摘要:

In certain applications, axial pulsating forces in a machine need to be isolated so as to reduce the vibration or transmitted force of the main support. This paper illustrates the trade-offs that must be considered for such vibration isolation. It considers tile use of active feedback control and duly notes the control algorithm difficulties that are anticipated in the use of a magnetic bearing as the means for implementing the isolation. Complete vibration isolation is theoretically possible in a machine over certain frequency ranges for a sinusoidally varying exciting force, but at the cost of large vibration amplitudes of the shaft or very large control forces at low frequencies. Conversely, optimum (reduced) transmitted forces may be determined on the basis of a maximum prescribed amplitude of vibration that is acceptable for a particular machine.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981723

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Steady, turbulent two-phase fluid flow in a rotating annular seal with no eccentricity is analyzed. The fluid is assumed to be a homogeneous mixture of liquid and vapor in thermodynamic equilibrium. Further, the flow is assumed to be adiabatic, but the effects due to heat generation by viscous dissipation are accounted for fully. Solution of the model governing differential equations is accomplished by use of a fourth-order Runge-Kutta numerical integration scheme.

ISSN:0569-8197    

DOI:10.1080/05698198708981724

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

An extensive survey of the papers pertaining to thermal effects in hydrodynamic bearings, particularly the slider/thrust bearings, is presented with a summary of the important contributions of leading researchers and designers.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981725

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This Paper presents a survey of important papers pertaining to thermal effects in journal bearings. It includes discussions on theoretical, computation, and experimental works pertaining to heat effects in journal bearings published in various technical journals.Presented at the 4191 Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981726

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The effect of small, spherical, rigid particles, droplets or bubbles (henceforth referred to as particles) on the performance of a hydrodynamic bearing is theoretically investigated. A low Reynolds number solution for a single particle is utilized to obtain the integrated effect of a dilute suspension.

ISSN:0569-8197    

DOI:10.1080/05698198708981727

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This report describes experiments on friction of Si3N4and SiC sliding against themselves and against each other in water at room temperature. The friction coefficient of Si3N4against itself is f = 0.7 at low speeds (0.2 cm/s). At speeds above 6.5 cm/s and 4.91-N load, hydrodynamic lubrication sets in, with f = <0.002 and an estimated water film thickness of 70 nm. Between 0.2 and 5 cm/s, mixed lubrication occurs. This remarkably thin hydrodynamic film is made possible by the tribochemical wear of Si3N4which occurs by dissolution in water and an absence of wear particles. The friction coefficient of SiC, against SiC or Si3N4in water at low speeds is f = 0.26. Wear occurs by dissolution and fracture pitting. Small wear particles are observed. The friction coefficient of SiC against SiC is independent of sliding velocity between 0.2 and 20 cm/s. Hydrodynamic lubrication is obtained with a Si3N4pin on SiC plate near 10 cm/s, mixed lubrication is obtained with a SiC in on Si3N4plate at v < 20 cm/s.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981728

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A model utilizing simple structural defect theory in molecular monolayers quantitatively accounts for the relationship between measured friction coefficients at monolayer coverage and additive properties such as enthalpy of fusion, chain length, chain symmetry, and solubility in hydrocarbon media. This model is an extension of a recent model of boundary lubrication for a simple two-component lubricant (i.e., base lubricant and one additive) relating friction coefficient to surface coverage. For a given polar end group, it is shown that the lateral cohesive interactions between the hydrocarbon chains in the monolayer play the major role in reducing friction and that the sum total of these interactions approximates the enthalpy of fusion. The coupling between friction coefficient at monolayer coverage and solubility directly follows from thermodynamics.Presented at the 41st Annual Meeting, in Toronto, Ontarlo, Canada, May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981729

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Computer modeling of wear in a solid-lubricated ball bearing for high-speed turbine applications is considered in terms of local interactions and the overall dynamics of the bearing elements. With prescribed coefficients of wear at the various interfaces between the interacting bearing elements, the computer model ADORE is used to obtain the time-averaged wear rates for the balls, races, and the cage as a function of the operating conditions typical of a gas turbine application. The model presents analytical estimates of wear in the ball pockets and at the guide lands of the cage, and it provides some guidance for optimizing cage design in solid-lubricated ball bearings.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981730

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Fluid-film forces generated by squeeze-film dampers (SFD) in response to small-amplitude centered motions are of special interest for stability analyses of rotating machinery employing SFDs with strong centering springs. They form the basis for calculation of linearized damping and inertia force coefficients obtained by subjecting the journal center to very small perturbations in velocity and acceleration. The analysis considers the fluid flow in an open-ends SFD due to small-amplitude circular-centered motions. Simplified governing equations are derived; and regarding the flow to be stable and laminar, the linear flow equations are solved exactly for arbitrary values of the Reynolds number. Exact damping and inertia force coefficient are then derived for open ends SFDs with arbitrary L/D ratios.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981731

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Fluid-film forces generated by squeeze-film dampers (SFD) in response to small-amplitude motions about an off-center equilibrium configuration are of considerable importance for stability analyses of rotating machinery employing SFDs with weak or no centering springs. This approach is the basis for calculation of linearized force coefficients obtained by subjecting the journal to small perturbations in velocity and acceleration.

ISSN:0569-8197    

DOI:10.1080/05698198708981732

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor