Simulation and analysis of the over-expanded flow field in asymmetric nozzles with lateral expansion

Abstract Numerical simulations of a three-dimensional asymmetric nozzle with lateral expansion were carried out, focusing on the characteristics of the three-dimensional flow field in the over-expanded state and the influence of the sidewall surface profiles on the over-expanded flow field. The results show that the sidewall profiles cause the separation zones inside the nozzle to exhibit different shapes. The center separation bubble and the corner zone separation bubble are independent of each other in the lower wall surface confined shock wave separation mode. In the upper wall-constrained shock wave separation mode, the center separation bubble, the corner zone separation bubble, and the sidewall surface separation bubble are interconnected. Under the same drop pressure ratio, changes in the sidewall profile affect the shape and size of the separation zones, and the convex wall can slow the occurrence of separation to a certain extent.