Three-dimensional linear stability approach to transition on wings and bodies of revolution at incidence

The calculation of transition on an infinite swept wing at several angles of incidence for several sweep angles and on a body of revolution at one incidence is investigated with the e(n) method based on the eigenvalue formulation of Cebeci and Stewartson in which the relationship between the two wave numbers-alpha and beta are determined by making use of the saddle-point method. The method, which is based on the solution of the boundary-layer and Orr-Sommerfeld equations by a finite difference procedure, is evaluated in terms of measurements reported for the flow around a swept wing equipped with a cambered leading edge and attached to a half fuselage and for the flow around a prolate spheroid at 10-deg incidence. It is shown to be convenient to use, particularly because the neutral stability curves (zarfs) facilitate the calculation and avoid uncertainties associated with the choice of magnitude and location of the critical frequencies. In general, the calculated values of the onset of transition are in good agreement with measured values.