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

本研究的目的是开发具有最佳配置的雪栅（吹散式），以防止积雪堆积和提高道路能见度。根据流体动力学原理进行了设计，并利用真实的雪粒在风洞中进行了吹雪模拟，并利用拖曳槽进行了流动可视化，对其性能进行了评价。为了进行实验，还开发了图像处理技术。发现雪栅后的积雪和能见度阻塞是由于通过雪栅底部的间隙流卷起造成的。研究发现，通过控制与顶部分离的剪切层，可以防止底部间隙流的卷起。根据这一发现，以控制其剪切层为目标，设计了几种类型的雪栅栏。结果发现，用穿孔板代替位于围栏顶部的板可以大大提高能见度。在本研究中，开发并测试了另一种类型的围栏。这种类型的设计是利用迎面风运动的动量，而不是像许多旧类型的栅栏那样阻挡气流运动。为了利用风力，采用了大迎角的弧形翼形板。结果表明，翼型板消除了挡墙后的气流停滞区，减弱了剪切层的卷起，从而增加了巷道的吹散效果。因此，使用这种雪栅，可以进一步提高暴雪能见度。

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.