Wind pressure characteristics of a short circular cylinder in supercritical regime using a novel force measurement method

Abstract

The pressure distribution around a cylinder is one of the classical aerodynamic problems involving Reynolds number (Re) effects. This paper presents the development of a novel distributed synchronous force measurement system, which experimentally investigates the effects of surface roughness and incoming turbulence on a short cylinder model with a diameter of 5 m under a supercritical regime (Re = 2 × 106, 3.5 × 106). The study indicates that both surface roughness and incoming turbulence significantly alter the pressure distribution, albeit through distinct mechanisms. Roughness disrupts large-scale vortices, leading to distortions in the fluctuating wind pressure. The characteristic turbulence of the flow around a cylinder in the uniform flow is overshadowed by the characteristics of the incoming turbulence, which, in turn, affects the wind pressure distribution characteristics, particularly the fluctuating wind pressure. This turbulence effect is also mitigated by higher roughness. In current structural designs, the Re effect is typically approximated by attaching roughness strips to scaled models, while distortions in the fluctuating wind pressure due to high roughness are commonly neglected. Based on the statistical characteristics of wind pressure time series, it can be inferred that surfaces with high roughness significantly reduce the influence range of large-scale structural vortices by a factor of 6–10. This implies that when simulating the Reynolds effect by adding surface roughness to scaled models, distortions in the fluctuating wind pressure curve may occur, necessitating careful verification of the results obtained from the roughness model on the scaled model.