An Experimental Parametric Study of Geometric, Reynolds Number, and Ratio of Specific Heats Effects in Three-Dimensional Sidewall Compression Scramjet Inlets at Mach 6
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 CF4 Tunnel in tetrafluoromethane (where gamma=1.22) and in the Langley 15-Inch Mach 6 Air Tunnel in perfect gas air (where gamma=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.
COMPUTATIONAL INVESTIGATION OF THE EFFECT OF NOSE BLUNTNESS ON THE EXTERNAL AND INTERNAL COMPRESSION IN A MIXED INLINE INTAKE
A computational study has been carried out to find out the flowfield inside a two dimensional hypersonic intake. The study has been carried out for a free stream Mach number of 6.5, a unit Reynolds number 1.6 x 10 6 per meter with an intake contraction ratio of 2.88. The purpose of this analysis was to investigate the effect of nose bluntness on the external and internal compression in a mixed compression inline intake. An intake models with different nose bluntness has been analyzed using 2-D numerical simulations based on a commercially available CFD code. The CFD code and the turbulence model used is validated by comparing the experimental results available in literature with computational results. Computational results show that the nose bluntness has significant influence on pressure distribution and skin friction coefficient distribution on intake components. Nose bluntness affects the shock wave / boundary layer interactions on intake upper surface significantly. Numerical results also indicate that the nose bluntness has a significant influence on intake performance parameters.
Numerical Simulation of Flow Through a Two-Strut Scramjet Inlet
A three-dimensio nal, Reynolds-averaged Navier-Stokes code has been used to numerically analyze flow through a two-strut, supersonic combustion ramjet (scramjet) inlet configuration. It solves the governing equations in full conservation form using either a fully explicit or explicit-implicit method. An algebraic, two-layer eddy-viscosity model is used for turbulent flow calculations. The analysis allows inclusion of end effects that are caused by the aft placement of the cowl on the underside of the inlet. A special grid has been developed to accomodate the struts embedded in the inlet flowfield. Detailed numerical results are presented here for the two-strut configuration, and a comparison is made with the available experimental results.