Oil Film Research Articles

Effect of composite textured rough surfaces on the lubrication performance of cylindrical roller bearings

PurposeThe purpose of this paper is to study the impact of different types of textures on the friction lubrication performance of cylindrical roller bearings.Design/methodology/approachIn the present study, the composite texture hydrodynamic lubrication model that takes into account the effects of surface roughness is established, and the Reynolds equation for the oil film is numerically solved using the finite difference method. The study investigates the oil film carrying capacity and maximum pressure of bearings under two different arrangements of four composite textures and conducts a comparative analysis of the oil film characteristics under various texture parameters and surface roughness levels.FindingsWhen the roughness of the inner texture surface and the contact surface are equal, the bearing capacity of the composite texture is intermediate between the two textures. The impact trend of surface roughness on fluid dynamic pressure effects varies with the type of composite texture; the internal roughness of the texture affects the micro-hydrodynamic pressure action. Composite textures with different depths exhibit improved bearing capacities; elliptical cylindrical parallel and elliptical hemispherical parallel textures perform better when their area densities are similar, while other types of composite textures show enhanced bearing performance as the ratio of their area densities increases.Originality/valueThis paper contributes to the theoretical investigations and analyses on designing the textured rolling bearings with high lubrication performance.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0050

Development And Application Of A New Visualization Technique Using Photochromism For Transport Process Of Lubricating Oil Around The Engine Piston

A new visualization technique using photochromism for the movement of oil film was developed and applied to an optical gasoline engine. A photochromic dye was dissolved in the oil and an arbitrary position of the oil film was illuminated by UV laser light, which makes a marker in the oil film via a photochromic reaction. The lifetime of color change by photochromism is relatively long and therefore, by tracking the movement of a marker makes it possible to visualize the movement of oil film directly. The color density was quantified based on the absorbance calculated from images taken before and after coloring in two wavelengths. Through the experimental and theoretical considerations, it was confirmed that the calculated absorbance is effective in reducing a noise originated by the color, the shape of the piston surface, the temporal variation of oil film thickness and the illuminating light intensity distribution. Furthermore, the value of the absorbance is in a very good linear relationship with the oil film thickness. This technique was applied to an optical gasoline engine and confirmed the availability of this technique. In the top land of piston surface, the oil film between the piston and cylinder liner was separated and the majority of the oil is at the piston surface and moved with the piston motion. The oil film thickness on the cylinder liner was very thin. On the contrary, at the piston skirt region, a wider region of the oil film is connected between the linear and the piston skirt. However, there are regions where the oil film between the liner and the skirt is separated by cavitation and the majority of the oil film is on the piston skirt. The change of the flow direction by the operating condition, i.e., the throttle condition, was able to clearly visualize, though the movement of oil film on the piston surface was very slow in normal case. The relatively fast complexed flow for opposite direction was also able to visualize by this technique.

Innovative insights into nanofluid-enhanced gear lubrication: Computational and experimental analysis of churn mechanisms

This study offers unique insights into the churn lubrication mechanism in gear transmission systems through the utilization of nanofluids for the first time. Various performance parameters of the prepared nanofluid lubrication oil are measured, along with the discussion of suspension stability. Based on the overset mesh method and VOF multiphase flow model, a rotating fluid domain calculation model considering the nanofluid-air two-phase is proposed. The high-speed nanofluid lubrication experiment platform is established to track churn phenomena and identify the oil volume fraction on the gear surface. Comparing simulation results with experimental data confirms the calculation accuracy in depicting oil flow and churn lubrication. Result shows that the interaction between droplets and the gear surface involves splash, rebound, adhesion, and diffusion. The nanofluid exhibits improved adsorption, resulting in a higher oil volume fraction. When the rotation speed is increased, intensified oil spatter and atomization are observed. The ranking of nanofluid lubrication performance is Al2O3, SiO2, Fe3O4, CuO, and TiO2 particles, which are approximately aligned with contact angle magnitudes. For 3 % nanoparticles concentration, less oil is swung off, more is drawn into the gear meshing zone, and subsequently squeezed out. Image recognition results align with numerical simulation, indicating that the oil distribution of nanofluid is better than that of base fluid lubrication. This work serves as a foundational exploration for future nanofluid lubrication and heat dissipation, offering insights into preventing oil film rupture, tooth surface wear, gluing and other failure mechanisms.

Improving the triphenylphosphine/triphenylphosphine oxide (TPP/TPPO)‐based method for the absolute and accurate quantification by FTIR‐ATR of hydroperoxides in oils or lipid extracts

AbstractResearch on natural sources of polyunsaturated fatty acids (PUFAs) for both food and nutraceutical prospects has significantly grown in recent years. Some plant oils and lipid extracts contain carotenoids, xanthophylls, sterols, and/or phenolic compounds that can provoke a lipid hydroperoxides (LOOHs) overestimation when quantifying them using nonselective colorimetric assays. Herein, we have optimized a mid‐infrared method using Fourier‐transform infrared spectroscopy coupled with attenuated total reflectance (ATR) to quantify LOOHs in oils or lipid extracts. This method is based on the conversion of triphenylphosphine (TPP) to triphenylphosphine oxide (TPPO) in the presence of hydroperoxides, with a direct assessment of TPPO levels following the formation of an oil film on the ATR crystal's surface, allowing for a low detection limit of 0.5 mmol of LOOH kg−1. The concentration of oil and TPP, as well as the reaction time, were optimized. It was demonstrated that the presence of pigments, unsaponifiable compounds, phenolics, and/or PUFAs on oils, do not disrupt the analysis. Furthermore, the stoichiometry of the TPP/LOOH reaction was examined, confirming the reliability of the method in detecting various forms of hydroperoxides. An accelerated oxidation study was carried out and the hydroperoxide contents measured using TPP/TPPO were found to be comparable to those obtained using the ferric thiocyanate method. Our method offers a fast, simple, robust, and sensitive approach to accurately quantify hydroperoxides, regardless of the chemical composition of oil or lipid extracts.Practical Application: The hydroperoxide assay method outlined in this study allows for the rapid and straightforward detection of hydroperoxides in pure oil matrices. The method's elevated sensitivity facilitates the early identification of oxidation indicators in oils, especially those with significant carotenoid or xanthophyll contents since these compounds may affect the results when using methods based on colorimetric quantification of hydroperoxides. This accurate, precise, and reproducible approach requires only small quantities of test samples and chemical products, making it well suited to routine application in laboratories and industrial environments.

Numerical analysis of lubrication performance of variable cross-section sealing rings

A variable section seal ring is a special type of sealing element that features a regularly changing sealing boundary. This paper proposes a numerical analysis method for calculating the elastohydrodynamic lubrication performance of the sealing surface of a variable section seal, considering factors such as the surface morphology of the seal lip, the initial compression rate of the seal, and the micro-elastic deformation of the rough surface of the seal lip. The three-dimensional distribution of the oil film thickness was obtained. The results show that the oil film thickness on the sealing lip of the variable section seal changes both circumferentially and axially, being thicker in the middle and thinner at the sides when viewed axially, and thicker at the peaks than at the troughs when viewed circumferentially. Higher compression rates of the seal lead to greater friction during operation; different compression rates significantly affect the distribution of the oil film and the oil film pressure on the variable section seal, which directly impacts the lubrication and sealing effectiveness of the seal. Therefore, choosing an appropriate initial compression rate for the seal is very important.

Analysis of wheel-rail contact under oil lubrication conditions

Abstract This investigation centers on the characteristics of the contact between the wheel and rail when lubricated with oil, with a consideration of the impact of surface roughness. Confronting significant challenges related to low adhesion, a thorough examination is undertaken to analyze the changes in film thickness under oil lubrication, investigating trends at varying vehicle speeds and axle loads. Employing detailed modeling based on micro-elastohydrodynamic theory, the distribution of oil film thickness under diverse operational conditions is determined. The findings indicate that, under oil lubrication, a film thickness in the range of several tens of micrometers is established, effectively insulating the surfaces of the wheel and rail, thereby reducing adhesion. With increasing vehicle speed, the thickness of the oil film also rises, whereas an elevation in axle load results in a marginal decrease in film thickness. This research contributes to a comprehensive comprehension of the wheel-rail contact mechanism in oil lubrication scenarios, providing theoretical backing to address concerns related to low adhesion. The implications are substantial for improving the safety and economic efficiency of efficient railway transportation.

Whey edible film enhanced with ginger essential oil: characterization and antimicrobial activity

Abstract Antimicrobial edible films made from whey and ginger essential oil extend the shelf life of packed goods by reducing, preventing, or delaying the growth of germs that may be found in the packaging of food or materials. This research aims to develop a film using whey and ginger essential oil film, focusing on properties such as thickness, solubility, elongation, tensile strength, water vapor transfer rate (WVTR), microstructure, color measurement, and antibacterial properties of ginger essential oil, and its ability to inhibit pathogenic microorganisms. An experimental study was conducted to analyze the physical and antibacterial characteristic of edible film, utilizing a randomized design with four different treatments. The film was made with 7% whey protein concentrate (WPC), 0.28% tapioca starch, and various amount of ginger essential oil (C0: 0% ginger essential oil, C1: 0.1% ginger essential oil, C2: 0.3% ginger essential oil, C3: 0.5% ginger essential oil). The concentration of ginger essential oil affected the tensile strength, WVTR, and microbial inhibitory action. Based on all characteristics, the optimal treatment is 0.5% GEO concentration, with a thickness of 0.12 ± 0.01 mm, solubility 3.67 ± 0.58%, elongation of 4.35 ± 0.66 %, tensile strength of 2.72 ± 0.38N, WVTR 14.67 ± 0.33 g/m2.day−1 and Escherichia coli and Staphylococcus aureus inhibition. According to the findings, including ginger essential oil can potentially increase the antibacterial characteristics of whey edible film composites.

Reviewing experimental and theoretical efforts and key findings regarding hydrodynamic journal bearing geometry

Abstract Journal bearing operation particularly in regard to marine applications is significantly affected by the performance of the most critical operational factors. Specifically, the lubricating oil film within journal bearing is so often than not subject to hazardous deterioration and ultimate failure in real operating conditions. Considering such fact, the current study is intended to carry out a literature survey regarding the efforts towards enhanced journal bearing performance based on proper selection of geometrical design for journal bearing. The aggregated data were thoroughly analyzed and assessed utilizing experimental, theoretical as well as numerical means. The outcomes derived from the conducted review represent firm grounds for carrying out extensive modifications into journal bearing design for marine applications. Further, such data will possibly be employed in future research investigations to extend the capability of journal bearing and its functions to attain the most possible enhanced performance in actual operating conditions. Apparently, the vast majority of both experimental and theoretical studies into journal bearing geometrical designs for enhanced performance, 66 in all, have been focused on surface texture accounting for 26.67 % (29 research studies) and 32.43 % (33 research studies) of the total investigations under study respectively. Regarding the experimental studies, realizing promoted performance of lubricating oil film by working on pressure profile has evidently obtained the largest contribution representing 35.5% of the overall bulk of the reviewed efforts, Figure 6.

Temperature Dependence of Viscoelasticity of Lubricating Oil with Adsorptive Polymer Additives Sheared in Nanogaps

Adsorptive polymer additives have been reported to improve the retention capacity of oil films under hydrodynamic lubrication and to reduce friction under boundary lubrication. These effects are believed to result from the formation of a polymer adsorption film on the surface that acts as a lubricious coating. Polymer adsorption films have become dominant in nanometer-order microscopic gaps. However, their mechanical properties are difficult to quantify. This hinders the development of polymer additives. In our previous study, we successfully measured the shear viscoelasticity of lubricants (base oils) sheared in nanogaps using an originally developed measurement method called the fiber wobbling method (FWM). In this study, we measured the shear viscoelasticity of polymer-added lubricants in nanogaps by using FWM. In addition, we developed a heating stage in the FWM to quantify the temperature dependence of shear viscoelasticity in nanogaps. As a result, the viscosity index improved and elasticity was observed in the nanogap, where the polymer adsorption film was dominant. Furthermore, our results indicated that the elasticity of the adsorbed polymer film originated from entropic elasticity.Graphical

IMPACT OF LOADS ON LOCOMOTIVE MOTOR AXLE BEARINGS ON THE CONDITIONS OF FORMATION OF OIL FILM ON FRICTION SURFACES

During the active operation of locomotives, a significant portion of failures (up to 20 %) is attributed to the malfunction of motor-axial bearings. This is due to the imperfection of the lubrication system of the motor-axial bearings, the proper functioning of which largely depends on various factors such as climatic conditions, the level of wear of lubricating oil, and lubrication devices, among others. There is a need to improve the existing lubrication systems for motor-axial sliding bearings. One of the methods to address this issue involves examining the factors influencing the lubrication process of the friction surfaces of motor-axial bearings and the conditions of lubricant material supply. The article provides calculations of the loading forces on the motor-axial bearings, their action vectors, and analyzes the impact of these parameters on the ability to form an oil film on the friction surfaces of motor-axial bearings. To determine the magnitude of the load, technical specifications of the locomotive were used, and the relationship between power usage and locomotive speed was analyzed. The study involved an analysis of recent publications regarding the generation of contact pressure force between the contact surfaces of friction pairs, the magnitude of which exceeds permissible limits, considered one of the primary factors leading to bearing failure. Additionally, the existing bearing lubrication system used on the locomotive was analyzed, its shortcomings were identified, and methods for addressing these issues were discussed. The calculations were performed for the 2TE116 locomotive with traction electric motors ED-118B, based on the operational characteristics of the locomotive in the speed range of 0-80 km/h.

Vibration characteristics of dual-rotor system with staggered-type double elastic ring squeeze film dampers under maneuvering flight

The vibration of the rotor system is significantly intensified during maneuvering flight, rendering traditional elastic ring squeeze film dampers (ERSFDs) insufficient or unstable. To improve the applicability of dampers, a novel structure of staggered-type double elastic ring squeeze film dampers (SDERSFD) is proposed in this paper. Through the synergistic effect of double elastic rings, the damping effect is significantly enhanced, and the circumferential stiffness anisotropy of the damper is improved, which is more suitable for vibration reduction requirements under complex working conditions. Utilizing the Reynolds equation, the internal and external pressure field control equations of the double elastic rings are established. The finite difference method is then employed to solve the dynamic characteristics of the damper. Additionally, a finite element model of the dual-rotor system with SDERSFDs considering complex dynamic factors such as unbalanced force, oil film force, gravity, and additional inertial force caused by maneuvering flight is established for the study of nonlinear rotor dynamic characteristics and the analysis of SDERSFDs vibration reduction effect. Based on the model, the influence of various factors such as maneuvering speed, maneuvering radius, rotor speed and unbalance on the transient response of dive-pull up condition is analyzed. The results reveal that during dive-pull up, the vibration of the rotor system intensifies significantly. When compared with the ERSFDs, the SDERSFDs effectively reduce the vibration amplitudes of the rotor system under maneuvering flight condition, achieving the maximum vibration reduction ratio of 48.9%. Furthermore, the SDERSFD exhibits robustness against large maneuvering loads, enhancing the stability of the rotor system under extreme conditions.

Exploring Tribological Behaviors of Profile-Shifted Spur Gears: An Experimental Investigation

The tribological behavior of an addendum modified altered tooth sum optimized spur gear set were experimentally compared with that of the standard spur gear under several loading conditions including the wear morphology study and wear debris analysis. The temperature, viscosity, elastohydrodynamic oil film thickness, specific film thickness, and combined surface roughness variation under increasing operating load were analyzed experimentally. Finally, the performance impact of addendum shifted altered tooth sum optimized gear was examined. Results show that the tribological improvement strongly depends on the addendum alteration and modified tooth sum condition. The modification of the addendum in gears with a negatively altered tooth sum facilitates the transition from single-tooth contact to two-tooth contact, broadening the lubrication range while preserving optimal film thickness and improving wear resistance. However, it is reverse to decrease the film thickness and increase wear for standard and profile-modified positively altered tooth sum gear. The gear tribological performance can be significantly improved by profile modification and negatively altered tooth sum approach with a lower rate of degradation of oil and damage on the tooth contacting surface.

Effect of crescent-shaped texture based on different depths and orientations on the frictional properties of cam tappets

The cam tappet friction pair is one of the three major friction pairs in an internal combustion engine, and the surface of the tappet undergoes severe wear during operation. To improve the wear resistance of the cam tappet friction pair during operation, in this study, crescent-shaped micro-textures were prepared on the surface of the tappet material of GCr15 steel by laser machining technique, and the effects of the orientation and depth of the texture on the friction properties of GCr15 steel were studied. The processed test samples were tested and characterized by friction and wear tests, scanning electron microscopy (SEM), 3D morphometry, and EDS. The flow field simulation model of micro-texture was established by using Fluent finite element software. The simulation and experimental results show that the crescent-shaped microtexture prepared on the surface of GCr15 steel can play a certain role in reducing friction and wear resistance, meanwhile orientation and depth of the texture affect the friction performance. In the fluid simulation, the positively oriented texture can produce higher oil film pressure than the opposite texture. When the texture depth is 20 μm, it has a better friction and wear reduction effect, and the friction coefficient decreases by 65.81% compared with that of the untextured surface, and the amount of wear decreases by 74.19%. This is mainly due to the existence of texture in the friction process to reduce the contact area and the shallower depth of texture can produce a larger oil film pressure in the oil lubrication state, so it has better tribological performance. The research data provide a certain reference for the design and optimization of the cam tappet friction pair.

Effect of oil film stiffness on vibration of full ceramic ball bearing under grease lubrication

PurposeThis paper aims to understand the vibration characteristics of full ceramic ball bearings under grease lubrication, reduce the vibration of the bearings and improve their service life.Design/methodology/approachThe Hertz contact stiffness formula for full ceramic ball bearings is constructed; the equivalent comprehensive stiffness calculation model and vibration model of full ceramic ball bearings are established. The dynamic characteristic test of full ceramic ball bearing under grease lubrication was carried out by using the bearing life testing machine, and its vibration was measured, and its vibration acceleration root-mean-square was obtained by software calculation and compared with the simulation results.FindingsAt the rotational speed of 12,000 r/min, the root-mean-square value of vibration acceleration is maximum 10.82 m/s2, and the error is also maximum 7.49%. As the rotational speed increases, the oil film stiffness decreases. In the radial load of 600 N, the vibration acceleration root-mean-square is minimum 6.40 m/s2, but its error is maximum 6.56%. As the radial load increases, the vibration of the bearing decreases and then increases, so under certain conditions increasing the radial load can reduce the bearing vibration. With different types of grease, the best preload is also different; low-speed heavy load should be used when the viscosity of the grease is large, and high-speed light load should be used when the choice of smaller viscosity grease is made.Originality/valueIt provides a theoretical basis for the application of full ceramic ball bearings under grease lubrication, which is of great significance for reducing the vibration of bearings as well as enhancing the service life of bearings.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0094/

A synergetic binary system of waste cooking oil-derived bio-based surfactants and its interfacial performance for enhanced oil recovery

Bio-based surfactants have garnered significant interest nowadays in wide applications particularly in the oil recovery field owing to their renewable property, outstanding surface/interface activity and eco-friendliness. The ultra-low interfacial tension between crude oil and brine is one of the key parameters for evaluating surfactants used in enhanced oil recovery. In this study, we developed a new binary surfactant system formulated by a bio-based zwitterionic surfactant (POA) and a bio-based nonionic surfactant (SOG), and the binary surfactant system exhibits a strong interfacial activity at a very low surfactant dosage. With the total surfactant concertation in a range of 0.1–3 g/L and the mass ratio of POA to SOG in a range of 5:5–9:1, the interfacial tensions of the binary system between crude oil and simulated formation brine could be significantly reduced to an ultra-low level (∼10−3 mN/m), indicating a strong synergistic effect between molecules in the binary system. Meanwhile, with the total surfactant concertation of 0.5 g/L and the mass ratio of POA to SOG of 7:3, the binary system demonstrates ultra-low interfacial tensions (∼10−3 mN/m) between crude oil and simulated formation brine at the temperature up to 80 ℃, NaCl up to 75 g/L and Ca2+ ions up to 20,000 mg/L, and the emulsification and oil film peeling ability are also improved compared with those of the individual POA and SOG. This study opens a new window for the binary bio-based surfactants and provides insights in designing and optimizing the cost-effective displacement systems for enhanced oil recovery with ensuring environmental sustainability.

Visco-elastohydrodynamic lubrication and wear model amended by deformation velocity

The deformation velocity caused by viscoelasticity is one of the drives of the Lubrication flow field and significantly influences the mixed lubrication and wear characteristics of journal bearings under dynamic loads. However, research considering the deformation velocity has yet to be reported. To address this research gap, we defined three-dimensional (3D) deformation velocities to amend the bearing surface velocity and proposed its calculation method based on the derivative function of the temporal association deformation equation and the finite element method. Therefore, a new mixed visco-elastohydrodynamic lubrication model amended by 3D deformation velocities was built and a nested solution method was proposed in which the sub-iterative process for deformation velocities was embedded into the oil film pressure iterative process. Furthermore, the lubrication model was coupled with the Archard model to predict wear. The viscoelastic parameter of the bearing was experimentally measured, and numerical simulations of lubrication and wear were performed for an ordinary bearing under a simple dynamic load and for the crankshaft main bearing of an internal combustion engine (ICE) under impact. The simulation results indicate that the deformation velocities reduce the extrusion effect and increase the contracting effect in the lubrication flow field. This enables the new model to identify the micro asperity contact, impact, and early wear features of bearings more accurately than the traditional mixed lubrication model. In addition, an increase in the ICE load intensifies the early wear of the bearing.

Hierarchical design of microcapsules-based epoxy resin coating enhanced with Ti3C2Tx for improving thermal, tribological, anti-corrosive performance

Self-lubricating coating has sparked significant research interest due to its remarkable tribology performance. However, traditional microcapsules-based self-lubricating coating still faces challenges in long-term serviceability and poor anti-corrosion performance. In this paper, a novel self-lubricating epoxy resin coating was proposed based on hierarchical design and energy wear theory. Microcapsules (MC) containing Polyalphaolefin (PAO40) were prepared via the solvent evaporation approach. Ti3C2Tx MXene (T) with high thermal conductivity was then incorporated into the MC-enhanced epoxy resin coating (EP) to construct the novel self-lubricating EP coating (T-MC-EP). Compared to the EP coating, the thermal conductivity of the T-MC-EP coating increased by 79.4%. Finite element analysis indicated that T constructed thermally conductive network in the coating, serving as the main heat carrier. Furthermore, the wear rate decreased by 91.2%, primarily attributed to the formation of lubricating oil film during friction and the reduction of epoxy resin molecular oxidation fracture caused by friction heat. After 31 days of salt spray testing, the T-MC-EP coating also exhibited superior anti-corrosion performance. This work provides an innovative insight into designing multifunctional coating, including excellent mechanical, thermal, tribological, and anti-corrosive performance.

Role of light microplastics in the dispersion process of spilled crude oil in the marine environment

Oil spill and microplastic (MP) pollution are the main problems in the marine environment. After an oil spill, the oil film may be dispersed into the water column in the form of droplets under the action of ocean waves. In this study, the sea condition was simulated through the batch conical flask oscillation experiment. Merey crude oil was selected as experimental oil, and polyethylene (PE) and polystyrene (PS) were used as experimental MP. The effects of MP properties (type, concentration and size) on the dispersion of spilled oil were investigated. It is found that for each MP, the oil dispersion efficiency (ODE) increased rapidly at first and then tended to be stable, which all reached the maximum at 360 min. When the concentrations of PE and PS increased from 0 to 100 mg/L, the maximum ODE decreased from 32.64 % to 13.72 % and 10.75 %, respectively, indicating that the presence of MP inhibits the oil dispersion. At the same oscillation time, the volumetric mean diameter (VMD) of dispersed oil increased with the MP concentration. When the particle size of PE and PS increased from 13 to 1000 μm, the maximum ODE increased from 24.74 % to 31.49 % and 28.60 %, respectively. However, the VMD decreased with the size of MP. In addition, the time series of the oil adsorption rate by the MP were well fitted by the kinetic models. The results of this research deepen the understanding of the migration law of spilled oil to the marine environment in the presence of MP, and may further improve the ability of marine environmental scientists to predict the fate of oil spill.

Dynamics modeling and analysis of planetary gear mechanism under mixed elastohydrodynamic lubrication

Mixed elastohydrodynamic lubrication is the main lubrication style of planetary gear mechanism. In this paper, the dynamic characteristics of planetary gear mechanism under mixed elastohydrodynamic lubrication are investigated using a computational methodology. First, the mathematic model of mixed elastohydrodynamic lubrication is proposed, in which the scaling factors are introduced to depict the balance between the asperities and the oil film. A stiffness formula of the oil film is presented to describe the time varying stiffness of the teeth pair. Then, the stiffness of the oil film and the general stiffness are obtained. Finally, dynamic model of the planetary gear mechanisms is established and the dynamic responses of planetary gear mechanism are analyzed. The influences of operational parameters on stiffnesses and dynamic characteristics of the planetary gear mechanisms are investigated. The simulation results indicate that the nonlinear dynamics characteristics are significantly influenced by the lubrication conditions.

Visualization of vane chattering in rotary compressor

In this study, the impacts of various factors on the chattering phenomenon in sliding vane compressors, which is a crucial aspect that influences their performance and efficiency were explored. The analysis focused on the compressor rotational speed, pressure ratio, and operating temperature, considering both ambient and heated conditions. The aim was to provide a comprehensive understanding of the relationship between these factors and the occurrence of chattering at different operational intervals, as well as the vane sealing performance and adherence to the chamber wall.The methodology involved examining vane behavior and the chattering occurrence across three intervals under various conditions, specifically looking at oil films formation and sealing performance degradation. The experimental results provided notable insights into the chattering phenomenon. It was shown that as the pressure ratio increased and the compressor rotational speed decreased, the sealing performance deteriorated. Moreover, when operating under heated conditions, a decrease in oil viscosity leads to reduced friction between the vane and bearing, improving vane adherence compared to ambient conditions.The methodology and findings of this study provide insights into the chattering phenomenon in vane compressors by considering the interplay between various factors. The results emphasize the importance of optimizing the compressor oil refueling flow, rotational speed, pressure ratio, and operating temperature, to ensure proper lubrication and efficient interaction between the vanes and compression chamber walls for improved compressor performance and reduced operational challenges.