THE INFLUENCE OF LENGTH OF WINDBREAK ON LATERAL VARIATION OF WIND SPEED AT DIFFERENT DISTANCES ON DOWNWIND SIDE

Abstract

his study was carried out to determine the influences of different windbreak lengths on the wind speed of the downwind side of windbreaks. The windbreaks and the wind speed sensors were constructed from locally available materials. The lengths of the windbreak were varied by gradually adding panels in the frames initially prepared for this purpose. Seven wind speed sensors were arranged at equal separation along a quadrant of a circle on the downwind side of a windbreak. Measurements were conducted for short durations only when wind speed was sufficient enough to rotate the sensors. The results of measurements showed that wind speeds decayed exponentially on the downwind side of the windbreak only up to a certain distance which in this study was found to be 6 m. After this distance wind speed recovery took place and the exponential decay was good only up to this distance. Windbreaks of small length (< 3.6 m) did not perform well in clearly demarking the protection zone. The length of windbreak 3.6m, 4.8m, 6m and 7.2m are effective because they managed to reduce the wind speed up to 6m completely. The average managing percentage was 82%. In this test we found the influence of windbreak on the leeward to be about four times the height of the windbreak. We therefore emphasize the importance of calibration of the wind sensor if the method is to be used for future work.