Characteristics of wall pressure fluctuations for a flat plate turbulent boundary layer with pressure gradients

The wall pressure fluctuations beneath a turbulent boundary layer with zero and non-zero pressure gradients were measured at a flat plate configuration in the Acoustic Windtunnel Braunschweig. The fluctuating pressure was measured by an array of subminiature pressure transducers. In addition, the mean flow velocity profiles within the turbulent boundary layer were obtained using hot wires. Adverse and favorable pressure gradients were realized by placing a rotatable NACA 0012 airfoil with a chord length of 40 cm above the flat plate. The one-point spectra and the two-point correlation properties are analysed. An empirical spectral model for the wall pressure fluctuations beneath an adverse pressure gradient boundary layer is developed based on the measured data. The effects of the pressure gradients on the characteristics of the wall pressure fluctuations are discussed