Computational and Experimental Study of Rarefied Aerodynamic Forces of Blunted Cone

To solve the disagreement of aerodynamic properties between the direct simulation Monte Carlo (DSMC) calculations using dsmcFoam code and SR3 experiment measurement, rarefied hypersonic flows over the 70 deg blunted cone are revisited by performing a combined computational/experimental study. The calculated results are acquired by using the open-source DSMC code SPARTA, and the experimental measurement is carried out in the hypersonic low-density wind tunnel FD-19 at China Academy of Aerospace Aerodynamics. Normal forces and pitching moments calculated by the two DSMC codes (dsmcFoam and SPARTA) keep evidently lower than experimental data for all nonzero angles of attack (AOA), though an acceptable agreement is observed between dsmcFoam and SPARTA simulations. The discrepancies between DSMC computations and SR3 measurement become larger with growing AOA. The decease of surface accommodation coefficient from 1 to 0.8 makes the discrepancies even larger, indicating that one cannot attribute the discrepancy to the uncertainty of accommodation coefficient. The excellent agreement of aerodynamic properties between SPARTA calculations and FD-19 experiment achieves a mutual validation between DSMC computations and low-density wind-tunnel experiment. Therefore, the system deviation resulting from some additional uncertainties that are not accounted for in the SR3 experiment is responsible for the disagreement between the DSMC simulations and SR3 experiment measurement. One possible deviation source is the nonuniform freestream in the test section of SR3 wind tunnel.