Experimental study on the oblique shock waves and expansion waves in the supersonic carbon dioxide two-phase flow

Recently, with the appearance of the two-phase flow ejector in refrigeration air conditioning and heat pump systems, the efficiency of the cycle has largely been improved in comparison with that of conventional cooling and heating systems. We have been developing an ejector for the refrigeration cycle and fundamentally researching the behavior of two-dimensional expansion waves and oblique shock waves to clarify the characteristics of waves occurring during high-speed two-phase flow. In previous studies, it was revealed that an oblique shock wave is generated at the nozzle exit of the ejector and affects the flow field of the supersonic two-phase flow inside the mixing section in the ejector. This is because the speed of sound for a two-phase flow is low compared to that for a single-phase flow. In the present study, we elucidate the behavior of oblique shock waves and expansion waves of supersonic two-phase flow by experiments using carbon dioxide refrigerant. The angle of the oblique shock waves and the expansion waves were experimentally measured, and corresponded well with those calculated using a theoretical model.