Study On Internal Flow Field And Aerodynamic Noise Change Law Of Mine Local Fan

Coal plays an important role in both heavy industry and light industry.Various industrial sectors have different needs to a certain extent.However,in order to reduce gas accidents in the mining operations of coal mines,ventilation of the mines is inevitable.At present,the most widely used mine ventilation equipment is a local mine ventilation fan.As the noise of the local mine ventilation fan not only affects the operation of the mine workers,but also covers downhole safety warning signals and causes accidents,the local mine ventilation fan is used.The analysis of the internal flow field and aerodynamic noise is particularly important.In this paper,the numerical simulation of the internal flow field of a mine axial flow fan with a rated power of 55 KW,rated speed of 3000 r/min and a rated pressure of 5050 pa is simulated.The flow field of the fan is calculated by the large eddy simulation method and the subgrid calculation model,and the eddy distribution cloud of the internal flow field is obtained.The time domain information of the noise is obtained by using the FW-H acoustic model.The time domain information of the noise is converted to the frequency domain information to get the spectrum of the noise calculation point.The aerodynamic noise of the first order impeller is larger than that of the two stage impeller.In the process of the blade root to the tip of the leaf,the aerodynamic noise increases first and then decreases,and the front edge noise of the first impeller blade is larger than the rear edge,and the front edge noise of the two stage impeller blade is less than the rear edge.Using the B&K noise test system,the single point test method was used to test the noise in the near wake exit area of the fan impeller at 1000 r/min,2000 r/min,and 3000 r/min respectively.Analytical test results show that in the aerodynamic noise of the ventilator,the low frequency noise is dominated by the impeller rotation noise,while the high frequency noise is mainly eddy current noise;while in the process near the ventilator exit,the aerodynamic noise is gradually reduced.The trend is consistent with the results obtained by numerical calculation and the error is within 10%,which proves the feasibility of numerical calculation.In order to reduce high-frequency noise,a modified design may be considered for the leading edge of the first-stage impeller and the trailing edge of the second-stage impeller;to reduce the energy loss caused by vorticity,the first-stage impeller suction surface and the secondary impeller tip may be considered for modification.design.It provides a theoretical basis for the noise reduction and energy saving design of the fan.