Numerical and Experimental Investigations on a Variable Sonic and Subsonic Ejector

Abstract

A numerical and experimental investigation of the sonic and subsonic ejector system has been conducted to develop a hydrogen recirculation ejector system for fuel cell vehicle. In this study, a new method to improve the efficiency of a hydrogen fuel cell system in variable operating conditions of the vehicle was introduced. The ejector has the variable recess length in the distance between a main nozzle exit and a mixing chamber inlet, so that it can control the secondary mass flow rate by adjusting supply pressure. The results showed that ejector in the condition of sonic and subsonic could control the recirculation ratio effectively by changing the supply pressure and position of nozzle.