Modeling of Unsteady Flow Effects in Throughflow Calculations

Abstract: In this work an evaluation of a deterministic stress transport model and a linearized Navier-Stokes harmonic approach for including unsteady effects in the steady mixing-plane computations of a multistage transonic compressor has been performed. The results of these two models are compared with those of time-average time-accurate solutions. The transport model for the deterministic stress terms (DST) was developed in the same manner as Wall(99), and the harmonic approach follows the work of Ning(98), He(98) and Chen(00). The harmonic approach accurately predicts the desired DST terms, while the transport model is shown to have some numerical problems close to solid walls, where the production of the deterministic stress is very high due to large gradients. Therefore the dissipation model is probably inaccurate . The harmonic approach also has the advantage of providing the periodic time variations as a result, and with some additional development also the ability to include clocking effects and noise predictions.