Abstract

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Computational uid dynamics tools have been used extensively in the analysis and development of the X-43A Hyper-X Research Vehicle. A signi cant element of this analysis is the prediction of integrated vehicle aeropropulsive performance, which includes an integration of aerodynamic and propulsion ow elds. The development of the Mach 7 X-43A required a pre ight assessment of longitudinal and lateral-directional aeropropulsive characteristics near the target ight-test condition. The development of this pre ight database was accomplished through extensive aerodynamic wind-tunnel testing and a combination of three-dimensional inviscid airframe calculations and cowlto-tail scramjet cycle analyses to generate longitudinal performance increments between mission sequences. These increments were measured directly and validated through tests of the Hyper-X ight engine and vehicle owpath simulator in the NASA Langley Research Center 8-Foot High Temperature Tunnel. Predictions were re ned with tip-to-tail Navier-Stokes calculations, which also provided information on scramjet exhaust plume expansion in the aftbody region. A qualitative assessment of lateral-directional stability characteristics was made through a series of tip-to-tail inviscid calculations, including a simulation of the powered scramjet ight-test condition. Additional comparisons with wind-tunnel force and moment data as well as surface pressure measurements from the Hyper-X ight engine and vehicle owpath simulator model and wind-tunnel testing were made to assess solution accuracy. Nomenclature C A = axial force coef cient C l¯= rolling moment derivative, /deg C M = pitching moment coef cient C N = normal force coef cient C n¯= yawing moment derivative, /deg C p = pressure coef cient C y¯= side force derivative, /deg X; Y; Z = spatial coordinates, m ® = angle of attack, deg

An innovative concept utilizing the natural porosity of refractory-composite materials and hydrogen coolant to provide CONvective and TRANspiration (CONTRAN) cooling and oxidation protection has been numerically studied for surfaces exposed to a high heat flux, high temperature environment such as hypersonic vehicle engine c0mbustor walls. A boundary layer codc and a porous media finite difference code were utilized to analyze the effect of convection and transpiration cooling on surface heat flux and temperature.The boundary layer code determined that transpiration flow is able to provide blocking of the surface heat flux only if it is above a minimum level due to heat addition from combustion of the hydrogen transpirant.The porous media analysis indicated that cooling of the surface is attained with coolant flow rates that are in the same range as those required for blocking, indicating that a coupled analysis would be beneficial.

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