Hailong Zhao, Lirong Luo, Fangwei Guo, Xiaofeng Zhao and Ping Xiao
The purpose of this paper is to investigate the tribological performance of Cr3C2–NiCr–Mo–BaF2 composite sliding against a Si3N4 ball at high temperatures.
Abstract
Purpose
The purpose of this paper is to investigate the tribological performance of Cr3C2–NiCr–Mo–BaF2 composite sliding against a Si3N4 ball at high temperatures.
Design/methodology/approach
A Cr3C2–NiCr composite and a Cr3C2–NiCr–Mo–BaF2 composite were prepared using spark plasma sintering. Tribological properties of the composites were investigated using a ball-on-disk type tribotester. The relationships among the microstructure, wear mechanism and tribological performance were determined by analyzing the wear track morphologies and the glaze layer’s phase composition.
Findings
The wear rate of the Cr3C2–NiCr–Mo–BaF2 composite was approximately one order of magnitude lower than that of the Cr3C2–NiCr composite from 700°C to 900°C when sliding against a Si3N4 ball. The favorable tribological performance of the Cr3C2–NiCr–Mo–BaF2 composite at high temperatures results from the synergistic lubrication of MoOx, BaF2 and BaMoO4.
Originality/value
This paper reports a new Cr3C2–NiCr matrix self-lubricating composite with better tribological properties than Cr3C2–NiCr composite at temperatures up to 900°C through Mo and BaF2 addition.
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Haibin Chen, Jie Zhu, Fangwei Xie, Xinjian Guo and Xudong Zheng
The purpose of this paper is to use the viscosity of fluid to transmit power known as the hydro-viscous drive (HVD) to research the effect of two-phase flow on transmission…
Abstract
Purpose
The purpose of this paper is to use the viscosity of fluid to transmit power known as the hydro-viscous drive (HVD) to research the effect of two-phase flow on transmission characteristics.
Design/methodology/approach
In this paper, a 3D computational model of oil film between friction pair was built to study the transmission characteristics of a two-phase oil film, and the distribution contours of pressure and temperature of oil film were investigated using the computational fluid dynamics technology.
Findings
The finding of the paper suggests that the distribution law of pressure and temperature of two-phase oil film is almost linear along the radial direction. However, since the physical phenomena near the outlet of the oil film are entirely different, there exists fluctuation. Meanwhile, the volume fraction of air was obtained at different rotation speeds, and the maximum value is 10.55 percent. Compared to the single-phase oil film, the torque transferred by the oil film is not linear with the rotation speed, its value decreases gradually.
Originality/value
This paper’s conclusions are very important for the study of HVD and its applications, which provide a new idea to further study the mechanism of oil film transmission and its cavitation. The development of fluid viscous speed clutch is dedicated to a large industrial fan and water pump speed regulation and energy saving. With the successful application of the technology, it will have more wide applications in different fields, such as, in steel, water, petrochemical, power plant of slag pump and exhaust fan.
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Qi Sun, Fangwei Xie, Kuaidi Wan, Xinjian Guo, Jie Zhu, Van Xo Nguyen and Yun Wang
The purpose of this paper is to study the influences of the oil film thickness between the friction pairs, the rotational speed of the active and passive friction disks and the…
Abstract
Purpose
The purpose of this paper is to study the influences of the oil film thickness between the friction pairs, the rotational speed of the active and passive friction disks and the inlet pressure of the lubricant on the transmission efficiency.
Design/methodology/approach
A mathematical model of transmission efficiency was established, and the efficiency of transmission was studied by means of numerical analysis.
Findings
The results demonstrate that the transmission efficiency decreases with the thickness of the oil film increases. When the thickness of oil film d = 0.1 mm, the relationship between transmission efficiency and transmission ratio is linear, that is, with the transmission ratio increases, the transmission efficiency also increases which does not change with the inlet pressure changes. However, when d = 0.1 mm, their relationship is non-linear; the efficiency increases first and then decreases as the transmission ratio increases, but decreases as the inlet pressure increases.
Originality/value
The authors obtained a rule is that increasing the rotational speed and reducing the inlet pressure of the lubricating oil can improve the transmission efficiency. This study can provide a theoretical basis for power transmission designing of hydro-viscous clutch.
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Fangwei Xie, Xinjian Guo, Diancheng Wu, Bing Zhang, Xudong Zheng, Dengshuai Wang and Yun Wang
In this paper, a kind of an oil groove structure which could improve the transmission torque of an oil film was designed, i.e. the width and depth of oil groove gradually decrease…
Abstract
Purpose
In this paper, a kind of an oil groove structure which could improve the transmission torque of an oil film was designed, i.e. the width and depth of oil groove gradually decrease with the increase in the radius.
Design/methodology/approach
Effects of the structural parameters of the oil groove on the hydro-viscous drive (HVD) characteristics with variable rotational speed were investigated by means of numerical calculation.
Findings
Research results show that with the decrease of the width and depth of the oil groove at the outer diameter, transmission torque increases, while the temperature is almost unchanged. Keeping the effective area unchanged, comparing the transmitted torque under the oil groove angle θ2 = 0.5° and θ2 = 4.5°, the former was almost 200 per cent of the latter; the torque transmitted with h2 = 0.05 mm was almost 150 per cent of that with h2 = 0.2 mm.
Originality/value
In this paper, the authors analyze the friction surface of the friction plate between the oil groove, oil distribution and oil film transfer torque from the oil groove structure parameters and found methods to improve the transmission torque. For the first time, the influence of the structural parameters of oil groove on the characteristics of HVD was studied under the condition of variable rotational speed, and a better method to improve the transmission torque was proposed.
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Keywords
Zhibao Li, Fangwei Xie, Junyu Sun, Jie Zhu, Xudong Zheng, Xinjian Guo, Yun Wang and Yinqun Hua
The purpose of this paper is to study the temperature characteristics of hydro-viscous clutch with different structure of friction disks and obtain the distribution of film…
Abstract
Purpose
The purpose of this paper is to study the temperature characteristics of hydro-viscous clutch with different structure of friction disks and obtain the distribution of film temperature.
Design/methodology/approach
The mathematical model of oil film between friction disks with radial grooves is established. Based on the flow rate equation, the temperature rise equation of oil film is deduced. Considering two-phase flow, the temperature distribution in the oil shear stage and the effects of the ratio of inner radius to outer radius on film temperature rise is studied by using computational fluid dynamics (CFD) technology.
Findings
The results show that when input speed is constant, the increase in the ratio of inner to outer radius leads to an increase in the peak temperature and the decrease in the ratio results in a larger increasing rate of temperature.
Originality/value
These results are of interest for the study of hydro-viscous drive and its applications. This study can also provide a theoretical basis for the mechanism of temperature rise by considering the effect of two-phase flow.
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Fangwei Xie, Jie Zhu, Jianzhong Cui, Xudong Zheng, Xinjian Guo, Yun Wang and Ramesh K. Agarwal
The purpose of this paper is to study the dynamic transmission of the oil film in soft start process of hydro-viscous drive (HVD) between the friction pairs with consideration of…
Abstract
Purpose
The purpose of this paper is to study the dynamic transmission of the oil film in soft start process of hydro-viscous drive (HVD) between the friction pairs with consideration of surface roughness, and obtain the distribution law of temperature, velocity, pressure, shear stress and viscous torque of the oil film.
Design/methodology/approach
The revised soft-start models of HVD were derived and calculated, including average Reynolds equation, asperity contact model, load force model and total torque model. Meanwhile, a 2D model of the oil film between friction pair was built and solved numerically using computational fluid dynamics (CFD) technique in FLUENT.
Findings
The results show that the maximum temperature gradually reduces from the intermediate range (z = 0.5 h) to the inner side of the friction pair along the direction of oil film thickness. As the soft-start process continues, pressure gradient along the direction of the oil film thickness gradually changes to zero. In addition, tangential velocity increases and yet radial velocity decreases with the increase of the radius.
Originality/value
In this paper, it was found that the viscous torque calculated by the numerical method is smaller than that by the CFD model, but their overall trend is almost the same. This also demonstrates the effectiveness of the numerical simulation.
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Kaiyu Dai, Fangwei Xie, Qingsong Gao, Desheng Zhang, Erming Ding and Xinjian Guo
The purpose of this paper is to study the pressure response characteristics of the cartridge electromagnetic relief valve, which offers the problems caused by low pressure…
Abstract
Purpose
The purpose of this paper is to study the pressure response characteristics of the cartridge electromagnetic relief valve, which offers the problems caused by low pressure response and low efficiency in hydraulic plate shearing machines.
Design/methodology/approach
First of all the mathematical model of the cartridge electromagnetic relief valve is deduced to analyze the influence of the relevant parameters on the system pressure response. Then experiments are conducted to research the dynamic characteristics on building and relieving pressure. Through comparison of theoretical and experimental research, the results are found.
Findings
The results show that the input flow, working pressure, diameter of adjacent damping hole, and spring stiffness of the main valve have great influence on building pressure of the system, and have no influence on relieving pressure, while diameter of damping hole of control cover plate has influence on the building and relieving pressure of the system.
Originality/value
The research results provide powerful theoretical support for the parametric design of the cartridge electromagnetic relief valve in the hydraulic system of plate shearing machine.
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Fangwei Xie, Xudong Zheng, Yaowen Tong, Bing Zhang, Xinjian Guo, Dengshuai Wang and Yun Wang
The purpose of this paper is to study the working characteristics of hydro-viscous clutch at high rotational speeds and obtain the trend of flow field variation of oil film.
Abstract
Purpose
The purpose of this paper is to study the working characteristics of hydro-viscous clutch at high rotational speeds and obtain the trend of flow field variation of oil film.
Design/methodology/approach
The FLUENT simulation model of the oil film between the friction disks is built. The effect of variation of working parameters such as input rotational speed, oil flow rate and film thickness on two-phase flow regime and transmission torque is studied by using the volume of fluid model.
Findings
The results show that the higher the rotational speed, the severer the cavitation is. In addition, the two-phase flow region makes the coverage of oil film over the friction pairs’ surface reduce, which results in a decrease in transmission torque for the hydro-viscous clutch.
Originality/value
These simulation results are of interest for the study of hydro-viscous drive and its applications. This study can also provide a theoretical basis for power transmission mechanism of oil film by considering the existence of a two-phase flow regime consisting of oil and air.
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Hongtuo Liu, Fangwei Xie, Kai Zhang, Xinxing Zhang, Jin Zhang, Cuntang Wang and Hao Li
The shock absorber is an important component of vehicle suspension that attenuates the vehicle vibration. Its running state directly affects the performance of the vehicle…
Abstract
Purpose
The shock absorber is an important component of vehicle suspension that attenuates the vehicle vibration. Its running state directly affects the performance of the vehicle suspension. The purpose of this paper is to quantitatively study the relationship between damping characteristics and air chamber and oil properties in single-tube pneumatic shock absorber.
Design/methodology/approach
Combined with the principle of fluid dynamics and hydraulic transmission technology, the rebound stroke and compression stroke mathematical models, and damping characteristics simulation model are established to investigate the effect of the air chamber and oil property on damping characteristics.
Findings
Research results show that the initial pressure of the air chamber is the key parameter which influences the damping characteristics of the shock absorber. The change of the initial pressure has more impact on damping force, and less impact on the speed characteristic; the initial volume of the air chamber almost has no effect on the damping characteristics. The density and viscosity of the oil have certain influence on the damping characteristics. Therefore, selecting suitable damping oil is very important.
Originality/value
Using Matlab/Simulink software to build simulation models, its results are very accurate. The conclusions can provide a theoretical reference for the structure design of a single-tube pneumatic shock absorber.