NEAR-FIELD SHOCK STRUCTURE OF DUAL COAXIAL JETS

Experimental results on the shock structure of dual co-axial jets are presented. The effects of the geometric parameters of the inner nozzle , jet static pressure ratio (ratio of the exit plane static pressures of the inner and outer nozzles) and the ratio of outer to inner nozzle throat area on the shock structure were studied. A superimposed outer and inner jet structure was observed in the schlieren photographs. Th e inner flow is compressed by the outer flow resulting in the formatio n of a Mach disc and an exit shock. A parameter incorporating the effe ct of Mach number of the inner nozzle and jet static pressure ratio wa s found to correlate the observations regarding the Mach disc location .