Experimental study on the pressure fluctuation caused by two-phase flow shock wave at the nozzle outlet

Recently, the refrigeration air conditioner and heat pump system using the two-phase flow ejector is beginning to appear, as the efficiency of the ejector cycle is improved largely in comparison with the conventional system. Shock and expansion waves can occur in the internal flow fields of the ejector, and the effect of the pressure fluctuation by those waves must be considered on the designs of the ejector. In this study, the pressure fluctuation of the shock wave appeared at the outlet of the two-phase flow nozzle are measured in the HFO1234yf refrigeration cycle. It was clarified by experiment that the amplification frequency components of pressure fluctuations are increased with the strength of the shock waves and the attenuation frequency components are increased with increase of liquid void fraction of downstream shock waves.