Experimental Investigation of the Role of Downstream Ramps on a Supersonic Injection Plume
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An experimental study was conducted to investigate penetration and plume expansion enhancement of a discrete low-angled (25 deg) supersonic (M = 1.9) injection into a supersonic (M = 2.9) crossflow. The enhancement was achieved by injecting the low-angled jet parallel to a compression ramp. Seven compression ramp configurations were studied. The jet-ramp interaction enhancement mechanisms included baroclinic torque vorticity, ramp spillage vorticity, bulk compression, and the Magnus force. Shadowgraph photography was used to identify shock structures. Measurements of mean flow properties quantified the flowfield total pressure losses. Mie scattering images were used to qualitatively assess the flowfield and to quantify the plume size, trajectory, and concentration decay rate. The results indicated that up to a 22% increase in penetration, a 39% plume expansion (approx. mixing), and a 27% increase in the concentration decay rate, with a corresponding 17% increase in total pressure loss, can be achieved by injection over a compression ramp as compared with low-angled injection alone.