Experimental investigation of the effects of base mass addition on the near wake of a slender body

Abstract

The near wake of a two-dimensional wedge was studied at Mach 4. Static pressure, Pitot pressure, total temperature, injectant concentration and hot-wire fluctuations were measured. Helium, argon and SF_6 were injected into the base, and their diffusion in laminar and turbulent wakes was studies. The locations of the wake stagnation points as a function of injection rate, and the critical rates required to eliminate the recirculation flow were determined. It was found that the Tear-wake flow with injection does not scale with the mass flux, nor do the momentum or the volume fluxes serve to correlate the data over the entire range of injection. Fluctuation measurements show that SF_6 has a destabilizing effect on the wake, whereas helium has a stabilizing influence, compared to the wake without injection. Model cooling (T_W/T_0∞ = 0.25) resulted in a forward shift of the rear stagnation point and a pronounced decrease in both the velocity defect and the wake width but had a lesser effect on the distribution of the injected species.

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