Vortex Asymmetry Development on a Tangent Ogive,
NAVAL SURFACE WEAPONS CENTER SILVER SPRING MD
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A rigidly supported tangent ogive model has been tested in low turbulent, incompressible flow at an incidence of 45 deg. A constant streamwise Reynolds number of 1.5 105 was maintained which produced laminar boundary layer separation. The sharp nose tip was replaced in some tests with a 10 spherically blunted one. In the sharp nose experiments it was found necessary to stabilize the flow field by adding a small trip. Both unsteady surface pressures and flow field velocities in the crossflow plane were measured, the latter with a two component Laser Doppler Velocimeter. The flow field in the vicinity of the leeside of the model surface, including the primary separation region was examined in detail. Results indicate that the flow field generally features two secondary structures on each side of the model which contain vorticity of opposite sign. Asymmetry starts with the windward crossflow plane streamline from the primary saddle point, which detaches from the body. It appears to be completed when the crossflow plane focus of the shed vortex combines with the primary saddle point. The introduction of nose bluntness is not found to fundamentally change the leeward flow field, although it does significantly reduce the level of asymmetry and the side force magnitude.
- Fluid Mechanics