CFD Simulations of the Space Launch System Ascent Aerodynamics and Booster Separation

Abstract

This paper presents details of Computational Fluid Dynamic modeling of the Space Launch System during ascent. The primary focus of the paper is the flow simulation of the vehicle during ascent using the Overflow Navier-Stokes code. Computations of 739 first-stage flight conditions covering a range of Mach numbers, angles of attack, and roll angles were computed. The overset grid system contained 375 million grid points, and over 28 million CPU hours were used in the simulations. The simulations were run on the Pleiades supercomputer at the NASA Advanced Supercomputer Center at Ames Research Center. The data products from this work include integrated line-loads, surface pressure coefficients, venting pressures, and protuberance air-loads. Detailed comparisons were made of the aerodynamic performance predicted by Overflow and the wind-tunnel derived aerodynamic database. A small number of the cases were run with two different turbulence models and with two differencing schemes. These results were used to quantify the sensitivity to the choice of the turbulence model and to the differencing scheme. The paper also introduces an effort to use the inviscid, unstructured Cartesian solver Cart3D to compute the aerodynamics during booster separation. Adaptive mesh refinement is being used to enable accurate simulations of sixteen booster-separation-motor plumes. The use of this tool is explored in preparation for building a booster-separation aerodynamic database.

Output-Based Adaptive Meshing Applied to Space Launch System Booster Separation Analysis

“…The Overset grid system was a derivative of that used in recent work to assess the protuberance loads during ascent [10]. For the current simulations, this grid system was modified by removing all of the smaller protuberances-a process made relatively easy by the overset grid approach.…”

Three-dimensional fluid-structure interaction simulations of a yarn subjected to the main nozzle flow of an air-jet weaving loom using a Chimera technique

“…Such simulations are difficult to implement using a single deforming grid as the motion of the yarn would require the simultaneous use of mesh deformation, layering and sliding interfaces. 27 ). The Chimera technique has often been applied in the CFD study of high-lift devices (Rogers et al 28 , Liao, Cai and Tsai 29 , Levesque, Pigeon and Deloze 30 ) and, more recently, for windturbine simulations (Santo et al.…”

Fast deterministic solution of the full Boltzmann equation on graphics processing units

“…We further increased the size of phase space to billion grid points. Table (4) shows the performance of the solver on 14 and 12 nodes. The largest case requires nearly 100 trillion floating point calculations at every timestep.…”

“…For numerical simulations of flow behavior, the Navier-Stokes (NS) equations [2] are widely used. For aerospace applications in particular, NS have been used in simulating flow phenomenon in early 90's space-shuttle missions [3], as well as the recent deep-space Space Launch System (SLS) launch vehicles [4]. Yet, the Navier-Stokes fails when it comes to simulation of flow in low density environment, for instance, the atmospheric re-entry at high altitudes, as well as the flows in micro-geometries such as blood vessels.…”