A solution on the F-18C for store separation simulation using Cobalt(60)

A demonstration is presented of the ability of Computational Fluid Dynamics (CFD) methods to predict store carriage loads and support store trajectory generation. A complete, complex aircraft, the F/A- 18C, was modeled with actual stores in their carriage positions. Cobalt,, a parallel, implicit unstructured flow solver was used to calculate the flow field and resultant aerodynamic loads on grids composed of tetrahedral cells. Three grids were used to simulate three different flow field approximations. The first grid was a purely inviscid grid containing 3.15 million cells. The second grid was made up of 3.96 million cells clustered to capture viscous effects on only the store components. The third grid was a full viscous grid containing 6.62 million cells. Store carriage loads for two flight conditions were calculated and compared with wind-tunnel measurements and flight-test data for each of the above grids. The resulting carriage loads were used in a separate six degree-of-freedom (6DOF) rigid-body motion code to generate store trajectories. All CFD solutions were second-order accurate and run to steady-state with CFL numbers of one million. Turnaround times ranged from 6 to 21 hours, depending on the number of processors used.