Computational study of the effect of cascade parameters on stall propagation in axial compressors

Propagating stall in a linear cascade of airfoils is simulated using a vortex tracking method. The novel features of this method are the use of periodic vortex arrays to simulate infinite cascades, the use of a vortex merging algorithm to allow computations for large times, the imposition of the no slip and the impenetrability boundary conditions in an integral sense, the use of integral boundary layer methods to locate the separation points and the use of Fourier analysis techniques to compute the velocities of the propagating stall. The role of the vortex merging algorithm is examined in some detail, and the recent improvements are discussed. A systematic parametric study is conducted within the stable ranges to extend the available results. Conclusions are drawn concerning the key parameter of interblade phase angle, or its surrogate the stall patch wavelength at a specified frequency.