垂直轴导流涵道与非导流涵道水轮机熵产特性对比

Comparison on Entropy Production Characteristics for Ducted and Non-Ducted Vertical Axis Turbines

为了对比分析垂直轴导流涵道水轮机与垂直轴非导流涵道水轮机之间的熵产及性能特点,通过引入熵产理论并结合SST k-ω湍流模型对二者进行三维数值模拟研究。结果表明:导流涵道水轮机比非导流涵道水轮机具有更高的输出功率和更小的功率波动幅度,但黏性耗散熵产和湍流耗散熵产及其波动幅度均比非导流涵道水轮机有所增加;2种水轮机的黏性耗散熵产和湍流耗散熵产均随尖速比的增大而增大;2种水轮机处于不同尖速比下时的湍流耗散熵产也远大于黏性耗散熵产。流场分析显示大部分的熵产主要发生在水轮机叶片的后缘和导流涵道的外侧,原因是此处形成了较大范围的流动分离和涡流。研究结果揭示了二者的熵产和性能特点,为垂直轴导流涵道水轮机的优化设计提供了一定的参考依据。

In order to compare and analyze the characteristics of the entropy production and performance between a vertical axis ducted turbine and a vertical axis non-ducted turbine, a three-dimensional numerical simulation is carried out by introducing entropy production model in combination with SST k-ω turbulence model. The results show that the ducted turbine has higher output power and smaller power fluctuation than the non-ducted turbine. However, the viscous dissipative entropy production, the turbulent dissipative entropy production and their fluctuation amplitude of the ducted turbine are higher than those of the non-ducted turbine.Meanwhile, the viscous dissipative entropy production and turbulent dissipative entropy production of each turbine increase with the increase of tip speed ratio. The turbulent dissipation entropy production of the two turbines is much greater than that of the viscous dissipation entropy production at different tip speed ratio. Flow field analysis shows that most of the entropy production takes place at trailing edge of the turbine blade and outer side of the duct due to the large formation of flow separation and vortex. The research results reveal the entropy production and performance characteristics for the two turbines and accurately locate the entropy production concentration area, which provides a certain reference for the optimal design of vertical axis ducted turbines.