TIME-LINEARIZED AND HARMONIC BALANCE NAVIER-STOKES COMPUTATIONS OF A TRANSONIC FLOW OVER AN OSCILLATING BUMP

摘要

To predict onsets of aeroelastic instabilities in turbo machineries, as the unsteady flow is mainly periodic, linearized and harmonic-balance methods have been developed to reduce computational costs. Harmonic balance and time-linearized methods are evaluated in this work on shock-wave/boundary layer interaction over an oscillating bump in a transonic nozzle. The results are compared with experimental data obtained at Royal Institute of Technology (KTH, Sweden). Harmonic-balance calculations with Reynolds stress model and nonlinear unsteady RANS calculations with the revisited k-ω turbulence model of Wilcox show good agreement with experimental results. Time-linearized computations succeed in reproducing the URANS results when the turbulence model is fully derivated, whereas frozen turbulence assumption does not give satisfactory results to predict the aeroelastic stability.