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Article
Publication date: 12 May 2022

Cheng Zhang, Jianfeng Zhou and Xiannian Meng

In the magnetorheological fluid (MRF) sealing, a large amount of friction heat is generated in the fluid film with micron thickness due to the viscosity dissipation, which leads…

325

Abstract

Purpose

In the magnetorheological fluid (MRF) sealing, a large amount of friction heat is generated in the fluid film with micron thickness due to the viscosity dissipation, which leads to seal failure and MRF deterioration. The purpose of this study is to investigate the mechanism of temperature rise of MRF film under the action of the three-field coupling of the flow field, temperature field and magnetic field.

Design/methodology/approach

The fluid film was simplified as a Couette flow in this work to simulate the temperature change in the sealing fluid film under different working conditions. The corresponding experiment for test the temperature rise was also carried out, and the temperature of the characteristic point of the stationary ring was measured to validate the model.

Findings

The results show that the temperature rise is mainly affected by the rotational speed, magnetic field strength and fluid film thickness. The magnetic field enhances the convective heat transfer in the MRF film. The thinner the fluid film, the more frictional heat generated. The MRF film reaches its maximum temperature at the contact with the end face of rotating ring due to frictional heat.

Originality/value

A method for temperature rise analysis of MRF fluid sealing films based on Couette flow is established. It is helpful for the study of liquid film frictional heat in MRF seals.

Details

Industrial Lubrication and Tribology, vol. 74 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 December 2023

Yunhao Zhang, Chunlei Shao, Jing Kong, Junwei Zhou and Jianfeng Zhou

This paper aims to prevent gasket sealing failure in engineering, accurately predict gasket life, extend system life and improve sealing reliability. The accelerated life test…

117

Abstract

Purpose

This paper aims to prevent gasket sealing failure in engineering, accurately predict gasket life, extend system life and improve sealing reliability. The accelerated life test method of flexible graphite composite–reinforced gaskets is established, the life distribution law of flexible graphite composite–reinforced gaskets is revealed, and the life prediction method of flexible graphite composite–reinforced gaskets with different allowable leakage rates is proposed, which can provide a reference for the life prediction of other types of gaskets.

Design/methodology/approach

In this study, flexible graphite composite–reinforced gaskets were tested for long-term high-temperature sealing performance on a multi-sample gasket accelerated life test rig. The data were also analyzed using the least squares method and the K-S hypothesis calibration method. A gasket time-dependent leakage model and an accelerated life model were also developed. Constant stress-accelerated life tests were conducted on flexible graphite composite–reinforced gaskets. On this basis, a gasket life prediction method at different allowable leakage rates was proposed.

Findings

The life distribution law of flexible graphite composite–reinforced gaskets is revealed. The results show that the life of the gasket obeys the Weibull distribution. The time-correlated leakage model and accelerated life model of the gasket were established. And the accelerated life test method of the flexible graphite composite–reinforced gasket was established. The life distribution parameters, accelerated life model parameters and life estimates of gaskets were obtained through tests. On this basis, a gasket life prediction method under different leakage rates was proposed, which can be used as a reference for other types of gaskets.

Practical implications

The research in this paper can better provide guidance for the use and replacement of gaskets in the project, which is also very meaningful for predicting the leakage condition of gaskets in the bolted flange connection system and taking corresponding control measures to reduce energy waste and pollution and ensure the safe operation of industrial equipment.

Originality/value

A multi-specimen gasket-accelerated life test device has been developed, and the design parameters of the device have reached the international advanced level. The life distribution law of the flexible graphite composite–reinforced gasket was revealed. The accelerated life test method for the flexible graphite composite–reinforced gasket was established. The life prediction method of the flexible graphite composite–reinforced gasket under different allowable leakage rates was proposed.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0254/

Details

Industrial Lubrication and Tribology, vol. 76 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 29 May 2019

Penggao Zhang, Boqin Gu, Jianfeng Zhou and Long Wei

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

152

Abstract

Purpose

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

Design/methodology/approach

The viscosity relationship of magnetic fluid in external electromagnetic field was deduced. The temperature distribution of sealing ring was calculated by the method of separation variables.

Findings

It has been found that the rotating ring absorbs most friction heat. The temperatures on the end faces of rotating ring and stationary ring decrease from inner radius to outer radius, the temperature of magnetic fluid film decreases from rotating ring to stationary ring and the highest temperature of the sealing system is at the junction of the inner radius and the end face of rotating ring.

Originality/value

Selecting the sealing rings with higher thermal conductivity and reducing the volume fraction of solid particles in magnetic fluid can reduce the temperature of sealing system effectively.

Details

Industrial Lubrication and Tribology, vol. 71 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 October 2018

Penggao Zhang, Boqin Gu, Jianfeng Zhou and Long Wei

The purpose of this study is to investigate the hydrodynamic lubrication characteristics of ferrofluid film for spiral groove mechanical seal in external electromagnetic field and…

208

Abstract

Purpose

The purpose of this study is to investigate the hydrodynamic lubrication characteristics of ferrofluid film for spiral groove mechanical seal in external electromagnetic field and to analyze the effects of the volume fraction of ferrofluid, parameters of the electromagnetic field, operating parameters and geometrical parameters of mechanical seal on the characteristics of ferrofluid film.

Design/methodology/approach

The relationship between the ferrofluid viscosity and the intensity of external electromagnetic field was established. Based on the Muijderman narrow groove theory, the pressure distribution was calculated with the trial method by trapezoid formula.

Findings

It was found that pressure, average viscosity, average density and opening force of ferrofluid between end faces increase with the increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential and spiral angle; decrease with the increase in temperature; and increase at first and then decrease with the increase in the ratio of groove width to weir and the groove length. All of them reach the maximum value when the ratio of width of groove to weir is 0.7 and the ratio of groove length is 0.6. Leakage of ferrofluid increases with an increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential, spiral angle and ratio of groove length; decreases with an increase in temperature; and increases at first and then decreases with the increase in the ratio of groove width to weir. The tendencies of characteristics of silicone oil are consistent with those of ferrofluid, and the characteristics of silicone oil are smaller than those of ferrofluid under the same condition.

Originality/value

The volume fraction of ferrofluid, rotating speed, spiral angle, ratio of groove width to weir, groove length and temperature have a significant influence on the characteristics of ferrofluid film; however, intensity of current and the pressure differential have slight influence on the characteristics of ferrofluid film. An analytical method for analyzing hydrodynamic lubrication characteristics of ferrofluid film in a spiral groove mechanical seal was proposed based on the Muijderman narrow groove theory.

Details

Industrial Lubrication and Tribology, vol. 70 no. 9
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 25 June 2019

Chunlei Shao, Aixia He, Zhongyuan Zhang and Jianfeng Zhou

The purpose of this paper is to study the transition process from the crystalline particles appearing before the pump inlet to the stable operation of the pump.

131

Abstract

Purpose

The purpose of this paper is to study the transition process from the crystalline particles appearing before the pump inlet to the stable operation of the pump.

Design/methodology/approach

Firstly, a modeling test method was put forward for the high-temperature molten salt pump. Then, according to a modeling test scheme, the experiment of the solid–liquid two-phase flow was carried out by using a model pump similar to the prototype pump. Meanwhile, the numerical method to simulate the transition process of a molten salt pump was studied, and the correctness of the numerical model was verified by the experimental results. Finally, the transition process of the molten salt pump was studied by the verified numerical model in detail.

Findings

In the simulation of the transition process, it is more accurate to judge the end of the transition process based on the unchanged particle volume fraction (PVF) at the pump outlet than on the periodic fluctuation of the outlet pressure. The outlet pressure is closely related to the PVF in the pump. The variation of the outlet pressure is slightly prior to that of the PVF at the pump outlet and mainly affected by the PVF in the impeller and volute. After 0.63 s, the PVF at each monitoring point changes periodically, and the time-averaged value does not change with time.

Practical implications

This study is of great significance to further improve the design method of molten salt pump and predict the abrasion characteristic of the pump due to interactions with solid particles.

Originality/value

A numerical method is established to simulate the transition process of a molten salt pump, and a method is proposed to verify the numerical model of two-phase flow by modeling test.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 26 November 2021

Chunlei Shao, Ning Bao, Sheng Wang and Jianfeng Zhou

The purpose of this paper is to propose a prediction method of gas-liquid two-phase flow patterns and reveal the flow characteristics in the suction chamber of a centrifugal pump.

159

Abstract

Purpose

The purpose of this paper is to propose a prediction method of gas-liquid two-phase flow patterns and reveal the flow characteristics in the suction chamber of a centrifugal pump.

Design/methodology/approach

A transparent model pump was experimentally studied, and the gas-liquid two-phase flow in the pump was numerically simulated based on the Eulerian–Eulerian heterogeneous flow model. The numerical simulation method was verified from three aspects: the flow pattern in the suction chamber, the gas spiral length and the external characteristics of the pump. The two-phase flow in the suction chamber was studied in detail by using the numerical simulation method.

Findings

There are up to eight flow patterns in the suction chamber. However, at a certain rotational speed, only six flow patterns are observed at the most. At some rotational speeds, only four flow patterns appear. The gas spiral length has little relationship with the gas flow rate. It decreases with the increase of the liquid flow rate and increases with the increase of the rotational speed. The spiral flow greatly increases the turbulence intensity in the suction chamber.

Originality/value

A method for predicting the flow pattern was proposed. Eight flow patterns in the suction chamber were identified. The mechanism of gas-liquid two-phase flow in the suction chamber was revealed. The research results have reference values for the stable operation of two-phase flow pumps and the optimization of suction chambers.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 13 January 2020

Chunlei Shao, Zhongyuan Zhang and Jianfeng Zhou

The purpose of this paper is to accurately predict the cavitation performance of a cryogenic pump and reveal the influence of the inlet pressure, the surface roughness and the…

271

Abstract

Purpose

The purpose of this paper is to accurately predict the cavitation performance of a cryogenic pump and reveal the influence of the inlet pressure, the surface roughness and the flow rate on the cavitation performance.

Design/methodology/approach

Firstly, the Zwart cavitation model was modified by considering the thermodynamic effect. Secondly, the feasibility of the modified model was validated by the cavitation test of a hydrofoil. Thirdly, the effects of the inlet pressure, the surface roughness and the flow rate on cavitation flow in the cryogenic pump were studied by using the modified cavitation model.

Findings

The modified cavitation model can predict the cavitation performance of the cryogenic pump more accurately than the Zwart cavitation model. The thermodynamic effect inhibits cavitation development to a certain extent. The higher the vapor volume fraction, the lower the pressure and the lower the temperature. At the initial stage of the cavitation, the head increases first and then decreases with the increase of the roughness. When the cavitation develops to a certain degree, the head decreases with the increase of the roughness. With the decrease of the flow rate, the hydraulic loss increases and the cavitation at the impeller intensifies.

Originality/value

A cavitation model considering the thermodynamic effect is proposed. The mechanism of the influence of the roughness on the performance of the cryogenic pump is revealed from two aspects. Taking the hydraulic loss as a bridge, the relationships among flow rates, vapor volume fractions, streamlines, temperatures and pressures are established.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 8 January 2020

Jianfeng Jia, Shunyi Zhou, Long Zhang and Xiaoxiao Jiang

Drawn upon the perspective of implicit voice theory, the purpose of this paper is to explore the underlying mechanism as well as the boundary effect in the relationship between…

1850

Abstract

Purpose

Drawn upon the perspective of implicit voice theory, the purpose of this paper is to explore the underlying mechanism as well as the boundary effect in the relationship between paternalistic leadership and voice behavior.

Design/methodology/approach

Multiple-wave survey data from a sample of 368 employees in China were used to test the hypothesized moderated mediation model.

Findings

The findings show that both benevolent leadership and moral leadership related positively to voice behavior, whereas authoritative leadership played a negative role in influencing voice behavior. Employees’ implicit voice belief played a partial mediating role between paternalistic leadership and voice behavior. Furthermore, perceived HRM strength weakens both the mediation relationship among benevolent leadership, implicit voice belief and voice behavior, and the mediation relationship among moral leadership, implicit voice belief and voice behavior. However, the moderated mediation effect of implicit voice belief on the relationship between authoritative leadership and voice behavior is not significant.

Practical implications

Leaders are encouraged to behave benevolently and morally whereas to avoid excessive authoritative style at work, so that employees can be encouraged to speak out. Organizations are advised to introduce management practices like training and development sessions and to improve employees’ perceived HRM strength so that the implicit voice belief can be reduced, and the voice behavior can be stimulated.

Originality/value

The research provided a fresh theoretical perspective on the underlying mechanism between paternalistic leadership and employees’ voice behavior by unveiling employee implicit voice belief’s partial mediating role between paternalistic leadership and employee voice behavior. Furthermore, the study contributed to the literature of voice by adopting a more integrative perspective and exploring the role of the implementation of the organization’s system, i.e., perceived HRM strength that provided a boundary condition in the above mediation model.

Details

Employee Relations: The International Journal, vol. 42 no. 2
Type: Research Article
ISSN: 0142-5455

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Article
Publication date: 5 February 2025

Wanying Guo, Heyun Bao, Jianfeng Cao and Yiping Zhou

The symmetry error generated in the machining process of herringbone gears will destroy the stability of the transmission system. The purpose of this paper is to establish a…

11

Abstract

Purpose

The symmetry error generated in the machining process of herringbone gears will destroy the stability of the transmission system. The purpose of this paper is to establish a symmetry error measurement model of herringbone gear based on spiral measurement method, and to evaluate the transmission accuracy of herringbone gear based on the measured symmetry error.

Design/methodology/approach

A symmetry error measurement model of herringbone gear based on spiral measurement method is proposed. The measurement method is verified by three coordinate measuring instrument. The transmission error analysis model of herringbone gear is established. The influence of speed and load on it is analyzed.

Findings

At the same speed, when the load increases from 100 N·m to 500 N·m, the transmission error increases and the transmission accuracy of the system decreases. Under the same load, the speed is increased from 100 rpm to 500 rpm, which has little effect on the transmission error.

Originality/value

The measurement method and analysis model used in this paper provide reference value and significance for the measurement and analysis of symmetry error.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2024-0350/

Details

Industrial Lubrication and Tribology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 11 May 2022

Lele Fan, Xing Zhou, Jing Ren, Jianfeng Ma, Yang Yang and Wenling Shao

Drawing from self-regulation theories, this study aims to present a model linking customer mistreatment to hotel employees’ displaced workplace deviance via self-regulatory…

1272

Abstract

Purpose

Drawing from self-regulation theories, this study aims to present a model linking customer mistreatment to hotel employees’ displaced workplace deviance via self-regulatory depletion, with disposition-based mindfulness as a first‐stage moderator.

Design/methodology/approach

The authors conducted a multisource, multiwave investigation with 245 focal–coworker dyads at 14 full-service hotels in southern China. Descriptive statistics, confirmatory factor analysis and regression analysis were performed.

Findings

The results demonstrated the mediating role of self-regulatory depletion in provoking hotel employees’ displaced deviant reactions to customer mistreatment. Additionally, employees with high trait mindfulness are less vulnerable to self-regulatory depletion and, thus, less likely to exhibit displaced workplace deviance.

Practical implications

This study enables hospitality administrators to understand that organizations and their employees, whether directly mistreated by customers, are potential victims of such negative events. Hospitality organizations should enhance mindfulness-based interventions and provide more humane care for employees to maintain their self-regulatory abilities, thereby reducing displaced workplace deviance.

Originality/value

First, in contrast to studies focusing primarily on internal factors that trigger employees’ deviant responses, the research suggests that mistreatment by external customers is a potentially meaningful yet largely unexamined antecedent of workplace deviance. Second, this study moves beyond “self-gain” explanations, suggesting that employees display deviance not because of a malicious intent to harm the organization or its members but because they are incapable of controlling their undesirable behaviors. Third, the research highlights how mindfulness mitigates customer mistreatment and displaced workplace deviance relationships.

Details

International Journal of Contemporary Hospitality Management, vol. 34 no. 7
Type: Research Article
ISSN: 0959-6119

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