A decoupled procedure for convection-radiation simulation in scramjets

Following an order analysis of key parameters, a decoupled procedure for simulation of convection-radiation heat transfer problems in supersonic combustion ramjet(scramjet) engine was developed. The radiation module of the procedure consisted of Perry 5GG weighted sum gray gases model for spectral property calculation and discrete ordinates method S4 scheme for radiative transfer computation, while the flow field was computed using the Favrè average conservative Navier-Stokes(N-S) equations, in conjunction with Menter's k-ω SST two-equation model. A series of 2D supersonic nonreactive turbulent channel flows of radiative participants with selective parameters were simulated for validation purpose. Radiative characteristics in DLR hydrogen fueled and NASA SCHOLAR ethylene fueled scramjets were numerically studied using the developed procedure. The results indicated that the variations of spatial distributions of the radiative source and total absorption coefficient are highly consistent with those of the temperature and radiative participants, while the spatial distribution of the incident radiation spreads wider. It also demonstrated that the convective heating is significantly affected by the complexity of the flow field, such as the shock wave/boundary layer interactions, while the radiative heating is simply an integral effect of the whole flow field. Although the radiative heating in the combustion chambers reaches a certain level, an order of magnitude of 10 k W/m2, it still contributes little to the total heat transfer(<7%).