scholarly journals An Analytical Method to Predict Efficiency of Aircraft Gearboxes

1986 ◽  
Vol 108 (3) ◽  
pp. 424-432 ◽  
Author(s):  
N. E. Anderson ◽  
S. H. Loewenthal ◽  
J. D. Black
Keyword(s):  
Friction Coefficient ◽  
Test Data ◽  
Analytical Method ◽  
Power Loss ◽  
Large Scale ◽  
Prediction Method ◽  
Computer Programs ◽  
Spur Gear ◽  
Spur Gears ◽  
Gear Efficiency

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 oill based on disk 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.

scholarly journals Baseline Experimental Results on the Effect of Oil Temperature on Shrouded Meshed Spur Gear Windage Power Loss

2017 ◽  
Author(s):  
Irebert R. Delgado ◽  
Michael J. Hurrell
Keyword(s):  
Experimental Test ◽  
Power Loss ◽  
Spur Gear ◽  
Spur Gears ◽  
Test Results ◽  
Oil Viscosity ◽  
Gear Teeth ◽  
Temperature Load ◽  
Loss Efficiency

Rotorcraft gearbox efficiencies are reduced at increased surface speeds due to viscous and impingement drag on the gear teeth. This windage power loss can affect overall mission range, payload, and frequency of transmission maintenance. Experimental and analytical studies on shrouding for single gears have shown it to be potentially effective in mitigating windage power loss. Efficiency studies on unshrouded meshed gears have shown the effect of speed, oil viscosity, temperature, load, lubrication scheme, etc. on gear windage power loss. The open literature does not contain experimental test data on shrouded meshed spur gears. Gear windage power loss test results are presented on shrouded meshed spur gears at elevated oil inlet temperatures and constant oil pressure both with and without shrouding. Shroud effectiveness is compared at four oil inlet temperatures. The results are compared to the available literature and follow-up work is outlined.

An Experimental Study of Influence of Lubrication Methods on Efficiency and Contact Fatigue Life of Spur Gears

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
J. Moss ◽  
A. Kahraman ◽  
C. Wink
Keyword(s):  
Experimental Study ◽  
Power Loss ◽  
Contact Fatigue ◽  
Spur Gear ◽  
Spur Gears ◽  
Power Losses ◽  
Contact Fatigue Life ◽  
The Impact ◽  
Jet Velocities ◽  
Lubrication Conditions

An experimental investigation of spur gear behavior was conducted with the aim of quantifying the impact of lubrication methods and conditions on the power losses and contact fatigue lives. Variations of dip and jet-lubrication are defined, and these behaviors were observed as a function of the lubrication conditions. Both types of measurements were performed using the same type of back-to-back test machines and the same spur gear test articles such that their evaluations can be correlated. Power loss experiments were performed under both loaded and unloaded conditions to determine both load-independent (spin) and load-dependent (mechanical) losses. Sets of long-cycle contact fatigue experiments were performed under the same lubrication conditions to determine macropitting lives in a statistically meaningful manner. Results indicate that the spin power losses are impacted by the lubrication method significantly while the mechanical losses are not influenced. Contact fatigue lives from jet-lubricated tests are comparable to those under dip-lubricated conditions ones as long as jet velocities are sufficient.

scholarly journals Design of Spur Gears for Improved Efficiency

1982 ◽  
Vol 104 (4) ◽  
pp. 767-774 ◽  
Author(s):  
N. E. Anderson ◽  
S. H. Loewenthal
Keyword(s):  
Power Loss ◽  
Spur Gear ◽  
Operating Conditions ◽  
Gear System ◽  
Spur Gears ◽  
Wide Range ◽  
Pitch Ratio ◽  
Design Requirements ◽  
System Power

A method to calculate spur gear system power loss for a wide range of gear geometries and operating conditions is used to determine design requirements for an efficient gearset. The effects of spur gear size, pitch, ratio, pitch-line-velocity, and load on efficiency are shown. A design example is given to illustrate how the method is to be applied. In general, peak efficiencies were found to be greater for larger diameter and fine pitched gears and tare (no-load) losses were found to be significant.

Experimental Investigations About the Power Loss Transition Between Churning and Windage for Spur Gears

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Romain Quiban ◽  
Christophe Changenet ◽  
Yann Marchesse ◽  
Fabrice Ville
Keyword(s):  
Power Loss ◽  
Spur Gear ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Power Losses ◽  
Loss Model ◽  
Torque Measurements ◽  
Oil Immersion ◽  
Oil Jet ◽  
Very High

Abstract Oil sump lubrication is commonly used in gearboxes. When considering consistent speeds, oil immersion is usually set to low level in order to reduce associated power losses. This configuration is already used in some parts of helicopter mechanical transmissions, and it is under consideration as a lubrication solution for future electric powertrain where gearbox input speeds may be very high. The gear drag power losses are generally evaluated from either a churning power loss model for classic oil sump lubrication or a windage power loss model for oil jet lubrication. One may thus wonder how to estimate drag losses when considering a gear that only a small part is immersed. In this study, the authors investigate the transition between churning and windage phenomena for a spur gear. A series of torque measurements on a single spur gear rotating in an oil bath at numerous oil immersion levels have been carried out. Based on these results, a criterion to indicate which power loss model to use is proposed.

A Prediction Method of Wear on Tooth Surface for Spur Gears

2013 ◽  
Author(s):  
Shotaro Inoue ◽  
Kiyotaka Ikejo ◽  
Kazuteru Nagamura ◽  
Natsuhiko Seyama ◽  
Shinya Nakagawa
Keyword(s):  
Failure Modes ◽  
Gear Tooth ◽  
Testing Machine ◽  
Prediction Method ◽  
Tooth Wear ◽  
Spur Gear ◽  
Tooth Surface ◽  
Wear Depth ◽  
Spur Gears ◽  
Gear Drives

Gear drives are widely used in various mechanical systems. Therefore, the understanding for the failure mode of gear tooth provides the improvement of various machines. The wear on the tooth surface is one of the important failure modes for the gear drives. The tooth wear changes its profile, and frequently increases gear vibration and noise. However, there are many unclear phenomena about the wear on the tooth surface for the gear drive. In this study, we investigated wear of spur gear using a power circulating-type gear testing machine, and measured the change in tooth profile of the test gears. Furthermore, we developed a computer program to predict the amount of the wear on the tooth surface for the spur gears. The method employs two equations. One is based on the wear theory under lubricated condition that was deduced by Soda. The other is derived from the ploughing wear model. Using these equations, the wear depth on the tooth surface is calculated with the contact stress, the sliding velocity, the oil film thickness, etc. The calculated value of the wear agreed with the experimental data.

Performance enhancement of spur gear formed through asymmetric tooth

2019 ◽  
Vol 233 (9) ◽  
pp. 1361-1378 ◽  
Author(s):  
R Prabhu Sekar
Keyword(s):  
Wear Resistance ◽  
Performance Enhancement ◽  
Spur Gear ◽  
Spur Gears ◽  
Comparative Performance ◽  
Gear Design ◽  
Load Carrying ◽  
Gear Efficiency ◽  
Increasing Demand ◽  
The One

Tooth fracture and surface wear are the major failure causes in a gearing system. With increasing demand for high power density gear applications, the need of effective gear design becomes an important requirement to improve gear life. This article presents a method to enhance the load carrying capacity in bending and contact, as well as wear resistance to increase gear efficiency through asymmetric tooth. Asymmetric gear is the one whose pressure angles at pitch circle on drive and coast sides are different. In the present investigation, the load shared by a teeth pair, fillet and contact stresses, wear resistance, frictional power losses and the respective mechanical efficiencies have been determined for comparative performance assessment of symmetric and asymmetric spur gears.

scholarly journals Assembly Accuracy Prediction And Optimization of Aeroengine Rotor Under The Separation Condition Of Assembly And Measurement

2021 ◽  
Author(s):  
Minghua Li ◽  
Yunlong Wang ◽  
Qingchao Sun ◽  
Xiaokai Mu
Keyword(s):  
Test Data ◽  
Large Scale ◽  
Prediction Method ◽  
Optimization Method ◽  
Small Displacement ◽  
Transfer Model ◽  
Direct Optimization ◽  
Geometric Characteristics ◽  
Accuracy Test ◽  
Assembly Accuracy

Abstract The measurement and assembly of aeroengine rotor are separated from each other, the uncertainty of the test position leads to the test data cannot reflect the geometric characteristics of the rotor itself, which makes it difficult to accurately measure and predict the assembly accuracy. Combined with the fact that the geometric characteristics of parts / components are not related to the measurement datum, an assembly accuracy test and prediction method is proposed to reduce the datum deviation and ensure the consistency of test data. Firstly, the small displacement torsor is used to describe the datum deviation, the inverse matrix transformation is applied to reduce the datum deviation, and the datum independent matrix is utilized to express the pose characteristics of the parts / components, which provides the data basis for the accurate prediction of assembly accuracy. Then, the pose transfer model based on the datum independent matrix is established, which is more comprehensive and clearer than the traditional accuracy prediction model. Furthermore, a direct optimization method is also established, which is more efficient than the traditional genetic algorithm. The assembly experiment of aeroengine rotor shows that the model and method proposed in this paper are beneficial to reduce the coaxiality of the front and rear fulcrum and they can better reflect the geometric characteristics of the rotor itself. The related research also has reference significance for other large-scale and high-precision mechanical product assembly.

An Experimental Study of Influence of Lubrication Methods on Efficiency and Contact Fatigue Life of Spur Gears

2017 ◽  
Author(s):  
J. Moss ◽  
A. Kahraman ◽  
C. Wink
Keyword(s):  
Power Loss ◽  
Contact Fatigue ◽  
Spur Gear ◽  
Test Machine ◽  
Spur Gears ◽  
Power Losses ◽  
Contact Fatigue Life ◽  
The Impact ◽  
Jet Velocities ◽  
Lubrication Conditions

An experimental investigation of spur gear behavior was conducted with the aim of quantifying the impact of lubrication methods and conditions on the power losses and contact fatigue lives. Variations of dip and jet-lubrication were defined and these behaviors were observed as a function of the lubrication conditions. All measurements were performed using the same back-to-back test machine and the same spur gear test articles such that all evaluations were correlated. Power loss experiments were performed under both loaded and unloaded conditions to determine both load-independent (spin) and load-dependent (mechanical) losses. Sets of long-cycle contact fatigue experiments were performed under the same lubrication conditions to determine macro-pitting lives in a statistically meaningful manner. Results indicate that the spin power losses are impacted by the lubrication method significantly while the mechanical losses are not influenced. Contact fatigue lives from jet-lubricated tests are comparable to those under dip-lubricated conditions ones as long as jet velocities are sufficient.

A mixed finite element and analytical method to predict load, mechanical power loss and improved efficiency in non-standard spur gear drives

2017 ◽  
Vol 231 (11) ◽  
pp. 1408-1424 ◽  
Author(s):  
R Prabhu Sekar ◽  
V Edwin Geo ◽  
Leenus Jesu Martin
Keyword(s):  
Power Loss ◽  
Mixed Finite Element ◽  
Mechanical Efficiency ◽  
Spur Gear ◽  
Gear Ratio ◽  
Accurate Estimation ◽  
Power Losses ◽  
Contributing Factors ◽  
Comparative Performance ◽  
Gear Efficiency

A reasonably accurate estimation of gear power loss is desirable to maximize gear performance. The load share by teeth pair, contact stress, sliding speed, elastohydrodynamic film thickness and coefficient of friction are some of the most important contributing factors which determine frictional power losses in gears. This paper presents an improvement concept to minimize the load-related power losses (sliding and rolling power losses), which will lead to an enhancement in gear efficiency by selection of non-standard gears. The tooth thickness at the pitch circle of the pinion and gear is different in non-standard gears (kpπm > 0.5 πm and kgπm < 0.5 πm), whereas it is equal in standard gears (kpπm = kgπm = 0.5 πm). In this work, the load share-based frictional power loss and the respective mechanical efficiency have been determined for comparative performance of standard and non-standard gears. Finally, the influence of various gear and drive parameters such as gear ratio, pressure angle pinion teeth number and addendum height factor on gear efficiency has also been investigated and the results of the parametric study are discussed.

scholarly journals Forecast of International Trade of Lithium Carbonate Products in Importing Countries and Small-Scale Exporting Countries

2021 ◽  
Vol 13 (3) ◽  
pp. 1251
Author(s):  
Yichi Zhang ◽  
Zhiliang Dong ◽  
Sen Liu ◽  
Peixiang Jiang ◽  
Cuizhi Zhang ◽  
...  
Keyword(s):  
International Trade ◽  
Large Scale ◽  
Prediction Method ◽  
Lithium Ion ◽  
Lithium Carbonate ◽  
Raw Material ◽  
Small Scale ◽  
Trade Restrictions ◽  
Energy Field ◽  
Structure Of Trade

As the raw material of lithium-ion batteries, lithium carbonate plays an important role in the development of new energy field. Due to the extremely uneven distribution of lithium resources in the world, the security of supply in countries with less say would be greatly threatened if trade restrictions or other accidents occurred in large-scale exporting countries. It is of great significance to help these countries find new partners based on the existing trade topology. This study uses the link prediction method, based on the perspective of the topological structure of trade networks in various countries and trade rules, and eliminates the influence of large-scale lithium carbonate exporting countries on the lithium carbonate trade of other countries, to find potential lithium carbonate trade links among importing and small-scale exporting countries, and summarizes three trade rules: (1) in potential relationships involving two net importers, a relationship involving either China or the Netherlands is more likely to occur; (2) for all potential relationships, a relationship that actually occurred for more than two years in the period in 2009–2018 is more likely to occur in the future; and (3) potential relationships pairing a net exporter with a net importer are more likely to occur than other country combinations. The results show that over the next five to six years, Denmark and Italy, Netherlands and South Africa, Turkey and USA are most likely to have a lithium carbonate trading relationship, while Slovenia and USA, and Belgium and Thailand are the least likely to trade lithium carbonate. Through this study, we can strengthen the supply security of lithium carbonate resources in international trade, and provide international trade policy recommendations for the governments of importing countries and small-scale exporting countries.

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