Angular Contact Ball Bearings: Track Position at High Speeds

1969 ◽  
Vol 184 (1) ◽  
pp. 351-370
Author(s):  
K. C. Falcon ◽  
C. Andrew
Keyword(s):  
High Speed ◽  
Contact Angles ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Test Rig ◽  
Outer Race ◽  
High Speeds ◽  
Surface Displacements ◽  
Lubricant Flow

The track position of the balls on the outer race of an angular contact bearing of the series and size used on the main shaft of aero gas turbine engines was measured in a test rig. The test rig was capable of simulating the operating conditions of the bearing with respect to axial load, inner race speed and high lubricant flow rates. The contact angle, defined by the track position, was deduced from the measurement of sub-surface displacements in the race using a number of small transducers embedded therein. The resulting contact angles were compared with values predicted from a number of unconfirmed theories in current use. At conditions of high speed and low load the correlation is poor; an over-estimation of the cage speed, arising from the false assumption that gross ball slip does not occur, gives rise to an over-estimation of the changes of contact angles from their nominal values.

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 a High-Speed Rotating Test Rig for Adaptive Seal Systems

2015 ◽  
Author(s):  
Laura S. Beermann ◽  
Corina Höfler ◽  
Hans-Jörg Bauer
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
High Speed ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Parameter Study ◽  
Test Rig ◽  
Swirl Chamber ◽  
Mass Flows ◽  
Gap Width

Gas turbine engines are subject to increased performance and improved efficiency, which leads to rising core temperatures with additional cooling needs. Reducing the parasitic leakage in the secondary flow system is important to meet the challenging requirements. New seal designs have to be tested and optimized at engine like conditions, like high pressure of up to 9 bar and surface speed of up to 280 m/s as well as an adjusted flow field. Flexible seal designs are an innovative approach to reduce leakage mass flows significantly. Axial and radial movements during transient operating conditions can be compensated easily, thus allowing a smaller gap width and minimizing rub and heat load. This paper describes the design and construction of a new rotating test rig facility. To the knowledge of the authors, this is the only test rig with an adjustable gap width and flow field in a high pressure and speed range. The facility is capable of up to 8 bar differential pressure across the seal and up to 4 bar back pressure. The high revolution engine facilitates a surface speed of up to 280 m/s. A traversable casing allows a quick change of the gap width during operation and simulates radial and axial rotor/stator movements in the engine. The seal movement as well as the resulting gap width are measured during operation to fully understand the seal behavior. An important feature of the new test rig is the continuously adjustable pre-swirl system. It has been designed to cover the different flow conditions in the real engine. Therefore, a RANS parameter study of the pre-swirl chamber has been conducted, which shows the adjustability of different pre-swirl ratios for constant and changing inlet mass flows.

scholarly journals Hybrid Ceramic Bearing Development for Gas Turbine Engines

1994 ◽  
Author(s):  
Frederick D. Slaney
Keyword(s):  
Silicon Nitride ◽  
Gas Turbine ◽  
High Speed ◽  
Development Program ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Hybrid Bearing ◽  
Engine Testing ◽  
Hybrid Ceramic

Over the past seven years, an extensive hybrid bearing development program has been conducted at Textron Lycoming. This paper will report the details of testing and the extraordinary results which can be obtained with silicon nitride balls as applied in hybrid bearings on gas turbine engines. This paper describes the analytically predicted advantages which low mass silicon nitride balls offer at speeds over 2.0MDN. Rig testing comparing hybrid bearings to standard bearings is reported. Testing included heat generation evaluation which showed that hybrid bearings generate an average of 40% less heat than standard bearings. Rig simulation of the AGT1500 mission duty cycle demonstrated that the hybrid silicon nitride bearing system is robust enough to handle the most severe operating conditions. Testing under severe slipping/skidding conditions demonstrated good resistance to skid failure. Under conditions selected to produce high wear, no wear was induced in a hybrid bearing while severe wear was induced in the M50 steel bearing. These preliminary successes lead to active engine testing on the AGT1500 and a new test program to demonstrate operation at 4.0 MDN. As a result of these programs Textron Lycoming now considers hybrid ceramic bearings as a viable design to be used in high speed development applications. This paper provides design detail and test data covering the work outlined above.

Renovation features of powder high-speed steels broaches with plazma hardening

2021 ◽  
pp. 82-85
Author(s):  
A.S. Politov ◽  
R.R. Latypov
Keyword(s):  
Gas Turbine ◽  
Comparative Studies ◽  
High Speed ◽  
Atmospheric Plasma ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Cold Atmospheric Plasma ◽  
Plasma Hardening

The comparative studies results of the durability of cutting properties of new and restored by regrinding and repeated plasma hardening with the application of multi-layer Si—O—C—N nanocoating system (PECVD by cold atmospheric plasma) powder high — speed steels broaches teeth for the processing of hard-to-process materials profilecomposite gas-turbine engines components are presented.

Subsynchronous Vibration Patterns Under Reduced Oil Supply Flow Rates

2017 ◽  
Author(s):  
B. R. Nichols ◽  
R. L. Fittro ◽  
C. P. Goyne
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Operating Conditions ◽  
System Stability ◽  
Supporting Evidence ◽  
Test Rig ◽  
Flow Rates ◽  
Oil Supply ◽  
Bending Mode ◽  
Wide Range

Many high-speed, rotating machines across a wide range of industrial applications depend on fluid film bearings to provide both static support of the rotor and to introduce stabilizing damping forces into the system through a developed hydrodynamic film wedge. Reduced oil supply flow rate to the bearings can cause cavitation, or a lack of a fully developed film layer, at the leading edge of the bearing pads. Reducing oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses due to shear forces. While machine efficiency may be improved with reduced lubricant flow, little experimental data on its effects on system stability and performance can be found in the literature. This study looks at overall system performance of a test rig operating under reduced oil supply flow rates by observing steady-state bearing performance indicators and baseline vibrational response of the shaft. The test rig used in this study was designed to be dynamically similar to a high-speed industrial compressor. It consists of a 1.55 m long, flexible rotor supported by two tilting pad bearings with a nominal diameter of 70 mm and a span of 1.2 m. The first bending mode is located at approximately 5,000 rpm. The tiling-pad bearings consist of five pads in a vintage, flooded bearing housing with a length to diameter ratio of 0.75, preload of 0.3, and a load-between-pad configuration. Tests were conducted over a number of operating speeds, ranging from 8,000 to 12,000 rpm, and bearing loads, while systematically reducing the oil supply flow rates provided to the bearings under each condition. For nearly all operating conditions, a low amplitude, broadband subsynchronous vibration pattern was observed in the frequency domain from approximately 0–75 Hz. When the test rig was operated at running speeds above its first bending mode, a distinctive subsynchronous peak emerged from the broadband pattern at approximately half of the running speed and at the first bending mode of the shaft. This vibration signature is often considered a classic sign of rotordynamic instability attributed to oil whip and shaft whirl phenomena. For low and moderate load conditions, the amplitude of this 0.5x subsynchronous peak increased with decreasing oil supply flow rate at all operating speeds. Under the high load condition, the subsynchronous peak was largely attenuated. A discussion on the possible sources of this subsynchronous vibration including self-excited instability and pad flutter forced vibration is provided with supporting evidence from thermoelastohydrodynamic (TEHD) bearing modeling results. Implications of reduced oil supply flow rate on system stability and operational limits are also discussed.

Marine Operation of Gas Turbine Engines and Waterjet Pumps for Small Passenger Vessels

1979 ◽  
Author(s):  
S. M. Kowleski ◽  
C. D. Harrington
Keyword(s):  
Gas Turbine ◽  
San Francisco ◽  
High Speed ◽  
San Francisco Bay ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Golden Gate ◽  
Operational Problem ◽  
Golden Gate Bridge ◽  
Selection Of

This paper describes the planning, developmental, equipment selection and operational problem phases of the high-speed ferry system presently being operated on San Francisco Bay by the Golden Gate Bridge, Highway and Transportation District. The reasons for the selection of the vessel propulsion package consisting of gas turbine engines and waterjet pumps are discussed in some detail. Most importantly, the paper covers the problems experienced to date with this equipment in continuous marine operation.

Conjugate Heat Transfer Analysis of a Small Annular Combustor With Centrifugal Fuel Injection System

2019 ◽  
Author(s):  
Rampada Rana ◽  
Alosri Prajwal ◽  
Gullapalli Sivaramakrishna ◽  
Raju Dharappa Navindgi ◽  
Nagalingam Muthuveerappan
Keyword(s):  
Structural Integrity ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Injection System ◽  
Maximum Temperature ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Ansys Fluent ◽  
Annular Combustor

Abstract Over the years, the requirements of higher specific thrust and lower specific fuel consumption have been necessitating a continual increase in the maximum temperature and pressure in gas turbine engines. However, such an increase has a direct impact on the structural integrity of various modules of the engine; combustor being one of the severely affected modules. This makes the combustor designer’s task of achieving the targeted life of liner, the hottest component of combustor, a challenging one. Estimation of liner metal temperature, thereby arriving at the combustor life, is an essential part of the design process. In the present study, CHT analysis of a radial annular combustor has been carried out. RANS based analysis of a sector combustor with periodicity in flow and geometry has been performed at realistic engine operating conditions using ANSYS Fluent. Predicted liner metal temperatures have been compared with the measured data and a close agreement has been noted between them, the maximum variation being ± 10%.

scholarly journals Experimental Investigation of the Diagnosis of Angular Contact Ball Bearings Using Acoustic Emission Method and Empirical Mode Decomposition

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Ramtin Tabatabaei ◽  
Aref Aasi ◽  
Seyed Mohammad Jafari ◽  
Enrico Ciulli
Keyword(s):  
Acoustic Emission ◽  
Empirical Mode Decomposition ◽  
High Speed ◽  
Early Stage ◽  
Signal To Noise Ratio ◽  
Operating Conditions ◽  
Outer Race ◽  
Mode Decomposition ◽  
Speed Performance ◽  
Envelope Spectrum

Early detection of angular contact bearings, one of the important subsets of rolling element bearings (REBs), is critical for applications of high accuracy and high speed performance. In this study, acoustic emission (AE) method was applied to an experimental case with defects on angular contact bearing. AE signals were collected by AE sensors in different operating conditions. Signal to noise ratio (SNR) was calculated by kurtosis to entropy ratio (KER), then acquired signals were denoised by empirical mode decomposition (EMD) method, and optimal intrinsic mode function (IMF) was selected by the proposed method. Finally, envelope spectrum was applied to the denoised signals, and frequencies of defects were obtained in different rotating speeds, loadings, and defect sizes. For the first time, a small defect with width of 0.3 mm and loading of 475 N was detected in early stage of 0.04 KHz. Moreover, a comparison between theoretical and extracted defect frequencies suggested that our method successfully detected localized defects in both inner and outer race. Our results show promise in detecting small size defects in REBs.

scholarly journals The Basics of Powder Lubrication in High-Temperature Powder-Lubricated Dampers

1991 ◽  
Author(s):  
Hooshang Heshmat ◽  
James F. Walton
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Basic Mechanism ◽  
Test Facility ◽  
Experimental Program ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Powder Lubrication ◽  
Basic Features ◽  
Selection Of

The objective of this investigation is to develop a novel powder-lubricated rotor bearing system damper concept for use in high-temperature, high-speed rotating machinery such as advanced aircraft gas turbine engines. The approach discussed herein consists of replacing a conventional oil lubrication or frictional damper system with a powder lubrication system that uses the process particulates or externally-fed powder lubricant. Unlike previous work in this field, this approach is based on the postulate of the quasi-hydrodynamic nature of powder lubrication. This postulate is deduced from past observation and present verification that there are a number of basic features of powder flow in narrow interfaces that have the characteristic behavior of fluid film lubrication. In addition to corroborating the basic mechanism of powder lubrication, the conceptual and experimental work performed in this program provides guidelines for selection of the proper geometries, materials and powders suitable for this tribological process. The present investigation describes the fundamentals of quasi-hydrodynamic powder lubrication and defines the rationale underlying the design of the test facility. The performance and the results of the experimental program present conclusions reached regarding design requirements as well as the formulation of a proper model of quasi-hydrodynamic powder lubrication.

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