Effects of nozzle geometry on parallel injection into a supersonic flow

Fuel injection from the base of a two-dimensional extended strut bounded above and below by nominal Mach 2 freestreams was investigated, Without injection, a two-dimensional wake now exists behind the base of the strut. When fuel, simulated with helium, is injected parallel to the nominal Mach 2 freestreams, a highly three-dimensional complex how-held results. The behavior of the flowfield generated by a circular injection nozzle was compared to the results obtained using two asymmetric nozzle geometries: 1) an elliptic nozzle and 2) a circular nozzle with vortex-generating tabs. The results show that the injected fuel jets are confined to the wake region downstream of the strut; thus the spread of the jets in the transverse direction is highly limited. The jet emanating from the circular nozzle with two tabs oriented normal to the span of the extended strut exhibited the best mixing. The second best mixing was exhibited by the elliptic nozzle, with its major axis normal to the span of the extended strut.