Numerical investigation on flow characteristics and working performance in oil-injected sliding vane rotary compressors

Abstract

Oil is injected into Sliding Vane Rotary Compressors (SVRCs) for cooling, sealing and lubrication purposes. This paper presents numerical investigations on the oil-gas two-phase flow characteristics of the SVRC followed by studying the effects of the oil injection parameters on the compressor performance. The analytical grid generation methodology was employed to discretise the rotating and deforming rotor fluid domain. The Computational Fluid Dynamics (CFD) model of the SVRC was developed and validated with experimental test data. The flow topology was analyzed to illustrate the flow and oil distribution features within the compressor. Moreover, the influence of the oil injection parameters (oil to gas ratio, oil injection angle, oil injection temperature and rotational speed) on the compressor performance were explored. The results show that the oil accumulates at the leading sides of the blades and then flows into the blade tip region, which helps to reduce the internal leakage. In the reference case, the compressor achieves the volumetric efficiency of 95.1 %, the adiabatic efficiency of 60.3 %, the exhaust temperature of 337.4 K and the specific power of 9.86 kW/(m³ min^-1). Furthermore, increasing oil to gas ratio leads to better cooling and sealing performance, but also results in higher specific power. Oil to gas mass ratio has higher sensitivity than oil injection temperature or angle. About 8° shift in oil injection angle results in 4.2 % decrease in specific power. The lubricating oil capacity should be increased accordingly to the increasing rotational speed.