Error Estimates of the Ares I Computed Turbulent Ascent Longitudinal Aerodynamic Analysis

摘要

Numerical predictions of the longitudinal aerodynamic characteristics for the Ares I class of vehicles along with the associated error estimates derived from an iterative convergence approach using a coarse, base, and fine grid levels are presented. Computational results are obtained from an unstructured grid, Reynolds-averaged Navier-Stokes analysis. The error estimates, based on an extrapolated infinite-size grid, is derived from two consecutive grid levels. The validity of this procedure was first demonstrated on a model at representative ascent flow conditions for which the wind-tunnel data existed. Such analysis at M = 0.9 revealed a maximum deviation of about 23% between the computed longitudinal aerodynamic coefficients with the base grid and the measured data across the entire roll angles. This maximum deviation from the wind-tunnel data was associated with the computed normal force coefficient at M = 0.9 and was reduced to approximately 16% based on the infinite-size grid. However, all the computed aerodynamic coefficients with the base grid at the supersonic flow conditions showed a maximum deviation of only about ±8% with that level being improved to approximately ±5% for the infinite-size grid. The results and the error estimates based on the established procedure are also presented for the flight flow conditions.