Problem: The Capsule Parachute Assembly System (CPAS) is used to decelerate the Orion Multi-Purpose Crew Vehicle (MPCV) crew module (CM) for landing during entry. The subsonic/transonic wake of the CM during heatshield forward descent interacts directly with the CPAS and is a critical factor that must be accounted for in the CPAS design. The aerodynamic character of the CM wake can have a significant impact on the deployment sequence and performance of the parachutes. Computational fluid dynamics (CFD) simulations play a key role in predicting the aerodynamic behavior of the wake since wind tunnel testing of CPAS concepts and configurations is costly and limited. However, below Mach 1, CFD prediction of the MPCV wake flow is questionable and thus leads to conservative design decisions. As a result, CPAS component designs can be oversized to account for uncertainty in the CFD-derived wake aerodynamics.[image-62]
NESC Contribution: The NESC team is sponsoring an ambitious wind tunnel test at the ARC Unitary Plan Wind Tunnel to acquire detailed wake flow measurements behind a capsule model. The test will use particle image velocimetry in concert with more conventional test techniques to acquire high-fidelity unsteady flowfield data in the capsule wake. These data will be used to characterize the flowfield behind MPCV-class vehicles and as validation data for the CFD simulations used in the CPAS design. In addition to ARC, this study relies on multiple NASA Centers, including LaRC, JSC, and KSC, to assist in test formulation, model design and fabrication, and data acquisition and analysis. The model is being designed as a generic capsule so the data will be broadly available to the engineering community. The team is also collaborating with the Aeronautics Research Mission Directorate (ARMD) to supply data that can be used for advanced CFD method development sponsored by the ARMD.
Result: Initial results are expected in 2012 with initial report to stakeholders at that time.