Effect of 2D ice accretion on turbulent boundary layer and trailing-edge noise

Abstract

Trailing-edge noise is known to be sensitive to airfoil shapes, and ice accretion is one cause of an airfoil shape deformation. This paper investigates how trailing-edge noise is affected by the airfoil shape deformation due to ice accretion. The formation of ice-induced flow separation and the development of a turbulent boundary layer are analyzed to understand the correlation between the altered flow physics due to ice accretion inside the boundary layer and trailing-edge noise. The near-wall flow behind the leading-edge ice accretion is analyzed by using Reynolds-Averaged Navier Stokes CFD in OpenFOAM, and trailing-edge noise is investigated using an empirical wall pressure spectrum model in conjunction with Amiet’s trailing-edge noise theory. Validations of tools against measurement data are presented. Liquid water content, freestream velocity, and ambient temperature are varied to investigate the impact of flow conditions on the ice accretion shape and the resulting boundary layer flow characteristics at the trailing edge. It is found that a more significant leading edge deformation due to ice accretion generates larger ice-induced flow separation bubbles, which increases the trailing-edge boundary layer thickness. As a result, an increase in low- and mid-frequency noise is observed. The purpose of this paper is not only to understand the effect of ice accretion on trailing-edge noise but also to comprehensively analyze how flow physics inside the turbulent boundary layer is altered by the presence of various ice accretion shapes.