Effect of Nozzle Contour on Flow Separation in Overexpanded Rocket Nozzles

抄録

In the present paper, parametric numerical analyses of the separated transonic flows in overexpanded rocket nozzles are conducted. Several types of nozzles are examined numerically to clarify the detailed mechanisms of the occurrence of restricted shock separation (RSS) in compressed truncated perfect (CTP) nozzles. The effects of nozzle length and geometric compression factor are examined. In CTP nozzles with large length and small compression factor, a positive pressure gradient appears downstream of the Mach disk before the occurrence of RSS. Under the positive pressure gradient, the flow, which passed through the Mach disk, rolls up and forms a large vortex ring around the nozzle exit. The vortex ring pushes the separated jet towards the nozzle wall and results in RSS.