| Coal dust hazard is one of the most important five disasters in coal mine. Preventing coal dust from diffusing to the driver of the roadheader with high pressure air curtain which uses pressure gas was put forward. Theoretical research was done from three aspects:the uniform air distribution pipe, air jet theory and dust-isolation theory. High pressure air curtain experimental system was established. Experimental study was carried out about uniform diameter jet orifice and multiple diameter jet orifices high pressure air curtain. The experiment outcome shows, the static pressure on the section of air curtain producer and the outlet velocity of jet orifice have the same variation rule with the distance from the inlet. The outlet velocity of orifice, the outlet flow and the jet end velocity of uniform jet orifice diameter air curtain producer are not even; however, the outlet flow and jet end velocity of multiple jet orifice diameter air curtain producer are even. The multiple diameter jet orifice air curtain producer is more proper for the tunneling face to use. Based on experimental data, attenuation model of high pressure air curtain velocity was established. Numerical simulation about high pressure air curtain producer and dust isolation of high pressure air curtain was carried out. The air-isolation effect is the best when the ratio of jet distance H and nozzle hole diameter d equal to 200. The process to study and produce high pressure air curtain was put forward. The formula of high pressure air curtain air flow Q, high pressure air curtain pipe diameter D, high pressure air curtain nozzle hole areaσi and high pressure air curtain pressure Eo was obtained. Considering the local condition of a tunneling face, produced a high pressure air curtain, established high air curtain dust-isolation system. The system was used. The field data shows:the dust-isolation rate was 41%. The noise of the high pressure air curtain did not influence the workers. |
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