Active Control of Separated Flow over a Bump Under Unsteady and Turbulent Conditions
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Low-pressure turbines (LPT) encounter laminar and/or turbulent boundary layer separation during operation in a low-Reynolds regime [1,2]. This phenomenon is frequently analyzed using a wall-bounded bump geometry, which simulates the suction side of LPT blades. Separated flow leads to adverse effects on aerodynamics and performance, prompting the exploration of flow control strategies aimed at reducing the size of the separated flow region to enhance efficiency[3]. This study investigates laminar and turbulent separation over a wall-bounded bump geometry. Direct Numerical Simulations (DNS) results are examined to unveil the impact of harmonic inflow and flow actuations with zero-net-mass-flow. Three distinct scenarios involving KH-instability and/or vortex clusters are revealed. Furthermore, turbulent boundary layer separation is explored using wall-modeled large-eddy simulations (WMLES) to comprehend the influence of pressure gradient and freestream turbulence on the separation region with aim for active control strategies.
