逆流冷却罗茨鼓风机涡流与排气脉动的数值分析

Numerical simulation of vortex and discharge pulse in positive discharge blowers with countercurrent cooling

运用计算流体动力学方法对逆流冷却在削弱罗茨鼓风机排气过程中存在的排气脉动方面进行了数值模拟，以动网格方法实现了计算域的变化并保证与转子旋转角度的匹配，在预进气与基元容积的动、静交接区域采用了非一致网格界面．对涡流与脉动流动瞬态特性的分析证明，逆流冷却可以避免排气口处的回流现象；在一个运行周期内，逆流冷却鼓风机的小脉动幅值仅为空冷鼓风机的20％～25％，这种小幅值脉动在降低排气气动噪声方面起重要作用．

The vortex and discharge flow with fluctuation of involute type three-lobe positive discharge blowers with countercurrent cooling was numerically investigated by means of computational fluid dynamics （CFD）. The dynamic mesh techniques were used to approach the rotating displacement of cell cubage and the alterability of computational area. The non-uniform mesh was applied to the rotor-stator coupled area. The characteristic of inner air flow was discussed. Based on the analysis of instantaneous characteristics of vortex and pulse flow, it＇s founded that countercurrent cooling could avoid the backflow eddy at the discharge outlet. At the same time, the pulse amplitude in countercurrent cooling is about 20%-25% of that in air cooling in a working cycle. This pulse flow greatly weakened could play an important role in reducing aerodynamic noise in positive discharge blower.