the inlet guide Vanes. Furthermore, a suitable choice of design factor for the gap has been suggested.
Abraham Engeda - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical investigation of the performance of a 240 kw centrifugal compressor with different diffusers
Experimental Thermal and Fluid Science, 2003Co-Authors: Abraham EngedaAbstract:Abstract Eight low solidity vaned diffusers (LSVD1–LSVD8) were designed for a 240 kW centrifugal compressor. All eight LSVDs and for comprison purposes along with two standard and high performing vaneless diffusers and one conventional vaned diffuser were tested downstream of the same impeller. The objective was to understand the pressure recovery phenomena in each of the three types of diffusers, and the effect of design parameters on performance. Also, the results were compared with the results from numerical simulation. The design parameters include the solidity, turning angle, vane setting angle, and the number of Vanes. The experimental investigation was performed at three different rotational speeds ( M u =0.69, 0.88, 1.02). The experimental results proved the superior merits of the LSVDs relative to the vaneless and vaned diffuser. The LSVDs fulfilled the high expectations, since they seemed to combine the advantages of the conventional diffusers by providing a good pressure recovery over a wide flow range.
Manabu Takao - One of the best experts on this subject based on the ideXlab platform.
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Guide Vanes for Darreus Water Turbine in Tidal Current
Renewable Energy and Power Quality Journal, 2013Co-Authors: Kojo Hiraki, Manabu Takao, Kohei Nishida, Ryo Wakita, Toshiaki WatanabeAbstract:On purpose to enhance the performance of a Darrieus-type water turbine for the power generation using a tidal current, the technique with guide Vanes were applied. The guide Vanes placed in front of the turbine, were expected to allow the turbine to rotate with higher speed by turning the direction of the current partially. The device was tested in both the wind and water tunnels, and its effect was recognized at both tests. Since the configuration with the twin turbines in parallel was considered advantageous especially under the weaker tidal current, the guide Vanes suitable for the twin-turbine configuration were investigated using the wind tunnel, based on the previous results obtained in the single-turbine configuration. The experimental results showed that the guide Vanes placed on the center line increased the rotational speed in the regions of lower tip-speed ratio.
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current status of self rectifying air turbines for wave energy conversion
Energy Conversion and Management, 2006Co-Authors: Toshiaki Setoguchi, Manabu TakaoAbstract:This paper reviews the present state of the art on self rectifying air turbines, which could be used for wave energy conversion. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been evaluated numerically and compared from the viewpoints of their starting and running characteristics. The types of turbine included in the paper are: (a) Wells turbine with guide Vanes (WTGV); (b) turbine with self-pitch-controlled blades (TSCB); (c) biplane Wells turbine with guide Vanes (BWGV); (d) impulse turbine with self-pitch-controlled guide Vanes (ISGV); and (e) impulse turbine with fixed guide Vanes (IFGV). As a result, under irregular wave conditions, it is found that the running and starting characteristics of impulse type turbines could be superior to those of the Wells turbine. Moreover, the authors have explained the mechanism of the hysteretic behavior of the Wells turbine and the necessity of links for improvement of the performance of the ISGV.
