Advances in Space Launch System Booster Separation Computational Fluid Dynamics

The Space Launch System (SLS) employs two Space Shuttle-derived solid rocket boosters, which separate from the SLS core while still experiencing appreciable aerodynamic loads. Creating an aerodynamic database for this phase of flight can be challenging due to the large number of independent variables needed to fully constrain the problem and the complex flow induced by exhaust plumes of the booster separation motors and core main engines impinging on other parts of the vehicle. This paper details recent efforts in generating aerodynamic data used to create databases for the SLS during the booster separation event using viscous computational fluid dynamics (CFD) simulations obtained using NASA's FUN3D solver. Particular challenges faced when modeling a complex problem, such as booster separation, are presented. Reductions in interpolation error estimates were observed through the introduction of a physics-based covariance approach to building the CFD run matrix, eliminating infeasible booster location permutations that could potentially skew final response surfaces. Interpolation error control is shown using test cases outside of the main database. Code-to-code comparisons between the FUN3D and OVERFLOW solvers are also presented to further verify the results.