The spectral radiative transfer problem for a supersonic gas flow with suspended particles at the front surface of a blunt body is solved using the combined two-step model based on transport approximation for the scattering phase function. The particle laden flow is calculated taking into account both dynamic and temperature non-equilibrium of micron-sized particles suspended in the carrier gas. A computational study of the problem showed that the effect of collisions between polydisperse particles including those reflected from the body is significant for both the flow field of particles behind the shock wave and the radiative heat transfer. At the same time, one can use a monodisperse approximation instead of complete calculations to estimate both the radiation flux and equilibrium temperature of the body surface. (C) 2015 Elsevier Ltd. All rights reserved.