Computational Challenges in Simulating Powered Flight of the Orion Launch Abort Vehicle

Some of the simulation work performed by the computational aerosciences project under the NASA Constellation program is presented. The challenges of simulating the powered flight of the Orion launch abort vehicle for the purposes of building an aerodynamics database are discussed. During an abort this vehicle fires both a four-nozzle abort motor together with an eight-nozzle attitude control motor. The interactions of the jet plumes provide a significant challenge to the computational tools. A few of the computed results using overset grids and the Overflow solver are presented. Some very complex behavior in the jet plumes was observed, including asymmetric yaw-inducing plume interactions. The problem of jet-plume simulation was studied using a simpler jet-in-crossflow problem. A number of these simulations also produce asymmetric results for a completely symmetric problem. The results from the use of different turbulence models, different grid resolution, and various differencing schemes are presented for the jet-in-crossflow problem. All steadystate cases are shown to be asymmetric, while time-averaged solutions from time-accurate simulations are symmetric.