Papers by Keyword: Hybrid Bearing

Abstract: Proton exchange membrane (PEM) fuel cells intended for new energy automotives require a high efficiency and reliability motorized compressor to supply pressurized air. This paper presents a study and development of a motorized centrifugal air compressor using water-lubricated bearings. Comparing the performance of water-lubricated bearing with gas-lubricated bearing, we found that under the same power consumption the load capacity of water-lubricated bearings are more suitable for high speed motorized compressor system. A prototype was built and tested to verify the possibility of the developed motorized centrifugal air compressor. The results show that the system can operate at a stable rotating speed up to 80,000 rpm. The flow rate of the pressurized air is 350Kg/h and pressure ratio is 1.52 at 60,000 rpm, with a global efficiency of approximately 80%.

Abstract: The paper examines the issues of improving the rotor units by means of using support units with actively changeable characteristics. An overview of the known solutions related to the use of active bearings in various types of turbomachinery is provided. A closer look is given at the design and features of active radial bearings, the main elements of which are fluid film bearings. The results of mathematical modeling of active hybrid bearings are presented. The prospects of the use of this type of supports to improve the dynamic characteristics of rotating machinery, including reducing vibrations caused by various factors, are analyzed. Promising directions of development of active bearings are considered, which primarily involves the modification of system components and rotor motion control system algorithms, including intelligent technologies and artificial intelligence methods.

Abstract: Reliability of rotating machinery is determined to a considerable degree by the bearing units. For several applications the requirements in rotation speed, bearing load and maximal vibration level are so extreme that neither rolling-element bearings nor fluid-film bearings could provide necessary performance characteristics during all regimes of operation. Hybrid bearings, which are a combination of rolling-element and fluid-film bearings, can improve performance characteristics and reliability of the rotor-bearing systems. The aim of this work is to analyze the advantages and disadvantages of the hybrid bearings. Known real applications of hybrid bearings are discussed. Analysis shows that depending on the application different hybrid bearing types could improve dynamic characteristics and life time of the bearing unit, increase load capacity and DN limit of the rolling-element bearing.

Abstract: An analysis is conducted and solutions are provided for the dynamic performance of high speed hybrid thrust bearing. By adopting bulk flow theory, the turbulent Reynolds equation is solved numerically with the different orifice diameter and supply pressure. The results show that increasing supply pressure can significantly improve the bearing stiffness and damping, while the orifice diameters make a different effect on the bearing stiffness and damping.

Abstract: The high-speed hybrid ceramic bearing system is simulated by FLUENT, and its temperature rise characteristics under different situations are tested. Meanwhile, an experiment is performed to verify the results. It also shows that simulation with FLUENT is a very useful and low cost method in finishing some complex experiments for substitute.

Abstract: The Hybrid (hydrodynamic/ hydrostatic) journal bearing system has found wide spread application in high speed rotating machines such as compressors, gas turbines, steam turbines, etc. The present studies include solution of Reynolds equation for hydrodynamic journal bearing with infinitely long approximation (ILA), infinitely short bearing approximation (ISA) and finite journal bearing approximation. Further Finite Journal bearing approximation considers two dimensional solution of Reynolds equation with natural boundary condition, which cannot be solved by analytical method. So, here the solutions for finite journal bearing have been done with finite difference method (a MATLAB^® code is prepared for finite difference method) to get bearing performance parameters such as load capacity, Sommerfeld no., etc.

Abstract: In order to establish an optimal material combination for the production of polymer thrust bearings, two types of components: retainer and PPS races - PPS retainer were tested by rolling contact fatigue (RCF). The wear properties of both bearing types were investigated and a relationship between thrust load, rotation speed and wear loss was established. It is concluded that by using a PTFE retainer, it is possible to improve the

Abstract: Reynolds equation is the fundamental equation to solve the static performance for sleeve bearings. For hydrodynamic and hydrostatic oil film bearing with three oil recesses, the specific expressions of the fluid mechanics lubrication Reynolds equation are presented. The gridding model of the bearing is proposed, the boundary condition of the bearing is set, the static characteristics are solved and the pressure distribution of the bearing is plotted by using FLUENT software. The computation results from FLUENT are considerably accordance with the computation results from finite difference method.

Abstract: Due to having the features of high accuracy, high stiffness, high load capacity and longer service life, the hybrid bearing spindle system is widely used in grinding. This paper presents an analysis method of hybrid bearing spindle dynamic characteristics. The method uses CFD method to solve the oil film pressure field, instead of Reynolds equation, in order to obtain the oil film stiffness and damping. With the obtained oil film stiffness and damping to build the appropriate constraints, 3D finite element model of the hybrid bearing spindle system is established, and the modal analysis of the spindle system is carried out. Compared the analysis results with the theoretical calculation results, the feasibility and correction of the method are proved.

Abstract: For high speed hybrid journal bearing with deep/shallow pockets, film thickness and film Reynolds number vary considerably in different position. Laminar flow and turbulent flow exist simultaneously in the bearing film. This paper establishes the laminar and turbulent mixed film control equations and the pressure boundary conditions together with the restrictor flow equation for a deep/shallow pockets journal hybrid bearing compensated by interior restrictor. The static characteristics such as attitude angle, load carrying capacity, friction power loss and flow volume rate are given by solving the equations with Finite Element Method. By comparing the laminar, turbulent and mixed flow results, it can be seen that the coefficients are proximity under journal speed 5000 rpm (only part of deep pockets is turbulent flow). But the characteristics coefficients of three flow models contrast evidently under journal speed 50000 rpm (deep and shallow pockets are turbulent flow, part of bearing land is laminar flow). Laminar and turbulence mixed flow lubrication theory is more accurate to high speed hybrid bearing with deep/shallow pockets.