| This thesis is aimed at improved understanding of unsteady turbomachinery flow physics using time-accurate computational fluid dynamics (CFD) techniques. Two pressure-based algorithms have been adapted for the numerical computation of turbulent, two and three-dimensional, steady and unsteady flows through turbomachinery. The differential model employed is the incompressible Reynolds averaged Navier-Stokes equations. In this work, several new and/or modern techniques have been adapted, implemented, and applied. These include higher order accurate structured and hybrid unstructured discretization, an inlet wake passing strategy, an interface sliding technique for the computation of rotor-stator interactions, parallel processing capability and full-two-fluid modeling for multiphase flow analysis. The methods are employed in the analysis of several unsteady turbomachinery flows. These results are presented, compared with experimental data and interpreted, elucidating several important intrinsically unsteady physics in these machines.; Details of the physical and numerical modeling strategies of these algorithms are presented, with emphasis placed on new contributions. Specifically, details of the wake passing and rotor-stator interaction schemes are treated, as are details of the discretization practices, structured and unstructured grid generation strategies, multiphase flow analysis treatments, and parallel processing implementation.; Several unsteady turbomachinery test cases are computed and compared with available experimental data. These results illustrate the effectiveness and generality of the schemes developed, and elucidate important, unsteady physics in the machines considered: First, the unsteady flow field through a second stage stator of a two-stage compressor is carried out with the inlet wake passing strategy. The effects of rotor-stator blade row spacing and the rotor/stator blade count ratio on the turbomachinery unsteady flows are investigated. It is found that a decrease in the rotor-stator blade row spacing causes more decay of the upstream wake and leads to increases in the unsteady pressure fluctuations on the blade surface. The nonlinear effects and variations in the harmonic content are captured by the Navier-Stokes code. Loss mechanisms are evaluated. They include: (1) losses due to the decay of the wake upstream of the blade row; (2) losses due to the decay of the wake inside the stator passage, including modification of the wake profile by the stator pressure field; and (3) the blade profile losses, which are affected by the passing of the inlet wake. (Abstract shortened by UMI.)... |
