Diana D. Glawe

Experimental Investigation of the Role of Downstream Ramps on a Supersonic Injection Plume

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) crosse ow. The enhancement was achieved by injecting the low-angled jet parallel to a compression ramp. Seven compression ramp cone gurations 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 e ow properties quantie ed the e owe eld total pressure losses. Mie scattering images were used to qualitatively assess the e owe eld 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 (» 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.

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 flow 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 flowfield 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.

The Role of Downstream Ramps on Penetration and Mixing Enhancement for Supersonic Injection Flows

An experimental study was conducted to investigate penetration and mixing enhancement of a discrete lowangled (25°) supersonic (M=1.9) injection into a supersonic (M=2.9) cross flow. 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 (~ mixing efficiency), 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 to low-angled injection alone.