Criterion for Spanwise Spacing of Stall Cells

摘要

Based on the classical lifting-line theory, an explanation for the appearance of stall cells was provided. In addition, an analytical model for the prediction of the spanwise spacing of stall cells was postulated. The model prediction is in good agreement with measurements by Yon and Katz . Unfortunately, no other experimental dataset providing both the lift curve and the number of stall cells could be found in the literature, and further model validation has to wait until such data become available. Common to linear stability analysis, the present model considers small amplitude disturbances. Implicitly, the assumption is made that the stall cell spacing does not change as the amplitudes grow until a mean flow deformation sets in. Finally, the model predicts stall cells for all airfoils with a negative lift curve beyond the angle of attack for maximum lift (c_(l,max)). According to Broeren and Bragg, this may not be the case. Additional mechanisms may be at work that would have to be implemented into the present model to account for the observation by Broeren and Bragg.