Compliant Wall Motion Effects on the Unsteady Surface Pressure in a Turbulent Boundary Layer

The study of flow-induced structural vibration involves detailed understanding of the unsteady surface pressure. The present study examines the effects of a compliant wall on the unsteady pressure in a turbulent boundary layer. The objective was to observe how the pressure spectra change due to a section of wall that is vibrating. Membranes with varied tension were fabricated and flush mounted to a rigid wall and placed in an anechoic wind tunnel. The flow over the membrane and pressure sensors was a canonical, zero-pressure-gradient turbulent boundary layer. The pressure was measured at locations downstream of the compliant wall. The results indicated that even very small amplitude of membrane vibration was sufficient to alter both the mean velocity field and the pressure spectra. Increases in unsteady pressure magnitude up to 7 dB were observed with passive wall motion. Increases of 30 dB were observed with relatively large amplitude external forcing applied to the membrane.