The Scheme Research Of Ventilation System For Squirrel Cage Asynchronous Motor

With the development of society and economy,China's economy grows remarkably and the strength of scientific research improves continuously.There are many great achievements in various fields,for example,electricity,aviation,nuclear power and especially some important fields.With increasing unit capacity of the motor and electromagnetic and thermal loads,it directly affects the safe operation and working life of the motor.Thus,the flow and heat transfer in the motor problems need to be solved.This paper bases on computational fluid dynamics theory and uses finite volume CFD numerical methods to predict the temperature rise of the various components,providing visual and compact designs for selecting motor ventilation solutions,and it has important implications for the development of the motor manufacturing industry.This article uses high-speeding squirrel-cage induction motor of 4.8MW as model,and establishes the whole three-dimensional solid model of multi-scheme including a stator,rotor,stator coil,plate,etc.,to research the flow field and temperature field in computing domain,including the distribution of pressure,flow,temperature.Firstly,a three-dimensional model has been created which bases on drawings which were supplied the original machine factory and the whole flow field and temperature field are calculated based on the actual boundary conditions.The results shows that: the highest temperature is 140.75?,locating at the junction of the stator core tooth portion and yoke portion.The stator winding insulation is Class F and calculated temperature meets the insulation requirements.Secondly,the unnecessary parts such as key,slots,snap,have been simplified in the whole motor flow field and temperature field calculation.There is error between the results and the actual operating temperature.Because the motor is applied to some important fields with long-term operation and without basic maintenance,to avoid motorover-temperature,motor stator core structure at the maximum temperature portion is optimized,changing the length of the stator core wind ditches from125 mm to 130 mm,the result is 133.92 ?.Finally,some temperature field calculations of the factors have been studied,finding that the whole flow field have turbulent and shear flows,namely liquidity situation is extremely complicated,so,model variations affect the results of the calculation.The results shows: the calculated lowest temperature applying Standard k-? model is140.75 ?,the calculated highest temperature applying RNG k-? model is147.36?.The whole half maximum temperature is 142.89?,2.14? higher than the overall maximum temperature.Research methods and conclusions of this paper can provide reference and guidance for the numerical simulation of the motor cooling and ventilation system design of squirrel cage induction motors.