Effect of Multi-Layered Piezo Ceramic Actuator on Transonic Flow

An experimental study is done to check the influence of multi-layered piezoceramic actuator at the throat and downstream of transonic diffuser. The diffuser has circular arc upper wall and flat bottom wall where the piezo ceramic actuator is installed. The diffuser throat height h* is 3 mm and multi-layered piezoceramic actuator is driven at the frequency of 100–600 Hz at 90 V. Pressure ratio across the diffuser is set up from 1.1 to 1.6. Schlieren technique is used for flow visualization. The displacement of the piezoceramic actuator is 45micro meter for the supplied voltage of 120 V, which is quite small for the usual flow activation. As a result, even though the displacement of the piezoceramic actuator is invisible, the effect of the piezoceramic actuator on the throat pressure fluctuation is found to be clear. The rectangular input voltage signal causes the similar pressure fluctuation at the throat. And the dominant frequency of the throat pressure fluctuation corresponds to the input voltage signal. Moreover, its effect on the pressure fluctuation of the diffuser throat depends on the pressure ratio.