Development of a 1D solution algorithm to predict ejector performance in high altitude wind tunnels

In this study, a new 1D solution algorithm named CAP_EJ was proposed to predict the performance of ejectors in high altitude wind tunnels. CAP_EJ combined the constant area mixing (CAM) and constant pressure mixing (CPM) ejector concepts, and assumed that the mixing of the primary and secondary flows occurs within a constant area mixing duct, with equal static pressures at the mixing point. Prediction results by CAP_EJ were consistent with existing studies, showing that the entrainment ratio was inversely proportional to the total pressure of the primary flow, and increased as the area ratio increased. Verification was performed through comparison with 2D numerical simulation and other 1D analysis methods, showing good agreement within 5 % deviation. However, when using CAP_EJ to analyze CAM ejectors, upper bounds on the area of the secondary flow need to be confirmed.