Application of Lifting Line Theory to Streamsurface Theory in Subsonic Flow

The paper shows that the streamsurface theory does not take account of the effect of the trailing vorticity on the performance of a subsonic rotor. Based on the S₂-streamsurface, an equation for the perturbations in velocity induced by the trailing vorticity is derived. Numerical examples for the change in the total pressure behind an annular rotating cascade in a circumferentially sinusoidal inlet flow are given in the assumptions of lifting line theory. The results agree quite well with Henderson’s data. Also, the calculated results are given for the conditions of nonuniform circulation along the span. Compared with existing results, the results of the present paper are reasonable. The conclusion is that the perturbation equation presented can be applied as an additional consideration when the design is based on the streamsurface theory.