Assessment of CFD-based Response Surface Model for Ares I Supersonic Ascent Aerodynamics

摘要

During a design analysis cycle for the Ares I Crew Launch Vehicle, a wind tunnel mishap in the Unitary Plan Wind Tunnel at NASA Langley Research Center delayed delivery of the ascent aerodynamics database for supersonic Mach numbers above 1.6. An interim ascent database based on computational simulations was developed to mitigate the impact of the delay. The Ares I aerodynamics team built the interim database using radial basis functions to model the aerodynamic coefficients based on the computational data and extensive knowledge from databases for previous Ares I designs. The team also estimated the computationally based database uncertainty using data available at the time of development. The ascent database was updated based on the wind tunnel results after the test was completed, and the team assessed the quality of the computationally based database, both qualitatively and quantitatively, relative to the final experimentally based database. The computationally based database closely matched the general behavior of the experimentally based database, and the estimated uncertainty intervals for the computationally based database contained nearly all of the experimentally based database data. This assessment confirms that a reasonable aerodynamic database for launch vehicles at supersonic conditions can be constructed using only computational data, provided that sufficient knowledge of the physics and expected behavior is available. The assessment also demonstrates that nonparametric response surface models can adequately model complex aerodynamic behavior throughout a large data space.