Aerothermodynamic Analysis of Stardust Sample Return Capsule with Coupled Radiation and Ablation

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An aerothermodynamic analysis of the forebody aeroshell of the Stardust Sample Return Capsule is carried out using the axisymmetric viscous shock-layer (VSL) equations with and without fully coupled radiation and ablation. Formulation of the VSL equations with shoulder radius as the length scale and implementation of the Vigneron pressure condition allow resolution of the flowfield over the shoulder. With a predominantly supersonic outflow over the shoulder, a globally iterated solution of VSL equations can be obtained. The stagnation-point results are obtained along a specified trajectory, whereas detailed calculations along the body are provided at the peak heating point. The coupled laminar and turbulent flow solutions with radiation and ablation are obtained using the equilibrium flow chemistry, whereas a nonequilibrium chemistry model is used for solutions without ablation and turbulence. The equilibrium calculations are physically consistent and a practical way to conserve surface (and flow-field) elemental composition for the current small ablation injection rates, where the surface elemtal composition is a mixture of freestream and ablator elements. A maximum stagnation heating of about 1100 W/cm2 is obtained for the no ablation injection case with nonequilibrium flow chemistry and an equilibrium catalytic wall boundary condition. The corresponding radiative quilibrium flow chemistry and an equilibrium catalytic wall boundary condition. The corresponding radiative quilibrium wall temperature is about 3800 K. A similar stagnation heating value is obtained with equilibrium flow chemistry. With ablation injection, this value is reduced by about 35 percent. Reduction in heating due to ablation is slightly less downstream of the stagnation point, along the conical flank, and over the shoulder. For the ablation injection and turbulent flow solutions, with instantaneous transition just downstream of the stagnation line, the heating is reduced by only about 13 percent on the conical flank and shoulder from a non-ablating laminar solution. The reduction in heating by ablation injection appears to be partially offset by augmentation due to turbulence in this case.