A simulation protocol has been developed for modeling rocket plumes of heavy lift launch vehicles (HLLV) during ascent. The procedure uses a series of sensitivity studies applied to the Saturn V launch vehicle to establish accurate plume physics modeling of HLLV main engines. These analyses include a comparison of calorically and thermally perfect gas models, a grid dependence study, a sensitivity analysis of nozzle exit boundary conditions for both single and multi-species gas assumptions, and a thorough turbulence model sensitivity study. The results of the analyses are assessed by comparing the predicted plume induced flow separation (PIFS) distance, an important quantity for thermal protection system design. This quantity is also used to validate the results with existing flight data. The viscous Computational Fluid Dynamics (CFD) code OVERFLOW, a Reynolds Averaged Navier-Stokes flow solver for structured overset grids is utilized. This work is a continuation of the CFD best practices for Ares V aero-database simulation, 1 with the additional complexity of plume physics modeling.
An engineering approach is presented for database generation of aerodynamic force and moment coefficients on Solid Rocket Boosters (SRBs) during separation from a Heavy Lift Launch Vehicle. The approach balances accuracy and affordability by generating a steadystate database of solutions using the inviscid flow solver Cart3D with adjoint based adaptive mesh refinement. The procedure also includes point checking the database using the viscous Reynolds Averaged Navier-Stokes solver OVERFLOW. The simulation matrix consists of 3 degrees of freedom by planar translation and rotation of the SRBs from their original attached positions. Good agreement with viscous multi-species simulations has confirmed that the single-species inviscid assumptions are valid for this plume impingement flow. The database provides axial forces, side forces, and yaw moments on the SRBs during separation from the core. This data is to be used for vehicle and trajectory planning to avoid re-contacting the core. Nomenclature β Rotation angle (degrees) HLLV Heavy Lift Launch Vehicle γ Ratio of specific heats M Mach number ∆x Translation downstream (normalized) P Pressure (Pa) ∆y Translation cross-stream (normalized) SRB Solid Rocket Booster ρ Density (kg/m 3) V Velocity (m/s) A Area of nozzle cross-section (m 2) c Speed of sound (m/s) CA Axial force coefficient CG Center of Gravity CLN Yaw moment coefficient CY Side force coefficient F&M Force and Moment
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