Stability of a Non-Orthogonal Stagnation Flow to Three Dimensional Disturbances
Abstract
A similarity solution for a low Mach number non-orthogonal flow impinging on a hot or cold plate is presented. For the constant density case, it is known that the stagnation point shifts in the direction of the incoming flow and that this shift increase as the angle of attck decreases. When the effects of density variations are included, a critical plate temperature exists; above this temperature the stagnation point shifts away from the incoming stream as the angle is decreased. This flow field is believed to have applications to the reattachment zone of certain separated flows or to a lifting body at a high angle of attack. Stability characteristics of the flow are given as a function of the parameters of this study: ratio of the plate temperature to that of the outer potential flow and angle of attack. In particular, it is shown that the angle of attack can be scaled out by a suitable definition of an equivalent wavenumber and temporal growth rate, an the stability problem for the non- orthogonal case is identical to the stability problem for the orthogonal case. By use of this scaling, it can be shown that decreasing the angle of attack decreases the wavenumber and the magnitude of the temporal decay rate, thus making nonlinear effects important. For small wavenumbers it is shown that cooling the plate decreases the temporal decay of the least stable mode, while heating the plate has the opposite effect. For moderate to large wavenumbers, density variations have little effect except that there exists a range of cool plate temperatures for which these disturbances are extremely stable.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1991
- Accession Number
- ADA239522
Entities
People
- D. G. Lasseigne
- T. L. Jackson