EXPERIMENTAL AND NUMERICAL STUDY OF SWEPT RAMP INJECTION INTO A SUPERSONIC FLOWFIELD

Time-averaged measurements of pressure, temperature, velocity, and inj ectant mole fraction are presented using the planar laser-induced iodi ne fluorescence technique in the complex three-dimensional compressibl e flowfield around a swept ramp fuel injector. Within the range of the rmodynamic conditions present in the test case studied, the technique' s accuracy is estimated to be 4% for pressure, temperature, and veloci ty and 3% for injectant mole fraction. Comparisons with numerical simu lations using the SPARK three-dimensional Navier-Stokes computer code with an algebraic turbulence model are made at the centerplane of the flowfield as well as on three crossflow planes downstream of the injec tor. Calculations and measurements are in good agreement throughout th e flowfield, with deviations on the order of 5%; however, in specific regions, such as in the base of the ramp, deviations are larger. A wea k asymmetry in the incoming flowfield appears to be amplified by bound ary-layer separation occurring when the ramp-generated shock reflects off the tunnel walls. Ramp-generated vortices are weaker in the calcul ated results due to the effects of numerical viscosity in the vortex c ores. This leads to less turning and mixing of the jet plume than obse rved in the experiments. The rate of decay of the maximum injectant mo le fraction with streamwise distance is greater for the present ramp i njection scheme than for previously measured transverse injection sche mes. In the recirculation region at the base of the injector, laminar calculations show better agreement with the measurements than turbulen t calculations.