Improving Performance of Savonius Rotor for Harvesting Energy from Water Stream by Local Flow Acceleration

• Main Authors: Chiang, Yi-Hsun, 江奕勳
• Other Authors: Lin, Tsing-Fa
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/54291675464683145916

碩士 === 國立交通大學 === 機械工程系所 === 104 === In this study an experiment is conducted to investigate the possibility of improving the efficiency of extracting kinetic energy from water flow in a rectangular-channel by a Savonius rotor through installing a block upstream of the rotor in the channel. The channel is only partially blocked. The partial channel blockage intends to direct and strengthen the water flow toward the advancing blade of the rotor and meanwhile weaken the flow hitting the returning blade. A small-scale laboratory experimental system is established to test this concept. The rectangular channel is 15 cm wide and 12 cm high. In the experiment the mean water speed is varied from 0.1 to 0.8 m/s and four blocks with different shape and size are tested. To further augment the turbine rotation, the rotor is placed in a diverging section of the channel with a side wall of the channel inclined outward at angle of 15 and 30 . The experimental parameters include the water speed, rotor location, shape and size of the flow acceleration block, and diverging angle of the channel wall. The measured data for the efficiency of the power generation from the hydrokinetic energy indicate that in the straight channel the rotor performance can be increased more than 10 times by a suitable choice of the block and rotor location. Specifically, the power generation efficiency can be increased from 0.04 to 0.42. But in the side wall-diverging channel the installation of the blocks does not result in significant improvement of the rotor performance. Besides, it is noted that the rotor performance varies nonmonotonically with all experimental parameters. It is difficult to provide a simple criterion for choosing the optimal block. However, based on the streamline patterns in the channels affected by the blocks, which can be calculated numerically where there is no rotor in the channel, a suitable choice of the experimental parameters to substantially improve the rotor performance is possible. It can be concluded that the use of a flow acceleration block is effective in improving the performance of a Savonius rotor for harvesting the hydrokinetic energy.