Experimental Investigations of Active Flow Control Using a Piezo Adaptive Blade in a Compressor Cascade Under Periodic Boundary Conditions with High Strouhal-Number

As a consequence of constant volume combustion in gas turbines, pressure waves are generated that propagate upstream the main flow into the compressor system are generated leading to incidence variations. Numerical and experimental investigations of stator vanes have shown that Active Flow Control by means of adaptive blade geometries is beneficial when such periodic incidence variations occur. A less susceptible to stall and choking for compressors dealing with periodic disturbances can be achieved. Experimental investigations with high Strouhal numbers using such a method have not yet been done in order to demonstrate the effects. Therefore, this work investigates a linear compressor cascade that is equipped with a piezo-adaptive blade structure utilizing macro-fiber-composite actuators. A throttling device is positioned downstream of the trailing edge to emulate an unsteady combustion process. Periodic transient throttling events with Strouhal numbers up to 0.144 were being investigated due to incidence changes. Consequently, pressure fluctuations on the blade’s surface occur, having a significant impact on the pressure recovery downstream of the stator cascade. Experimental results of harmonically actuating the piezo-adaptive blade with Strouhal numbers of up to 0.72 show that the impact of disturbances at resonance can be nearly reduced to zero. Therefore, the blade design must be matched to the type of disturbances to achieve further improvements in the technology.