Turbine airfoils are known to suffer severe performance degradation at off-design conditions that can be mitigated by active flow control methodologies. In the present study, acoustic excitation is used to control the separation over such airfoils and different strategies are developed to determine flow and excitation parameters for optimum control of separation for varying airfoil shapes. These guidelines are developed based on detailed experimental campaign measuring surface pressure and velocity field around the airfoils.
Experiments are performed using an in-house low speed acoustic wind tunnel facility equipped with laser diagnostic techniques (PIV) and other relevant instrumentation (static
pressure probes, flow velocity meter and thermocouples). The excitation parameters (amplitude and frequency of global excitation), flow parameters (velocity) and shape of airfoils are individually varied. These experiments not only bring out the most favorable conditions but also enable us to uncover the flow mechanisms leading to desired modifications in airfoil performance.
