Empirical Spectral Model of Surface Pressure Fluctuations beneath Adverse Pressure Gradients

Abstract

The fluctuating surface pressures acting on a body from turbulent boundary layer flow are a source of vibration and radiated sound. This study investigated the unsteady aerodynamic forcing which occurs near the trailing edge of airfoils with chordwise Reynolds numbers between 2 and 6 million. Static pressure, unsteady surface pressure, and velocity measurements were made throughout the trailing edge region of an airfoil model with three, interchangeable, symmetric trailing edge sections. The data of the present study was utilized to develop a new model that provides the predictive capability for the fluctuating surface pressure auto-spectral density beneath 2-D boundary layer flow experiencing an adverse pressure gradient of variable strength. This new model has been utilized to compare with data from six separate experimental investigations from literature, and has been compared against a separately developed empirical model of the fluctuating surface pressure.