Investigation of the Effects of Lateral Cowl Length in an Inward Turning Scramjet Inlet

摘要

Experimental and computational studies were conducted to evaluate the performance of a scramjet inlet as the side cowl length is changed. A slender inward turning inlet of a total length of 304.8 mm, a span of 50.8 mm with the compression at 11.54 deg and CR = 4.79 was used. The side cowl lengths were 50.8 mm and 76.2 mm. Experiments were conducted in a shock tunnel with nominal stagnation enthalpy of 0.67 MJ/kg and stagnation pressure of 3.67 MPa. Freestream conditions were Mach number 8.6 and Reynolds number of 1.94 million per m. Test times were 300-500 μs. Numerical simulations using RANS with the Wilcox k-ω turbulence model were performed using ANSYS® Fluent. The experiment showed that the cowl length has a pronounced effect in the pressure distribution on the inlet and a minor effect in the exit flow Mach number. The numerical results confirmed these trends and showed that a complex flow structure is formed in the cowl-ramp corners; a non-uniform transverse shock structure was found to be related to the cowl leading edge position. Cross flow due to the side expansion increases the flow angularity as the cowl length decreases.