Assessment of a body force representation for compressor stability estimation

Abstract

This thesis presents a methodology for the integration of blade row body forces, derived from axisymmetric and three- dimensional flow fields, for use in the stability analysis of axial compressors. The body force database represents the body forces as a function of the local flow coefficient times the overall flow coefficient; doing this overcomes a source of non-uniqueness in the representation. Stability calculations using body force databases from this methodology as well as from a legacy method, applied to axisymmetric streamline curvature calculations, are compared. A procedure for joining body forces extracted from axisymmetric and three-dimensional CFD calculations is presented along with an assessment of the sensitivity of the stall prediction and onset behavior to the shape of the body force curves. The slope of the body force curves near the point corresponding to peak pressure rise, as well as those near zero flow, are found to be important in determining the stall point and inception type. Comparisons to previous work and test data from a single stage research compressor are made.