Analysis of Discharge Pressure Pulsation of Scroll Compressor

The noise prediction of scroll compressor is one of the most important subjects to develop a more calm and efficient air conditioner. A scroll compressor has a finite volume ratio, which Is defined by the scroll shape. Because of this finite volume ratio, the noise increases in the high-pressure ratio conditions. This study is the first step to predict the noise, which is caused by pressure pulsation. In previous works, we analyzed the discharge pressure pulsation by CFD with 1-dimensional straight tube model, which had same cross-sections. However the model was in need of the experimental values such as the equivalent sound length of compression chambers. From this reason it was impossible to predict the frequency pattern of noise. In this stydy, we developed a new 1-dimensional tube model, which has variable cross-sections to consider the change of compression chamber shapes. From analysis of the pressure pulsation frequency spectrum, it is confirmed the new model can predict reasonably the change of the sound power level by the setting of the lead valve.