A combined experimental and analytical investigation of the vortex stability over sharp-edged slender bodies

摘要

A combined experimental and analytical investigation is conducted to assess the stability of the symmetric vortex pair over three different sharp-edged slender bodies at high angles of attack. The analysis is based on a previously developed eigenvalue stability method. Corresponding experimental studies involving flow visualization in the water tunnel, force and pressure measurement in the wind tunnel are carried out. The angles of attack tested range from 15 degrees to 40 degrees. Overall, the experiments confirm the stability behaviors as determined from the analysis. The analytical solutions indicate that an absolute type of instability is the mechanism for the breakdown of symmetry of the vortex flow over slender conical bodies at high angles of attack. Both the experiments and the analysis reveal that a sharp-edged slender body with a smaller volume on the leeward side and a bigger volume on the windward side increases the overall stability of the symmetric vortex pair. A shape with extended sharp edges in the outboard direction on its sides further enhances the stability of the vortex pair. The analytical method can be a useful tool for exploring shapes that favor stability or instability. (C) 2007 American Institute of Physics.