Development of Snow Fence based on Aerodynamic Characteristics of Cross-sectional Shape of Road to Prevent from Snowstorm

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The purpose of the present study was to develop the snow fance (blow off type) with an optimum configuration for preventation of the snowdrifts and inprovement of visibility on roadways. The design was made in accordance with fluid dynamic principles, and its performance was evaluated by the blowing-snow simulation in a wind tunnel wich uses real snow particles and by towing tank for flow visualization. In order to conduct the experiments, image processing techniques were also developed.The snowdrifts and visibility blockage behind the snow fance were found to be caused by the rolling-up of the gap flow passing through the bottom part of the fence. It was found that the rolling-up of the bottom gap flow could be prevented by controlling a shear layr separated from the top part. In accordance with this finding, several types of snow fences were designed with the objective of the controlling their shear layr. As a result, it was found that a perfolated plate replaced the plate located very top part of the fence can yields considerable improve in visibilty.In the present study, another type of fences were developped and tested. This type is designed to use momentum of on comming wind movement instead of blocking flow motion as many old types of fence behave. In order to use wind momentum, cambered wing shaped plaptes with large angle of attack were emploied. As a results, it was found that the wing shaped plates elminate stagnant region of flow behind the fance, and weaken the roll up of shear laryer, and then increases blow off effect on the roadway. Hence, with this type of snow fence, furthe improvement of visibility in snowstorm is obtained.