Regarding the calculation of wind and dust suppression nets

Currently, environmental regulations are strict, and there is a great need in Shandong to address dust issues arising from unloading and storage. I wonder whether such a net can help suppress fine dust particles

How to deal with the dust generated during unloading?

After checking some information, this device is used to block the wind; it reduces the strength of the wind in areas where there is dust, thereby preventing the wind from carrying away the dust.

So a scientific calculation is needed

Anything related to wind and rain – so-called scientific calculations are actually nonsense. Initially, foreign research on this topic relied on \"blowing\", that is, wind tunnel tests. Some universities and research institutions in China have also carried out similar studies. Since it involves blowing, the data used must be empirical in nature. Design institutes in China in the fields of electricity, steel, railways, etc., all carry out design work of this kind; determining just the height isn’t difficult at all. The following text is quite common on the Internet, and it often appears in the feasibility study and design documents of various organizations: 1. The height of the wind and dust suppression net is determined by factors such as the stack height, the area of the stack, and the requirements regarding environmental quality. The wind and dust suppression net should be installed near the material pile, with the dust generation level required to be below the **standard. Based on wind tunnel tests conducted by Nanjing University of Technology, it has been determined that an optimal height for such a net is 2–3 meters above the level of the material pile. 2. The height of the wind protection net in the material storage area mainly depends on factors such as the stacking height and the size of the storage area. Wind tunnel tests show that when the height of the wind and dust suppression net is 0.6 to 1.1 times the height of the stack, the net height is proportional to the dust suppression effect ； When the height of the wind and dust suppression net is 1.1 to 1.5 times the height of the stack, the change in net height and dust suppression efficiency becomes gradually more gradual ； When the height of the wind and dust suppression net is more than 1.5 times the stack height, there is no significant change in the net height or the dust suppression effect. Therefore, the height of the wind and dust prevention net is generally selected within the range of 1.1 to 1.5 times the stack height. According to relevant studies, a wall height of 1.1 to 1.2 times the height of the coal pile is considered appropriate. 3. The determination of the height of the wind and dust prevention net should also take into account the size of the storage area to be protected, ensuring that it remains within the effective coverage area of the wind prevention net. Wind tunnel tests show that within a distance of 2 to 5 times the height of the net downstream of the net, the dust reduction rate achieved by stacking can exceed 90% ； Within a distance of 16 times the net height downwind of the net, the comprehensive dust reduction efficiency of the stacking system reaches over 80% ； A good dust reduction effect is achieved at a distance of 25 times the mesh height behind the mesh ； At a distance of 50 times the mesh height from the net, it still achieves a 20% reduction in wind speed. To meet environmental quality standards, most dust prevention and control nets used in China are required to have a dust reduction efficiency of over 80%; therefore, the height of such nets should be more than 1/16 of the height of the area protected by them. Points 1 and 2 are easy to understand: the height of the net should be 2 to 3 meters higher than the height of the material pile. For example, if the height of the coal pile is 10 meters, then the designed height for the net should be 12 meters. The net height is 12/10 = 1.2 times the height of the coal pile. These are all empirical values; there’s no need to calculate them, nor is it possible to do so, as there’s no formula for it. . . The third point is a bit confusing; this shelter area isn’t easy to understand. An example will make it clear: take that coal pile from earlier again. It is 10 meters high, with a base length of 200 meters and a width of 120 meters – these are the design parameters of the coal pile. The area of 200x120 meters constitutes the shelter area. If the height of the net is set at 12 meters, then isn’t that 1/16 of the height? In the length direction, 12/200 = 0.06, while 1/16 equals 0.0625; this is not acceptable, as the value needs to be greater than 0.0625. By increasing it to 13m, 13/200 = 0.065, which is fine. In terms of width, it’s definitely sufficient – 12m already results in a value of 0.1, so 13m is certainly enough. . . In terms of height alone, these are already sufficient. . . . In fact, these devices weren’t developed in China; they were simply imported from abroad. They aren’t as complex as one might think. Unless it’s a project like the Qinghai-Tibet Railway, where foreigners don’t have deserts or barren areas at such high altitudes, in such cases it becomes necessary to conduct experiments to develop protective nets on one’s own. . . Don’t think that these design institutes are actually that highly skilled. I talked with a unit in Xinjiang (which is said to be an authoritative organization in China that has developed formulas for calculating dust generation). They simply said that those heights are based on empirical data and can be used directly; they can’t be calculated To truly prevent and control dust, the number of layers of nets is crucial; if one layer isn’t enough, two layers can be used. Design agencies also pay considerable attention to the installation of water spraying devices in storage areas. The height of the nets alone isn’t that important – it can be chosen arbitrarily. . ;P

I strongly agree with your view. Some clients just want a theoretical basis. At present, this dust filter only has experience values.

It’s simple enough – just adopt an angry tone and tell the owner to go into the wind tunnel himself and feel it. . . ;P In fact, it’s all the truth – our Su27, introduced from the former Soviet Union, was developed through exaggerations. The Soviets had limited expertise, and many fundamental parameters were obtained by overstating them, which naturally led to heavy costs. Wind tunnel tests are extremely expensive. . .

Haha, was the problem solved? If you need it, I can give you some references on empirical calculations

Not yet, I’ve sent it to your email privately~~ Thank you! ! ! !