The effects of using wind fences to reduce wind-blown coal dust were studied through wind tunnel tests. The mean and fluctuating pressure distributions over the surface of reduced coal pile models were measured. The tests were performed at a 1/300 scaled model of a typical coal pile of the Companhia Vale do Rio Doce (CVRD) open storage yard, at Vitória, Brazil. Different fence porosities (68%, 53%, 37%, 0%) as well as different fence positions and heights were tested. Further to the pressure measurements, the field velocities over the surface and surroundings of the piles were obtained through hot-wire anemometry measurements. The fence with no porosity (0%) caused and increase in the re-circulating zone behind the fence, therefore increasing the negative pressures over the pile surface, being soon disregarded. The fences with porosities ranging from 53% to 68% were most effective in reducing the pressure fluctuations on the windward face of the pile, without increasing significantly the mean pressures over it. These pressures are closely related to the dust emissions from the surface, directly affecting the surrounding environment. Although most effective for reducing pressure fluctuations, the best combined effect together with the drag surface velocities were found for the fences with intermediate porosities.
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