Experimental and Numerical Performance Analysis of a Self-Starting Three-Dimensional Scramjet Intake

Abstract

In this work, a three-dimensional intake model was investigated in a blowdown wind tunnel and results were compared and complemented with Reynolds-averaged Navier–Stokes simulations. The intake model was equipped with a movable cowl with which the internal contraction ratio was set to the self-starting limit. Three different conditions were investigated: first, a v-shaped cowl geometry at a freestream Mach number of seven; second, a straight cowl geometry at a freestream Mach number of seven; and, finally, a v-shaped cowl geometry at a freestream Mach number of six. Furthermore, a one-dimensional postanalysis was performed to calculate overall engine parameters from stream-thrust-averaged intake performance parameters. Numerical results were within the experimental uncertainty, except for small displacements near separation regions. The mass capture ratio of the v-shaped cowl was slightly higher as compared to the straight cowl. When increasing the Mach number from six to seven, the specific impulse dropped from 2561 to 2100 s, respectively. For the Mach 7 configurations, a maximum sustainable backpressure ratio of approximately 115 was measured. For the Mach 6 case, the maximum sustainable static backpressure ratio dropped to about 85. The maximum sustainable backpressure to operating backpressure ratio was around 4:1, and it was independent of the Mach number.