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结构的防雪栅（吹离型），以防止雪堆和改善道路上的能见度。根据流体动力学原理进行了设计，并通过在风洞中使用真实的雪颗粒进行吹雪模拟和通过拖曳水池进行流动显示来评估其性能。为了进行实验，还开发了图像处理技术，发现雪栅栏后面的雪堆和能见度障碍是由通过栅栏底部的差距流卷起引起的。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，设计了几种类型的防雪栅栏，目的是控制它们的剪切层。结果表明，用穿孔板代替栅栏顶部的穿孔板可以显著提高栅栏的性能。这种类型的设计是利用对来风运动的动量，而不是阻止流动运动，因为许多旧类型的栅栏的行为。为了充分利用风的动量，采用了大攻角的弧形翼片。结果表明，翼形板消除了翼后的滞流区，减弱了剪切层的卷起，从而增加了对巷道的吹离作用。因此，这种类型的防雪栅栏，进一步改善能见度在暴风雪中获得。

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.