Effects of Heat Generation in an Air Hydrostatic Journal Bearing

1970 ◽  
Vol 92 (4) ◽  
pp. 607-616
Author(s):  
R. E. Baker ◽  
K. G. Hornung
Keyword(s):  
Heat Transfer ◽  
Heat Generation ◽  
High Speed ◽  
Journal Bearing ◽  
Temperature Measurements ◽  
Heat Transfer Analysis ◽  
Hydrostatic Bearing ◽  
Thermal Deformations ◽  
The Subject ◽  
Viscosity Variation

A rather complete heat transfer analysis is carried out for a specific air hydrostatic bearing. The effects of viscosity variation and thermal deformations are included. The result is a prediction of film temperature of the bearing at high speed. Torque and temperature measurements are made on the subject bearing and show fair correlation with the theory.

scholarly journals Natural Convection Flow along an Isothermal Vertical Flat Plate with Temperature Dependent Viscosity and Heat Generation

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Md. Mamun Molla ◽  
Anita Biswas ◽  
Abdullah Al-Mamun ◽  
Md. Anwar Hossain
Keyword(s):  
Heat Transfer ◽  
Shear Stress ◽  
Nusselt Number ◽  
Wall Shear Stress ◽  
Heat Generation ◽  
Average Nusselt Number ◽  
Variation Parameter ◽  
Viscosity Variation ◽  
Wall Shear ◽  
Vertical Flat Plate

The purpose of this study is to investigate the natural convection laminar flow along an isothermal vertical flat plate immersed in a fluid with viscosity which is the exponential function of fluid temperature in presence of internal heat generation. The governing boundary layer equations are transformed into a nondimensional form and the resulting nonlinear system of partial differential equations is reduced to a convenient form which are solved numerically using an efficient marching order implicit finite difference method with double sweep technique. Numerical results are presented in terms of the velocity and temperature distribution of the fluid as well as the heat transfer characteristics, namely, the wall shear stress and the local and average rate of heat transfer in terms of the local skin-friction coefficient, the local and average Nusselt number for a wide range of the viscosity-variation parameter, heat generation parameter, and the Rayleigh number. Increasing viscosity variation parameter and Rayleigh number lead to increasing the local and average Nusselt number and decreasing the wall shear stress. Wall shear stress and the rate of heat transfer decreased due to the increase of heat generation.

Heat Transfer Controlled Collapse of a Cylindrical Vapor Bubble in a Vertical Isothermal Tube

1977 ◽  
Vol 99 (3) ◽  
pp. 392-397 ◽  
Author(s):  
D. R. Pitts ◽  
H. C. Hewitt ◽  
B. R. McCullough
Keyword(s):  
Heat Transfer ◽  
Vapor Bubble ◽  
High Speed ◽  
Experimental Results ◽  
Heat Transfer Analysis ◽  
Experimental Program ◽  
Bubble Collapse ◽  
Electric Heater ◽  
Vapor Bubbles ◽  
Experimental Apparatus

An experimental program was conducted to determine the collapse rate of slug-type vapor bubbles rising due to buoyancy through subcooled parent liquid in a vertical isothermal tube. The experimental apparatus included a vertical glass tube with an outer glass container providing a constant temperature water bath for the inner tube. The inner tube contained distilled, deaerated water, and water vapor bubbles were generated at the bottom of this tube with a pulsed electric heater. The parent liquid was uniformly subcooled with respect to the vapor bubble resulting in heat transfer controlled bubble collapse. Collapse rates and rise velocities were recorded by high-speed motion picture photography. Over a limited range of subcooling, the bubble collapse was well behaved, and a simple, quasi-steady boundary layer heat transfer analysis adapted from slug flow over a flat plate correlated the experimental results with a high degree of accuracy. Experimental results were obtained with tubes having inside diameters of 0.0127, 0.0218, and 0.0381 m and for a range of subcooling from 0.5 to 9.0 K.

Influence of Thermal Conductivity of Lubricant on the THD Characteristics of a Plain Journal Bearing

1991 ◽  
Author(s):  
C. Rajalingham ◽  
B. S. Prabhu ◽  
R. B. Bhat ◽  
G. D. Xistris
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Variation ◽  
Heat Generation ◽  
Journal Bearing ◽  
Lubricant Film ◽  
Fluid Film ◽  
Adiabatic Conditions ◽  
Viscous Heat ◽  
Hydrodynamic Journal Bearing

Abstract The viscous heat generation in the lubricant film of a hydrodynamic journal bearing causes a rise in temperature of the fluid film. Considering the influence of the temperature variation along and across the film, the performance of a journal bearing is investigated under adiabatic conditions for different values of thermal conductivity of the lubricant. In this analysis, the temperature of the journal surface has been chosen to ensure that there is no net heat transfer from the lubricant The results show that the variation of temperature across the film affects bearing performance significantly and that an increase in lubricant thermal conductivity enhances bearing performance.

scholarly journals Numerical treatment of radiative Nickel–Zinc ferrite-Ethylene glycol nanofluid flow past a curved surface with thermal stratification and slip conditions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Muhammad Ramzan ◽  
Nosheen Gul ◽  
Jae Dong Chung ◽  
Seifedine Kadry ◽  
Yu-Ming Chu
Keyword(s):  
Heat Transfer ◽  
Ethylene Glycol ◽  
Heat Transfer Rate ◽  
Heat Generation ◽  
Transfer Rate ◽  
Thermal Stratification ◽  
Zinc Ferrite ◽  
Curved Surface ◽  
Heat Transfer Analysis ◽  
Nickel Zinc

Abstract The inadequate cooling capacity of the customary fluids forced the scientists to look for some alternatives that could fulfill the industry requirements. The inception of nanofluids has revolutionized the modern industry-oriented finished products. Nanofluids are the amalgamation of metallic nanoparticles and the usual fluids that possess a high heat transfer rate. Thus, meeting the cooling requirements of the engineering and industrial processes. Having such amazing traits of nanofluids in mind our aim here is to discuss the flow of nanofluid comprising Nickel–Zinc Ferrite and Ethylene glycol over a curved surface with heat transfer analysis. The heat equation contains nonlinear thermal radiation and heat generation/absorption effects. The envisioned mathematical model is supported by the slip and the thermal stratification boundary conditions. Apposite transformations are betrothed to obtain the system of ordinary differential equations from the governing system in curvilinear coordinates. A numerical solution is found by applying MATLAB build-in function bvp4c. The authentication of the proposed model is substantiated by comparing the results with published articles in limiting case. An excellent concurrence is seen in this case. The impacts of numerous physical parameters on Skin friction and Nusselt number and, on velocity and temperature are shown graphically. It is observed that heat generation/absorption has a significant impact on the heat transfer rate. It is also comprehended that velocity and temperature distributions have varied behaviors near and far away from the curve when the curvature is enhanced.

Heat Transfer Across Ball Bearings in Vacuum

2005 ◽  
Author(s):  
Yoshimi R. Takeuchi ◽  
James T. Dickey ◽  
Steven M. Demsky ◽  
Matthew A. Eby
Keyword(s):  
Heat Transfer ◽  
Axial Load ◽  
High Speed ◽  
Thermal Conductance ◽  
Thermal Conditions ◽  
Test Results ◽  
Angular Contact Ball Bearing ◽  
Conductance Data ◽  
The Subject ◽  
Aerospace Corporation

Accurate spacecraft bearing temperature predictions often require both system and bearing level heat source and thermal conductance information. Bearing thermal conductance data is usually the most significant unknown in the development of the thermal model and little has been published in open literature on the subject. Consequently experiments have been conducted at The Aerospace Corporation to address this topic, with special attention given to applications such as high-speed momentum and flywheels. An experiment was designed to measure thermal conductance across a single bearing under both static and dynamic states. This paper will describe the test results for an angular-contact ball bearing under controlled inner race rotational speed, axial load, and thermal conditions. Tests were conducted on both dry and Nye Pennzane SHF2001 synthetic oil lubricated bearings. Test data showed that thermal conductance is sensitive to a complex interdependent set of variables including maximum run-in speed, axial load and temperature. A basic physical understanding of the heat transfer mechanism across a bearing was developed based on experimental results.

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