The atmospheric entry of ballistic spacecrafts causes hypersonic shock layers of extreme temperatures due to compression of gases. Defence systems make use of the heated vehicle to identify and trace it by the optical signature. Especially due to civil space research, basic phenomena and effects are well known. Hence, high temperatures such as they appear in hypersonic shock layer during atmospheric entry cause significant radiation heat flux and chemical reaction in equilibrium and nonequilibrium. Gradients within the shock layer are extreme and the radiation heat flux might effect the fluid flow computation. To relate characteristics, generic scenarios are investigated using numerical methods. By applying these methods the effect of coupling between fluid flow and radiation computation are analyzed for the emittance of the vehicle. The coupling procedure is realized through the radiation divergence heat flux. For the fluid flow computation an Euler-boundary-layer method in chemical equilibrium and nonequilibrium is used. Here, the divergence heat flux is included into the governing energy equation of the flow solver. For the computation of the radiation transport a fully three dimensional Photon-Monte-Carlo method and a one dimensional approximation is implemented. Procedures to enhance numerical efficiency such as spectral binning and nonphysical random number relations are introduced and applied. Furthermore, the use of the GPU device for ray tracing is discussed. For spectral modeling the databases PARADE and HITRAN are applied within this investigation. A discussion of the numerical methods with focus on these developed within this investigation is concluded based on the Fire II flight experiment. For the investigation of a ballistic reentry vehicle, a generic test geometry is used and analyzed for three characteristic reentry trajectories. In the first place, one flight point is documented in detail as an example. Furthermore, many flight points are analyzed through the reentry trajectory. The focus of this investigation is the intrinsic emittance radiation of the vehicle, which suits the analysis of coupling effects. It is demonstrated in this investigation that the coupling effect is small for the emittance of the entry vehicle, but the effect of chemical nonequilibrium is significant. The emittance of the entry vehicle is dominated by the black body emittance of the heated solid wall. In addition, it is important to distinguish between heat flux and heat flux per area. The heat flux per area is large in the nose region. However, the heat flux is greater in the shoulder region of the reentry vehicle, due to the area of emittance.    «

The atmospheric entry of ballistic spacecrafts causes hypersonic shock layers of extreme temperatures due to compression of gases. Defence systems make use of the heated vehicle to identify and trace it by the optical signature. Especially due to civil space research, basic phenomena and effects are well known. Hence, high temperatures such as they appear in hypersonic shock layer during atmospheric entry cause significant radiation heat flux and chemical reaction in equilibrium and nonequilibri...    »