The Research On Shelter Effect Of Wind-break Net

In recent years, with the increasingly importance of environmental protection, wind-break net as a new way of dust prevention has been becoming more and more popular. While as a new technology, it is a short time to research on shelter effect of wind-break net. The actual work experience is limited, and there are still many problems to be solved. The widely-used wind-break net demands a higher technological content for the standard of design parameters.According to the requirements of the subject in the western, the experiments in the wind tunnel are used to reveal the relationship of the shelter effect of wind-break net with the net height and the material. Taking a large coal yard in Jingtang port as the background, we can get the results of the shelter effect of wind-break net, using the methods of numerical simulation. Compared the experimental results and numerical simulation results, the relationship between of them will be revealed. At the same time, we can use the results of numerical simulation to calculate the quantity of coal dust. It is really can be carried to test the shelter effect in the scene, using the project of wind-break net. We can summarize the key jobs and results as follows:(1) Though investigating the application of wind-break net at home and abroad, it aimed at understanding the design of the net structure, the net price of materials and the shelter effect of wind-break net. According to the investigation, people often use a device that releases water from overhead pipe as the main measure for prevention and control of dust pollution. The use of the wind-break net is becoming more and more widespread in the small coal yard. It produced obvious results using the combination of watering and wind-break in Japan. But the yard area is relatively small, and the circumference is generally less than 2000 meters. There are three domestic structural styles at present, such as cantilever steel column, trussed structure and space structure. Net design also does not have the technical standards as references. We can only use the sense to judge the effect of wind-break net.(2) Combination of domestic and foreign markets, we plan to select hard net and soft net to conduct wind-tunnel test. It is used to reveal the relationship of the shelter effect of wind-break net with the net height and the material. According to the experimental results, it indicates that the wind speed significantly decreased behind the windbreak, by 80% at most. It is also found that the double-deck net is more effective than the monolayer. The best result of the shelter effect is from 2 times to 6 times as high net. Behind the 6 times, the shelter effect of wind-break net decreases progressively along with enlargement of horizontal distance. When the horizontal distance is about its 20 times high, the wind speed almost constant by 10%.(3) As indicated by two-dimensional numerical calculations, the numerical simulation curves and wind tunnel curves have the same tend. While there are differences between of them, the result of numerical simulation is less effective than the result of wind tunnel. The wind speed decreased behind the windbreak, by 60% at most.(4) Relying on the meteorological data in 2006, we can calculate the dust of the coal yard. The results show that the best measure of dust prevention is the combination of watering and setting up net.(5) As indicated by testing in the scene, it shows that the construction of wind-break net can decrease dust obviously, especially in the gale weather.