Unstructured rotor-stator analysis of axial turbomachinery using a pressure based method

An implicit, unstructured, parallel CFD formulation is presented for the analysis of multistage turbomachinery flow fields. The differential model employed is the compressible Reynolds averaged Navier-Stokes equations. A cell-centered finite-volume pressure based scheme is employed. The use of hybrid unstructured grids, second order discretization numerics and an interface sliding algorithm enable efficient and accurate resolution of wake decay and wake-blade interaction physics. Specifically, stationary-rotating reference frame interfaces can be easily placed very close to the leading edge of downstream blade rows. Also, a large number of elements can be used to resolve the wake and down-stream blade inlet regions without an attendant increase in the total number of elements associated with block and overset structured mesh schemes. In this paper, details of the CFD formulation and physical modeling are first summarized, with emphasis placed on unstructured, rotor-stator and parallel processing elements. Results are presented for the analyses of a single stage axial turbine and a single stage axial pump, both of which have been the subject of numerous experimental and computational studies.