The effects of varying the cooling air flow and its distributionon the heat transfer in a high-voltage, strip-wound, four-pole inductionmotor are reported. The variations in the air flow were achieved byaltering the motor speed, by removing the wafters, by increasing theflow resistance of the motor air inlets, or by the insertion of heattransfer augmentation devices in the stator-frame ducts. Heat transfercoefficients were deduced from measurement of the input power and fromminiature heat flux gauges attached to the end windings. The overallheat transfer coefficient on the end winding at the air outlet end (thefan end) was roughly double that at the air inlet end, the converse ofthe situation for lap and concentric wound motors. Large spatialvariations in the end winding local heat transfer coefficients occurred.This is attributed to the open nature of the winding which results inthe individual loops behaving as separate bodies, each with a flowpattern dependent upon the angle of the approaching flow. There was alarge increase in the overall heat transfer coefficient on the windingat the fan end when the wafters were removed. The use of transverse ribsin the stator frame ducts was found to enhance heat transfer
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