贯流风机内部旋涡非定常演化的数值模拟

COMPUTATIONAL FLUID DYNAMICS SIMULATION OF UNSTEDAY EVOLVEMENT OF VORTICES FLOW IN CROSS FLOW FAN

本文采用非定常三维Navier-Stokes方程、κ-ε两方程模型分析了贯流风机内部旋涡产生、发展、耗散、消失的演化过程。数值模拟显示:偏心涡产生于进气侧,随后横穿叶轮内部朝出气侧移动,最后位于出气侧叶片内圆周上。叶轮外圆周脱落的旋涡是不稳定的,它们互相融合,最后被吸入叶轮内部。数值模拟的结果显示偏心涡先于贯流而产生,是由于偏心涡的存在导致了贯流的产生,并非贯流形成了偏心涡。本文证实了ECK的旋涡理论和文献[3]的实验结果。

This paper analyzed the unsteady evolvement process of vortices in cross flow fan using CFD simulation. Numerical analysis was based on unsteady three-dimensional Navier-Stokes equations coupled with κ - ε Turbulence model. It was observed that an eccentric vortex was generated from the blade's trailing edge of the entry side after starting of the fan. It passed through impeller's interior region and moved towards the fan's exit side. The strong throughflow was controlled by the existence of the eccentric vortex. The vortices shed from impeller's outer circumference were unstable. They coalesced, gradually decayed, and were sucked into the impeller's interior region finally. The study clarified that it was the eccentric vortex brought about the throughflow, but not the occurrence of throughflow formed the eccentric vortex. The CFD simulation results approved Eck's vortex principle and validated the previously published experimental conclusion.