Thrust Collar Research Articles

Reduction in power loss and increased safety of thrust collar bearings through profiling of the treads – Application of rolling bearing profiles and crowning on thrust collar bearings

Thrust collar bearings can be used to increase the efficiency of megawatt-scaled turbo drivetrains by transferring the compressor thrust from the highspeed shaft to the low-speed shaft, where it can be efficiently supported in the low-speed bearings. This also allows the bearing on the high-speed shaft to be replaced by bearing types with lower power loss. In the following, measures to reduce the thrust collar power loss are investigated. In particular, the effect of different tread profiling is addressed. It is shown that the usual profiling of tribologically similar rolling bearings is no better suited to thrust collars than fully crowned profiles.

Rigid Mode Vibration Control for 250 HP Air Compressor System With Integrated Hybrid Air-Foil Magnetic Thrust Bearing (i-HFMTB)

Abstract This study aims to verify the effectiveness of the 250 HP class compressor system to which the integrated hybrid air-foil magnetic thrust bearing (i-HFMTB) proposed in (Ha et al., 2023, “Integrated Hybrid Air Foil-Magnetic Thrust Bearing (i-HFMTB) Part I: Preliminary Experimental Test for Rotordynamic Parameter Identification and Behavior With PD Control,” ASME Paper No. GT2023-102860) [1] is applied, and the vibration and instability problems of air-foil journal bearing (AFJB) occurring in the rigid mode are controlled by i-HFMTB. The compressor rotor is supported by two AFJB (journal diameter = 60 mm) and an i-HFMTB, and the length and mass of the rotor are 550 mm and 15.24 kg, respectively. i-HFMTB has a structure in which air-foil thrust bearing (AFTB) pads are inserted into eight slotted active magnetic thrust bearings (AMTB), and PD control (proportional gain: 4000; differential gain: 10) is applied. The operating area was identified through AFJB’s dynamic coefficients and rotordynamic analysis. As a result, in the experiment with the 250 HP compressor system supported only by two AFJB, sub- and super-synchronous vibrations were generated owing to the AFJB’s insufficient load capacity and damping in the rigid mode (7000 rpm) region, and this instability did not disappear even upon increasing the speed to 15,000 rpm. However, when i-HFMTB was turned on in rigid mode, it was confirmed that the sub- and super-synchronous vibrations were significantly reduced. The thrust collar tilt angle was calculated through orbit trajectory analysis of the impeller and cooling side, and it was confirmed that the tilt angle of the thrust collar was reduced during i-HFMTB operation.

Comparison of quasi-three-dimensional and full three-dimensional formulations of thrust bearing operation

The results of calculating the characteristics of a thrust bearing with fixed pads of a centrifugal or screw compressor, determined on the basis of a numerical implementation of a periodic thermoelastohydrodynamic mathematical model in quasi-three-dimensional and full three-dimensional formulations, are compared. In the first case, the energy equation is solved on the middle radius of the bearing, and the result of the calculation is extended to the entire fluid flow of the lubricant film and boundary layer (Sm2Px2T program). In the second case, the full three-dimensional equation of the energy of the lubricant film and boundary layer, the thrust collar and the pad is solved, taking into account the heat exchange between the working areas of the bearing and with the environment (Sm2Px3Txτ program). Appropriate conclusions are made.

Design and Analysis of Fixed-Segment Carrier at Carbon Thrust Bearing

Abstract: This thesis work aimed to provide a design and analysis of fixed segment carrier at carbon thrust bearing. With increased the bearing efficiency and reduced the frictional loss and wear resistance. Thrust bearings plays vital role in submersible pumps. Thrust bearings are fixed bottom of the submersible pumps so total thrust or axial load acting on the thrust collar. Thrust collar are manufacturing with resin mixed carbon and casting material and the segments are manufacturing with casting material and stainless steel material. Two types of materials combines to manufacture the segment carrier. The materials hardness and density properties are different from on materials to another material. If suddenly power cut is happen the total load acting on thrust collar. The collar under heavy load carbon surface and segment carrier surface are scratched or damaged the carbon surface. This type of damages are affecting submersible pump. Submersible pumps are fixed with maximum 900 feet under the boar well but this damages are happen we spend more money to lifting the pump from well and also time is wasted. Segment carrier segment surface and thrust pad surface in between micron level film thickness. If the loose segment carrier the loose segment will tilt under the load and vibration of pump. The thrust collar surface is scratched with thrust collar is not rotate because the thrust collar is fitted with rotating shaft with key way. In this study the segment carrier were made with same materials and the hardness of the materials is same and making process are compared to normal bearing were reduced. The segment carrier is made with stainless steel 410 material. The materials are bought a rod or using pattern with investment casting. After the materials is after completing machining process will goes to hardening and materials surface will go to grinding process. The segment surfaces are grinded and achieve the required surface finish. The surface finish techniques are available no of methods. Triondur coating system is more effective than other process. The grinded segment carrier surfaces are goes to next process of lapping. Here the surface is lapped and get required level of surface roughness. In this process the surface roughness is get required level. Because the lapping coating ratio is high the material removal and surface roughness is get more level like 0.2 micron. The diamond powder coating using 100 CRT is lapping process to achieve the required surface finish. The main purpose of the study is to reduce the bearing damages and frictional loss and wear loss and pump damages. And increase the pump life and reduce the raw materials usage

Topology Optimization of Static Turbomachinery Components

Additive Manufacturing has enabled the design of complex components in several technical fields. Considering turbomachinery components, additive manufacturing has unlocked the achievement of significant performances for dynamic rotoring components. The application of topology optimization methods is one of the main factors accelerating the technological development of this sector. This paper presents a procedure for the optimization of static turbomachinery components. The frame-work proposed compares the results obtained by introducing a lattice structure and a solid optimized shape. The procedure is presented with reference to a specific case study. To validate the proposed framework, the complete re-design of a thrust collar of a major Italian-based Oil&Gas company is carried out, demonstrating that the re-thinking of the component in terms of Topology Optimization is a straightforward approach to increase the overall performance of the produced part.

Wear monitoring method of water-lubricated polymer thrust bearing based on ultrasonic reflection coefficient amplitude spectrum

The water-lubricated thrust bearings of the marine rim-driven thruster (RDT) are usually composed of polymer composites, which are prone to serious wear under harsh working conditions. Ultrasonic is an excellent non-destructive monitoring technology, but polymer materials are characterized by viscoelasticity, heterogeneity, and large acoustic attenuation, making it challenging to extract ultrasonic echo signals. Therefore, this paper proposes a wear monitoring method based on the amplitude spectrum of the ultrasonic reflection coefficient. The effects of bearing parameters, objective function, and algorithm parameters on the identification results are simulated and analyzed. Taking the correlation coefficient and root mean square error as the matching parameters, the thickness, sound velocity, density, and attenuation factor of the bearing are inversed simultaneously by utilizing the differential evolution algorithm (DEA), and the wear measurement system is constructed. In order to verify the identification accuracy of this method, an accelerated wear test under heavy load was executed on a multi-functional vertical water lubrication test rig with poly-ether-ether-ketone (PEEK) fixed pad and stainless-steel thrust collar as the object. The thickness of pad was measured using the high-precision spiral micrometer and ultrasonic testing system, respectively. Ultimately, the results demonstrate that the thickness identification error of this method is approximately 1%, and in-situ monitoring ability will be realized in the future, which is of great significance to the life prediction of bearings.

Optically observed turbulence in thrust collars at low critical Reynolds number with numerical predictions

Critical Reynolds number is a dimensionless parameter defining a transition between laminar and turbulent flow that can only be experimentally determined. As machine design pushes towards higher efficiencies, individual components such as bearings operate at higher speeds and loads. Proper modeling of bearing elements, especially at higher speeds requires accurate turbulence modeling. This paper presents the first critical Reynolds number for a Thrust Collar (TC). A high-speed camera observes the oil flow of a TC through a transparent window. The optical results show a consistent flow turbulence area in the entrance region of the flow field that increase in overall area with increasing spin speed, and decreasing axial load. The areas of turbulence correspond to a critical Reynolds number between 300 and 500. Additionally, the experimental results show that increasing the inlet velocity of the oil initially increases the turbulent area, until the speed of the oil surpasses the surface speed of the TC, at which point the turbulence disappears. Finally, the paper also presents a Computational Fluid Dynamics (CFD) turbulence model based on the k−ϵ equations. The model, aimed at characterizing the turbulence flow, correlates well to the experimental results. The CFD model predicts a slight increase in load capacity and power loss (<1%) that could become more significant for larger spin speeds and axial loads.

Improvements to gearbox acoustics via thrust collars

Thrust collars relieve the gearbox housing of the axial force and tilting moments generated by helical gears. The different transfer path also reduces the vibration excitation of the housing due to meshing, which could lead to improved acoustics. This paper presents measurements of noise level reduction of an experimental gearbox. A gearbox dynamics simulation model is used to investigate the effects resulting from the inclusion of thrust collars.

Three-dimensional periodic thermoelastichydrodynamic modeling of hydrodynamic processes of a thrust bearing

The article presents the basic principles of three-dimensional mathematical modeling of the operation of a thrust plain bearing with fixed pads of the compressor. The model is based on the periodic thermoelastichydrodynamic (PTEHD) theory which allows calculating the temperature at the inlet to the pad and considering the complete thermal pattern. A description of the main provisions of the numerical implementation is given. In the stationary mode of the bearings operation, using the Sm2Px3Tx program, numerical experiments were carried out aimed at studying different boundary conditions to the Reynolds equation, the physics of the hydrodynamic process in the lubricating and boundary films of the bearing and the heat propagation in the body of the pad and thrust collar.

Experimental study on the influence of friction pair material hardness on the tribological behaviors of water lubricated thrust bearings

Purpose This paper aims to confirm that increasing the hardness of thrust collars can improve the load carrying capacity (LCC) and wear resistance of water lubricated thrust bearings (WTBs) made of polymers paired with non-polymeric thrust collars, and to design a WTB with high LCC and durability for a shaftless pump-jet propulsor of an autonomous underwater vehicle. Six kinds of WTBs were manufactured by matching aluminum bronze, stainless steel and silicon nitride with two different polymer bearing materials. Their tribological behaviors were tested and compared. Design/methodology/approach The tribological behaviors of the WTBs made with different materials were investigated experimentally on a specially designed test rig. Findings Aluminum bronze is not suitable for crafting thrust collars of heavy load WTBs due to severe abrasive wear. Two body abrasive wear first occurred between the thrust collar and the polymer bearing. Next, aluminum bronze wear particles were produced. The particles acted between the two materials and formed three body abrasive wear. Stainless steel/polymer bearings showed better wear resistance while Si3N4/polymer bearings were the best. Improving the hardness of thrust collars is significant to the LCC and service life of WTBs. Originality/value The wear mechanism of WTBs under heavy load conditions was revealed. Improving the hardness of the thrust collar was confirmed to be a preferable method to improve the wear resistance and LCC of WTBs. The results of this study may provide an important reference for the selection of water lubricated materials and the design of heavy load WTBs.

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

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.

Vibration diagnosis of turbomachinery coupled with induction motor

This paper is focusing on diagnosis for longitudinal and radial vibrations of turbomachinery coupled with induction motors. In this context, extensive field vibration measurements are conducted and analysed to identify the source of predominant vibrations on rotor bearing system in a chosen centrifugal compressor in the radial and longitudinal directions. As a first step, the measured overall vibration levels at multiple locations on bearing surface are compared with the existing ISO standard limits. These measurements showed severe longitudinal vibration values and failure of thrust collar assembly which were not considered in turbomachinery (API) design standards. The second step in diagnosis for vibration spectrum measurements are conducted both in longitudinal and radial directions during transient and steady state operations to find the vibration source and thrust collar assembly failure mechanism. This study on vibration diagnosis and analysis on turbomachinery is useful in correcting the severe longitudinal vibrations and damage control measures and corrections associated with static eccentric airgaps through motor air gap diagram.

A Computational Model for the Analysis of the Static Forced Performance of Self-Equalizing Tilting Pad Thrust Bearings

Abstract While failure analyses in the archival literature report thrust collar misalignment as a major cause of collapse in oil lubricated thrust bearings (TB), a self-equalizing tilting pad thrust bearing (TPTB) improves operation reliability by adjusting its pads to account for thrust collar tilt. This paper describes a kinematics model for the equalizing mechanism integrated into an existing thermo-elastohydrodynamic (TEHD) analysis tool to deliver load performance predictions for self-equalizing TPTBs. The analysis considers the actual leveling plates geometric model as obtained from a solids modeling commercial software and accounts for the sliding friction forces acting at the contact points of the leveling plates and the rolling friction at their pivots. Further, a Hertz contact analysis model uses the predicted forces to deliver a peak pressure and deformation over the contact area between the leveling plates. Next, this paper presents predictions for an example self-equalizing TPTB operating with a thrust collar static misalignment φ = 0.01 deg. The bearing 126 mm in outer diameter has six pads, operates at 4 krpm (26 m/s maximum surface speed) and under a specific load/pad ranging from 0.5 to 3.5 MPa. Compared to a nonequalizing TPTB, a self-equalizing TPTB operates with up to 50% larger minimum film thickness and about ½ largest elastic deformation. Friction forces acting at the contact points of the leveling plates show a significant effect on the performance of the pad leveling system as they reduce the film clearance and increase a pad peak pressure. Predictions from the Hertz contact analysis agree with those from a commercial finite element analysis tool and show a significantly large peak pressure at the contact points of the leveling plates (&amp;gt; 0.9 GPa) when the bearing supports a 3 MPa/pad specific load. This paper stresses the importance of conducting a comprehensive multiple-pad analysis to accurately evaluate the performance and reliable operation of self-equalizing TPTBs.

Разработка ветроэнергетической установки для размещения на дымовые трубы энергообъектов морской инфраструктуры

The article focuses on implementation and operation of the wind power plant of the original design for mounting on the chimneys of seaport power facilities. The worked out wind power unit makes it possible to use secondary thermal energy (heat from the exhaust gases of a boiler house, a mini-thermal power plant based on gas reciprocating plants, etc.) to generate electricity in an amount sufficient to satisfy or partially compensate the needs of the power facility. The aspect of the wind power plant design and the concept of energy generation have been worked out. The hot surface area of the stack serves as the source of energy for upward air flows in the developed original design of the wind power plant. The wind power plant placed on top of the stack is an additional environmentally friendly way of using the potential of renewable energy sources for electric power generation. This method differs from the existing ones in that the pipe is used not as a high support where higher wind speeds prevail, but as a source of thermal energy from secondary energy resources (flue gases of the fuel plant). Wind power plant design includes chimney, generator rotor, permanent rotor magnet, thrust collar for stator winding assembly, thrust collar for bearing assembly, brake drum, brake shoe, brake drive lever, rotor brake drive cable, brake handle and other elements. The introduction of such power units will partially or fully compensate for the own needs of the power facilities that generate thermal and electric energy for the reliable and uninterrupted operation of port services

Stability analysis of rubber-supported thrust bearing in a rotor-bearing system used in marine thrusters under disturbing moments

The transient model of a rotor-bearing system in marine thrusters was established, including 5-DOF model of the rotor and 3-DOF model of the rubber-supported water lubricated thrust bearing. In the model, mixed-TEHD was coupled and the damping of the rubber was characterized by damping loss factor. Furthermore, the responses of the system and the lubrication performance of the thrust bearing were studied under external disturbing moments. The simulation results show that with the increase of the disturbing moments, deflection angle of the thrust collar increases and the rubber-supported pads of the thrust bearing present the problem of insufficient mobility. The contact pressure near inner diameter of bearing pad increase dramatically, which may lead to the risk of friction. In addition, experiments were also carried out. The experimental results show that the thrust bearing appeared worn with the increase of deflection angle of the thrust collar, which is accordant to the simulation results.

Experimental research on tribological and vibration performance of water-lubricated hydrodynamic thrust bearings used in marine shaft-less rim driven thrusters

Aiming at the demand of marine shaft-less rim-driven thrusters(RDTs) for high load capacity, long life, low friction and low vibration water lubricated hydrodynamic thrust bearings(WLHTBs), three types of WLHTBs were designed and manufactured: pivot-supported, rubber-supported and fixed pads bearings. A series of experiments were carried out to study their tribological and vibration performance. Axial force, friction torque, axial displacement of the thrust collar, water temperature and vibration characteristics under different working conditions were acquired by a load cell, a torque meter, 4 proximity sensors, 2 thermometers and 3 B&K pulse sensors during a planned 200 h’ test for each bearing. The experimental results indicate that pivot and rubber-supported bearings have good lubrication and load carrying properties under different conditions. With the rotation speed of the thrust collar increases from 100 to 600 r min−1, the friction coefficient of both bearings is lower than 0.06 under the specific pressure of 0.1 MPa, and reduces similarly to lower than 0.01 under 0.5 MPa. The vibration acceleration amplitude of the rubber-supported WLHTB in X, Y and Z directions are all less than the value of pivoted and fixed pads ones under same speed and load condition. After 200 h of test, the average height and mass loss of the pivot and rubber-supported pads of each WLHTB have only reduced 35 µm/0.0232 g and 42.4 µm/0.0296 g respectively. On the contrary, the performance of the fixed pads bearing is the worst. Under the specific pressure of 0.5 MPa condition, the friction factor increases to 0.2 when the speed reaches 600 r min−1, and the outlet cooling water temperature increases to 70 °C in 20 min. The thrust collar is damaged and the pads’ polymer surfaces are burnt. The experimental research results provide an important reference for the design of WLHTBs for RDTs.

Static and Dynamic Coefficient Measurements for a Thrust Collar Used in an Integrally Geared Compressor

This paper introduces a test facility specifically designed to measure the axial stiffness and damping coefficients of an oil-lubricated thrust collar (TC). The geometry, load, and speeds of the test facility are representative of a production integrally geared compressor (IGC). Separate electric motors spin the shafts according to an assumed gear ratio; a pneumatic air piston loader provides a noncontacting, static thrust force; a remotely controlled impact hammer delivers a perturbation force; and eddy-current motion probes record the resulting vibration. The paper uses a one degree-of-freedom (1DOF) axial motion model that neglects the static and dynamic stiffness of the bull wheel (BW) and presents estimates of the TC oil-film dynamic coefficients for pinion spin speeds between 5 and 10 krpm, and static loads between 200 and 400 N, using time-domain (log-dec and damped period) and static load-deflection techniques. The measurements show that the TC oil-film develops appreciable stiffness (tens of MN/m), and the 1DOF model used here is inadequate for higher loads. Axial runout on the interfacing surfaces of the test facility TC and BW complicates parameter identification, but time-domain averaging effectively attenuates the runout while preserving the transient vibration that results from the impact hammer. Measurements of the TC oil-film stiffness, damping, and virtual mass coefficients are useful to machinery original equipment manufacturers (OEMs) or end-users seeking to predict or diagnose subsynchronous vibration in their machine that might be TC-related.

10 MW급 초임계 CO₂ 발전용 축류 터빈의 구성 설계 및 회전체 동역학 해석

This paper presents component design and rotordynamic analysis results of axial turbine applied to a 10 MW super-critical CO₂ cycle. The axial turbine consists of 3 stage turbine blades and a shaft supported by two fluid film bearings. To prevent the leakage, we installed two seals near the turbine inlet and exit side. We adopts a tilting pad bearing for the stable operation of the rotor. The tilting pad bearing consists of 5 pads and leading edge grooves are installed for the effective thermal management. Based on the rotor layout, we conduct a rotordynamic analysis. The dynamic coefficients of the tilting pad bearings were calculated based on the thin film lubrication theory. Turbine blades, thrust collar and seals were modeled as equivalent inertia. The predicted Campbell diagram showed that there are three critical speeds, namely the conical and the first , second and third bending critical speeds under the rated speed and it is predicted that the rotor have 20% separation margin for the fourth bending critical speed. In addition, unstable modes are not presented under the rated speed and the unbalance response prediction showed that vibration levels are controlled within 0.02 mm for all speed ranges owing to the high damping ratio of the modes.

Static Load Performance of a Water-Lubricated Hydrostatic Thrust Bearing

In rotating equipment, thrust bearings aid to balance axial loads and control shaft position. In turbomachinery, axial loads depend on shaft speed and pressure rise/drop on the impellers. This paper details a water-lubricated test rig for measurement of the performance of hydrostatic thrust bearings (HTBs). The rig contains two water-lubricated HTBs (105 mm outer diameter (OD)), one is the test bearing and the other a slave bearing. Both bearings face the outer side of thrust collars of a rotor. The paper shows measurements of HTB axial clearance, flow rate, and recess pressure for operation with increasing static load (max. 1.4 bar) and supply pressure (max. 4.14 bar) at a rotor speed of 3 krpm (12 m/s OD speed). Severe angular misalignment, static and dynamic, of the bearing surface against its collar persisted and affected all measurements. The HTB axial clearance increases as the supply pressure increases and decreases quickly as the applied load increases. The reduction in clearance increases the flow resistance across the film lands, thus reducing the through flow rate with an increase in recess pressure. In addition, an estimated bearing axial stiffness increases as the operating clearance decreases and as the supply pressure increases. Predictions from a bulk flow model qualitatively agree with the measurements. Alas they are not accurate enough. The differences likely stem from the inordinate tilts (static and dynamic) as well as the flow condition. The test HTB operates in a flow regime that spans from laminar to incipient turbulent. Quantification of misalignment at all operating conditions is presently a routine practice during operation of the test rig.

Tribological Properties of Aluminum Nanoparticles as Additives in an Aqueous Glycerol Solution

The object of this research is to investigate the tribological properties of glycerol lubricant with aluminum nanoparticles as an additive and sodium dodecyl sulfate (SDS) as the dispersive medium for iron to iron friction using a thrust collar tribotester. Meanwhile, the effects of different concentrations of aluminum nanoparticles, SDS, and deionized water in glycerol on tribology properties of iron to iron friction were studied. The experimental parameters were set up according to the Taguchi technique, their influence on the coefficient of friction (COF) and wear rate were examined by response surface methodology (RSM) and analysis of variance (ANOVA) methods. The analysis results were employed to optimize the parameters to obtain the best lubricant effects. The optimal combination of the parameters for both minimum COF and wear rate was found to be 0.6667 weight percent (wt %) of aluminum nanoparticles, 2 wt % of SDS, and 10 wt % of deionized water content of glycerol. The wear surface topography and the average roughness of the surface were also examined using a scanning electron microscope (SEM) and a Mitutoyo Surftest SJ-400 instrument. The results show that aluminum nanoparticles used as an additive in lubricant reduce the surface roughness of a collar remarkably. The energy dispersive spectrometer (EDS) was utilized to confirm the deposition of aluminum nanoparticles on the collar surface leading to decreased friction and wear.