Numerical prediction of the whistling potentiality of a turbulent channel flow with corrugated walls

Abstract

This study explores the turbulent flow-induced whistling phenomena in a channel with corrugated wall surfaces, which is crucial for mitigating the acoustic fatigue problem in the aerospace field. By solving a compressible linearized Navier–Stokes equation in the frequency domain, the interference between the turbulent flow field along the corrugated wall and the incident acoustic field is studied, including the acoustic wave scattering phenomenon caused by turbulence and the fluid perturbation induced by acoustic waves. In conjunction with this, the acoustic two-ports method is utilized to investigate the transfer-function model and predict the whistling potentiality of the turbulent flow along corrugated walls. Experimental validations through the literature results confirm the numerical accuracy of this aeroacoustic simulation strategy. Subsequently, the investigation extends to different cavity configurations with different cavity profiles and numbers, and the two-port scattering matrix is applied to quantify the acoustic transmission and damping coefficients caused by the background flow field and turbulent eddy viscosity. The acoustic power conversion mechanism between the turbulent flow field and the incident acoustic field is established, allowing for quick prediction and effective analysis of the generation frequency range of the whistling phenomenon. Furthermore, the modulation effect of sound waves on the fluid is studied by analyzing the response of the incident sound wave frequency to the phase interference momentum and shear layer of different configurations of corrugated cavities. The results show that compared with the right-edge configuration, the rounded-edge configuration produces whistling at a lower frequency due to the turbulence effect, and the number of cavities adjusts the intensity, not the frequency, of the sound power generated. In addition, the oscillation of the shear layer caused by sound waves is related to the cavity configuration and the sound wave frequency.