An experimental parametric study of geometric, Reynolds number, and ratio of specific heats effects in three-dimensional sidewall compression scramjet inlets at Mach 6

Abstract

Since mission profiles for airbreathing hypersonic vehicles such as the National Aero-Space Plane include single-stage-to-orbit requirements, real gas effects may become important with respect to engine performance. The effects of the decrease in the ratio of specific heats have been investigated in generic three-dimensional sidewall compression scramjet inlets with leading-edge sweep angles of 30 and 70 degrees. The effects of a decrease in ratio of specific heats were seen by comparing data from two facilities in two test gases: in the Langley Mach 6 CF 4 Tunnel in tetrafluoromethane (where g=1.22) and in the Langley 15-Inch Mach 6 Air Tunnel in perfect gas air (where g=1.4). In addition to the simulated real gas effects, the parametric effects of cowl position, contraction ratio, leading-edge sweep, and Reynolds number were investigated in the 15-Inch Mach 6 Air Tunnel. The models were instrumented with a total of 45 static pressure orifices distributed on the sidewalls and baseplate. Surface streamline patterns were examined via oil flow, and schlieren videos were made of the external flow field. The results of these tests have significant implications to ground based testing of inlets in facilities which do not operate at flight enthalpies. NomenclatureCp pressure coefficient, 2 g M 2

Experimental Investigation of a Two-Dimensional and a Three-Dimensional Scramjet Inlet at Mach 7

“…Pure sidewall compression systems have been investigated in great detail by Holland and Murphy [14] and Holland [15] by means of pressure plots and oil-flow photographs and by Tani et al [16], showing the crossing shock system. Zuber et al [17] investigated the flowfield structure for crossing shocks for different sidewall contraction ratios and described the heat flux distribution on the base plate and the complex vortex structure.…”

Performance enhancement of three-dimensional hypersonic inlet with sidewall compression

“…Many studies have been implemented on the threedimensional hypersonic inlets with sidewall compression. In the early period, Trexler [1,2], Holland and Murphy [3], and Holland and Perkins [4] had carried extensive parametric studies on purely sidewallcompressing inlets by both experiments and numerical simulations. Zhang et al [5] had also studied the key geometry parameters of the purely sidewall compression inlets through experiments.…”