10th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The temporal behavior of a flow separation in the hub-suction side corner of a transonic diffuser is studied thanks to unsteady numerical simulations based on the phase-lagged approach. The validity of the numerical results is confirmed by comparison with experimental unsteady pressure measurements. An analysis of the instantaneous skin-friction pattern and particles trajectories is presented, and highlights the structure of the separation and its temporal behavior. The location of the separation is found to be fixed, in spite of the strongly unsteady flow at diffuser inlet, and corresponds to the one predicted by the steady-state numerical simulations. It can justify the development of a control strategy from steady-state simulations.