摘要:

The classical differential equations of motion for the rollers and cage, in a high-speed cylindrical roller bearing, are integrated under prescribed operating conditions and bearing geometry. The generalized cage motion is parametrically evaluated as a function of clearances both in the cage pockets and at the cage-to-race guide lands. Definite correlations between certain cage instabilities and the operating clearances provide practical guidance for optimization of cage clearances for a given performance specification.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982002

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A gas bearing with a bi-directional hydrodynamic geometry is presented and analyzed. The configuration considered is an equally spaced set of alternating land and radial groove sectors, together forming a bearing surface.

ISSN:1040-2004    

DOI:10.1080/10402009108982003

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper studies the effect of a series of factors on the friction and wear behavior of steel with a brush plated layer of Pb, Sn or Pb-Sn-Cu under boundary lubrication. Factors studied include: load, sliding speed, thickness of plated layer and substrate hardness. The experimental set-up consists of a ball-on-disc machine. Based on the stress state of the ball and disc during rubbing, a mathematical expression of the friction coefficient is derived. The theoretical values were found to be in good agreement with the experimental values. Finally, the effect of various factors on the frictional coefficient is discussed in detail using this model.Presented at the 45th Annual Meeting In Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982004

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The lubricated sliding friction characteristics of both electrochemically precharged and uncharged piston ring specimens were determined m a laboratory friction apparatus. The iron phosphate films deposited on precharged piston ring specimens from a specific lubricant blend reduced both static and dynamic friction by as much as 25 to 35 percent. The mechanisms of friction reduction using electrochemically deposited films were investigated and interpreted in terms of surface roughness reduction and reaction film formation.

ISSN:1040-2004    

DOI:10.1080/10402009108982005

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In this paper, the characteristics of noncircular bearings, considering the effects of turbulence and cavitation, are numerically analyzed. Four bearing profiles are considered: circular, worn-circular, two-lobe and elliptical. To model the turbulence, the linearized lubrication theory of Ng and Pan is used. Reynolds' equation is suitably modified to account for both turbulence and cavitation. The equation is incorporated into the Elrod cavitation algorithm. This numerical procedure, which conserves mass throughout the bearing, implicitly incorporates the JFO boundary conditions at rupture and reformation boundaries. JFO theory is considered to accurately model cavitation in moderately to heavily loaded bearings. Performance predictions are compared to results presented in a variety of earlier papers.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982006

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Engine friction reduction through lubricant modification is an appealing approach for improving vehicle fuel economy because the benefits realized can be readily applied to all vehicles. Since tribological processes are influenced by electrochemical interactions between a lubricant and the lubricated sliding surface, electrochemical techniques should be valuable in reducing engine friction. An iron phosphate reaction film has been coated on cast iron electrodes by means of electrolysis of a lubricant containing 2.5 mass percent dilauryl hydrogen phosphate (DHP or “acid phosphate”). Friction tests showed a 20 percent lower friction coefficient for iron phosphate-coated piston ring specimens in comparison to uncoated ones. Laboratory reaction studies indicated that the electrolysis process accelerated a spontaneous corrosion reaction between the electrode and the acid phosphate. Increasing either the electric field or the agitation of the lubricant also accelerated the reaction rate for iron phosphate film formation. A mechanism for the electrolysis reaction was proposed, which involves the formation of ferrous ions at the anode, and hydrogen evolution at the cathode. The consumption of hydrogen ion in producing hydrogen at the cathode enhances the dissociation of acid phosphate to form more acid phosphate anion. The phosphate anion, in turn, chemically reacts with ferrous ion to generate phosphate films on the electrodes.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982007

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

It is known that the antioxidants which are used to maintain the quality of turbine oil are “sacrificed” additives. That is, they cause a chemical reaction and undergo a change in quality while they are performing their function during use. However, there has been no detailed systematic investigation of this phenomenon.

ISSN:1040-2004    

DOI:10.1080/10402009108982008

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The load capacity, film rupture location and lubricant flow rate are computed using a modified Reynolds equation combined with the modified Coyne-Elrod boundary conditions. It was found that the pressure in the convergent portion of the bearing, and hence the load capacity, is increased significantly as the Reynolds number it increased. For small surface tension parameter, the load capacity is increased with increasing surface tension parameter, but is virtually independent of N*for N*> 2.5.

ISSN:1040-2004    

DOI:10.1080/10402009108982009

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper presents an assessment of the stability margin of plane hydrodynamic journal bearing systems mounted on flexible damped pedestals. The stability margin expressed in terms of critical speed (or critical mass) of journal are obtained using the conventional linearized theory. The assessment investigations are then carried out by delineating the motion of an accelerating or decelerating journal. This involves time marching solutions of the equations of motion of the journal and the bearing coupled with the Reynolds equation. It has been found that the motion of an accelerating or decelerating journal concurs with linearized theory in the stable region. However, at the accelerated speeds in the unstable region, the journal and bearing may either execute low amplitude limit cycles or become unstable. This work also furthers the ideas concerning the limiting speed as developed in an earlier work of the present authors.

ISSN:1040-2004    

DOI:10.1080/10402009108982010

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A method to visualize and characterize the complex flow fields in simulated single and double brush seals is presented. The brush seal configuration was tested in a gravity fed water tunnel and a pump driven pressurized oil tunnel. Visualization of the flow field revealed regions that are characteristically river jetting, vortical, crossflow and exist upstream, downstream or within the seal. Such flows are especially engendered by variations in fiber void that are spatial and temporal and affect changes in seal leakage and stability. While the effects of interface motion and cylindrical configuration have not been considered herein, it is believed that the observed flow fields and pressure drop patterns characterize flow phenomenology in brush seals. The axial pressure profiles upstream, across and downstream of the brush have been measured under a variety of inlet pressure conditions and the ensuing pressure maps are presented and discussed. Through the application of the Full Flaw Field Tracking method developed by the authors, the flow patterns and the accompanying fluid velocities inside the brush were non-intrusively determined and graphically reconstructed.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982011

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor