A Model to Predict Stall Inception of Axial Flow Fan / Compressors with Annular Duct

摘要

A three dimensional compressible flow stability model is presented in this paper, which focus on multi-stage axial flow compressors with a finite large radius annular duct configuration. It is shown that under some assumption the perturbation field is described by linearized Euler equations, which can be solved by mode decomposing plus appropriate boundary condition. Further by using the mode-matching technique and applying the conservation law and conditions reflecting the loss characteristics of a compressor at the two sides of rotors and stators modeled as a series of actuator disks, a group of homogeneous equations will yield from which the stability equation can be obtained. After solving the eigenvalue problem by collocation method, the stability can be judged by the nondimensional imaginary part of the resultant complex frequency eigenvalue. Finally, two numerical evaluation cases are conducted to validate this model.