Numerical Investigation of Shock-Reflection Phenomena in Overexpanded Supersonic Jets

The transition from regular to Mach reflection in a supersonic planar jet operating under overexpanded conditions has been studied numerically. First, inviscid computations are performed by the solution of Euler equations. The results demonstrate that a hysteresis phenomenon is observed as the jet/ambient pressure ratio decreases and increases, causing a change in the angle of incidence of the nozzle-lip shock and, as a consequence, the transition from regular to Mach reflection and back. The angles of forward and backward transitions are close to the theoretical detachment and von Neumann criteria, respectively. Furthermore, turbulent computations (by the use of an improved two-equation model) are conducted to investigate the transition in a more realistic situation