基于熵产的侧流道泵流动损失特性研究

侧流道泵是一种介于容积式泵和离心泵之间的径向式叶片泵。泵内流体以螺旋轨迹方式在叶轮和侧流道中反复运动，整个运动是一种典型的全三维、高湍流强度、空间非对称的湍流流动，因此不可避免地产生较大的流动损失。利用热力学第二定律，基于熵产的流动损失分析方法对一种单级侧流道泵模型湍流流动损失进行研究，主要通过理论和数值计算求解湍流流动过程中增加的熵产，定性分析侧流道泵流动损失出现的位置及分布特点。结果表明，侧流道泵内部流动损失主要与湍流流动增加的熵产有关，而热量交换产生的熵产相对较小，在侧流道泵的损失研究中可以忽略；叶轮流道和侧流道内的湍动耗散率均远远大于直接耗散率；叶轮流道内的损失主要出现在叶轮内缘至0.4 r处，在侧流道内，流动损失主要出现在流道进口、流道中间靠近内缘部分以及出口附近。

Study on Flow Loss Characteristics of Side Channel Pump Based on Entropy Production

The side channel pump is a kind of radial vane pump between displacement pumps and centrifugal pumps. The fluid flows repeatedly in the impeller and the side channel as a helical pattern. The flow inside the side channel pump is a typical three-dimensional, high turbulence intensity and asymmetric turbulent flow, so the flow loss generates inevitably in the process of the highly turbulent flow. The distribution characteristics of the losses in side channel pump are investigated theoretically and numerically by calculating the entropy production in flow, in which the second law of thermodynamics is adopted. The results show that the flow loss in the side channel pump is mainly related to the entropy production in the turbulent flow, and the entropy production caused by the heat transfer is only a little part which can be ignored. The turbulent dissipation is always significantly larger than the direct dissipation no matter in the impeller passage or in the side channel. The area locating between the hub and 0.4 r of impeller passage shows greater flow losses than other flow region obviously, and it shows a great loss at the inlet and outlet of side channel as well as the middle part near the inner edge.