Reliability Analysis On A Type Of Centrifugal Fan

Centrifugal fan is indispensable for the nuclear power as well as large firepower.With technology changing each passing day,fan is developing toward the direction of large-scale,high power,high speed and low noise.So people have higher requirements to its security and efficiency,however,due to the rapid development of fan,it also makes a lot of problems on the design and manufacture,working reliability,working life and so on of the fan,especially fan's strength failure often occurs.Therefore,it is necessary for centrifugal fan to analyze its working strength reliability,so that we can ensure the performance of fan.Taking HD 4-73-11 D centrifugal fan as a research object,we firstly analyze the fan's FMEA and CA to determine its critical failure components and calculate its related stress,then accomplish the work reliability prediction of the fan in its service period according to the dynamic reliability model of the impeller and the rolling bearing.The main works are as follows:(1)Structure and composition,function and possibility failure of the centrifugal fan are analyzed,then the critical failure parts and failure mode of the fan are determined using the risk priority number method.(2)The 3-D geometric models of the centrifugal fan and the flow field in the volute are drawn,grid division of the impeller and the flow field are accomplished and boundary conditions are determined.(3)The airflow inside the volute and distribution of its velocity vector and pressure are researched and discussed according to the actual situation,as well as get the pneumatic pressure on the surface of the impeller;then research the impeller's static stress under different stress situation,and based on the maximum static stress,calculate the safety coefficient and the static strength reliability of the impeller.(4)Research vibration of the impeller,and obtain the maximum dynamic stress,then calculate the fatigue reliability and the safety coefficient of the impeller.Based on the uncertainty of natural frequency and excitation force of the impeller,research the vibration reliability assessment of the impeller under the most dangerous mode.(5)Based on quasi-static method,obtain stress distributions of the impeller and the bearing under random torque's effect.According to the stress-strength interference theory,regarded the loading process as a random process,the intensity as a random variable,considering the influence of number of loading and strength degradation,carry out modeling and analysis of the centrifugal fan reliability.