Aerothermodynamic Environment for a Generic Missile

Abstract

There are a variety of computer codes of varying degrees of rigor that can be used by the designers of highspeed missile systems to dee ne the aerothermodynamic environment at e ight conditions. It is assumed that the e ow models and the numerical algorithms used in these codes have been validated by their developers. However, the users of such codes must exercise them against a quality database, gaining knowledge of the intricacies in the use of such codes and calibrating the range of conditions over which the code can be used to predict specie c parameters that are important to the design objectives without necessarily verifying that all of the features of the e ow are correctly modeled. Forces and moments, surface pressures, surface temperatures, and e ow-visualization photographs have been obtained in theTri-Sonic Wind Tunnel at the U.S. Air Force Academy at Mach 4.28. When comparing the e owe eld parameters computed using state-of-the-art codes with the corresponding experimental parameters, streamwise oscillations were observed in thecomputed pressure distribution on the windward surface of the missile at angle of attack. These anomalous results were eliminated by modifying the grid to cluster points for capturing the bow shock wave. Nomenclature A = axial force CA = axial-force coefe cient, A=.q1S/ CM = pitching-moment coefe cient referenced to the apex of the model, M=.q1SD/ CN = normal-force coefe cient, N=.q1S/ D = diameter of the cylindrical portion of the model, 1.25 in. L = model length, 10.00 in. M = pitching moment referenced to the apex of the model N = normal force P = static pressure Pt1 = total pressure in the tunnel reservoir Rn = nose radius Re1;L = Reynolds number based on the freestream conditions and on the model length ReL = Reynolds number based on the freestream conditions and on the model length in millions, i.e., Re1;L £10 i6