Abstract
This paper deals with flow around a bluff body of hyperboloid shape. It consists of results gathered in the course of research by means of Particle Image Velocimetry (PIV). The experiments were carried out by means of low-frequency 2D PIV in a range of Reynolds numbers from 40000 to 50000. A hyperboloid-shaped model was measured in a wind tunnel with a modelled atmospheric boundary layer (and additionally, in a low-speed wind tunnel with low turbulence). The model was tested in a subcritical range of Reynolds numbers and various planes in a wake of the model were captured with the intention of getting an estimation of 3D flow structures. The tunnel with the modelled atmospheric boundary layer has a high rate of turbulence, so the influence of the turbulence of incoming flow on the wake could be outlined. The ratio of the height of the model to a thickness of the modelled boundary layer in the tunnel was 1/3, meaning the turbulence in the boundary layer strongly influenced the flow around the model; it suppresses the wake which leads to a lot shorter area of recirculation than low turbulence incoming flow would cause.
Highlights
In this contribution, research in the mechanics of fluids, that developed from the experimental testing of a model for civil engineering will be presented
The tunnel used for the measurement was the Boundary Layer Wind Tunnel (BLWT) for simulating atmospheric boundary layer and built mainly for civil engineering measurements
The wake of a hyperboloid-shaped model was measured in the wind tunnel with a modelled atmospheric boundary layer
Summary
Research in the mechanics of fluids, that developed from the experimental testing of a model for civil engineering will be presented. This paper is not going to deal with the cooling towers, it only originated there It was explained in [1] and [2], that the model of the cooling tower later started to be called a hyperboloidshaped model because an original civil-engineering problem solved in a classical way (wind loadings on cooling towers were measured and evaluated) later turned into a pure mechanics of fluids problem. The model remained covered by small grains from the civil engineering experiments, our last piece of known theory fails Such rough surface forces the transition in the boundary layer on the model to occur at higher Reynolds numbers. The high rate of turbulence of incoming flow has opposite effect This phenomenon together with quite large high wall blockage and the low aspect ratio of the model, ensures the measurement with such model involved is filled with results different from the classic circular cylinder knowledge. The equipment used for the experiment limited us, and this paper could not go deeper into this particular detail
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