Effect of curvature on fluctuating pressure in turbulent boundary layers

Fluctuating pressure within the turbulent boundary layer is a primary source of structural vibration and flow-induced noise, which is crucial for extending the operational life of aircraft, enhancing the stability of ships, and improving the stealth capabilities of underwater vehicles. This work investigates the flow characteristics of wall fluctuating pressures on flat and curved plates in a high-speed water tunnel using miniature fluctuating pressure sensors. The results indicate that an adverse pressure gradient causes flow separation on the lower surface of a concave curved plate, leading to pronounced fluctuations in large-scale pressure signals over time. The wavelet energy of the mid-to-high-frequency band signal significantly increases. This effect becomes more pronounced as curvature increases. Additionally, multi-scale analysis reveals the wavelet energy dynamics of fluctuating pressure as water flow speed changes. It shows that fluctuations are most evident within the mid-scale frequency bands. These findings suggest that fluctuating pressure is primarily driven by the interaction of large-scale vortices within the turbulent flow field. This study provides valuable data support and theoretical foundations for the optimization and development of subsequent fluctuating pressure prediction models, contributing to enhanced accuracy in flow-induced noise calculations.