Thin-Layer Navier-Stokes Solutions of the Asymmetric Vortical Flow on a Tangent Ogive Body.

摘要

Laminar solutions for asymmetric vortical flow on a five caliber tangent ogive with an eight caliber cylindrical afterbody were calculated with a thin-layer Navier-Stokes code on a one block algebraic grid. Solutions were obtained for Mach 1.4 at 25, 30, 37.5, 38.5 and 40 deg angle of attack. The Reynolds number for all cases was 200,000 based on maximum body diameter. Two-dimensional particle traces in cross-sections of the flow and the limiting streamlines were calculated from the solutions. Validity of the thin-layer approximation in the flow field far away from the boundary layer was studied by recomputing the 37.5 deg case with the viscosity turned off at a distance away from the body. The solution was not significantly different, indicating that the outer vortex flow is basically inviscid. Both symmetric and asymmetric cases were calculated and analyzed. Secondary flow was shown in detail. Secondary flow increased with angle of attack. Crossflow topology diagrams were given in detail for symmetric and asymmetric conditions to illustrate the fundamental difference between these conditions. According to this research, asymmetry was characterized by the change in the topological structure near the saddle point associated with the primary vortices. Creation of vortex, by pinching of another vortex, was found to occur. This phenomenon was observed in both primary and secondary flow. (edc)