nozzle, pressure profile, flashing flow, vortex, flow control
Vortex control is a novel two-phase convergent-divergent nozzle restrictiveness control mechanism which requires no change to the physical dimensions of the nozzle geometry. The control is achieved by adjustable nozzle inlet vortex. A nozzle with inlet vortex was called vortex nozzle (or swirl nozzle). Previous experiments on vortex nozzle with initially subcooled R134a showed that the nozzle becomes more restrictive as the strength of the inlet vortex increases. The maximum vortex control range has been observed to be 42% of maximum choked total mass flow rate through the nozzle. The control range of inlet pressures and mass flow rates that can be achieved by vortex control appears to be large enough to be suitable for numerous technical applications. This novel mechanism can potentially provide flow control with less sacrifice of nozzle efficiency, which is extremely important for ejector cooling cycle performance. It is also less vulnerable to clogging since the flow control is achieved without changing the flow area. However, the underlying mechanism behind the vortex control is still unclear. Measurement of the pressure profile of the vortex flashing flows in convergent-divergent nozzles under different conditions can provide more insights into the vortex nozzle flows and help to explain the above-mentioned phenomena. It also provides validation for modeling of vortex flashing flows. In this study, the experimental investigation of the pressure profile of the vortex flashing flows is presented. The results are discussed and different behaviors of vortex nozzle flow are explained with the insight provided by the pressure measurements.