旋风分离器旋进涡核的大涡数值模拟

Large Eddy Simulation of Vortex Core Processing in Cyclone Separator

基于Smagorinsky-Lilly亚格子模型,将多面体网格应用于旋风分离器的大涡模拟,得到其平均流场和速度场脉动,并与实验值对比。对速度脉动进行快速傅里叶变换,以此探索旋进涡核的影响范围;通过涡速度云图,观察涡核中心的瞬态变化。结果表明,基于多面体网格的大涡模拟可以有效求解旋风分离器平均流场和速度脉动;斯特劳哈尔数的计算值为0.51,与实验值0.49非常接近。旋进涡核致使切向、轴向和径向的速度分量存在一致的主频;不考虑湍流边界层,旋进涡核存在于整个分离空间,且大部分位置的主频皆为11.54 Hz;旋进涡核中心在一定范围内围绕几何轴旋转,且旋转方向同主流方向一致。

Based on Smagorinsky-Lilly Subgrid-Scale model, polyhedral mesh was employed in large eddy simulation of a cyclone separator. The average flow profiles and velocity fluctuations were obtained and compared with experimental observations. In order to analyze the scope of impact of processing vortex core （PVC） , fast Fouier transform technique was applied to velocity fluctuations. Instantaneous changes of processional center of the core were investigated by vortex velocity contours. The obtained results indicated that the large eddy simulation with polyhedral mesh had a good performance in the simulation of the cyclone about average flow field and velocity fluctuation.The Strouhal number associated with the simulated PVC was 0. 51, close to experimental value of 0. 49. By the way, because of the existence of PVC, the tangential, the axial and radial components of velocity shared the same dominant frequency. PVC existed in all the separation region without considering turbulent boundary layer, with the dominant frequency of 11. 54 Hz at most positions.In a certain range the processional center of the core rotated around the geometrical axis of the cyclone, with the rotation direction being consistent with the mainstream direction.