Reducing Gear Windage Losses From High Speed Gears

2000 ◽  
Author(s):  
Don D. Winfree
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Total Power ◽  
Fort Worth ◽  
Trial And Error ◽  
Test Rig ◽  
Cost Overruns ◽  
Basic Set ◽  
Drive Trains ◽  
Reducing Gear

Abstract Windage losses in gearboxes account for a large portion of the total power loss in high-speed drive trains. Very little actual data has been collected specifically quantifying these losses. Traditional techniques to measure the effects of baffles in high speed gearing applications have been done by trial and error on very complex systems. This trial and error technique is used throughout the gearing industry to solve problems without isolating each individual gear windage effect. These solutions are usually sub-optimum. They cause time-consuming delays and cost overruns in many programs. This paper describes a gear baffle test rig that was built to quantify and minimize the gear windage losses in high-speed drive trains. These tests were conducted at the Lockheed Martin Aeronautics Company, Fort Worth Texas Facility. The intent of the gearbox baffle test rig was to isolate and measure the windage effects on a single high-speed bevel gear with various baffle configurations. Results of these tests were used to define a basic set of ground rules for designing baffles. Finally the set of ground rules was used to design an optimum baffle configuration.

Reducing Gear Windage Losses From High Speed Gears and Applying These Principles to Actual Running Hardware

2013 ◽  
Author(s):  
Don D. Winfree
Keyword(s):  
Complex Systems ◽  
Power Loss ◽  
High Speed ◽  
Total Power ◽  
Trial And Error ◽  
Test Rig ◽  
Cost Overruns ◽  
Basic Set ◽  
Drive Trains ◽  
Reducing Gear

Windage losses in gearboxes account for a large portion of the total power loss in high-speed drive trains. Very little actual data has been collected specifically quantifying these losses. Traditional techniques to measure the effects of baffles in high speed gearing applications have been done by trial and error on very complex systems. This trial and error technique is used throughout the gearing industry to solve problems without isolating each individual gear windage effect. These solutions are usually sub-optimum. They cause time-consuming delays and cost overruns in many programs. This paper describes two gear baffle test rigs that were built to quantify and minimize the gear windage losses in high-speed drive trains. The intent of the first gearbox baffle test rig was to isolate and measure the windage effects on a single high-speed bevel gear with various baffle configurations. The results of these tests were used to define a basic set of ground rules for designing baffles. This set of ground rules was then applied to another rig replicating the F-35 Liftfan gear box configuration. Immediate benefits were seen. Without this work Lockheed Martin’s X-35 STOVL aircraft would not have been able to operate.

Influence of angular misalignment on the tribological performance of high-speed micro ball bearings considering full multibody interactions

2020 ◽  
pp. 135065012094829
Author(s):  
Chengwei Wen ◽  
Xianghui Meng ◽  
Bugao Lyu ◽  
Jiaming Gu ◽  
Lin Xiao
Keyword(s):  
Fatigue Life ◽  
Axial Load ◽  
Power Loss ◽  
High Speed ◽  
Influencing Factor ◽  
Total Power ◽  
Angular Misalignment ◽  
Absolute Value ◽  
Life Model ◽  
Comprehensive Comparison

To study the angular misalignment effects on the high-speed micro ball bearing which is applied to the dental handpiece, an improved five-degree-of-freedom quasi-dynamic model considering full multibody interactions is established in this paper. Then the modified fatigue life model presented by Jones is adopted to further evaluate the influence of angular misalignment on the reliability of the bearing. The results show that the angular misalignment significantly influences the contact load and contact angle distributions as well as the skidding behavior under both pure axial load and combined axial and radial loads. After comprehensive comparison, it is found that the impacts of angular misalignment on total power loss and bearing fatigue life are different under the two types of loads. Under pure axial load, the total power loss increases consistently and the bearing fatigue life decreases significantly when the absolute value of angular misalignment becomes larger. However, under combined axial and radial loads, the effects of angular misalignment are rather complicated and the direction of angular misalignment turns out to be a key influencing factor.

scholarly journals A New Analysis Tool Assessment for Rotordynamic Modeling of Gas Foil Bearings

2010 ◽  
Author(s):  
Samuel A. Howard ◽  
Luis San Andre´s
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Structural Deformation ◽  
Analysis Tool ◽  
Test Rig ◽  
Contributing Factors ◽  
Foil Bearings ◽  
Rotordynamic Coefficients ◽  
Foil Bearing ◽  
Analytical Tools

Gas foil bearings offer several advantages over traditional bearing types that make them attractive for use in high-speed turbomachinery. They can operate at very high temperatures, require no lubrication supply (oil pumps, seals, etc), exhibit very long life with no maintenance, and once operating airborne, have very low power loss. The use of gas foil bearings in high-speed turbomachinery has been accelerating in recent years, although the pace has been slow. One of the contributing factors to the slow growth has been a lack of analysis tools, benchmarked to measurements, to predict gas foil bearing behavior in rotating machinery. To address this shortcoming, NASA Glenn Research Center (GRC) has supported the development of analytical tools to predict gas foil bearing performance. One of the codes has the capability to predict rotordynamic coefficients, power loss, film thickness, structural deformation, and more. The current paper presents an assessment of the predictive capability of the code, named XLGFBTH©. A test rig at GRC is used as a simulated case study to compare rotordynamic analysis using output from the code to actual rotor response as measured in the test rig. The test rig rotor is supported on two gas foil journal bearings manufactured at GRC, with all pertinent geometry disclosed. The resulting comparison shows that the rotordynamic coefficients calculated using XLGFBTH© represent the dynamics of the system reasonably well, especially as they pertain to predicting critical speeds.

scholarly journals Leakage and Power Loss Test Results for Competing Turbine Engine Seals

2004 ◽  
Author(s):  
Margaret P. Proctor ◽  
Irebert R. Delgado
Keyword(s):  
High Temperature ◽  
Power Loss ◽  
High Speed ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Test Results ◽  
Test Rig ◽  
Labyrinth Seals ◽  
Turbine Engine

Advanced brush and finger seal technologies offer reduced leakage rates over conventional labyrinth seals used in gas turbine engines. To address engine manufactures’ concerns about the heat generation and power loss from these contacting seals, brush, finger, and labyrinth seals were tested in the NASA High Speed, High Temperature Turbine Seal Test Rig. Leakage and power loss test results are compared for these competing seals for operating conditions up to 922 K (1200 °F) inlet air temperature, 517 KPa (75 psid) across the seal, and surface velocities up to 366 m/s (1200 ft/s).

Design of Novel Gas Foil Thrust Bearings and Test Validation in a High-Speed Test Rig

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Nguyen LaTray ◽  
Daejong Kim
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Load Capacity ◽  
Experimental Studies ◽  
Design Feature ◽  
Outer Diameter ◽  
Test Rig ◽  
Thrust Bearings ◽  
Speed Test ◽  
Light Load

Abstract Small gas foil bearings (FBs) with shaft diameter below 25 mm can find many applications in air compressors for fuel cells, electrical turbo chargers, small unmanned air vehicles, turbo alternators, etc. These small machines are characterized by very light load to the radial FBs, and thus rotordynamics stability is more challenging than load capacity. However, a main challenge of gas foil thrust bearings (GFTBs) is how to increase the load capacity, and the challenge remains the same regardless of the size. In previous publications on experimental studies on GFTBs, the measured load capacity is well below the prediction due to challenges in testing as well as manufacturing of GFTBs. Difficulty in achieving the design load capacity often leads to increasing the bearing size in actual applications with penalty of higher power loss. This paper presents design feature of a novel GFTB with outer diameter of 38 mm and static performance up to 155 krpm under external load of 75 N using a high-speed test rig. The 38 mm GFTB presented in this paper is a three-layered structure for easy design and manufacturing, and the unique design feature allows easy scale down and scale up to different sizes. Reynolds equations for compressible gas and the two-dimensional thin plate model were adopted for fluid–structure interaction simulation to predict load capacity and power loss of the GFTB. The predicted power loss and load capacity agree well with the measurements.

Annular Gap Windage Loss Measurements for High Speed Electrical Machinery

2017 ◽  
Author(s):  
Erik E. Swanson ◽  
P. Shawn O’Meara ◽  
Hsin-Hua Tsuei
Keyword(s):  
Test Data ◽  
Power Loss ◽  
High Speed ◽  
Reasonable Agreement ◽  
Smooth Surface ◽  
Test Facility ◽  
Empirical Correlations ◽  
Test Rig ◽  
Electrical Machinery ◽  
Annular Gap

Windage loss in small, high speed electrical machinery is often predicted using fairly simple quasi-empirical correlations. Many of the correlations used are primarily based on testing performed with larger test articles, at lower speeds, and often with liquid lubricants. This paper presents a new set of air gap windage loss test data for test articles that are more nearly representative of small, high speed electrical machinery. These data were obtained using a unique new test rig. This rig was designed around test articles that are representative of 50 to 200 kW machinery operating up to 60 krpm with air as the fluid in the rotor-stator clearance. This paper describes the new test facility and presents data for a smooth surface 72.4 mm rotor with both a smooth stator and a stator with simulated winding slots, for a range of clearances. The smooth surface results are shown to be in reasonable agreement with previously published results for annular gap windage power loss.

scholarly journals A New Analysis Tool Assessment for Rotordynamic Modeling of Gas Foil Bearings

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Samuel A. Howard ◽  
Luis San Andrés
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Structural Deformation ◽  
Analysis Tool ◽  
Test Rig ◽  
Contributing Factors ◽  
Foil Bearings ◽  
Rotordynamic Coefficients ◽  
Foil Bearing ◽  
Analytical Tools

Gas foil bearings offer several advantages over traditional bearing types that make them attractive for use in high-speed turbomachinery. They can operate at very high temperatures, require no lubrication supply (oil pumps, seals, etc.), exhibit very long life with no maintenance, and once operating airborne, have very low power loss. The use of gas foil bearings in high-speed turbomachinery has been accelerating in recent years although the pace has been slow. One of the contributing factors to the slow growth has been a lack of analysis tools, benchmarked to measurements, to predict gas foil bearing behavior in rotating machinery. To address this shortcoming, NASA Glenn Research Center (GRC) has supported the development of analytical tools to predict gas foil bearing performance. One of the codes has the capability to predict rotordynamic coefficients, power loss, film thickness, structural deformation, and more. The current paper presents an assessment of the predictive capability of the code named XLGFBTH©. A test rig at GRC is used as a simulated case study to compare rotordynamic analysis using output from the code to actual rotor response as measured in the test rig. The test rig rotor is supported on two gas foil journal bearings manufactured at GRC with all pertinent geometry disclosed. The resulting comparison shows that the rotordynamic coefficients calculated using XLGFBTH© represent the dynamics of the system reasonably well especially as they pertain to predicting critical speeds.

Analysis of Counter-Rotating Roller Bearing in Different Mounting Configurations

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Wenjun Gao ◽  
Daniel Nelias ◽  
Zhenxia Liu
Keyword(s):  
Thermal Behavior ◽  
Load Distribution ◽  
Power Loss ◽  
High Speed ◽  
Roller Bearing ◽  
Total Power ◽  
Kinetic Behavior ◽  
Uniform Load ◽  
Roller Ring ◽  
Differential Speed

Advanced engine configuration studies have shown large advantages for an engine with counter-rotating spools with intershaft counter-rotating roller bearings. Mounted on two counter-rotating differential-speed hollow rotors, the bearing internal kinetic behavior, dynamic behavior, and then thermal behavior change greatly, causing a severe challenge to engine designers using traditional analysis methods. A special quasi-dynamic model for counter-rotating roller bearing is proposed, considering rings deformation and windage effects, to analyze the bearing mechanical and thermal behavior in different mounting configurations. Roller sliding and bearing heat generation are calculated and compared with experimental data to verify the model capabilities. It shows that the configuration that connects the inner ring to the high-speed rotor has life cycle advantage with more uniform load distribution, smaller roller/ring clearance, and lower cage speed. This leads to less drag loss due to the rotation of the rollers and cage assembly. The decrease of the total power loss is a key element to minimize the quantity of oil required to lubricate the roller bearing.

scholarly journals On-CMOS Image Sensor Processing for Lane Detection

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3713
Author(s):  
Soyeon Lee ◽  
Bohyeok Jeong ◽  
Keunyeol Park ◽  
Minkyu Song ◽  
Soo Youn Kim
Keyword(s):  
Edge Detection ◽  
High Speed ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Image Resolution ◽  
Lane Detection ◽  
Frame Rate ◽  
Total Power ◽  
Detection Accuracy ◽  
Total Power Consumption

This paper presents a CMOS image sensor (CIS) with built-in lane detection computing circuits for automotive applications. We propose on-CIS processing with an edge detection mask used in the readout circuit of the conventional CIS structure for high-speed lane detection. Furthermore, the edge detection mask can detect the edges of slanting lanes to improve accuracy. A prototype of the proposed CIS was fabricated using a 110 nm CIS process. It has an image resolution of 160 (H) × 120 (V) and a frame rate of 113, and it occupies an area of 5900 μm × 5240 μm. A comparison of its lane detection accuracy with that of existing edge detection algorithms shows that it achieves an acceptable accuracy. Moreover, the total power consumption of the proposed CIS is 9.7 mW at pixel, analog, and digital supply voltages of 3.3, 3.3, and 1.5 V, respectively.

Sign in / Sign up

Export Citation Format

Share Document