Unsteady Rotor/Stator Interaction: An Improved Unstructured Approach

Abstract

A full-3D unstructured solver based on an upwind TVD finite volume scheme is developed and applied to the simulation of an unsteady turbine stage. Two different approaches are considered for the time accurate inviscid simulation of the unsteady stator/rotor interaction. The first consists of a classical explicit time accurate multi-step Runge-Kutta scheme. The second is based on a dual-time stepping strategy, which exploits the implicit time-marching Newton-Krylov method. In this case the linear solver of the implicit scheme consists of a preconditioned GMRES and ILU(0) incomplete factorisation. Both the explicit and implicit approaches are designed to run on parallel cluster of workstations. The development of the numerical strategy is discussed with particular concern on the validation of the unsteady model through a comparison against experiments, NISRE approach and a 3D steady stage computation. The results compare favourably with a set of time averaged and unsteady experimental data available for the turbine stage under investigation, which is representative of a wide class of aero-engines. Both the accuracy of the solver and the capability of the computational model are discussed.