Study of Turbulence-Radiation Interaction in Hypersonic Turbulent Boundary Layers

Direct numerical simulations are conducted to investigate the effect of turbulence–radiation interaction in hypersonic turbulent boundary layers, representative of the Orion crew exploration vehicle at the peak heating condition during reentry. Both the effects of emission and absorption are considered by solving the radiative transfer equation using the tangent slab approximation and a spectral model with line-by-line accuracy. Nondimensional governing parameters to measure the significance of turbulence–radiation interaction are proposed, and the direct numerical simulation fields with and without radiation coupling are used to assess turbulence–radiation interaction. Is it found that the fluid medium within the boundary layer is optically thick with local emission largely counterbalancedby the absorbed irradiation, which results inmuchweaker overall radiative source termr qR, and the thermal radiation has minimal backward influence on the turbulence flowfield. In addition, both the uncoupled and coupled results show that there is no sizable interaction between turbulence and radiation at the hypersonic environment under investigation. An explanation for small turbulence–radiation interaction intensity is also provided. Nomenclature A = total absorption,W=m3 H = shape factor, =, dimensionless h = specific enthalpy, J=kg M = Mach number, dimensionless n = number density, m3 q = turbulence kinetic energy, u02 v02 w02=2, m2=s2 qR = radiative heat flux,W=m 3 Re = Reynolds number, u=, dimensionless Re2 = Reynolds number, u=w, dimensionless