Rarefied Aerothermodynamics Technology Development for Future High-Altitude High-Speed Transport (EU-FAST20XX)

Abstract

First subject of the present paper has been the experimental and numerical characterization of test chamber flow of DLR-V2G low-density wind tunnel, in the frame of EU-FP7 FAST20XX project activities dedicated to the validation of numerical tools able to predict rarefaction effects in suborbital flight. Pitot pressure radial profiles measured at different positions downstream the test chamber have been compared at nozzle exit to numerical results obtained with different methodologies accounting for rarefaction effects (CFD with slip-flow boundary conditions, a hybrid CFD-DSMC procedure), and a re-definition of the V2G facility envelope in terms of flight-relevant parameters (Mach, Reynolds, Knudsen numbers) has been presented. A good agreement between experiments and numerical results has been achieved for M=12 and M=16 cases (not as good for M=22), thus confirming that the test chamber flow knowledge is of fundamental importance for a proper numerical rebuilding of an experimental test campaign. Further, the aerodynamic coefficients of lift, drag and pitching moment of the analyzed lifting body configuration have been experimentally determined by means of three component force and moment measurements in V2G and the influence of rarefaction onto the aerodynamic coefficients have been shown. The results have numerically been validated by means of DSMC calculations. After the validation of the numerical tools, the high altitude effects to the future hypersonic/suborbital re-entry vehicle SpaceLiner have been analyzed. Bridging functions have been developed and validated by means of DSMC calculations. The effects of rarefaction on global longitudinal aerodynamics of SpaceLiner in the range of altitude 65÷85 km have been pointed out by comparing to the aerodatabase in continuum regime conditions. DSMC computation has been done in the higher SpaceLiner altitude point confirming the bridging function results and providing heat transfer estimations. Two versions of SpaceLiner have been analyzed: SL4.3 and SL7.1. Nomenclature AcronymsCEV = Crew Exploration Vehicle CFD = Computational Fluid Dynamics DSMC = Direct Simulation Monte Carlo ENO = Essentially Not Oscillatory FTB-X = Flying Test Bed X HSM = Hard Sphere Model mcs = Mean collision separation NExT = Numerical Experiment Tool PFA = Projected Frontal Area PPA = Projected Planform Area RANS = Reynolds Averaged Navier Stokes WA = Wetted Area Downloaded by PURDUE UNIVERSITY on July 30, 2015 | http://arc.aiaa.org | Symbols A = Surface, m 2 C D = Drag coefficient C L = Lift coefficient C p = Specific heat at constant pressure, J/kg/K d = Diameter of particles, m E H = = Aerodynamic Efficiency Total enthalpy, MJ/kg h Kn = = Altitude, Km Knudsen number, /L L l = = Lift, N Reference length, m L/D = Aerodynamic efficiency LH 2 = Liquid hydrogen LO 2 = Liquid oxygen M = Mach number m = Mass of particles, g mcs = Mean collision separation distance, m P, p = Pressure, Pa or bar P ND , P NL q R = = = Parameters defined by Eq. 5 and Eq. 6 Dynamic Pressure, PA Radius, m R gas = Ga...