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Experimental Investigation of Shrouding on Meshed Spur Gear Windage Power LossWindage power loss in high-speed gearboxes results in efficiency losses and increased heating due to drag on the gear teeth. Test results for meshed spur gear windage power loss are presented at ambient oil inlet temperatures, both with and without shrouding. The rate of windage power loss is observed to increase above a gear surface speed of 10,000 feet per minute (51 meters per second), similar to results presented in the literature. Shrouding is observed to become more effective above 15,000 feet per minute (76 meters per second), decreasing power loss by 10 percent at 25,000 feet per minute (127 meters per second). The need for gearbox oil drain slots limits the effectiveness of shrouding in reducing windage power loss. Windage power loss is observed to decrease with increasing gearbox temperatures and to increase with oil flow. Windage power losses for unshrouded meshed spur gears are 7 times greater than losses determined from unshrouded single spur gear tests. A 6- to 12-times increase in windage power loss is observed in the shrouded meshed spur gear data compared with shrouded single spur gear data. Based on this preliminary study, additional research is suggested to determine the effect of oil drain slot configurations, axial and radial shroud clearances, and higher gear surface speeds on windage power loss. Additional work is also suggested to determine the sensitivity of windage power loss to oil temperature and oil flow. Windage power loss for meshed spur gears tested in both the shrouded and unshrouded configurations is shown to be more than double versus windage power loss for the same spur gears run individually in the same shroud configurations. Further study of the physical processes behind these results is needed to optimize gearbox shrouds for minimum windage power loss.
Document ID
20170009564
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Delgado, Irebert R. (NASA Glenn Research Center Cleveland, OH, United States)
Hurrell, Michael J. (HX5 Sierra, LLC Cleveland, OH, United States)
Date Acquired
October 5, 2017
Publication Date
September 1, 2017
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
E-19395
NASA/TM-2017-219536
GRC-E-DAA-TN44777
Funding Number(s)
WBS: WBS 664817.02.03.02.02
CONTRACT_GRANT: NNC15BA02B
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
drag
power loss
windage
gear

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