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Article
Publication date: 9 August 2013

Yuxing Peng, Zhu Zhencai, Minming Tong, Chen Guoan, Xingguo Shao, Wan Ma and Yilei Li

This paper aims to analyze the friction heat conduction and entransy of two friction linings in the high‐speed slide accident of a mine friction hoist.

Abstract

Purpose

This paper aims to analyze the friction heat conduction and entransy of two friction linings in the high‐speed slide accident of a mine friction hoist.

Design/methodology/approach

Firstly, the dynamic thermophysical properties were analyzed and their fitting equations were also obtained. Additionally, the dynamic heat partition ratio was obtained according to the dynamic thermophysical properties. Then, a simple method was developed to solve the temperature rise of friction lining. Finally, based on the theoretical model of temperature rise, the entransy of friction lining with respect to T and t were gained.

Findings

The error of temperature rise between simulation result and experiment result is less than 7 per cent, which proves that the theoretical model is correct. The entransy decreases with the temperature below 40°C and it increases after 40°C. The entransy of lining K is a little higher than that of lining G within 19 s, but the entransy of lining G is much higher than lining K after 19 s and the entransy difference gets great gradually. It is indicated that the lining K has good heat‐resistant property which is of great benefit to the tribological property of friction lining.

Practical implications

The authors' study provides a fundamental basis for developing a new friction lining with good heat‐resistant property, and it also brings forward a new quantitative method to evaluate the heat‐transfer capability of friction materials.

Originality/value

A simple method was introduced to calculate the temperature rise of friction lining with the consideration of dynamic thermophysical properties and dynamic heat partition ratio. And the entransy of friction lining was obtained to evaluate the heat‐transfer capability of friction linings quantitatively.

Details

Industrial Lubrication and Tribology, vol. 65 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 2 September 2014

Yanzhong Wang and Bin Wei

The purpose of this study is to investigate wet multi-disc brake temperature field and optimal oil supply under continuous braking condition. The oil supply of wet…

Abstract

Purpose

The purpose of this study is to investigate wet multi-disc brake temperature field and optimal oil supply under continuous braking condition. The oil supply of wet multi-disc brake has a direct impact on the drivability and fuel economy for tracked vehicles. Too small flow will result in the higher temperature and failure of brake while excessive one will lead to slow engagement increasing disengaged torque and the transmission efficiency could decline notably. The optimal oil supply and brake temperature field were obtained in this research.

Design/methodology/approach

This article investigated on the heat dissipation capability and optimal oil supply of the brake by the means of CFX model. The working condition was continuous braking and the lubricating and cooling factors were included in the model.

Findings

That the complex trends with increased oil flow is inconsistent with the traditional formula in which the effects of grooves were neglected. The fitting curve of optimal oil supply can predict various needed oil flow in various rotating speed and it provides a theoretical guidance for oil supply design.

Originality/value

Traditional empirical formula of heat transfer coefficient and Reynolds equation solved by different methods could be difficult to deal with the complex boundary conditions of wet multi-disc brake. CFX model can solve the problem of complex boundary condition. The optimal oil supply curve can provide a theoretical guidance for oil supply design.

Details

Industrial Lubrication and Tribology, vol. 66 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 14 March 2016

Fangwei Xie, Yaowen Tong, Diancheng Wu, Bing Zhang and Kaiyu Dai

The purpose of this paper is to study the influence of different cross-sectional shapes (rectangular, trapezoidal, oval and triangular) and layout forms of oil grooves…

Abstract

Purpose

The purpose of this paper is to study the influence of different cross-sectional shapes (rectangular, trapezoidal, oval and triangular) and layout forms of oil grooves (radial, circumferential, inclined, compound, helical and double-helical), and determine the optimal section shape and layout form of oil grooves on the temperature field.

Design/methodology/approach

Heat conduction theory model was established based on startup characteristics and friction heat principle of hydro-viscous clutch (HVC), and then the theoretical expression of angular velocity of the friction pair and control pressure were deduced, and the heat flux and its distribution on friction disk and separator disk were calculated. Finally, the finite element method was used to solve the temperature field of the friction pair.

Findings

The studies show that the circumferential oil groove got the highest temperature, and on the surface of all other structures, hot spots appear with different sizes and temperatures, and the maximum temperature difference in the friction zone is about 3°C, and in the oil groove zone is about 16°C, wherein the compound oil groove has the lowest average temperature. This research shows that the compound oil groove with rectangular cross-section is the best choice for the friction pair.

Originality/value

In this paper, it was found that the compound oil groove with rectangular cross-section is the best choice for the friction pair, and it provided a favorable theory reference and technical support for the structural design of the friction pair and optimized design of the high-power HVC.

Details

Industrial Lubrication and Tribology, vol. 68 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 August 2016

Lei Luo, Chenglong Wang, Lei Wang, Bengt Ake Sunden and Songtao Wang

The dimple is adopted into a pin fin wedge duct which is widely used in modern gas turbine vane cooling structure trailing edge region. The purpose of this paper is to…

Abstract

Purpose

The dimple is adopted into a pin fin wedge duct which is widely used in modern gas turbine vane cooling structure trailing edge region. The purpose of this paper is to study the effects of dimple depth and duct converging angle on the endwall heat transfer and friction factor in this pin fin wedge duct.

Design/methodology/approach

The study is carried out by using the numerical simulations. The diameter of dimples is the same as the pin fin diameter with an inline manner arrangement in relation to the pin fin. The ratio between dimple depth and dimple diameter is varied from 0 to 0.3 and the converging angle is ranging from 0° to 12.7°. The Reynolds number is between 10,000 and 50,000. Results of the endwall Nusselt number, friction factor, and flow structures are included. For convenience of comparison, the pin fin wedge duct with a converging angle of 12.7° without dimples is considered as the baseline.

Findings

It is found that the dimples can effectively enhance the endwall heat transfer due to the impingement on the dimple surface, reattachment downstream the dimple and recirculation in front of the pin fin leading edge. By increasing the converging angle, the heat transfer is also increased but with a large friction factor penalty. In addition, the heat transfer enhancement for deep depth cases is 1.57 times higher than that of the low depth case. The thermal performance indicates that the intensity of heat transfer enhancement depends upon the dimple depth and converging angle.

Originality/value

It suggests that the endwall heat transfer in a pin fin wedge duct can be increase by the adoption of dimples. The optimal dimple relative depth is 0.2 with low friction factor and high heat transfer performance.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 12 March 2018

Tengjiao Lin, Zi-ran Tan, Ze-yin He, Hong Cao and He-sheng Lv

This paper aims to introduce the moment of inertia of the driving and driven end of the clutch into the analysis of the transient temperature field of a friction plate and…

Abstract

Purpose

This paper aims to introduce the moment of inertia of the driving and driven end of the clutch into the analysis of the transient temperature field of a friction plate and studied the influencing factors on that, especially to a marine gearbox.

Design/methodology/approach

A three-dimensional transient heat transfer analysis model of a wet clutch friction plate used in a marine gearbox is developed, and the transient characteristics of the temperature field during engagement are analyzed with taking account of the influence factors such as the sliding friction coefficient, engaging revolving speed, moment of inertia and applied engagement pressure.

Findings

The paper found out that the hot spot appears on the surface of the friction plate, taking account of the effect of radial slots and spiral groove. To avoid damage to the friction plate as a result of overheating, the appropriate sliding friction coefficient, lower engaging revolving speed and reasonable selection of applied engagement pressure curve can ensure a favorable heating situation of the friction plate. The reasonable structural design for the clutch with a bigger moment of inertia of driving end and smaller moment of inertia of driven end can reduce the engaging time effectively and decrease the peak temperature of the friction plate.

Originality/value

This paper fulfils a method to study the transient temperature field of a wet clutch friction plate, especially used in a marine gearbox.

Details

Industrial Lubrication and Tribology, vol. 70 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 October 1955

W. Gordon Watson

THE problem of the expansion of a compressible fluid with friction and heat flow is one of great complexity. In this treatment it has been simplified to a one‐dimensional…

Abstract

THE problem of the expansion of a compressible fluid with friction and heat flow is one of great complexity. In this treatment it has been simplified to a one‐dimensional problem and the resulting relationships are thermodynamic. An expansion of this type cannot be described as reversible due to the presence of friction, and from this aspect the analysis may be suspect. However, any practical process is irreversible and it is common practice to apply to such processes an analysis which is theoretically confined to changes which occur reversibly. Thus, although the degree of irreversibility may be greater than usual in this case, there are many precedents for allowing the use of reversible thermodynamics in the analysis of irreversible changes. The relations for the expansion are well known, but the writer believes the analysis and discussion on the choking conditions of a nozzle are more general than anything yet published.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 14 June 2011

Oronzio Manca, Sergio Nardini and Daniele Ricci

The purpose of this paper is to investigate the flow and the heat transfer characteristics of a two‐dimensional rib‐roughned rectangular duct with the two principal walls…

Abstract

Purpose

The purpose of this paper is to investigate the flow and the heat transfer characteristics of a two‐dimensional rib‐roughned rectangular duct with the two principal walls subjected to uniform heat flux. In particular, the main goal is to generate friction and heat transfer data, for different values of p/e with square, rectangular, trapezoidal and triangular shape ribs for Reynolds numbers in the range between 20,000 and 60,000 and different heights and to describe the temperature and fluid‐dynamic fields around the ribs.

Design/methodology/approach

The model is constituted by a two‐dimensional duct. On the duct wall square, rectangular, triangular and trapezoidal ribs are introduced by changing different geometry ratios. Governing equations are solved numerically by means of the finite‐volume method.

Findings

Simulations show that maximum Nusselt numbers are detected in correspondence with dimensionless pitch equal to 12 and 10 for the square, trapezoidal and rectangular ribs, and triangular ones, respectively. Heat transfer rate is at most 2.45 times higher than the smooth duct, when dimensionless height is equal to 0.05, and 1.85 at a dimensionless height equal to 0.02; furthermore, the friction factor is the highest at a pitch ratio of ten for the rectangular, trapezoidal and square ribs while the triangular ones show the maximum values at a dimensionless pitch equal to 8. For Re>40,000 an asymptotic behavior is detected. Best thermal performances are provided by triangular ribs with w/e=2.0 while the rectangular ribs with w/e=2.0 present the lowest friction factor values. Local Nusselt number profiles reveal that the maximum values are detected from three to five times the rib height from the downstream turbulator. Finally, temperature fields and stream function contours are given in order to visualize the temperature distribution and flow pattern in presence of d‐type and k‐type roughness behavior also for triangular ribs.

Originality/value

The paper investigates evaluation of temperature and velocity fields thermal and fluid‐dynamic behaviors (in terms of average and local Nusselt number profiles and friction factors ones) of roughned ducts with different shapes, heights and aspect ratios of ribs in turbulent regime. The thermo‐physical properties of fluid are assumed to be dependent on temperature. The paper is useful to thermal designers.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 21 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 February 2008

P. Sathiya, S. Aravindan and A. Noorul Haq

Friction welding is a solid state bonding process, where the joint between two metals has been established without melting the metal. The relative motion between the…

Abstract

Friction welding is a solid state bonding process, where the joint between two metals has been established without melting the metal. The relative motion between the faying surfaces (surfaces to be joined) under the application of pressure promotes surface interaction, friction and heat generation which subsequently results in joint formation. Stainless steel is an iron based alloy, contains various combinations of other elements to give desired characteristics, and found a wider range of applications in the areas such as petro‐chemical, fertilizer, automotive, food processing, cryogenic, nuclear and beverage sectors. In order to exploit the complete advantages of stainless steels, suitable joining techniques are highly demanded. The Friction welding is an easily integrated welding method of stainless steel, which considered as non‐weldable through fusion welding. Grain coarsening, creep failure and failure at heat‐affected zone are the major limitations of fusion welding of similar stainless steels. Friction welding eliminates such pitfalls. In the present work an attempt is made to investigate experimentally, the mechanical and metallurgical properties of friction welded joints, namely, austenitic stainless steel (AISI 304) and ferritic stainless steel (AISI 430). Evaluation of the characteristics of welded similar stainless steel joints are carried out through tensile test, hardness measurement and metallurgical investigations.

Details

Multidiscipline Modeling in Materials and Structures, vol. 4 no. 2
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 10 August 2018

Yanzhong Wang and Chao Guo

This paper aims to study the change rule of sintered iron friction properties under high temperature and establish the model to predict the friction coefficient.

Abstract

Purpose

This paper aims to study the change rule of sintered iron friction properties under high temperature and establish the model to predict the friction coefficient.

Design/methodology/approach

The morphological measurements of sintered iron material with four different oxidation degrees are carried out. A prediction model of friction coefficient in high temperature oxide growth stage for sintered iron material is established based on the theory of flash temperature and adhesion friction. The relationship between friction coefficient and the key parameters is found through the test fitting.

Findings

The surface topography changes with oxidative wear. The wear debris will be compacted and sintered again to form a composite oxide layer with the temperature increasing. The validity and accuracy of proposed model are tested using the friction coefficient and temperature experiments. Results are in reasonable agreement with those obtained using values of load commonly used.

Originality/value

The significance lies in the change mechanism of high temperature friction characteristic is clarified. Three friction stages related to temperature of dry friction are put forward for sintered iron, and a meaningful reference is provided by the established model for high-temperature performance design of sintered iron friction material.

Details

Industrial Lubrication and Tribology, vol. 70 no. 8
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 22 September 2020

Lei Luo, Yifeng Zhang, Chenglong Wang, Songtao Wang and Bengt Ake Sunden

The pin fin is applied into a Lamilloy cooling structure which is broadly used in the leading edge region of the modern gas turbine vane. The purpose of this paper is to…

Abstract

Purpose

The pin fin is applied into a Lamilloy cooling structure which is broadly used in the leading edge region of the modern gas turbine vane. The purpose of this paper is to investigate effects of the layout, diameter and shape of pin fins on the flow structure and heat transfer characteristics in a newly improved Lamilloy structure at the leading edge region of a turbine vane.

Design/methodology/approach

A numerical method is applied to investigate effects of the layout, diameter and shape of pin fins on the flow structure and heat transfer characteristics in a newly improved Lamilloy structure at the leading edge of a turbine vane. The diverse locations of pin fins are Lp = 0.35, 0.5, 0.65. The diameter of the pin fins varies from 8 mm to 32 mm. Three different ratios of root to roof diameter for pin fins are also investigated, i.e. k = 0.5, 1, 2. The Reynolds number ranges from 10,000 and 50,000. Results of the flow structures, heat transfer on the target surface and pin fin surfaces, and friction factor are studied.

Findings

The heat transfer on the pin fin surface gradually decreases and then increases as the location of the pin fins increases. Increasing the diameter of the pin fins causes the heat transfer on the pin fin surface to gradually increase, while a lower value of the friction factor occurs. Besides, the heat transfer on the pin fin surface at a small root diameter increases remarkably, but a slight heat transfer penalty is found at the target surface. It is also found that both the Reynolds analogy performance and the thermal performance are increased compared to the baseline whose diameter and normalized location of pin fins are set as 16 and 0.5 mm, respectively.

Social implications

The models provide a basic theoretical study to deal with nonuniformity of the temperature field for the turbine vane leading edge. The investigation also provides a better understanding of the heat transfer and flow characteristics in the leading edge region of a modern turbine vane.

Originality/value

This is a novel method to adopt pin fins into a Lamilloy cooling structure with curvature. It presents that the heat transfer of the pin fin surface in a pin-fin Lamilloy cooling structure with curvature can be significantly increased by changing the parameters of the pin fins which may lead to various flow behavior. In addition, the shape of the pin fin also shows great influence on the heat transfer and flow characteristics. However, the heat transfer of the target surface shows a small sensitivity to different layouts, diameter and shape of pin fin.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

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