Behaviour of turbulent Prandtl/Schmidt number in compressible mixing layer

Abstract

The behaviour of turbulent Prandtl/Schmidt number is explored through the model-free simulation results. It has been observed that compressibility affects the Reynolds scalar flux vectors. Reduced peak values are also observed for compressible convective Mach number mixing layer as compared with the incompressible convective Mach number counterpart, indicating a reduction in the mixing of enthalpy and species. Pr t and Sc t variations also indicate a reduction in mixing. It is observed that unlike the incompressible case, it is difficult to assign a constant value to these numbers due to their continuous variation in space. Modelling of Pr t and Sc t would be necessary to cater for this continuous spatial variation. However, the turbulent Lewis number is evaluated to be near unity for the compressible case, making it necessary to model only one of the Pr t and Sc t. .

Numerical Simulations of Static Tested Ramjet Dump Combustor

“…A few researchers [32][33][34][35] have suggested use of complicated additional transport equations for the modeling of turbulent Prandtl/Schmidt numbers in the propulsive flows. The researchers [36] have carried out model free simulations for compressible and incompressible mixing layers and shown that the turbulent Prandtl/Schmidt numbers do not vary significantly for incompressible cases while observing a continuous variation of these numbers in compressible cases. Many numerical studies [37][38][39] carried out for subsonic combustor performance, have also shown that assumption of constant turbulent Prandtl/Schmidt numbers can give good prediction of the flow variables.…”