| With the development of coal mining technology,the driving distance of coal mine roadway is increasing,the volume and pressure of wind are proportional to the distance of the roadway.This leads to the problem that the volume and pressure of the wind and ventilation distance do not match during the ventilation of the mine local fan.In the short-distance ventilation,the air volume is excessive,the energy is wasteful,and it is easy to arouse the secondary pollution caused by coal dust.In the case of long-distance ventilation,the primary motor of the contra-rotating fan is underloaded,and the secondary motor is overloaded.Therefore,based on the research of the operating characteristics of the local ventilation system,a new type of single motor blade adjustable contra-rotating fan was designed.Then the simulation and experimental research of the fan were carried out.Firstly,this paper calculated the ventilation resistance of a roadway,then collected the data of FBD No.8.0 fan under different ventilation resistance by B type fan experimental device and obtained the relationship between fan performance and ventilation distance.The operating characteristics of the ventilation system under three ventilation modes of constant-speed ventilation,single and double stage switching ventilation and variable frequency ventilation were studied.The results show tha single and double stage switching ventilation is about 5% energy-saving than constant-speed ventilation,and variable-frequency ventilation is about 5% energy-saving than constant-speed ventilation.Then,based on the research of the operating characteristics of the local ventilation system,the design scheme of a single motor blade adjustable contra-rotating fan was proposed.This paper developed the contra-rotating transmission and blade angle adjustment mechanism and established Three-dimensional modeling of blade by reverse engineering.Based on the three-dimensional model of the blade,the overall model of single motor blade adjustable contra-rotating fan and the FBD No8.0 fan were established,and the simulation model of the FBD fan was verified.Since the area of impeller and the rear section of the fans are the same,The simulation model of the FBD fan's impeller and the rear section can be directly applied to single motor blade adjustable contra-rotating fan.For the front section of single motor blade adjustable contra-rotating fan,the same method as the rear section of the FBD fan is used to establish the simulation model.This method could ensure the reliability of the overall simulation model of the blade adjustable contra-rotating fan.After that,the Fluent simulation software was used to simulate the main flow components of single motor blade adjustable contra-rotating fan.The simulation results show that the ratio of the arc radius of current collector to the inlet hydraulic diameter of the fan should be 0.2 or more;the ratio of the length of the current collector to the radius of the collector arc should be 0.8;the angle between the collector and the air duct should be 0 degree.This paper also studied the effect of fairing and diffuser on the performance of the fan,the result shows that: the optimum angle of diffuser is 16°~18° when the diffuser length is equal to the diameter of the air cylinder.In the end,the experimental research on the blade angle adjustment mechanism of single motor blade adjustable contra-rotating fan was carried out.The modal test shows that the the blade angle adjustment mechanism does not resonate when the fan is running.Blade angle adjustment mechanism test shows that its structure can meet the design requirements.The dynamic balance correction of the impellers was carried out and the calibration result shows that the impellers' balance level reaches G5.6,which meets the technical standards. |
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