涡旋压缩机油气分离器分离特性及压降的数值模拟

Numerical Simulation of Separation Characteristics and Pressure Drop of Scroll Compressor Oil-gas Separator

电动汽车空调涡旋压缩机油气分离器的性能对空调系统的安稳运行及压缩机的润滑与密封均起着至关重要的作用。针对这种油气分离器结构尺寸小,要求其压降小,分离效率高,转速适用范围宽等特点,为探寻其内部的流动规律、压降及分离效率随转速的变化规律,首先选用适用于强旋流流动的雷诺应力模型(RSM),模拟计算了油气分离器中流体的流线图和速度分布;利用DPM模型对气液二相流进行数值模拟,计算了压缩机在不同转速下油气分离器中润滑油的分离效率及流体压降。分析结果表明,气体在分离器中做准自由涡流动和准强制涡流动,分离效率随油滴粒径的增大而提高,压缩机转速较低时,分离效率随转速的降低而急剧降低,压降与转速的平方成比例增大。最后,给出了优化设计电动涡旋压缩机油气分离器的设计方法。

The performance of oil-gas separator of scroll compressor for electric vehicle air conditioner plays a significant role in the stable operation of the air conditioning system and the lubrication and sealing of compressor.In view of small size of such oil-gas separator,it is required to have the characteristics of low pressure drop,high separating efficiency and wide application range of rotational speed.In order to explore the internal flow law,pressure drop and separation efficiency with the change of rotational speed,the Reynolds stress model(RSM)suitable for strongly swirling flow was chosen firstly,and the streamline diagram and velocity distribution of the fluid in the oil-gas separator were simulated.The DPM model was used to simulate the gas-liquid two-phase flow,and calculate the separation efficiency and fluid pressure drop of the lubricating oil in the oil-gas separator.The analysis results show that the gas performs quasi-free vortex flow and quasi-forced vortex flow in the oil-gas separator.The separation efficiency increases with the increase of the oil droplet size.When the compressor speed is low,the separation efficiency decreases sharply with the decrease of the rotational speed,and the pressure drop increases in proportion to the square of the rotational speed.Finally,the method for optimizing the design of the electric scroll compressor oil-gas separator was given.