Pressure-based Coupled Simulation of Pressure Recovery and Distortion in an S-Duct

Abstract

The problem of a compressible flow through an S-shaped compact offset intake diffuser is studied computationally using the general purpose CFD code ANSYS Fluent. Steady-state converged solutions are calculated using second-order upwind discretizations. A hierarchy of four computational meshes, one unstructured and three block-structured, is applied to evaluate grid independence. The near-wall resolution in all four meshes is fine enough to resolve the viscosity-affected near-wall region all the way to the laminar sublayer. Performance of four turbulence RANS models are compared: Spalart-Allmaras, SST k-, Realizable k-, and Reynolds Stress model with low-Re stress-omega formulation of the pressure-strain term. Numerical predictions of total pressure recovery and pressure distortion are compared with the experimental data. An excellent agreement is presented for pressure recovery, and favorable agreement is found in the prediction of distortion. An additional configuration of the S-duct model incorporating test probes is considered to evaluate the effects of experimental instrumentation at the Aerodynamic Interface Plane (AIP) on predicting distortion.