Evaluation of Computational Modeling of Electron Transpiration Cooling at High Enthalpies

Amodeling approach for electron transpiration cooling of high-enthalpy flight is evaluated through comparison to a set of experiments performed in a plasma arc tunnel for air and argon. The comparisons include air and argon flow at high enthalpies (27.9 and 11.6 MJ/kg, respectively), with a Mach number of 2.5 to 3. The conversion of the reported enthalpies and Mach numbers to freestream temperatures and velocities is discussed. The numerical approach is described, including implementation of a thermionic emission boundary condition and an electric field model. Also described is the implementation of a finite-rate chemistry model for argon ionization. Materials with different electron emission properties are also investigated, including graphite and tungsten. The comparisons include two different geometries with different leading-edge radii. The numerical results produce a wide range of emitted current due to the uncertainties in freestream conditions and emissive material properties, but they still agree well with the experimental measurements.