Article
Engineering, Mechanical
Xin Yu, Yunyun Sun, Shijing Wu
Summary: In this study, a generalized close-formed model of the friction coefficient between fractal surfaces in mixed lubrication is presented. A mathematical transformation from asperity area to oil film thickness is conducted to establish an analytical fractal model of oil film thickness. A dynamic film thickness model with external load under the determination of the surface roughness is proposed. The effects of fractal parameters and important working parameters on friction coefficient are analyzed, and comparison with experimental data is conducted. This work provides a general analytical expression for friction coefficient in mixed lubrication with explicit form and wide applications.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Engineering, Mechanical
Xiaohui Lin, Shun Wang, Shuyun Jiang, Shaowen Zhang
Summary: This study investigates the influence of interface effect and cavitation bubble distribution on the dynamic characteristics of high-speed water-lubricated spiral groove thrust bearings. A turbulent cavitating flow lubrication model is established based on two-phase fluid and population balance equation of bubbles. The stiffness and damping coefficients of the bearings are calculated using perturbation pressure equations. Experimental results validate the theoretical model. The findings suggest that the turbulent effect has a greater impact on the dynamic characteristics of the bearings compared to the cavitation effect.
CHINESE JOURNAL OF MECHANICAL ENGINEERING
(2022)
Article
Engineering, Mechanical
Qilin Liu, Wu Ouyang, Qichao Cheng, Jinjun Li, Qizhi Cheng, Ruiqing Li
Summary: This paper investigates the lubrication and dynamic characteristics of water-lubricated stern bearing under service conditions. It proposes a test scheme to analyze the pressure distribution and spatial shaft position of the bearing. The experiment reveals the pressure bias and bidirectional shaft inclination phenomenon, and a dynamic model considering bidirectional shaft inclination and lining deformation is established. The study explores the influences of various factors on lubrication and dynamic characteristics and provides guidance for the design and optimization of such bearings.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Engineering, Mechanical
G. H. G. van der Meer, F. Quinci, W. Litwin, M. Wodtke, R. A. J. van Ostayen
Summary: The study investigates the application of a modified MR fluid in lubrication performance using a journal bearing test bench. It is found that applying a local magnetic field can significantly reduce the transition speed of the bearing when lubricated with MR fluid, with only a minimal increase in friction. The lubricating performance of the MR fluid is compared to a reference oil.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Engineering, Mechanical
Chuang Wu, Yinbo Wang, Feng Chen, Xinhua Long
Summary: This paper uses the fractal theory to characterize the surface topography of water-lubricated bearings and journals, establishes a fractal contact model, and proposes a mixed-lubricated friction model based on fractal theory. Scanning experiments are conducted to obtain fractal parameters and measurements of the friction coefficient are performed to verify the effectiveness of the proposed model. Results indicate that when the grooves are in the non-main load-carrying regions, the friction characteristics of the bearing slightly change, and lower surface roughness is beneficial to improve the lubrication and friction properties of the bearing.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Yuan Gao, Liran Ma, Jianbin Luo
Summary: In this study, liquid crystal was used as a lubricant to actively control the friction coefficient by adjusting the molecular arrangement. By changing the temperature, the friction coefficient was synchronized with the temperature, providing new ideas for active control of lubrication in the fields of smart bearings and emergency braking.
Article
Engineering, Mechanical
Neminath Naduvinamani, Ashwini Angadi
Summary: This study investigates the dynamic characteristics of the Rayleigh step bearing with the influence of surface roughness and a porous medium. The results show that the couple stress fluid has a significant impact on the load-carrying capacity, stiffness, and damping coefficients of the bearing. Additionally, negatively skewed roughness reduces the volume flow rate.
Article
Engineering, Chemical
Nichole Moyle, Hao Dong, Haibin Wu, Constantine Y. Khripin, Chung-Yuen Hui, Anand Jagota
Summary: Controlling the lubricated sliding friction of compliant contacts is crucial in mechanical and biological systems. In this study, a structured two-phase material composed of a plastic mesh embedded in a compliant elastomer matrix was developed. The results showed that the embedded mesh structure exhibited increased lubricated sliding friction under specific conditions. Simulations suggested that the difference in lubrication regimes between the structured sample and the unstructured control was caused by areas of high contact pressure induced by the increased local contact stiffness near the embedded mesh.
Article
Engineering, Mechanical
Hiromitsu Kakudo, Satoshi Takada, Tomoko Hirayama
Summary: This research investigates the friction coefficient of SUS440C-Si3N4 lubricated by polytetrafluoroethylene (PTFE) under cryogenic environment and reveals the influence of contact pressure on the friction characteristics. The formation of PTFE film on the surface of SUS440C results in lower friction and better wear resistance due to moderate friction energy.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2023)
Article
Engineering, Mechanical
Jijo Jose, Niranjana Behera
Summary: The study shows that using dry powder lubricants can effectively eliminate oil degradation in hydrodynamic bearings under high temperatures and extreme conditions. The increase in ellipticity ratio affects the performance of three-lobed bearings, with larger powdered particles showing better load carrying capacity and stability compared to smaller particles.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2021)
Article
Engineering, Chemical
Ravindra S. Ghodake, Pankaj Doshi, Ashish Orpe
Summary: This study investigates the gravity driven flow of millimetric granular material coated with micron-sized lubricant particles. The experimental results show a non-monotonic behavior in the volumetric flow rate of the particles with increasing lubricant concentration. This behavior is attributed to the reduction of inter-particle friction caused by the adherence of lubricant particles to the granular surface, as well as the damping effect on inter-particle collision at higher lubricant concentrations.
Article
Thermodynamics
Chuang Wang, Mingkun Liu, Bingqi Wang, Ziwen Xing, Yue Shu
Summary: A mathematical model is constructed to analyze the power consumption distribution in different positions of a water-lubricated twin-screw air compressor at different rotating speeds. The results show that thrust bearings account for the largest power loss, while water vapor has the least impact, which is different from common oil-injected twin-screw compressors.
Article
Engineering, Mechanical
Pravin P. Patil, Yatika Gori, Ashwani Kumar, M. R. Tyagi
Summary: This research work examined the tribological performance of Polyisobutylene (PIB) as a viscosity index improver under boundary/mixed and hydrodynamic lubricated conditions. The study found that a 15% concentration of PIB blend significantly reduced wear and friction, but higher concentrations showed an increase in friction.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Manufacturing
Olga Smerdova, Omar Benchekroun, Noel Brunetiere
Summary: The experiment studied the friction and deformation of carbon fiber tow under transverse sliding, finding that the friction coefficient changed with sliding distance and identifying four stages of the friction process related to internal stress relaxation, shear deformation, microsliding, macrosliding, and final stress relaxation.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2021)
Article
Engineering, Mechanical
Zhongliang Xie, Jian Jiao, Kang Yang, Tao He, Rugang Chen, Weidong Zhu
Summary: The high temperature liquid Lead-Bismuth (PbBi) solution lubricated bearing plays a crucial role in the two-circuit main loop system of nuclear power stations. This study developed revised dynamic lubrication models considering cavitation effects and investigated the influences of clearances, rotating speeds, eccentricity ratios, and annular guiding grooves on the hydrodynamic characteristics. The results confirm the relationship between peak pressure, speeds, and eccentricity ratios, as well as the impact of clearances on maximum/minimum pressure. Theoretical analysis coincided with experimental data, verifying the rationality and correctness of the lubrication models.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Physics, Multidisciplinary
Xin Cao, Huan-ling Liu, Xiao-dong Shao
Article
Thermodynamics
Huan-ling Liu, Yu-qiang Shao, Zeng-tao Chen, Zhong-liang Xie
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2019)
Article
Nuclear Science & Technology
Zhongliang Xie, Nawei Shen, Weidong Zhu, Huanling Liu, Jing Shi, Yongkun Wang, Wenchao Tian
ANNALS OF NUCLEAR ENERGY
(2020)
Article
Engineering, Mechanical
Zhongliang Xie, Huanling Liu
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2020)
Article
Nuclear Science & Technology
Zhongliang Xie, Pan Song, Liang Hao, Nawei Shen, Weidong Zhu, Huanling Liu, Jing Shi, Yongkun Wang, Wenchao Tian
ANNALS OF NUCLEAR ENERGY
(2020)
Article
Nuclear Science & Technology
Zhongliang Xie, Nawei Shen, Jianding Ge, Weidong Zhu, Pan Song, Huanling Liu, Liang Hao, Wenchao Tian
ANNALS OF NUCLEAR ENERGY
(2020)
Article
Energy & Fuels
Qing Li, Yu-Qiang Shao, Huan-Ling Liu, Xiao-Dong Shao
Article
Chemistry, Analytical
Tao Zhou, Bingchao Chen, Huanling Liu
Summary: This article discusses the use of topology optimization to design heat exchangers, proposing a novel design with three inlets and one outlet. The impact of channel depth on heat exchanger design, as well as the flow and heat transfer performance of the heat exchangers, are also studied. Results show that topology optimization can significantly improve heat transfer performance compared to traditional design methods.
Article
Engineering, Mechanical
Stepan Lysykh, Vasily Kornopoltsev, Undrakh Mishigdorzhiyn, Yuri Kharaev, Zhongliang Xie
Summary: In this study, the surface mechanical properties of L6 and 5140 low alloy steels were improved by two-component surface hardening with boron and copper. The results showed that layers with thicknesses of up to 180-200 μm were formed on both steels. These layers had needle-like structures similar to pure boriding, and the microhardness and wear resistance were significantly improved.
Article
Engineering, Mechanical
Jianbo Zhang, Zhongliang Xie, Kun Zhang, Zhifang Deng, Danyang Wu, Zhimin Su, Xing Huang, Mingbo Song, Yitao Cao, Jingping Sui
Summary: This paper investigates the nonlinear behavior of a gas bearing-rotor system from the perspective of nonlinear dynamics. By establishing a dynamic model of a gas bearing rotor and solving the transient Reynolds equation with a hybrid method, the study reveals the existence of limited cycle motion in the autonomous rotor system and half-speed whirl in the nonautonomous rotor system.
Article
Engineering, Mechanical
Jianbo Zhang, Zhifang Deng, Kun Zhang, Hailiang Jin, Tao Yuan, Ce Chen, Zhimin Su, Yitao Cao, Zhongliang Xie, Danyang Wu, Jingping Sui
Summary: In this paper, the steady state and dynamic performances of aerostatic bearings are studied using the finite difference method. The linear stability of the aerostatic bearing is also investigated. The results show that geometry parameters, rotational speed, and supply pressure have significant effects on the performances of aerostatic bearings.
Article
Engineering, Mechanical
Tao He, Zhongliang Xie, Zhiwu Ke, Lu Dai, Yong Liu, Can Ma, Jian Jiao
Summary: This study investigates the influence of shaft bending deformation on the dynamic characteristics of the stern bearing and establishes a mixed lubrication model. The variation laws of equivalent stiffness and natural frequency are analyzed, revealing that the equivalent stiffness is more affected by speed, especially at low speeds. There is also a critical speed between 130 rpm and 150 rpm, at which the natural frequency reaches its maximum value.
Article
Engineering, Mechanical
Pingwei Chen, Tong Wang, Wensheng Ma, Zhongliang Xie, Guangbin Yu
Summary: This paper studies the rotordynamic characteristics of high-temperature water liquid seal, taking into consideration the fluid-solid-thermal coupling. Experimental and computational results show the effect of water temperature on leakage flow rate, drag power loss, and rotordynamic coefficients. These findings provide valuable insights for the development of high-temperature centrifugal pumps.
