Abstract: To clarify the two-phase flow characteristics in the horizontal compressor and control the oil discharge rate (ODR) at high frequency, the oil pool motion and its flow mechanism were studied. It is found the ODR of horizontal compressor is commonly higher than that of the vertical with same capacity, particularly under high rotating speed, and it is analyzed that the oil pool level is an important factor for ODR. Through CFD multiphase flow simulation and prototype test, the oil pool migration was studAied, and the key flow field information was extracted to clarify the level distribution and formation mechanism, which was also verified by experiment of a prototype compressor equipped with view-window. The oil level of motor and pump cavity is not consistent, showing the feature that oil level in pump cavity is higher than that in motor cavity. The reason is that the refrigerant is forced to flow through the long path under the effect of the guide shell. The pressure drop is large since the considerable throttling, which leads to the pressure in motor cavity significantly exceeds that of the pump cavity. Lubricants migrate to the pump cavity under the periodic pressure pulsation. The simulation results show the exhaust pressure drop is mainly proportional to the flowrate, followed by the rotational speed. Under the high flowrate or high rotating speed, the oil level of the pump cavity will be too high, resulting in severe turbulence of the oil surface, which may conduct a negative effect on ODR.

Key words: Horizontal compressor, Lubricating oil, Oil pool distribution, Flow disturbance, Multiphase flow simulation