Free-flight aerodynamic tests of reentry vehicles in high-temperature real-gas flow (Invited)

Abstract

Aerodynamic tests conducted in the HIEST free-piston high-enthalpy shock tunnel were reported. A novel multi-component force-measurement technique was implemented, which involved the test model being completely non-restrained for the duration of the test and thus experiencing free-flight conditions for a period in the order of milliseconds. Compared with conventional free-flight techniques, the present one has the advantage of no aerodynamic interference with the model support system and less variation in the model position and attitude during the test. The measurement accuracy and precision of the technique were compared to a conventional blow-down wind tunnel and evaluated in a HIEST test campaign with a blunted cone. During the test campaign, the pitching-moment coefficient under the HIEST high-enthalpy condition differed significantly from that of low enthalpy, which was considered attributable to high-temperature real-gas effects. The technique has already been applied to a HIEST test campaign for the Japanese HTV-R re-entry capsule to determine its trim angle at re-entry. Moreover, the technique was also adopted to measure the body flap (elevon) efficiency of the HYFLEX lifting body. NomenclatureAOA = Angle of attack CA = Axial force coefficient CN = Normal force coefficient CMy = Pitching moment coefficient P 0 = Stagnation pressure P Pitot = Free-stream Pitot pressure PI = Prediction interval X = Model displacement (x-direction) Y = Model displacement (y-direction)  = Standard deviation *

Free-flight aerodynamic test of elliptic cone in Shock Tunnel

“…The results demonstrated the high-precision measurement performance of the technique within a short test period in the order of milliseconds. The technique has already been applied to a pair of aerodynamic test campaigns in HIEST; threecomponent force measurement in capsule-shaped models 3 and a lifting body model 4 . During these test campaigns, A the test models used were less than 0.5 meter in size.…”