Wind tunnel tests on scale models of a large power station chimney

Abstract

This work is aimed at providing a better understanding of the parameters required for the wind-tunnel simulation of the wind loads on large power station chimneys. Measurements of mean and fluctuating pressure distributions have been made on scale models of Fawley power station chimney, for comparison with the full-scale measurements of Tunstall. The measurements have been made in a simulated atmospheric boundary layer of height 1.2 m (nominal scale 1:500), using the method developed by Counihan. Initial measurements of mean pressure distribution were made on a 1:250 scale model chimney in the 1:500 scale boundary layer, in order to obtain as high a Reynolds number as possible in the wind tunnel available. No fluctuating pressure measurements were made owing to the limited tunnel time available. Following the good agreement between mean pressure distributions obtained on the 1:250 model and full-scale measurements, a 1:500 scale model chimney was tested in the same simulated atmospheric boundary layer. Mean pressure measurements gave good agreement with full-scale measurements at a Reynolds number of 2.3 × 10 7, for model Reynolds numbers above 1.5 × 10 5, and with a smooth or slightly rough model surface. Good agreement was obtained between model and full scale for the distribution of fluctuating pressure coefficients, when the difference in turbulence intensity between the simulated and full-scale flow was considered. No coherent vortex shedding was found on the model, in agreement with full-scale measurements.