Investigation of steady and unsteady flow characteristics of space transport system during separation

Analysis of the steady and unsteady stage separation flow features of two-stage space transport system is performed. Two carrier stage models are used, namely a flat plate for simplifying interference effects and a fully detailed vehicle (ELAC). In both cases the orbital stage consists of a detailed configuration (EOS). The flow solutions are obtained by solving the unsteady Euler and Navier-Stokes equations using the explicit finite volume shock capturing method with the modified AUSM approach for convective flux evaluation. The simulations are performed on structured multi-block grids with elliptic grid smoothing based on the Poisson equations. Flowfield patterns demonstrating strong interference effects due to incident and reflected shock waves and expansion fans as well as corresponding surface pressure distribution and aerodynamic forces and moments of carrier and orbital stages are analyzed. From the steady case solutions for both configurations, very good agreement is found comparing numerical and corresponding experimental results. The unsteady results explain that unsteadiness must be carefully considered in the beginning of the separation manoeuvre when the orbital stage lift decreases.