TPSAS-NF1676L-14816-DND
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Engineering topics
Publications and source records attributed to David P. Lockard.
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Version 2.1ae of the NASA CFD code OVERFLOW has been used to simulate the flow past tandem cylinders. The multiblock grid system consisted of 15 overset meshes with a total grid count of 15.7 million points. The grid extended 3 cylinder diameters in the spanwise direction with periodic boundary conditions at the ends. Riemann conditions were used at the outer boundaries, and a no-slip condition on the cylinder surfaces. The 3rd order HLLC upwind spatial discretization scheme was used with a dual-time stepping algorithm. A modified version of the Delayed Detached Eddy Simulation hybrid RANS/LES turbulence model proposed by Spalart was used in a fully turbulent mode. The code was run on 53 Core 2 Duo nodes using MPI across nodes and OPENMP within each node. Simulation results will be compared with the available experimental data.
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Numerical simulations have been performed for a conventional high-lift version of the Common Research Model (CRM) model corresponding to landing and take- off configurations. Computed values of lift and drag for the landing configuration are compared with the experimental data acquired in the 14- by 22-Foot Subsonic Tunnel (14×22) at the NASA Langley Research Center (LaRC). Simulations replicated the experimentally observed improvements in the lift characteristics in the presence of a nacelle chine. Flow visualization images indicate that vortices generated by the nacelle chine reduce flow separation regions on the upper surface of the wing at higher angles of attack. Based on such observations, the take-off configuration considered is also equipped with a nacelle chine, and testing of this configuration is planned in the 14×22 tunnel in near future. Preliminary solutions are also presented to explore the feasibility of using a localized flap gap blowing (LFGB) active flow control concept for improving the aerodynamic performance at take-off conditions.