A Numerical Study of Strake Aerodynamics.

As part of a combined experimental and analytical study of vortex shedding at sharp edges characteristic of strakes on fighter aircraft, numerical simulations were made of a two-dimensional and a three-dimensional case. The former is a sharp-edge flat plate normal to the flow, for which some experimental data were taken earlier in this program. The latter is a double-delta, sharp-edged wing at angle of attack. In both cases, a free-stream Mach number of 0.5 was used. The objective of the work was to investigate the suitability of using the numerical simulation to augment experimental flow field data, after the major features of the simulation were verified by data. Two existing Navier-Stokes codes developed at Ames Research Center NASA were used for the numerical simulations. Neither code had been used in an application involving flow separation, sharp edges, and the aggregation of vorticity into small regions in the flow such as the two present applications demonstrate. The applications of the codes were largely successful, in that for both applications the numerical flow fields generally reproduced the gross flow features exhibited by experimental data.