Article
Engineering, Mechanical
Jing Hu, Bangcheng Zhang, Xinming Zhang
Summary: A new method for calculating the speed transmission characteristics of double-deck ball bearing is proposed in this paper, which combines various theories to establish a speed transmission analysis model. The correctness of the results is verified by experiments, providing a theoretical basis for further exploration and design of the potential application value of the double-deck ball bearing.
NONLINEAR DYNAMICS
(2022)
Article
Mechanics
Ali Rostami, Ri Li, Sina Kheirkhah
Summary: This study investigates the characteristics of droplets, clusters, and voids in sprays injected into a turbulent co-flow. Experimental methods including Mie scattering, interferometric laser imaging, and hotwire anemometry were used. The results show that the mean length scale of the clusters varies linearly with the Stokes number, while the mean void length scale is on the order of the integral length scale. The number density of droplets inside clusters is approximately 7 times larger than that in the voids, and the ratios of droplet number densities in clusters and voids to the total number density are independent of test conditions.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mathematics, Applied
Martin Ostoja-Starzewski
Summary: The equations governing turbulent flow of micropolar incompressible media are studied using Reynolds decomposition, with average force-stress and couple-stress augmented by new turbulent terms. Modifications to average heat flux and internal energy density expressions are made, and entropy inequality is examined in both classical and micropolar continuum settings.
ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK
(2021)
Article
Engineering, Mechanical
Shaoyu Zhu, Xiangjun Zhang
Summary: The modified average Reynolds equation for friction pairs with arbitrary three-dimensional rough surfaces lubricated by couple stress fluid is derived. The performance parameters under various factors, such as couple stress, surface roughness, journal misalignment, and thermal effect, are obtained using the finite difference numerical method. The results show that the surface roughness factor plays an important role in the performance of the friction pairs, even with small nominal eccentricity ratios.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2022)
Article
Engineering, Multidisciplinary
M. Y. Rafiq, Z. Abbas, M. Z. Ullah
Summary: This paper addresses the analysis of chemical reaction for mixed convection peristaltic movement of electrically conducting couple stress nanomaterial in an asymmetric tapered porous channel under the influence of heat generation/absorption. Mathematical modeling and numerical analysis are conducted to obtain expressions for various parameters such as temperature, pressure, concentration, and velocity. The results are compared with existing literature and found to be in excellent agreement, validating the accuracy and reliability of the developed code.
AIN SHAMS ENGINEERING JOURNAL
(2022)
Article
Mechanics
Mobin Alipour, Marco De Paoli, Sina Ghaemi, Alfredo Soldati
Summary: In this study, we investigated the dynamics of non-axisymmetric fibers in turbulent channel flow, exploring the impact of fiber curvature on their orientation and rotation rate through statistical analysis of their three-dimensional position, shape, and orientation. Our results provide insights into the behavior of curved fibers in turbulent flow environments and suggest similarities with previous studies on homogeneous isotropic turbulence.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Mechanical
Yang Shuai, Guo Hong, Zhang Shao-Lin, Xia Bo-Qian
Summary: The study focuses on the laminar and turbulent flow phenomena in the inner and outer fluid films of hybrid floating ring bearings, solving the lubrication model using numerical methods while considering mixed flow and thermal effects. The results show that mixed flow enhances load capacity and friction moment of bearings, while decreasing the system's critical speed.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2021)
Article
Engineering, Mechanical
Hao Zhang, Xiaohui Lin, Shuyun Jiang
Summary: This study proposes a turbulent flow model considering the effects of turbulence and cavitation in water-lubricated bearings, and validates the model through simulations and experiments. The results demonstrate that both turbulence and cavitation effects have significant impacts on the static characteristics of the bearing.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2023)
Article
Engineering, Mechanical
Mahdi Zare Mehrjardi, Asghar Dashti Rahmatabadi
Summary: This study presents the dynamic behavior of three-lobe noncircular hydrodynamic journal bearings lubricated with couple stress fluid and suggests solutions to improve rotor-journal bearing systems. By strengthening the couple stress properties of lubricant, the stiffness and damping ability of three-lobe bearings can be enhanced, leading to improved dynamic stability of rotor-bearing supports. The results also show that using noncircular three-lobe bearings and couple stress fluid instead of Newtonian lubricants can increase critical mass parameter and decrease whirl frequency ratio, enhancing the stability range of the bearings.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2022)
Article
Engineering, Mechanical
Woo-Ju Jeon, Sung-Ho Hong
Summary: A flexible structure is used to enhance the lubrication performance of a misaligned journal bearing. The bearing, which represents a sliding bearing, suffers damage from metal-to-metal contact caused by misalignment. To improve this issue, a journal bearing with a flexible structure is proposed. Numerical evaluation and elastohydrodynamic lubrication analysis considering elastic deformation are conducted, comparing lubrication performance based on variations in the flexible structure's geometry and minimum film thickness. Comparisons are also made between the journal bearing with and without the flexible structure. The flexible structure, in the form of a groove, is applied to the high load-bearing area of the journal bearing, experiencing elastic deformation through the generated oil film pressure to obscure a larger oil film. The numerical analysis demonstrates that the journal bearing with a flexible structure can enhance lubrication performance in misalignment conditions.
Article
Mathematics, Applied
P. Naga Lakshmi Devi, Phani Kumar Meduri
Summary: In this article, an exact solution for the flow of couple stress fluid past a contaminated fluid sphere is obtained using interfacial slip boundary condition. The solution considers different regions with and without cap. The velocity is expressed in terms of stream function and the drag coefficient is calculated. Special cases of a no-slip condition and a solid sphere are also studied and compared with existing literature. The results are in good agreement. Additionally, the flow of contaminated fluid past a couple stress fluid sphere and the flow of couple stress fluid past a contaminated viscous sphere are examined.
APPLIED MATHEMATICS AND COMPUTATION
(2023)
Article
Mechanics
Cheng Peng, Lian-Ping Wang
Summary: This study utilizes direct numerical simulations to investigate the changes in mean particle drag caused by turbulent environments and the responsible mechanisms. The study confirms that turbulent environments significantly enhance the particle drag, and the enhancement cannot be explained solely by the nonlinear dependency of drag force on the incoming flow velocity. Two mechanisms of particle-turbulence interactions are identified as responsible for the drag enhancements. General models accounting for turbulence anisotropy are proposed for quantitative drag enhancement predictions. It is also found that the overall particle drag increases with decreasing particle-particle relative gap distance, while the relative enhancement due to turbulence decreases with the particle-particle relative gap distance.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Engineering, Mechanical
Krishnkant Sahu, Satish C. Sharma, Nathi Ram
Summary: Misalignment affects the operation of the journal bearing system, and smart lubricants can enhance the performance of fluid film bearings. The study finds that journal misalignment reduces the fluid film thickness, increases the fluid film damping coefficient, and frictional torque.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Engineering, Mechanical
Eckhard Schueler, Olaf Berner
Summary: By machining optimized eddy grooves on the bearing surface, significant reduction in surface temperature and enhancement of bearing load capacity can be achieved, opening up new options for bearing design and turbomachinery applications.
Article
Engineering, Mechanical
Anil Singh, Satish C. Sharma
Summary: This study focuses on the numerical investigation of the performance effects of geometric imperfections on a porous hybrid journal bearing system operating under turbulent flow conditions. The Reynolds equation governing the lubricant flow in the bearing space is modified using turbulent lubrication theory, and the performance parameters are computed using FEM. The combined effect of turbulent flow conditions and geometric imperfections results in enhanced values of performance indicators.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2021)
Article
Engineering, Mechanical
Huiyi Yang, Yang Xu, Chao Xu
Summary: This study focuses on the impact of dry friction interfaces on the dynamics of jointed structures, particularly on the statistics of contact pressure distribution. Through experimental and simulation analysis, it is found that surface roughness and contact load have significant effects on contact area, contact stiffness, and mean contact pressure.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
Article
Engineering, Mechanical
Guanglan Hu, Houfu Dai
Summary: The effect of metal coating on the machinability of cubic silicon carbide was investigated using molecular dynamics simulation. The results showed that the type of coating has a significant impact on cutting force, surface morphology, stress, and tool wear. Among the three metals studied, Cu coating had the greatest impact on improving cutting performance.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
Article
Engineering, Mechanical
Yunfan Liu, Guozheng Ma, Lina Zhu, Cuihong Han, Zhen Li, Bin Zhang, Haichao Zhao, Haidou Wang, Shuying Chen
Summary: The service performance of coated self-lubricating spherical plain bearings can be improved by applying self-lubricating coatings, especially double-sided coatings. The presence of a large-area and complete mixed friction transfer film on the contact surfaces can cause a signal downstage before the signal mutation stage.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
Article
Engineering, Mechanical
Yakup Artun, C. Oktay Azeloglu, Gokhan Taylan
Summary: This article investigates the tribological properties of polymer journal bearings, particularly focusing on radial journal bearings made from UHMWPE and POM materials with different surface qualities. The study examines the performance of these bearings under varying load and speed conditions, and analyzes the relationship between material and surface roughness in tribological performance.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
