Free-flight tests of reentry capsule models in free-piston shock tunnel

摘要

Free-flight measurement technique in shock tunnel was developed for capsule shaped test models at JAXA Kakuda Space Center. With the technique, test models were non-restrained so that the model will be free from aerodynamic interaction with support system such like sting. The electro-magnet model hold and release system was newly designed for the capsule shaped configuration. With this modified model release system, precision of model angle of attack was guaranteed less than 1-degree. Feasibility test for force measurement and heat-flux measurement was achieved in HIEST with a 70% scaled Hayabusa SRC capsule model, in which a miniature on-board data-recorder and a miniature accelerometers or coaxial thermocouples were instrumented. Moreover, a wind tunnel test campaign to measure aerodynamics characteristics of a 6% scaled HTV-R Japanese reentry capsule model (250mm diameter) was also conducted. Series of wind tunnel tests were performed under stagnation enthalpy between H_0=3MJ/kg to 20MJ/kg, and stagnation pressure between P_0=14MPa to S2MPa, which stagnation condition was tuned to match with HTV-R vehicle reentry corridor. Under the flow condition above, the unit Reynolds number of the test free-stream was changed from 0.9 million/m to 4.5 million/m. Aerodynamic characteristics were obtained at model angle of attack between 0 degree to 20 degree with fully laminar or with partially turbulent boundary layer. Measurement showed that the precision of aerodynamics coefficient were CA=4%, CN=4% and Cm=8% (2-sigma).