A physics-based description and modelling of the wall-pressure fluctuations on a serrated trailing edge. (10th May 2022)

• Record Type: Journal Article
• Authors: Lima Pereira, Lourenço Tércio; Avallone, Francesco; Ragni, Daniele; Scarano, Fulvio
• Is Part Of: Journal of fluid mechanics. Volume 938(2022)
• Publication Date: 2022-05-10
• Subjects: aeroacoustics -- hydrodynamic noise; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2022.173
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract: Abstract : A physical description of the flow mechanisms that govern the distribution of the wall-pressure fluctuations over the surface of a serrated trailing edge is proposed. Three main mechanisms that define the variation of turbulent pressure fluctuations across the serrated edge are discussed and semi-empirical models are formulated accordingly. It is shown that the intensity of the wall-pressure fluctuations increases at the tips under the effect of an increased convective velocity as a result of sidewise momentum diffusion. Furthermore, the change of impedance across the edge causes a local reduction of the pressure fluctuations in the vicinity of the trailing edge. Finally, aerodynamic loading over the serrations due to the non-symmetric flow created at different angles of attack establishes secondary flow patterns that induce higher wall-pressure fluctuations over the serration edges. The latter effect is present only for serrations under high aerodynamic loading, while the former ones are observed under any conditions. Semi-empirical models are formulated for predicting the variation of the wall-pressure fluctuations over the serration surface based on the three physical mechanisms described. These models are calibrated and compared against experiments conducted on a symmetric airfoil model at high Reynolds numbers.