| Dust control has always been a big problem in the mine safety production. With the increasing of mechanization degree in mine production, make high efficient production of the mining face come true, but the following dust occupational hazard is not allowed to be ignored. Pneumoconiosis disease is the main occupational diseases of coal miners; it not only severely does harm to life health of workers, but also restricts the development and production of coal enterprises. According to statistics, every year China's new professional pneumoconiosis disease on average 1.5million or so, death caused by pneumoconiosis disease is 6 times of the death of injury, the digital is horrible.At present, main dust-fall measures used in the coal face are coal water injection, spray dust and ventilation dust. These measures make large particle size of dust under control, but there is still a lot of repairable dust spread to coal mines. As is known to all, individual defends is a highly effective method to control dust occupational hazards. Therefore, using the theory of fluid mechanics, jet mechanics and so on, I made a deep research to the theory related to slit jet, combined with the traditional safety helmet, carried on the new method research that using the dust-isolating slit-jet theory to mine safety helmet. The specific contents of the study and obtained research results are as follows:1. Contents of the study: Analysed the diffusion motion law of dust ,made a deep research to the theory related to slit jet, established the evaluation standard of influence dust-isolating efficiency, through numerical simulation to slit-jet that on various different working parameters, got the good working parameters of dust-isolation slit-jet.2. Methods of the study: On the basis of theoretical analysis and with the help of numerical simulation soft, combining with experiments, this paper eventually got the inherent characteristics that reflect slit-jet's isolation dust effect. 3. Main results of the study:(1)Through the use of fluid mechanics, jet mechanics and related theories and methods, it is concluded that fight diffusion capacity and volume-suck affection of the slit jet is two key factors that influence dust-isolating efficiency. This specific performance that fight diffusion capacity is proportional to dust-isolating efficiency, volume-suck affection is inversely proportional to the dust-isolating efficiency. In practical applications, this two effects are mutual contain, and should be taken into account in design the working parameters of slit-jet.(2)According to actual situation of safety helmet with slit-jet, the author puts forward the"three-region model", and established differential equations about these three regional dust concentration, and eventually got the inherent characteristics that reflect slit-jet's isolation dust effect.(3)Through numerical simulation to slit-jet that on various different working parameters, got the following good working parameters of dust-isolation slit-jet: export width is about 6mm, export angle on 10°is quite reasonable, slit jet wind supply of 7m/s is quite reasonable. ( 4) Made several modes of the similarity model experiment on slit-jet dust-isolation, and made further investigation on the influence of dust-isolation effect caused by slit-jet working parameters. Summery law of the experiments result and conclusion of the numerical simulation get very good match. |
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