Modeling scramjet flows with variable turbulent Prandtl and Schmidt numbers

A complete turbulence model is presented in which the turbulent Prandtl and Schmidt numbers are calculated as part of the solution and in which averages involving chemical source terms are modeled. The model avoids the use of assumed or evolution probability distribution functions and thus results in a highly efficient algorithm for reacting flows. The predictions from the model are compared with two sets of experiments involving supersonic mixing and one involving supersonic combustion. Two sets of H-2/air chemical kinetic mechanisms are considered: one involving 7 species and 7 reactions, the other involving 9 species and 19 reactions, with reaction rates being dependent on both pressure and temperature. The results demonstrate the need for consideration of turbulence/chemistry interactions in supersonic combustion. In general, good agreement with the experiment is indicated.