MODEL FOR THE SHOCK ACTUATION OF A WEDGE-SHAPED NOZZLE WITH ALLOWANCEFOR DETACHMENT OF THE FLOW

The motion of the starting gasdynamic discontinuities and of the detac hed flow arising upon the shock actuation of a wedge-shaped nozzle is examined in the framework of the problem of the decay of an arbitrary discontinuity at a jump in the cross-sectional area of the channel. Th e results of the calculation are compared with experimental measuremen ts of the spatial and time dependence of the starting discontinuities upon the shock actuation of submerged jets over a wide range of variat ion of the parameters governing the flow: at pressure ratios 100<(p) o ver bar<1700 and sound velocities 0.21<(a) over bar <2.4 of the issuin g and immersing gases, for issuing gas species with 1.16<gamma<1.67, a nd for various combinations of these parameters. The possibility of us ing this model to determine the relaxation time to an undetached super sonic flow in a wedge-shaped nozzle upon the shock actuation of slight ly underexpanded and overexpanded jet flows is analyzed. (C) 1997 Amer ican Institute of Physics.