The performance of Generation II journal gas foil bearing with misalignment

2020 ◽  
Vol 72 (7) ◽  
pp. 857-863
Author(s):  
Hao Li ◽  
Peng Hai Geng ◽  
Hao Lin
Keyword(s):  
Peer Review ◽  
Dynamic Performance ◽  
Hydrodynamic Pressure ◽  
Normal Operation ◽  
Content Type ◽  
Foil Bearing ◽  
Bearing Load ◽  
Small Perturbation Method ◽  
Stiffness And Damping ◽  
Experimental Researches

Purpose The normal operation of a rotor system is generally vulnerable to misalignment between gas foil bearing (GFB) and rotor. However, most theoretical and experimental researches about the characteristics of GFBs have ignored this phenomenon. Therefore, the main purpose of this paper is to evaluate the static and dynamic performance of GFBs considering misalignment. Design/methodology/approach The shaft is allowed to misalign in two directions. Then the variations of bearing load, friction force, restoring moment, stiffness and damping coefficients are thoroughly explored. The hydrodynamic pressure on the gas film is modeled with compressible Reynolds equation, and the deformation of the flexible bearing is calculated with finite element method. Small perturbation method is used to obtain the displacement and moment dynamic coefficients. Findings The film thickness and pressure distribution distort when misalignments appear. The inclination of GFBs can enhance the restoring moment to withstand the imposed misalignment. Furthermore, the simulation phenomenon demonstrates the misalignment around load direction should be avoided as much as possible, while a small value misalignment around another direction is allowed. Originality/value The value of this paper is the exploration of the influence of misalignments on the static and dynamic performance of the Generation II journal GFB. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0418/

Thermo-elastohydrodynamic analysis of the inhomogeneous foil bearing with misalignment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hao Li ◽  
Haipeng Geng ◽  
Hao Lin
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Dynamic Performance ◽  
Gas Temperature ◽  
Content Type ◽  
Rotor Systems ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Deformation Equation ◽  
Small Perturbation Method

Purpose The misalignment is generally inevitable in the process of machining and assembly of rotor systems with gas foil bearings, but the exploration on this phenomenon is relatively less. Therefore, the purpose of this paper is to carry out the thermo-elastohydrodynamic analysis of the foil bearing with misalignment, especially the inhomogeneous foil bearing. Design/methodology/approach The rotor is allowed to misalign in two non-rotating directions. Then the static and dynamic performance of the inhomogeneous foil bearing is studied. The thermal-elastohydrodynamic analysis is realized by combining the Reynolds equation, foil deformation equation and energy equation. The small perturbation method is used to calculate the dynamic coefficients, then the critical whirl ratio is obtained. Findings The gas pressure, film thickness and temperature distribution distort when the misalignment appears. The rotor misalignment can improve the loading capacity but rise the gas temperature at the same time. Furthermore, the rotor misalignment can affect the critical whirl ratio which demonstrates that it is necessary to analyze the misalignment before the rotordynamic design. Originality/value The value of this paper is the exploration of the thermo-elastohydrodynamic performance of the inhomogeneous foil bearing with misalignment, the analysis procedure and the corresponding results are valuable for the design of turbo system with gas foil bearings.

scholarly journals Influence of Floating Ring Seal Working Condition Parameters on the Dynamic Characteristics of Transient Gas Film

2021 ◽  
Vol 2108 (1) ◽  
pp. 012087
Author(s):  
Lishan Xu ◽  
Weizheng Zhang ◽  
Junjie Lu ◽  
Zhu Liu
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Spiral Groove ◽  
Low Leakage ◽  
Ring Seal ◽  
Stiffness And Damping Coefficient ◽  
Small Perturbation Method ◽  
Stiffness And Damping

Abstract The high requirements for sealing performance in high-speed rotating machinery has led to the design of floating seal with annular spiral groove that offer the advantages of low leakage and extended stability. However, efforts to model the dynamic performance of these floating seal have suffered from the great complexity of the flow field. The present work addresses this issue by establishing a transient Reynolds formulation of a floating seal with annular spiral groove in a rotating coordinate system based on the small perturbation method. In addition, the influence of radial eccentricity and film thickness on the solution divergence and calculation accuracy is calculated. The dynamic stiffness and dynamic damping matrixes are built. Then the variation rules of the dynamic stiffness and damping coefficient of the gas film with structure and working conditions are investigated in detail. The results show that the floating ring seal is more suitable for the service conditions of small film thickness, low pressure, high speed and large eccentricity. Accordingly, the results obtained lay a theoretical foundation for evaluating real-world applications of floating ring seal.

Effect of taper error on the performance of gas foil conical bearing

2020 ◽  
Vol 72 (10) ◽  
pp. 1189-1197
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Peer Review ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Cone Angle ◽  
Nonlinear Structure ◽  
Content Type ◽  
Axial Load Capacity ◽  
Stiffness Model ◽  
Direct Stiffness ◽  
Conical Bearing

Purpose This paper aims to study the bearing performance with different cone angle errors, to study the effect law of manufacturing taper error on the properties of gas foil conical bearing (GFCB). Design/methodology/approach For the GFCB supported by separated bump foil strips, a nonlinear structure stiffness model considering Coulomb friction and arch characteristics was proposed. The finite element method and finite difference method were used to solve the Reynolds equation and the film thickness equation by coupling, and the properties of the GFCB were obtained. The effect of foil and bearing structure parameters on the static and dynamic performance under different taper error cases was analyzed. Moreover, a test on the air compressor supported by GFCBs was conducted to verify the practicability. Findings The taper error has a largely adverse effect on the load capacity of GFCB. When the taper error is −0.03°, the radial load capacity Fr and axial load capacity Fz decrease by 37.5 and 58.3%, respectively. The taper error decreases the direct stiffness and cross-coupled damping of GFCB, which will weaken the bearing stability. Moreover, the performance of GFCB is closely related to the foil and bearing parameters. Originality/value The taper error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0089/

On the characteristics of gas foil conical bearings considering misalignment

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Critical Role ◽  
Friction Torque ◽  
Misalignment Angle ◽  
Content Type ◽  
Stiffness Model ◽  
Dynamic Performances

Purpose The purpose of this paper is to study the characteristics of gas foil conical bearings (GFCBs) considering the misalignment, the static and dynamic performances with different misalignment cases were studied. Design/methodology/approach A test rig on the air compressor supported by GFCBs has been developed to measure the practicability. A nonlinear bump stiffness model and one-dimensional beam top foil stiffness model were used as a basis for the calculation of static and dynamic performance. The finite element method and finite difference method are adopted to solve the Reynolds equation and the film thickness equation coupled, in which different misalignment cases were considered by changing the film thickness. Findings The supporting performance of GFCB is excellent, and the film clearance plays a critical role. The misalignment effects depend on the assembled angle and the misalignment angle. The load capacity, friction torque, temperature of GFCB decrease when the misalignment assembled angle is between 120° and 240°, while the dynamic bearing stability is improved. The static and dynamic performances show the opposite law for the other assembled angles, and the misalignment effect is more dramatic when there is a larger misalignment angle. Moreover, the bearing and running parameters largely affect the bearing performance. Originality/value The present study focuses on the static and dynamic characteristics of GFCB and investigates the effects of misalignment on the bearing performance. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0117

Analysis of dynamic characteristics of spiral groove liquid film seal under thermal–fluid–solid coupling

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Bo Yu ◽  
Muming Hao ◽  
Sun Xinhui ◽  
Zengli Wang ◽  
Liu Fuyu ◽  
...  
Keyword(s):  
Steady State ◽  
Liquid Film ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Analysis Model ◽  
Spiral Groove ◽  
Content Type ◽  
Sealing Performance ◽  
Stiffness And Damping

Purpose The purpose of this paper is to investigate the dynamic characteristics of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling. Design/methodology/approach The dynamic analysis model of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling was established by perturbation method. The steady-state and perturbation Reynolds equations were solved, and the steady-state sealing performance and dynamic characteristic coefficients of the liquid film were obtained. Findings Compared with the liquid film without coupling method, a divergent seal gap is formed between the seal rings under the effect of thermal–fluid–solid coupling, the minimum liquid film thickness decreases, the dynamic stiffness and damping coefficients of the liquid film are increased and the thermoelastic deformation of the end-face improves the dynamic performance of the liquid film seal. Originality/value The dynamic characteristics of the spiral groove liquid film seal under the effect of thermal–fluid–solid coupling are studied, which provides a theoretical reference for optimizing the dynamic performance of the non-contacting liquid film seal.

A Comparison of the Steady-State and Dynamic Performance of First- and Second-Generation Foil Bearings

2010 ◽  
Author(s):  
M. J. Conlon ◽  
A. Dadouche ◽  
W. M. Dmochowski ◽  
R. Payette ◽  
J.-P. Be´dard
Keyword(s):  
Steady State ◽  
Experimental Evaluation ◽  
First Generation ◽  
Second Generation ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Stiffness And Damping

Oil-free foil bearing technology has advanced intermittently over the years, driven by research efforts to improve both steady-state and dynamic performance characteristics, namely: load capacity, stiffness, and damping. Bearing designs are thus classified according to “generation”, with first-generation bearings being the most primitive. This paper presents an experimental evaluation of a first- and a second-generation foil bearing, and aims to provide the high-fidelity data necessary for proper validation of theoretical predictive models of foil bearing performance. The aforementioned test bearings were fabricated in-house, and are both 70mm in diameter with an aspect ratio of 1; bearing manufacturing details are provided. The work makes use of a facility dedicated to measuring both the steady-state and dynamic properties of foil bearings under a variety of controlled operating conditions. The bearing under test is placed at the midspan of a horizontal, simply-supported, stepped shaft which rotates at up to 60krpm. Static and dynamic loads of up to 3500N and 450N (respectively) can be applied by means of a pneumatic cylinder and two electrodynamic shakers. The bearings’ structural (static) stiffnesses are highly nonlinear, and this affects the accuracy of the dynamic coefficient determination. Both dynamic stiffness and damping are found to vary nonlinearly with excitation frequency, and are over-predicted by a structural experimental evaluation — the film plays an important role in bearing dynamics. The second-generation bearing is found to have a higher load capacity, dynamic stiffness, and damping than the first-generation bearing.

Fluid-structure interaction on the dynamic characteristics of the hydrostatic spindle in micro-scale

2019 ◽  
Vol 72 (3) ◽  
pp. 397-403
Author(s):  
Dongju Chen ◽  
You Zhao ◽  
Chunqing Zha ◽  
Jingfang Liu
Keyword(s):  
Film Flow ◽  
Dynamic Performance ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Content Type ◽  
Structure Interaction ◽  
Micro Scale ◽  
Before And After ◽  
Actual Operation ◽  
Stiffness And Damping

Purpose The purpose of this paper is to investigate the effect of fluid–structure interaction in micro-scale on the performance of the hydrostatic spindle and improve the analysis precision of the dynamic performance of hydrostatic spindle. Design/methodology/approach Dynamic analysis of hydrostatic spindle before and after fluid–structure interaction is carried out according to stiffness and damping performance of the bearing, which demonstrates that the natural frequency and peak response of the spindle are increased in the micro-scale. Findings It is concluded from the simulation and experimental results that there is micro-scale effect in the actual operation of the spindle system and slippage exists in the oil film flow. The error between the modal detection result and the theoretical value is within 10 per cent, which also verifies the correctness of the above conclusions. Originality/value This paper analyzes the changes of the bearing performance parameters at macro- and micro-scale, which present the influence of the static and dynamic performance of the spindle in the micro-scale.

Load carrying capacity of a novel magnetic-liquid double suspension fixed pad thrust bearing

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shengtong Wang ◽  
Ouyang Wu ◽  
Zhe Li ◽  
Bin Wang
Keyword(s):  
Peer Review ◽  
Magnetic Force ◽  
Thrust Bearing ◽  
Hydrodynamic Pressure ◽  
Magnetic Liquid ◽  
Content Type ◽  
High Speeds ◽  
Halbach Array ◽  
Lubrication Performance ◽  
New Type

Purpose Proposing a new type of water-lubricated thrust bearing meets the load-bearing requirements of high-power shaft-less rim driven thrusters. Design/methodology/approach The designs were tested by establishing a bearing thermal-fluid-magnetic comprehensive simulation model and developing bearing fluid film force and magnetic simulation. Lubrication performance tests were carried out on the bearing test rig. Findings The Halbach array of magnet blocks is able to reach the maximum magnetic force. The material of sheath can help increase the magnetism. The magnetism is able to reduce wear during low-speed and the start-stop phase, while the eddy current loss at high speeds will lead to a decrease in magnetic force. The experiment found that the bearing was more stable at low speeds and would not demagnetize due to the temperature rise, but it is necessary to pay attention to the running stability at high speeds to prevent rubbing and impact. Originality/value An innovative combination of hydrodynamic pressure and permanent magnetic repulsion was observed to form a magnetic-liquid double suspension bearing with large bearing capacity. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2020-0295

A novel technique to compute static and dynamic performance characteristics of aerostatic thrust bearing

2018 ◽  
Vol 70 (1) ◽  
pp. 84-96 ◽  
Author(s):  
Saurabh Kumar Yadav ◽  
Arvind Kumar Rajput ◽  
Nathi Ram ◽  
Satish Chandra Sharma
Keyword(s):  
Finite Element ◽  
Thrust Bearing ◽  
Dynamic Performance ◽  
Finite Element Formulation ◽  
Damping Coefficient ◽  
Element Formulation ◽  
Content Type ◽  
Novel Technique ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

Purpose This study aims to analyze the dynamic performance of aerostatic thrust bearing for different geometries of recess. Different geometries of recess of equal recess area, i.e. circular, elliptical, rectangular and annular, have been considered in analysis. The work also analyzes the influence of tilt angle on the performance of thrust bearing. To compute the unknown pressure field, the Reynolds equation governing the flow of compressible lubricant (air) has been solved using finite element formulation. Further, separate finite element formulations have been carried out to compute fluid film stiffness and damping coefficients directly. This method provides quick computation of stiffness and damping coefficients of aerostatic thrust bearing than the usual approach. Design/methodology/approach As the Reynolds equation governing the flow of compressible lubricant is nonlinear partial differential equation, the computation of the stiffness and damping coefficient follows an iterative procedure. It requires a lot of computational energy. Therefore, in the present work, a novel technique based on finite element formulation is suggested to compute air film stiffness and damping coefficient in aerostatic thrust bearing. Findings A novel technique based on finite element formulation is illustrated to simulate the performance of tilted pad aerostatic thrust bearing. On the basis of simulated results, following key conclusions may be drawn. The static and dynamic performance of a circular aerostatic tilted thrust pad bearing is significantly affected with a change in the value of tilt parameter and the shape of the recess. Research limitations/implications Implications are as follows: direct computation of air film damping coefficient is performed without perturbation method in finite element method (FEM); influence of tilt on aerostatic thrust bearing is studied; influence of recess shape on aerostatic thrust bearing is observed; and finite element formulation of aerostatic thrust bearing is performed. Originality/value The present work will be quite useful for bearing designer and academicians.

Effect of roundness error on the performance of novel gas foil conical bearings

2020 ◽  
Vol 72 (7) ◽  
pp. 895-904
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Peer Review ◽  
Dynamic Properties ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Friction Torque ◽  
Roundness Error ◽  
Content Type ◽  
Stiffness Model ◽  
Static Performance ◽  
Stiffness And Damping

Purpose The purpose of this paper is to study the effect law of roundness error on the properties of gas foil conical bearing (GFCB), and the performance of bearings with different non-circular sleeve shapes are calculated. Design/methodology/approach For the bump-type GFCB, the nonlinear bump foil stiffness model and 1-D beam top foil stiffness model are built. On this basis, the finite element method and finite difference method are used to solve the Reynolds equation and the film thickness equation coupled, and the static and dynamic properties of GFCB are calculated. The effect law of sleeve roundness error on the static performance under different conditions is obtained. Moreover, the dynamic stiffness and damping characteristics under different errors are also studied. Findings The roundness error will decrease the load capacity and friction torque of GFCB, and increase the attitude angle. The error effect is more dramatic when there is larger eccentric, small nominal clearance, larger error value and more error lobes, and the static performance exhibits a periodic change in the circumferential direction. The roundness error can also decrease the direct stiffness and cross-coupled damping of GFCB, while the cross-coupled stiffness increases largely, which will reduce the bearing stability. Originality/value The roundness error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0019/

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