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Effect of width-to-diameter ratio of impellers on waterwheel performance based on volume of fluid model |
LI Kexin, ZHENG Yuan*, HU Xueyuan |
College of Energy and Electrical Engineering, Hohai University, Nanjing, Jiangsu 211100, China |
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Abstract In order to study an eco-friendly and simple waterwheel device with a micro water head, a three-dimensional model of the waterwheel in the river was established. The volume of fluid(VOF)model was used, and the pressure-velocity coupling was solved in the PISO format. The width-to-dia-meter ratio of different impellers was calculated. Unsteady flow analysis was performed on the waterwheels. The results show that the chest shot waterwheel with an impeller width-to-diameter ratio of 3.93 has the widest efficiency zone and the highest optimal efficiency. The increase in the width-to-diameter ratio of the impeller increases the blocking effect of the flow channel, and the water level diffe-rence between the upstream and downstream increases, and the obvious vortex phenomenon appears.Torques of waterwheel blades with different width-to-diameter ratios show the same periodic change,when the waterwheel is running in the dry season, there will be a backflow phenomenon between the two blades immersed in the water during the movement of the blades, so that the torque has a small range of extreme values. The pressure between the two blades that are not immersed in water increases as the width-to-diameter ratio of the impeller increases. The front pressure of the waterwheel blades of five width-to-diameter ratios reaches the maximum at the tip of the blade, and the waterwheel with an impeller width-to-diameter ratio of 3.93 has the largest pressure difference between the front and back sides of the waterwheel blades, which improves the blade′s performance. The results play a gui-ding role in the design of the impeller structure of the chest shot waterwheel.
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Received: 16 July 2021
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