TRANSITION REGIME AERODYNAMIC HEATING OF MISSILES

The three-dimensional hows over the ARIES missile at approximately 138 -, 110-, and 91-km altitudes are simulated at zero angle of attack usi ng the direct simulation Monte Carlo method, At these altitudes, the a erodynamics near the missile range from the transition to near free-mo lecule flow regimes. The aerodynamic heating predictions along the mis sile surface from the simulations are used to benchmark three empirica l bridging relations. Furthermore, the effect of using an approximate free-molecular expression in the bridging relations is investigated. T he values predicted using the approximate free-molecular expressions f ail to predict any heat transfer along the cylindrical portions of the missile, and differ by as much as 90% along other sections. The bridg ing relations are found to predict heating rates within a factor of 2 of the simulated results, provided the full free-molecular expression from kinetic theory is used. It is found that no one bridging relation outperformed the others. Each has regions along the length of the mis sile, where it is in good agreement with the simulations, and other re gions, where significant differences are observed.