Efficiency of Nonstandard and High Contact Ratio Involute Spur Gears

Anderson, Neil; Loewenthal, S. H.

doi:10.1115/1.3260774

Cited by 37 publications

(31 citation statements)

References 3 publications

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“…Shrouding is a far more promising approach that is already widely used within industry. A number of authors have investigated shrouding for either spur or helical gears [2][3][4][5][6][7][8][9][10][11][12][13] and this study builds on previous work, investigating the effects of shrouding and tooth form modification. CFD data is compared with published experimental data where possible.…”

Section: Introductionmentioning

confidence: 99%

“…Whilst equations are available to predict the windage power loss of gears, all are based on experimental correlations [2][3][4][5][6][7][8][9][10][11][12][13] and are restricted in application in many cases. This means that designers have, at best, an estimate of the WPL and in addition, cannot take their design too far from previous, successful designs, thus limiting the design envelope.…”

Section: Introductionmentioning

confidence: 99%

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Modelling windage power loss from an enclosed spur gear

Al-Shibl

Simmons

Eastwick

2007

Proceedings of the Institution of Mechanical Engineers, Part A:

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Within a gearbox the majority of transmission losses can be attributed to bearing losses, meshing losses or losses due to windage/churning. In this paper the commercial CFD code Fluent 6.2.16 is applied in a 2D study of windage power loss (WPL) from a single spur gear rotating in air. By comparing CFD data to published experimental data appropriate grid density and modelling parameters are identified. The model is used to investigate how peripheral shrouding affects WPL and whether WPL can be reduced through minor modifications to tooth tip geometry.Non-dimensional shroud spacings (ratio of gap to gear PCD) of between 0.005 and 0.05 were investigated at shaft speeds between 5,000 rpm and 20,000 rpm. Although CFD data compared reasonably well to experimental data, trends were not reproduced and an optimum shroud could not be identified. A full 3D study is recommended.Modifying the tooth tip by adding a small chamfer on the leading edge reduced WPL by approximately 6%. A small fillet increased total WPL by a similar amount suggesting that WPL may increase as a gear wears. This preliminary study suggests further work in this area would be beneficial.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modelling windage power loss from an enclosed spur gear

Al-Shibl

Simmons

Eastwick

2007

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…The method utilized here for calculation of power loss was described in detail in [3,4] as applied to spur gears of standard proportions and in [5] for gears of nonstandard proportions.…”

Section: Transmission Power Loss Analysis Gear Power Loss Equationsmentioning

confidence: 99%

“…The friction coefficient used to calculate sliding loss [3][4][5] was based on disk machine data generated by Benedict and Kelley [ 6] for mineral oils.…”

Section: Transmission Power Loss Analysis Gear Power Loss Equationsmentioning

confidence: 99%

An Analytical Method to Predict Efficiency of Aircraft Gearboxes

Anderson¹,

Loewenthal

Black³

1986

Journal of Mechanisms, Transmissions, and Automation in Design

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A spur gear efficiency prediction method previously developed by the authors was extended to include power loss of planetary gearsets. A friction coefficient model was developed for MIL-L-7808 oil based on disc machine data. This combined with the recent capability of predicting losses in spur gears of nonstandard proportions allows the calculation of power loss for complete aircraft gearboxes that utilize spur gears. The method was applied to the T56/501 turboprop gearbox and compared with measured test data.Bearing losses were calculated with large scale computer programs.Breakdowns of the gearbox losses point out areas for possible improvement.

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“…(2) ). Recognizing that µ actually varies as gears roll owing to the variations of the contact parameters such as radius of curvature, normal load, sliding and rolling velocities, the works such as (3) relied on published empirical µ formulae. However, the experimentally collected data that were used to derive these formulae had relatively narrow ranges of operating temperature, speed and load, and surface roughness, limiting their applications (4) .…”

Section: Introductionmentioning

confidence: 99%

A Method to Derive Friction and Rolling Power Loss Formulae for Mixed Elastohydrodynamic Lubrication

Kahraman

2011

JAMDSM

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Prediction of mechanical power losses of gear pairs requires elastohydrodynamic lubrication (EHL) analyses to be carried out at every discrete contact position. This makes gear efficiency models computationally demanding. As a remedy to this problem, a method is proposed in this study to derive EHL-based friction coefficient and rolling power loss formulae to be used in gear efficiency models. This method employs a large number of EHL analyses covering a full matrix of all key contact parameters, namely normal load, rolling and sliding velocities, radii of curvature, lubricant parameters and surface roughness amplitudes, within typical ranges dictated by gear contacts. Linear regression of the results of the EHL analyses yields friction coefficient and rolling power loss formulae suitable for gear efficiency models. In the EHL model, the hydrodynamic fluid and asperity contact zones are treated in a unified manner. The sliding friction is computed as the sum of the viscous shear within the lubricant and the boundary friction at the local asperity contact spots. The rolling power loss induced by fluid pressure gradient is formulated to include the entire contact zone instead of only the inlet region, since the pressure gradient is substantial within the contact for rough surface condition. The proposed method is demonstrated using an example turbine fluid. Typical measured gear surface roughness profiles are used in the analyses. At the end, the results from the regression formulae are compared to actual EHL predictions to assess their accuracy under various contact conditions.

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Efficiency of Nonstandard and High Contact Ratio Involute Spur Gears

Cited by 37 publications

References 3 publications

Modelling windage power loss from an enclosed spur gear

Modelling windage power loss from an enclosed spur gear

An Analytical Method to Predict Efficiency of Aircraft Gearboxes

A Method to Derive Friction and Rolling Power Loss Formulae for Mixed Elastohydrodynamic Lubrication

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