Instantaneous performance of turbines in severe transient operation: a fundamental approach
Pulsed flows in turbines have many industrial applications. However, the influence of pulsed flow on turbine performance is complex and imperfectly understood. There is no evident consensus in the literature regarding generic trends. Those are difficult to extract since a majority of studies are based on industrial geometries (mainly turbocharging radial turbines), which involve strong interactions between many physical phenomena. In order to isolate and understand the main expression of the physics, the problem needs further simplifications, and a clear assessment of the relevant time scales of the problem together with performance indicators fit for unsteady flows. The seminar proposes a review of the research conducted on that purpose at ISAE-SUPAERO which led to consider the academic case of a severe transient regime inside a thin airfoil cascade, caused by a sudden change of inlet conditions. Simulations with increasing complexity (from 1D Euler, to 3D LES) are deployed in order to isolate the driving mechanisms.