scholarly journals Interaction of Rolling-Element and Fluid-Film Bearings Dynamic Characteristics in Hybrid Bearings

2017 ◽  
Vol 206 ◽  
pp. 61-67 ◽  
Author(s):  
R. Polyakov
Keyword(s):  
Dynamic Characteristics ◽  
Fluid Film ◽  
Fluid Film Bearings ◽  
Rolling Element

A Review on Active Bearings and Perspectives of Using Them in Rotating Machinery

2014 ◽  
Vol 630 ◽  
pp. 181-187
Author(s):  
Denis Shutin ◽  
Leonid Savin ◽  
Alexander Babin
Keyword(s):  
Mathematical Modeling ◽  
Artificial Intelligence ◽  
Control System ◽  
Motion Control ◽  
Dynamic Characteristics ◽  
Rotating Machinery ◽  
Fluid Film ◽  
Motion Control System ◽  
Fluid Film Bearings ◽  
System Components

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.

Effect of Bearing Profile on the Stability of Statically Indeterminate Rotor Bearing Systems

2007 ◽  
Author(s):  
N. S. Feng ◽  
E. J. Hahn
Keyword(s):  
Dynamic Characteristics ◽  
Rotating Machinery ◽  
Fluid Film ◽  
System Stability ◽  
Fluid Film Bearings ◽  
Flexible Rotors ◽  
Rotor Bearing ◽  
The Stability

The stability of rotating machinery consisting of flexible rotors supported by fluid film bearings is significantly affected by the dynamic characteristics of the bearings and in particular, the bearing profiles as well as the bearing reaction loads, which, in statically indeterminate systems, are in turn strongly influenced by the relative transverse alignment of the bearings. Using a simple four bearing statically indeterminate model, it is shown that relatively simple variants of the circular bearings, viz. elliptic and 2-pad offset bearings display better system stability characteristics systems in aligned situations and are also more likely to be stable in misaligned situations.

Reliability Improvement of Rotor Supports by Combining Rolling-Element Bearings and Fluid-Film Bearings

2014 ◽  
Vol 630 ◽  
pp. 188-198 ◽  
Author(s):  
Roman Polyakov ◽  
Leonid Savin ◽  
Denis Shutin
Keyword(s):  
Load Capacity ◽  
Life Time ◽  
Performance Characteristics ◽  
Fluid Film ◽  
Rolling Element Bearing ◽  
Rolling Element Bearings ◽  
Advantages And Disadvantages ◽  
Fluid Film Bearings ◽  
Rolling Element ◽  
Unit Increase

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.

Analysis of the conditions for the occurrence of the effect of a minimum of friction in hybrid bearings based on the load separation principle

2018 ◽  
Vol 233 (2) ◽  
pp. 271-280
Author(s):  
Roman Polyakov ◽  
Leonid Savin ◽  
Alex Fetisov
Keyword(s):  
Rolling Contact ◽  
Friction Reduction ◽  
Fluid Film ◽  
Rolling Element Bearing ◽  
Contact Friction ◽  
Rolling Element Bearings ◽  
Operating Characteristics ◽  
Fluid Film Bearings ◽  
Friction Regime ◽  
Rolling Element

Reliability of rotating machinery is determined to a considerable degree by the bearing units. For several applications the requirements in rotational speed, bearing load and maximal vibration level are so extreme that neither rolling-element bearings nor fluid-film bearings could provide necessary operating 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. A hybrid bearing, where a rolling-element bearing and a fluid-film bearing are positioned parallel to the vector of external load (PLEX), has the following advantages compared to a single bearing, whether rolling-element or fluid-film one: increase of life expectancy, load capacity increase, friction reduction, thermal regime enhancement, increase of stiffness, and damping properties. The present paper presents the results of theoretical and numerical research of friction characteristics of PLEX in mixed sliding and rolling friction, i.e. combination of viscous and rolling contact friction, regime. The conditions of minimum friction effect occurrence have been substantiated, and rational relations between characteristics of hybrid rolling-element bearings and fluid-film bearings needed for provision of such effect have been experimentally proven. Finally, the paper presents recommendations regarding design of such hybrid bearings for heavily loaded bearing nodes of rolling mills.

Morton-Newkirk Effect in Overhung Rotor Supported in Rolling Element Bearings

2009 ◽  
Author(s):  
Thom M. Eldridge ◽  
Andrew Olsen ◽  
Michael Carney
Keyword(s):  
Temperature Rise ◽  
Fluid Film ◽  
Rolling Element Bearing ◽  
Viscous Heating ◽  
Rolling Element Bearings ◽  
Fluid Film Bearings ◽  
Thermal Growth ◽  
Morton Effect ◽  
Rolling Element ◽  
Factory Testing

Morton Effect is a known rotordynamic phenomenon associated with fluid film bearings, where viscous heating creates a uni-directional temperature rise in the bearing journal, leading to thermal growth and subsequent bow of the rotor. This results in an unbalance distribution that exacerbates the original unbalance, increasing the heating and bow, resulting in an unstable, or self-amplifying, response. Heretofore, this phenomenon has only been reported in fluid film bearings, as it is traditionally associated with the viscous heating from shearing of the oil. There is also similar behavior associated with phenomenon named the Newkirk Effect where the same mechanics of heating, thermal growth and bowing of a shaft occurs, but the source of heating is a labyrinth rub. This paper describes an incident where such a series of interactions was experienced with a rolling-element bearing (REB). Instead of being driven by viscous shearing of the oil through the minimum film clearance, the uni-directional heating of the rotor results from unbalance and the sliding or dynamic friction of the balls on the inner race or rub of a near-by seal. Rotordynamic analysis was used to derive a correlation between measured vibration levels and temperature rise resulting in predictable bowing of the shaft in a 45,000 RPM fixed speed 250 kW microturbine having an overhung rotor supported by two rolling element bearings. Vibration response was measured with proximity probes along the rotor and temperature predictions were verified against physical evidence in the bearing races. The information gained in this effort was used to establish assembly tolerance and vibration acceptance criteria for factory testing of the turbine. This behavior has internally been described as “REB Morton Effect.” The paper describes the vibration investigation; bearing evaluation; rotordynamic modeling, analysis and verification; design and assembly corrections, and subsequent testing.

Dynamic Characteristics of Fluid Film Bearings

2013 ◽  
pp. 801-808
Author(s):  
Waldemar M. Dmochowski ◽  
Martin J. Conlon ◽  
Azzedine Dadouche ◽  
Michel Fillon
Keyword(s):  
Dynamic Characteristics ◽  
Fluid Film ◽  
Fluid Film Bearings

scholarly journals Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves

Lubricants ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Eckhard Schüler ◽  
Olaf Berner
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Fluid Film ◽  
Operating Characteristics ◽  
Fluid Film Bearings ◽  
Tilting Pad ◽  
Bearing Load ◽  
Bearing Loads ◽  
Tilting Pad Journal Bearing

In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.

Evaluation of the Rotor Temperature Distribution of an Automotive Turbocharger Under Hot Gas Conditions Including Indirect Experimental Validation

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Christopher Zeh ◽  
Ole Willers ◽  
Thomas Hagemann ◽  
Hubert Schwarze ◽  
Jörg Seume
Keyword(s):  
Temperature Distribution ◽  
Heat Flow ◽  
Internal Combustion Engines ◽  
Fluid Film ◽  
Experimental Investigations ◽  
Inlet Temperature ◽  
Hot Gas ◽  
Experimental Identification ◽  
Fluid Film Bearings ◽  
Validation Parameters

Abstract While turbocharging is a key technology for improving the performance and efficiency of internal combustion engines, the operating behavior of the turbocharger is highly dependent on the rotor temperature distribution as it directly modifies viscosity and clearances of the fluid film bearings. Since a direct experimental identification of the rotor temperature of an automotive turbocharger is not feasible at an acceptable expense, a combination of numerical analysis and experimental identification is applied to investigate its temperature characteristic and level. On the one hand, a numerical conjugate heat transfer (CHT) model of the automotive turbocharger investigated is developed using a commercial CFD-tool and a bidirectional, thermal coupling of the CFD-model with thermohydrodynamic lubrication simulation codes is implemented. On the other hand, experimental investigations of the numerically modeled turbocharger are conducted on a hot gas turbocharger test rig for selected operating points. Here, rotor speeds range from 64.000 to 168.000 rpm. The turbine inlet temperature is set to 600 °C and the lubricant is supplied at a pressure of 300 kPa with 90 °C to ensure practically relevant boundary conditions. Comparisons of measured and numerically predicted local temperatures of the turbocharger components indicate a good agreement between the analyses. The calorimetrically determined frictional power loss of the bearings as well as the floating ring speed are used as additional validation parameters. Evaluation of heat flow of diabatic simulations indicates a high sensitivity of local temperatures to rotor speed and load. A cooling effect of the fluid film bearings is present. Consequently, results confirm the necessity of the diabatic approach to the heat flow analysis of turbocharger rotors.

Stability-Optimized Clearance Configuration of Fluid-Film Bearings

2006 ◽  
Vol 129 (1) ◽  
pp. 106-111 ◽  
Author(s):  
Koichi Matsuda ◽  
Shinya Kijimoto ◽  
Yoichi Kanemitsu
Keyword(s):  
Fourier Series ◽  
Load Capacity ◽  
Fluid Film ◽  
Eccentricity Ratio ◽  
Rotating Speed ◽  
Fluid Film Bearings ◽  
Wide Range ◽  
Jeffcott Rotor ◽  
The Stability ◽  
Frequency Ratios

The whirl instability occurs at higher rotating speeds for a full circular fluid-film journal bearing, and many types of clearance configuration have been proposed to solve this instability problem. A clearance configuration of fluid-film journal bearings is optimized in a sense of enhancing the stability of the full circular bearing at high rotational speeds. A performance index is chosen as the sum of the squared whirl-frequency ratios over a wide range of eccentricity ratios, and a Fourier series is used to represent an arbitrary clearance configuration of fluid-film bearings. An optimization problem is then formulated to find the Fourier coefficients to minimize the index. The designed bearing has a clearance configuration similar to that of an offset two-lobe bearing for smaller length-to-diameter ratios. It is shown that the designed bearing cannot destabilize the Jeffcott rotor at any high rotating speed for a wide range of eccentricity ratio. The load capacity of the designed bearings is nearly in the same magnitude as that of the full circular bearing for smaller length-to-diameter ratios. The whirl-frequency ratios of the designed bearing are very sensitive to truncating higher terms of the Fourier series for some eccentricity ratio. The designed bearings successfully enhance the stability of a full circular bearing and are free from the whirl instability.

Sign in / Sign up

Export Citation Format

Share Document