Insight on the surface fluctuating pressures considering distorted turbulence around a rectangular bluff body

Abstract

The distortion of turbulence approaching a bluff body plays a dominant role in determining the unsteadiness of the fluctuating surface pressures. A three-dimensional (3D) spectral approach is proposed to decouple the effects of the distorted turbulence into the blocking effect, distortion effect, and 3D effect. Wind tunnel tests are conducted to investigate the unsteady behavior of the windward fluctuating surface pressures on a rectangular bluff body, considering the effect of the ratio of the turbulence scale to the structural feature size λ = Lu/D. The results show that the fluctuating pressure on the surface of a rectangular cylinder is mainly affected by the low-frequency blocking effect, the high-frequency turbulent distortion effect, and the full-frequency turbulence 3D effect. The low-frequency blocking effect is related to the surface spatial position, but is less affected by λ; the high-frequency distortion effect does not depend on the spatial position of the pressure but is affected by λ; the 3D effect is affected by both the spatial position of the pressure and λ. When λ approaches infinity, the distortion and 3D effects can be ignored, and the quasi-steady theory is valid for the fluctuating pressure. Finally, one-wavenumber and 2D fluctuating pressure generalized spectrum models considering the unsteady effects and the spatial position of the surface pressure are proposed, and their accuracy is effectively verified by the test results.