涡旋压缩机排气过程的三维数值模拟计算

Three Dimensional Numerical Simulation of Discharge Flow in a Scroll Air Compressor

根据涡旋压缩机实际排气过程的特点,通过对物理模型的合理简化,建立了描述排气过程的准静态三维湍流流动数值模拟计算模型,对排气一周内不同动盘转角时刻中心腔内的流动分布及通过排气孔的流动进行了详细的数值分析.数值计算结果表明,涡旋压缩机工作腔内存在大量环流,沿着轴向在靠近排气孔0～10mm(型线高度为52mm)的范围内轴向速度很大,比同一截面内径向速度大一个数量级.从无量纲压力损失系数分布图得出,排气流动阻力损失主要集中在排气孔开启阶段,排气孔的开启特性对流动损失影响最为明显.在开设排气孔时应着重考虑孔的开启特性,纠正了目前开设排气孔面积越大越好的观点,为排气孔口的合理开设提供了理论依据.

Based on the characteristics of a discharge process in a scroll air compressor, the reasonable simplification of the actual physical model was conducted and the three-dimension quasi-steady turbulent flow numerical simulation was performed. The numerical results show that complex vortex flow patterns exist in the discharge region throughout the entire axial extent of central chamber. Moreover the axial velocity component is very large at a small axial distance of 0-10 mm from the discharge port (when the height of the profile is 52 mm), and the axial velocity is greater than the radial velocity by an order of magnitude. On the basis of our numerical results, the dimensionless pressure loss coefficient was defined and the pressure loss at various crank angles after the onset of discharge was analyzed. It is shown that the discharge flow loss mainly occurs at the onset stage of discharge. The present result gives a new viewpoint that maximum area of discharge port is not always the best for designing the discharge port of a scroll compressor. The easier to open, the better the characteristic of discharge port is.