Research On Flow Field And Noise Of Counter-rotating Mine Fan

Counter-rotating mine Fan is a common ventilation device in coal mine.Its main function is to convey fresh air to the heading face and reduce gas concentration.The noise produced by Counter-rotating mine Fan is one of the main noise in the coal mine.Under the harsh working environment,it will strengthen the harm of this noise,not only affect the underground working efficiency but also threaten the health of workers.Therefore,it is of great significance to study the flow field and noise characteristics of Counter-rotating mine Fan.Based on the prototype of counter-rotating mine Fan,a Fan model with perforated blades is designed and established.Firstly,the flow field of the original model and the blade perforation model is simulated by using Fluent software,Researching the flow field characteristics of the Fan under different working conditions and perforation diameters.The results show that when the inlet velocity V = 16m/s,the internal airflow of the original model is smooth,the turbulence intensity and vorticity in the two-stage impeller region change little,and the Fan works stably and has good performance.For the Fan model with perforated blades,the larger the aperture is,the more the air leakage at the latter blade will lead to a sharp drop in the pressure rise of the Fan and a decrease in ventilation efficiency,which indicates that the perforated aperture of the blade should not be too large.Secondly,the broadband noise module in Fluent software is used to study the sound power of the Fan,and the sound power distribution cloud of the whole Fan is obtained.The results show that when the inlet velocity V=16m/s,the maximum sound power of the Fan reaches the minimum,and the main noise source of the Fan is the two-stage impeller region.With the increase of perforation aperture,the maximum sound power of the Fan will decrease.Then FW-H noise module in Fluent software and FFT technology are used to simulate the unsteady flow field of the Fan,and the aerodynamic noise characteristics and frequency domain diagrams of the Fan are obtained.The results show that the aerodynamic noise characteristics of the Fan are closely related to the passing frequency of the two-stage impeller.The aerodynamic noise mainly occurs in the area of the two-stage impeller,especially at the tip of the blade.The frequency range of the high sound pressure level is mainly concentrated in the low and middle frequency range.With the increase of perforation aperture,the position of the high sound pressure level of the Fan will be closer to the low frequency area,and the eddy flow degree of the rear impeller will be smaller,and the eddy current noise will be reduced.Finally,a Fan performance test-bed was built to test the performance of counter-rotating mine Fan,and the reasons for the unsteady working conditions of Fan were analyzed.Aerodynamic noise experiment of Fan was carried out by LMS noise test software.The experimental results show that the frequency range of the high sound pressure level of the Fan is mainly concentrated in the low and middle frequency band.The frequency of peak value is close to the multiple of the passing frequency of the two-stage impeller,which verifies the correctness of the simulation model.In addition,under the condition of small flow rate,the recirculation between the two-stage impellers is serious,which causes a large number of vortices and leads to the dominant eddy noise in this area.Figure [42] table [7] reference [56]...