Numerical investigation on starting performance of zero-secondary flow ejectors

To investigate how the geometry parameters can influence starting performance in zero-secondary flow ejector, flow field of different ejectors were solved by CFD. The numerical simulation results were also applied to analyze ejector typical operation modes, ranging from on-design to off-design point. Results suggest that A_d/A_t(area ratio of diffuser entrance to nozzle throat) and A_st/A_d(second-throat contraction ratio) are the most important parameters on the ejector performance, and L_st/D_st(ratio of length to diameter second-throat) and L_d/D_d(second-throat location) also greatly influence the performance. The critical starting pressure ratio is increased by increasing A_d/A_t. When A_st/A_d is higher than second-throat critical contraction ratio, its decrease benefits starting the ejector.