• 한국유체기계학회 논문집
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• 제5권2호
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• pp.43-49
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• 2002

In this paper, the steady-state performances analysis of a tilting pad gas bearing(TPGB) we analyzed by using finite element method for compressible Reynolds' equation. TPGB is used in a high-expansion-ratio expander running at a speed of 230,000 rpm. In order to solve the nonlinear finite element equations, the Newton-Raphson method is applied. The variations of the loading capacity, friction force and tilting angle of a single pad v.s. eccentricity direction of eccentricity and bearing number are investigated. The condition for the equilibrium of a pad, which is important for safe working of the bearing, is stated. The performances of the three pad bearing such as loading capacity, friction moment are predicted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1016-1021
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• 2004

The need for developing a mathematical model for pad-pivot friction in tilting pad proceeding bearings has been well-recognized, since previous experimental work about the performances of the bearings hypothesized that the friction in the bearings is closely related to their performances. Especially, the sliding friction between pad and pivot in the ball and socket type of the bearings can influence the performance of the bearing. We propose a mathematical model for pad-pivot friction in the ball and socket type, which considers the geometrics of the pad and pivot of the bearings, by assuming the sliding friction in the ball and socket bearing as Coulomb friction. By utilizing the proposed model for pad-pivot friction, we show the analysis of Reynolds equation and energy equation, which explain the thermo-hydrodynamic characteristics of tilting pad proceeding bearings, by taking into account the turbulence and inlet pressure building as well. The results of the study show that the performance of titling-pad proceeding bearings can be greatly influenced by the pad-pivot friction. In particular, we have shown that the analysis of the pad-pivot friction is useful to explain the static proceeding loci and the dynamic characteristics of the ball and socket type of the bearings. Furthermore, for a given operating condition, we can obtain various equilibrium states which satisfy the static equilibrium conditions, by considering the pad-pivot friction.

• Journal of Mechanical Science and Technology
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• 제17권2호
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• pp.246-253
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• 2003

The tribological mechanism between the valve plate and the cylinder block in oil hydraulic axial piston pumps plays an important role on high power density. In this study, the fluid film thickness between the valve plate and the cylinder block was measured with discharge pressure and rotational speed by use of a gap sensor, and a slip ring system in the operating period. To investigate the effect of the valve plate shapes, we designed two valve plates with different shapes . the first valve plate was without a bearing pad, while the second valve plate had a bearing pad. It was found that both valve plates behaved differently with respect to the fluid film thickness characteristics. The leakage flow rates and the shaft torque were also experimented in order to clarify the performance difference between the valve plate without a bearing pad and the valve plate with a bearing pad. From the results of this study, we found out that in the oil hydraulic axial piston pumps, the valve plate with a bearing pad showed better film thickness contours than the valve plate without a bearing pad.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.224-230
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• 2001

A numerical analysis for the gas lubricated flexure-pivot tilting pad journal bearing has been accomplished. The film pressure are obtained by Newton-Raphson method and the dynamic coefficients are evaluated by the pad assembly method. The effects of the pivot position of the pad on the static and dynamic characteristics are presented for three pads journal bearing with LBP. The optimum pivot positions for the static performance is different from that of the dynamic performance.

• 한국기계가공학회지
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• 제10권2호
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• pp.26-31
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• 2011

This article provides the systematic design methodology for a tilting pad journal bearing. First the dynamic factors for the bearing are selected with the critical speed analysis. The pad bearing is then designed to have its best mechanical efficiency by simulations with changing of the number of pad and the lubricant flow rate with meeting the design specifications such as metal temperature, clearance and so on. And the simulation results are reviewed to compare with an experimental test. Finally the stability of rotor with the designed bearing is investigated. This methodology is successfully applied to the rotor for 1.2MW turbo-blower.

• Tribology and Lubricants
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• 제20권6호
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• pp.330-336
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• 2004

In this paper, thermohydrodynamic characteristics of large tilting pad journal bearings which have $3\~8$ tilting pads were numerically analyzed. The turbulent lubrication equation and the energy equation were solved. The regime of operation of this bearing is laminar, turbulent and transitional. Also viscosity of working fluid was considered as function of only temperature and inlet pressure build-up was considered. Numerical results for a large tilting pad journal bearing showed pressure distribution, temperature distribution, eccentricity ratio, and friction torque. The effects of pad number on the static performances of a large tilting pad journal bearing are discussed.

• Tribology and Lubricants
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• 제10권1호
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• pp.35-45
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• 1994

The thermohydrodynamic analysis of tilting pad thrust bearing is studied with the consideration of elastic effect of pad. Reynolds equation, deflection equation and energy equation are solved simultaneously with the boundary conditions. Reynolds equation is modified as the approximate form. Pads are supported by the line pivot and the point pivot respectively. Pads are considered as the flat planes. Effects of pad thickness on the performance of thrust bearing are emphasized and the performances of rigid pad and elastic pad are compared. Effects of inlet temperature on performances of the bearing are compared. Dynamic characteristics of both pad supported by line and point pivot are compared.

• Tribology and Lubricants
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• 제36권1호
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• pp.27-33
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• 2020

Self-equalizing tilting pad thrust bearings are usually employed in turbomachines to achieve high stability and reliability. A tilting pad bearing can incorporate self-equalizing links to handle the misalignment between the bearing and the thrust collar. In this popular design method, the pads sit on the upper-level plates and the lower-level plates stay on the retainer base. With misalignment, the pads that are heavily loaded are pushed down. Consequently, the link pushes up the pads on the opposite side, keeping the bearing surface parallel to the thrust collar surface. The self-equalizing link is used to handle the misalignment from the thermal and mechanical effects. In this study, the experimental investigation deals with the performance of self-equalizing tilting pad thrust bearings. The test rig for evaluating the performance of bearing is developed which can control the misalignment angle. Simultaneous measurements are taken for the force acting on each pad. Pad metal temperature and oil film thickness are functions of the shaft speed, bearing load, misalignment angle, and design of leveling plates. The effect of misalignment on bearing performance is discussed. The results demonstrate that the load on each pad depends on the test conditions(especially misalignment angle), and the load influences the performance of bearings.

• 대한기계학회논문집
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• 제19권2호
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• pp.313-321
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• 1995

The effects of the temperature rise and the turbulence are very important factors to predict the accurate performance of a large tilting pad journal bearing. In this study, the dynamic characteristics of a large tilting pad journal bearing are analyzed, taking into account the three dimensional variation of lubricant viscosity and turbulence. The effects of the temperature rise and the turbulence on the stiffness and damping coefficients are investigated in comparison with the results from the laminar or isothermal theory. The stiffness and damping coefficients increase due to the turbulence but decrease due to the temperature rise. The results show that the effects of both the temperature rise and turbulence must be considered simultaneously in order to predict the dynamic characteristics of a large tilting pad journal bearing more accurately.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.99-100
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• 2002

Radial, tilting-pad proceeding bearings are applied in high speed rotating machines operating at stable small and mean loads and the peripheral speeds of proceeding reaching 150 m/s. The operation of bearing can be determined by static characteristics including the oil film pressure, temperature and viscosity distributions, minimum oil film thickness, load capacity, power loss, oil flow. The operation of 5-lobe tilted-pad proceeding bearing has been introduced at the assumption of adiabatic oil film. The oil film pressure, temperature and viscosity distributions habe received by iterative solution of the Reynolds', energy and viscosity equations. The resulting oil film force, minimum oil film thickness, power loss. oil flow, maximum oil film pressure, maximum temperature were computed for different sets of bearing geometric parameters as: bearing length to diameter ratio, pad angular length and width as well as pad relative clearance.