Radiative-gasdynamic coupling and nonequilibrium effect behind reflected shock waves

Results of calculations for the flowfields behind reflected shock waves in nitrogen resulting from incident shock velocities of 8 and 11 km /sec and initial pressures of 10 ~3 and 10 ~2 cm of Hg are presented. In obtaining these results the radiative properties of the gas have been represented by an approximate nongray absorption coefficient model, and the exchange of momentum and energy due to collisions between particles has been included. During the first microsecond after reflection the radiative cooling is strong enough to cause the end-wall pressure to decrease as much as 50% before increasing to its equilibrium value. The cooling also induces a velocity acceleration towards the wall and accelerates chemical and thermal relaxation. In the region immediately behind the shock wave the electron temperature is much lower than the heavy particle temperature, but even in the near equilibrium region next to the wall the electron temperature remains about two percent below the heavy particle temperature. Comparison calculations demonstrate that two temperature effects must be included to accurately predict end-wall pressure, radiative heat transfer, and radiative-gasdynamic coupling effects.