FSI model of valve motion and pressure pulsation for investigating thermodynamic process and internal flow inside a reciprocating compressor

Abstract

Predicting valve motion and pressure pulsation accurately plays an important role in evaluating thermodynamic performance of reciprocating compressors. In this paper, a 3-dimensional (3D) computational fluid dynamics (CFD) model of a double acting reciprocating compressor was presented, in which a mesh mapping method was proposed to realize the independent motion of each valve plate. Consequently, the transient flow inside the compressor and the interaction between valve motion and pressure pulsation could be resolved simultaneously. Moreover, two kinds of turbulence models, i.e. the RNG k-ε model and the DES model, were applied to examine their effect on pressure pulsation. Comparison between numerical models and experimental results showed that both turbulence models can predict the thermodynamic performance precisely regardless of some discrepancies on the valve lift. An FFT analysis showed that the RNG k-ε model predicted the pressure pulsation fairly well below 500 Hz. However, the DES model could resolve much higher frequencies of over 1500 Hz within an error range of 10% at 420 rpm.