Novel Approach for Optical Characterization of Thrust Collar Lubricated Area: Experimental and Numerical Results

2021 ◽  
Vol 143 (1) ◽  
Author(s):  
Thomas Kerr ◽  
Adolfo Delgado
Keyword(s):  
High Speed ◽  
Pressure Field ◽  
Load Capacity ◽  
Fe Model ◽  
Cfd Model ◽  
Axial Loads ◽  
Test Rig ◽  
Efficient Operation ◽  
Oil Film ◽  
All Speeds

Abstract Thrust collars (TCs) are bearing elements used in geared machinery that transmit axial loads from one shaft to another. TCs are primarily used in integrally geared compressors (IGCs) but are also found in gearboxes and marine propulsion applications. TCs are hydrodynamic elements featuring a converging-diverging wedge to generate a pressure field that reacts axial loads. Accurate modeling requires knowledge of the film characteristics such as cavitation, turbulence, and air ingestion, all of which reduce load capacity. Current models in the literature do not include mass-conserving cavitation algorithms or turbulence flow. The following paper introduces a new test rig that optically characterizes the thin film region of a TC. The test rig geometries, speeds, and loads match those typically seen in IGC applications. The test rig utilizes a transparent acrylic window in conjunction with a high-speed camera (HSC) to obtain high-speed images of the oil film. Images are filtered and averaged to obtain areas of interest in the oil film. Cavitation and turbulence areas are measured for pinion speeds of 2.5, 5, and 7.5 krpm and axial loads of 0.5, 1, and 1.5 kN. Cavitation occurs in the diverging (upper) region of the TC and appears at pinion speeds over 5000 rpm but does not change in shape after that speed. The cavitation is independent of applied load. Turbulence at the inlet region (bottom) occurs at all speeds but increases to almost 35% of the total area at the highest speed. This paper also presents a finite element (FE) model that includes predictions for the static characteristics of the TC, specifically the cavitation area. The cavitation modeling uses an iterative Elord's method, which conserves mass. The model predicts a similar cavitation area for all speeds and loads. A computational fluid dynamics (CFD) study predicts a similar cavitation area and pressure field to the FE model. The CFD model predicts turbulence in the lower region that increases for increasing spin speed, which matches the experimental results. The CFD model tends to under-predict the turbulence area compared to the experiments. As IGCs move into new application areas to satisfy new needs, the increase in efficiency and capacity comes at a cost of more load and higher speed requirements on the TCs. This work will help original equipment manufacturers model TCs more accurately to ensure safe and efficient operation.

Novel Approach for Optical Characterization of Thrust Collar Lubricated Area: Experimental and Numerical Results

2020 ◽  
Author(s):  
Thomas Kerr ◽  
Adolfo Delgado
Keyword(s):  
High Speed ◽  
Pressure Field ◽  
Load Capacity ◽  
Fe Model ◽  
Cfd Model ◽  
Axial Loads ◽  
Test Rig ◽  
Efficient Operation ◽  
Oil Film ◽  
All Speeds

Abstract Thrust collars (TCs) are bearing elements used in geared machinery that transmit axial loads from one shaft to another. TCs are primarily used in integrally geared compressors (IGCs), but are also found in gearboxes and marine propulsion applications. TCs are hydrodynamic elements featuring a converging-diverging wedge to generate a pressure field that reacts axial loads. Accurate modeling requires knowledge of the film characteristics such as cavitation, turbulence, and air ingestion, all of which reduce load capacity. Current models in the literature do not include mass-conserving cavitation algorithms or turbulent flow. The following paper introduces a new test rig that optically characterizes the thin film region of a thrust collar. The test rig geometries, speeds, and loads match those typically seen in IGC applications. The test rig utilizes a transparent acrylic window in conjunction with a high-speed camera to obtain high-speed images of the oil film. Images are filtered and averaged to obtain areas of interest in the oil film. Cavitation and turbulence areas are captured for pinion speeds of 2.5, 5, and 7.5 krpm, and axial loads of 0.5, 1, and 1.5 kN. Cavitation occurs in the diverging (upper) region of the TC and appears at pinion speeds over 5,000 rpm, but does not change in shape after that speed. The cavitation is independent of applied load. Turbulence at the inlet region (bottom) occurs at all speeds, but increases to almost 35% of the total area at the highest speed. This paper also presents a finite element (FE) model that includes predictions for the static characteristics of the TC, specifically the cavitation area. The cavitation modeling uses an iterative Elord’s method, which conserves mass. The model predicts a similar cavitation area for all speeds and loads. A computation fluid dynamics (CFD) study predicts a similar cavitation area, and pressure field to the FE model. The CFD model predicts turbulence in the lower region that increases for increasing spin speed, which matches the experimental results. The CFD model tends to underpredict the turbulence area when compared to the experiments. As IGCs move into novel application areas to satisfy new needs, the increase in efficiency and capacity comes at a cost of more load and higher speed requirements on the TCs. This work will help original equipment manufacturers model TCs more accurately to ensure safe and efficient operation.

The Comparison of Four Pressure-Thermal Models of Oil Film Bearing With the Non-Newtonian and Temperature-Viscosity Effects

2016 ◽  
Author(s):  
Feng Liang ◽  
Quanyong Xu ◽  
Xudong Lan ◽  
Ming Zhou
Keyword(s):  
Temperature Field ◽  
Numerical Model ◽  
High Speed ◽  
Reynolds Equation ◽  
Pressure Field ◽  
Journal Bearing ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Oil Film ◽  
Viscosity Effects

The thermohydrodynamic analysis of oil film bearing is essential for high speed oil film bearing. The temperature field is coupled with the pressure field. The numerical model can be built or chosen according to the complexity of the objects and requirement of the accuracy. In this paper, four pressure-thermal (P-T) models are proposed, which are zero-dimensional temperature field coupled with Reynolds equation (0D P-T model), two-dimensional temperature field coupled with Reynolds equation (2D P-T model), two-dimensional temperature with third dimensional correction coupled with Dawson equation (2sD P-T model), three-dimensional temperature field coupled with Dawson equation (3D P-T model). The non-Newtonian and temperature-viscosity effects of the lubrication oil are considered in all the four models. Two types of cylindrical journal bearing, the bearing with/without axial grooves, are applied for the simulation. All the simulated cases are compared with the solutions of the CFX. The results show that the 0D P-T model fails to predict the behavior of high speed bearing; The 2D and 2sD P-T model have an acceptable accuracy to predict the performance of the bearing without grooves, but are not able to simulate the P-T field of the bearing with grooves because of the under-developed thermal boundary layer; The 2sD P-T model shows a great improvement when calculating the pressure field compared with the 2D P-T model; the 3D P-T model coincides well with the CFX at any condition. The comparison of these four models provides a reference to help designer choose a proper numerical model for a certain project.

A high-speed rolling bearing test rig supported by sliding bearing

2020 ◽  
Vol 72 (7) ◽  
pp. 955-959
Author(s):  
Hui Li ◽  
Heng Liu ◽  
Shemiao Qi ◽  
Yi Liu
Keyword(s):  
Service Life ◽  
Peer Review ◽  
High Speed ◽  
Load Capacity ◽  
Rolling Bearing ◽  
Test Rig ◽  
Sliding Bearing ◽  
Content Type ◽  
Rotating Speed ◽  
Operating Stability

Purpose The purpose of this paper is to introduce a high-speed rolling bearing test rig supported by sliding bearing and its first experimental results. Design/methodology/approach Through analyzing the disadvantages of using rolling bearing as supporting bearing, the bottlenecks that need to be resolved urgently in the development of rolling bearing experimental technology, and the advantages of the sliding bearing, this study used the sliding bearing as the supporting bearing for the high-speed rolling bearing test rig for the purpose of prolonging the service life, increasing the load capacity and promoting the operating stability. Findings The experimental results show that the high-speed rolling bearing test rig supported by sliding bearing could stably rotate at 70,800 rpm without installing the test bearing; the temperature of the sliding bearing is increasing with the rotating speed and the maximum is less than 95°C. Moreover, the new test rig, installing an angular contact ball bearing as test bearing, could also stably rotate at 54,000 rpm with 2 kN axial load and 1 kN radial load; the temperature of the sliding bearing is increasing with the rotating speed and the maximum temperature is less than 97°C. Practical implications Rolling test rig has been established. Originality/value This paper proposes a high-speed rolling bearing test rig supported by sliding bearing, which greatly prolongs the service life, increases the load capacity and promotes the operating stability, moreover, reduces the risk of supporting bearing failure before the test bearing. This paper can also provide a new idea and reference for the design of similar bearing test rig. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0085/

Optimization of Thermal Performance of Hybrid Journal Bearings for High Speed Machine Tool Spindle with Small Diameter

2010 ◽  
Vol 139-141 ◽  
pp. 731-738 ◽  
Author(s):  
Xue Bing Yang ◽  
Wan Li Xiong ◽  
Zhi Quan Hou ◽  
Ju Long Yuan
Keyword(s):  
Machine Tool ◽  
High Speed ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Small Diameter ◽  
Journal Bearings ◽  
Oil Film ◽  
Machine Tool Spindle ◽  
High Efficient ◽  
Operation Parameters

Multi-array hole-entry hybrid journal bearings have been widely applied to support the high speed precision machine tool spindle with small diameter used in high efficient inner grinding, due to their prominent properties of high rotation accuracy, high dynamic stiffness, high vibration damping and long life. But the imperfection of the hybrid bearing is the significant temperature rising in the oil film on the condition of high speed operation, which brings about the sharp decreasing of load capacity and the larger thermal deformation of the bushing that cause the bearing failure immediately. In this paper, CFD analysis of the temperature fields of the multi-array hole-entry hybrid journal bearing with various bearing construction parameters and operation parameters are presented. According to the simulation results, the temperature rising in the oil film can be controlled efficiently by optimizing the matching of the bearing construction parameters and operation parameters and excellent characteristics of load capacity and static stiffness have been obtained simultaneously.

Design of Novel Gas Foil Thrust Bearings and Test Validation in a High-Speed Test Rig

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Nguyen LaTray ◽  
Daejong Kim
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Load Capacity ◽  
Experimental Studies ◽  
Design Feature ◽  
Outer Diameter ◽  
Test Rig ◽  
Thrust Bearings ◽  
Speed Test ◽  
Light Load

Abstract Small gas foil bearings (FBs) with shaft diameter below 25 mm can find many applications in air compressors for fuel cells, electrical turbo chargers, small unmanned air vehicles, turbo alternators, etc. These small machines are characterized by very light load to the radial FBs, and thus rotordynamics stability is more challenging than load capacity. However, a main challenge of gas foil thrust bearings (GFTBs) is how to increase the load capacity, and the challenge remains the same regardless of the size. In previous publications on experimental studies on GFTBs, the measured load capacity is well below the prediction due to challenges in testing as well as manufacturing of GFTBs. Difficulty in achieving the design load capacity often leads to increasing the bearing size in actual applications with penalty of higher power loss. This paper presents design feature of a novel GFTB with outer diameter of 38 mm and static performance up to 155 krpm under external load of 75 N using a high-speed test rig. The 38 mm GFTB presented in this paper is a three-layered structure for easy design and manufacturing, and the unique design feature allows easy scale down and scale up to different sizes. Reynolds equations for compressible gas and the two-dimensional thin plate model were adopted for fluid–structure interaction simulation to predict load capacity and power loss of the GFTB. The predicted power loss and load capacity agree well with the measurements.

Analytical and Experimental Study of Hydroinertia Gas Bearings for Micromachine Gas Turbines

2005 ◽  
Author(s):  
Kousuke Isomura ◽  
Shin-ichi Togo ◽  
Kousuke Hikichi ◽  
Satoshi Goto ◽  
Shuji Tanaka
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Speed ◽  
Load Capacity ◽  
Stable Operation ◽  
Test Rig ◽  
Suction Force ◽  
Gas Bearings ◽  
Bearing Stiffness ◽  
Gas Bearing

Hydro-inertia gas bearing is a type of static air bearing, which supports the rotor by suction force generated by supersonic flow in large bearing clearance [1]. A tool to analyze the flow inside the clearance of hydroinertia gas bearings have been developed, and validated by experiment. A tool to estimate the load capacity and the bearing stiffness of the hydroinertia gas bearing based on experimental data has also been developed. A micro spinner test rig has been fabricated to test an hydroinertia gas bearings designed by the developed tools, and stable operation of 4mm diameter shaft at 1,200,000 rpm has successfully been achieved. A micro-high-speed bearing test rig to test a rotor for micromachine gas turbine has been designed and fabricated. Current micromachine gas turbine’s configuration requires a rotor with 10mm diameter compressor and turbine impellers on each end of 4mm diameter shaft to operate stably at 870,000rpm. Based on the achievement of stable operation at the high-speed of 1,200,000 rpm, hydro-inertia gas bearing has been selected as a candidate for both the bearings for micromachine gas turbine. Currently, the rotor speed as high as 770,000rpm has been achieved in this test rig.

Effect of Bearing Structure on Oil-air Flow and Temperature of High Speed Ball Bearing by Combining Nonlinear Dynamic and CFD Model

2021 ◽  
Author(s):  
Song Deng ◽  
Guiqiang Zhao ◽  
Dongsheng Qian ◽  
Hua Lin
Keyword(s):  
Temperature Rise ◽  
Power Loss ◽  
High Speed ◽  
Volume Fraction ◽  
Air Flow ◽  
Ball Bearings ◽  
Cfd Model ◽  
Oil Film ◽  
High Speeds ◽  
Bearing Structure

Abstract To achieve effective cooling for high speed ball bearings, an investigation on the effect of bearing structure on oil-air flow and temperature inside bearing chamber is necessary. However, accurately defining boundary conditions of CFD model for high speed ball bearings has not been addressed completely. Adopting an improved dynamic model of bearings to calculate movements of balls and power loss to set the movement boundary and heat source of CFD model at high-low speeds and light-heavy loads. Then, rotational speed of cage and temperature of outer ring at various loads are tested to validate this proposed method. At high speeds, enlarging sealing degree of outlet not only reduces the temperature rise of bearings and improves the uniformity of temperature distribution, but also promotes the formation of oil-film on balls’ surfaces without increasing power loss. Yet it can reduce the temperature rise but can’t markedly improve the formation of oil-film at low and ultra-high speeds. Moreover, half birfield cage facing nozzle plays an important role in improving oil volume fraction inside the bearing cavity to reduce the temperature rise of bearings, and the next is birfield cage, they are again corrugated cage and half birfield cage back towards nozzle. These research results provide theoretical guidance for the improvement of bearing structure.

scholarly journals Porous Gas Journal Bearings: An Exact Solution Revisited and Force Coefficients for Stable Rotordynamic Performance

2021 ◽  
Vol 11 (17) ◽  
pp. 7949
Author(s):  
Luis San Andrés ◽  
Jing Yang ◽  
Andrew Devitt
Keyword(s):  
Exact Solution ◽  
High Speed ◽  
Load Capacity ◽  
Computing Time ◽  
Radial Clearance ◽  
Stable Operation ◽  
Fe Model ◽  
Shaft Speed ◽  
Supply Pressure ◽  
Mechanical Elements

Having come of age, gas film bearings enable high-speed oil-free (micro) rotating machinery with gains in efficiency and reliability, longer maintenance intervals, and a reduction in contaminants released to the atmosphere. Among gas bearing types, porous surface gas bearings (PGBs) have proven successful for 50+ years and presently are off-the-shelf mechanical elements. This paper reviews the literature on PGBs since the 1970s and reproduces an exact solution for the performance of cylindrical PGBs. Both the analytical model and an accompanying finite-element (FE) model predict the performance for two PGBs, a commercially available 76 mm diameter bearing and a smaller 25 mm diameter laboratory unit whose experimental performance is available. As expected, the FE model results reproduce the analytical predictions obtained in a minuscule computing time. For a set external supply pressure, as the radial clearance increases, the flow rate through the bearing grows until reaching a peak magnitude. The PGB load capacity is a fraction of the product of the set pressure difference (pS − pa) and the bearing projected area with a significantly large centering static stiffness evolving over a narrow region of clearances. Operation with shaft speed enhances the bearing load capacity; however, at sufficiently high speeds, significant magnitude cross-coupled forces limit the stable operation of a PGB. At constant operating shaft speed, as the whirl frequency grows, the bearing effective stiffness (Keff) increases, while the effective damping (Ceff) becomes positive for whirl frequencies greater than 50% shaft speed. Similar to a plain hydrodynamic journal bearing, the PGB is prone to a half-frequency whirl, albeit the system natural frequency can be high, mainly depending on the external supply pressure. In essence, for the cases considered, PGBs are linear mechanical elements whose load capacity is proportional to the journal eccentricity.

Experimental Study on Dynamic Coeffcients of Water Lubricated High-Speed Hybrid Bearings With Stepped Recesses

2012 ◽  
Author(s):  
Lin Wang ◽  
Hua Xu ◽  
Shilei Ma
Keyword(s):  
High Speed ◽  
Operating Parameters ◽  
Test Rig ◽  
Oil Film ◽  
Hydrodynamic Bearing ◽  
Rotating Speed ◽  
Dynamic Coefficients ◽  
Supply Pressure ◽  
Hybrid Bearing ◽  
Bearing System

In general, the oil-film forces can be characterized by linear oil-film coefficients of hydrodynamic bearing. This paper proposes an experimental method to recognize the dynamic coefficients of a water lubricated high-speed hybrid bearing with stepped recesses. A test rig is constructed and experimental data are acquired under different conditions. And the unbalance responses method is used to identify the dynamic coefficients of the hybrid bearing system. Comparisons are made to verify the validity and accuracy of the theoretical analysis. The influence of operating parameters, such as supply pressure and rotating speed, on the dynamic coefficients of the system is discussed. The results indicate that the dynamic coefficients increase with the rotating speed when the supply pressure is low.

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