Empirical Modeling of Pressure Spectra in Adverse Pressure Gradient Turbulent Boundary Layers

Abstract

This study investigated the unsteady aerodynamic forcing that 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 were used to develop a new model for estimation of fluctuating surface pressure autospectra beneath two-dimensional turbulent boundary layer flow experiencing an adverse pressure gradient of variable strength. This new model has been used 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. Additional empirical modeling of the coherent extents of the fluctuating pressure field in the longitudinal and lateral directions, as well as the convection velocity, is presented as a function of nondimensional variables dependent on the adverse pressure gradient flow condition.