scholarly journals Thermal Analysis of Herringbone Gears Based on Thermal Elastohydrodynamic Lubrication Considering Surface Roughness

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8564
Author(s):  
Xiaozhou Hu ◽  
Jie Chen ◽  
Minggui Wu ◽  
Jianing Wang
Keyword(s):  
Surface Roughness ◽  
Temperature Distribution ◽  
Numerical Method ◽  
Heat Generation ◽  
Heat Dissipation ◽  
Elastohydrodynamic Lubrication ◽  
Frictional Heat ◽  
Tooth Surface ◽  
Gear Pair ◽  
Herringbone Gear

To predict the temperature distribution of the tooth surface of a herringbone gear pair, a numerical method for the determination of frictional heat generation was proposed by establishing a thermal elastohydrodynamic lubrication (TEHL) model in the meshing zone taking surface roughness into account. According to the real micro topography of the tooth surface measured by a non-contact optical system and loaded tooth contact analysis, the friction coefficient was obtained by a TEHL analysis and then the heat generation in the contact zone was determined. With the combination of heat generation and heat dissipation analysis, the single tooth model of the herringbone gear pair due to the finite element method (FEM) was proposed and the steady-state temperature distribution of the tooth surfaces was predicted by FEM simulations. The simulation and the experimental results demonstrated good agreement, which verified the feasibility of the present numerical method.

Brush Seal Temperature Distribution Analysis

2005 ◽  
Vol 128 (3) ◽  
pp. 599-609 ◽  
Author(s):  
Yahya Dogu ◽  
Mahmut F. Aksit
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Operating Conditions ◽  
Frictional Heat ◽  
Distribution Analysis ◽  
Cfd Analysis ◽  
Oxidation Rates ◽  
Frictional Heat Generation ◽  
Brush Seal

Brush seals are designed to survive transient rotor rubs. Inherent brush seal flexibility reduces frictional heat generation. However, high surface speeds combined with thin rotor sections may result in local hot spots. Considering large surface area and accelerated oxidation rates, frictional heat at bristle tips is another major concern especially in challenging high-temperature applications. This study investigates temperature distribution in a brush seal as a function of frictional heat generation at bristle tips. The two-dimensional axisymmetric computational fluid dynamics (CFD) analysis includes the permeable bristle pack as a porous medium allowing fluid flow throughout the bristle matrix. In addition to effective flow resistance coefficients, isotropic effective thermal conductivity as a function of temperature is defined for the bristle pack. Employing a fin approach for a single bristle, a theoretical analysis has been developed after outlining the brush seal heat transfer mechanism. Theoretical and CFD analysis results are compared. To ensure coverage for various seal designs and operating conditions, several frictional heat input cases corresponding to different seal stiffness values have been studied. Frictional heat generation is outlined to introduce a practical heat flux input into the analysis model. Effect of seal stiffness on nominal bristle tip temperature has been evaluated. Analyses show a steep temperature rise close to bristle tips that diminishes further away. Heat flux conducted through the bristles dissipates into the flow by a strong convection at the fence-height region.

scholarly journals Numerical analysis of meshing heating of involute spur gear

2021 ◽  
Vol 2133 (1) ◽  
pp. 012033
Author(s):  
Jie Mu ◽  
Yusheng Zhai ◽  
Chengzhi Wang ◽  
Ruiguang Yun ◽  
Jianfeng En ◽  
...  
Keyword(s):  
Heat Flow ◽  
Heat Generation ◽  
Tangential Velocity ◽  
Frictional Heat ◽  
Tooth Surface ◽  
Flow Density ◽  
Heat Flow Density ◽  
Average Heat ◽  
Surface Meshing ◽  
Driving Wheel

Abstract Involute spur gears generate heat due to tooth surface meshing friction. Excessive temperature rising affects transmission accuracy and reduces work reliability.. By establishing the normalized coordinates of the meshing curve and based on the frictional heat generation theory, the mathematical analysis model of the meshing surface heating is studied, the factors affecting the average heat flux density of meshing are explored, and the distribution law of these factors along the normalized coordinate of the meshing is analysed. The analysis shows that the tangential velocity of the meshing point and the half-bandwidth of the time domain contact have the greatest influence on the average heat flow density; the average heat flow density distribution of the driving wheel and the driven wheel are similar. The heat flow density of the driving wheel is greater than that of the driven wheel. Tooth shape modification minimizes tooth surface meshing contact stress, reduces meshing heat generation, controls temperature rise and improves transmission reliability.

Evaluation and Improvement of the Spindle Thermal Transfer

2013 ◽  
Vol 436 ◽  
pp. 225-232 ◽  
Author(s):  
Emil Udup ◽  
Claudiu Florinel Bîșu ◽  
Miron Zapciu
Keyword(s):  
Temperature Distribution ◽  
Heat Generation ◽  
Heat Dissipation ◽  
Numerical Models ◽  
Friction Torque ◽  
Water Cooling ◽  
Axial Deformation ◽  
Finite Element Software ◽  
Thermal Transfer ◽  
Spindle Shaft

The main source of heat generation in a spindle is the friction torque in the ball bearing angular contact. The thermal and structural behavior of both spindle shaft/housing and bearings is characterized by the thermal expansion and the rate of heat generation depending on the operating speed. To evaluate the temperature distribution and its effects on the axial and radial deformations a simulation procedure is required. This paper is a presentation of the numerical models performed using the (ANSYS) commercial finite element software in order to assess the thermal behavior effect on the spindle nose axial deformation. Two numerical models were designed and simulated; the first model is a classic spindle in which heat dissipation of the bearings is removed by conduction and convection with the environment and with the second model, the generated heat is removed by water cooling circuits to improve the temperature distribution and axial deformation in the housing and spindle shaft.

Investigation on the effect of coating properties on lubrication of a coated spur gear pair

2017 ◽  
Vol 232 (3) ◽  
pp. 277-290 ◽  
Author(s):  
Huaiju Liu ◽  
Caichao Zhu ◽  
Zhanjiang Wang ◽  
Xiangyang Xu ◽  
Jinyuan Tang
Keyword(s):  
Surface Displacement ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Transform Method ◽  
Influence Coefficients ◽  
Stress Components ◽  
Squeeze Effect ◽  
Energy Equations

A thermal elastohydrodynamic lubrication model is proposed for a coated gear pair in which the influence coefficients for the elastic deformation and the subsurface stress components are obtained through the frequency response functions. The generalized Reynolds equation is utilized to represent the non-Newtonian effect. Energy equations of the contacting solids and the oil film are derived and solved based upon the marching method. The discrete convolute, fast Fourier transform method is used for fast calculation of the tooth surface displacement and the stress components underneath the surface. Variations of the slide-to-roll ratio, rolling speed, and the tooth load during gear meshing are considered and the film squeeze effect is taken into account. Effects of the coating thickness on the tribological performance, i.e. the film thickness, the pressure, the frictional behavior as well as the stress components are investigated under both the smooth and rough surface assumptions. Effects of the root mean square value of the tooth surface roughness on the pressure and stresses are discussed.

scholarly journals Effect of roughness on meshing power loss of planetary gear set considering elasto-hydrodynamic lubrication

2020 ◽  
Vol 12 (2) ◽  
pp. 168781402090842
Author(s):  
Xinlei Wang ◽  
Changle Xiang ◽  
Chunming Li ◽  
Shenlong Li ◽  
Yimin Shao ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Dynamic Model ◽  
Friction Force ◽  
Power Loss ◽  
Hydrodynamic Lubrication ◽  
Planetary Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Surface Geometry ◽  
Loss Calculation

Meshing power loss is one of the most important parts in power loss calculation of planetary gear set. However, most of the conventional methods assumed the friction coefficient between gears as a constant value in the meshing power loss calculation, and most importantly, the influence of gear tooth surface geometry is usually ignored, for example, roughness. Therefore, a new meshing power loss calculation model for planetary gear set that considers tooth surface roughness is proposed on the basis of elasto-hydrodynamic lubrication method. With the proposed model, a planetary gear set dynamic model that considers friction force between gears is first established to study the time-varying meshing forces, sliding speeds, and curvature radii of the gear pairs. Then, an elasto-hydrodynamic lubrication model of the gear pair contact interface is constructed to investigate and modify the friction force distribution in the gear meshing process of the dynamic model iteratively until the meshing forces converge to stable values. Furthermore, the relationship between the tooth surface roughness and film thickness is studied in the elasto-hydrodynamic lubrication model. After that, the meshing power loss is calculated based on the obtained meshing forces, friction coefficients, sliding speeds, and so on. The results show that there is a sudden growth of the meshing power loss at the end of the meshing cycle, which has a good agreement with the meshing force impact. And, it is found that tooth surface roughness has a direct influence on the meshing power loss of sun–planet gear pair, which yields an increasing tendency as the surface roughness growing.

Investigation of Conjugate Heat Transfer in Brush Seals Using Porous Media Approach Under Local Thermal Non-Equilibrium Conditions

2015 ◽  
Author(s):  
Bo Qiu ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Frictional Force ◽  
Conjugate Heat Transfer ◽  
Frictional Heat ◽  
Equilibrium Conditions ◽  
Frictional Heat Generation ◽  
Brush Seal ◽  
Brush Seals

As a type of contacting seal technology, brush seals provide superior sealing performance and flexible behavior. Brush seals have found increasing application in more challenging high-temperature locations in recent years. Thus, the frictional heat generation between the seal bristles and mating surfaces is becoming another major concern for stable operation of brush seals. This study presents detailed investigations on the conjugate heat transfer behavior of brush seals using Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) approaches. A dual-energy equation was proposed to describe the conjugate heat transfer in the porous bristle pack region under local thermal non-equilibrium conditions. The heat transfer CFD model was established with consideration of anisotropic thermal conductivity and a radius-dependent porosity of the bristle pack. The frictional heat generation was calculated from the product of the bristle-rotor frictional force and sliding velocity. The bristle-rotor frictional force was obtained from the brush seal FEM model with consideration of internal friction and aerodynamic load on the bristles. The temperature distribution of the brush seal was predicted at various operational conditions using the iterative CFD and FEM brush seal model. The effects of pressure ratios and rotational speeds on the temperature distribution and bristle maximum temperature of the brush seal were investigated based on the developed numerical approach. The effect of frictional heat generation on brush seal leakage was also analyzed.

Subsurface stress-field analysis of generating ground helical gear based on finite line-contact mixed elastohydrodynamic lubrication

2020 ◽  
Vol 235 (1) ◽  
pp. 3-17
Author(s):  
Zonglin Gu ◽  
Caichao Zhu ◽  
Huaiju Liu ◽  
Jinyuan Tang
Keyword(s):  
Surface Roughness ◽  
Stress Field ◽  
Smooth Surface ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Tooth Surface ◽  
Finite Line Contact ◽  
Finite Line ◽  
Subsurface Stress ◽  
Maximum Stresses

Tooth surface roughness and lubrication status have significant influence on the contact performance and fatigue life of helical gear pair. Yet, despite the development in elastohydrodynamic lubrication-based contact analysis and solution of subsurface stress field, researches in subsurface stress field of helical gears considering both lubrication and surface roughness are not quite comprehensive. In this study, three-dimensional surface roughness of generating ground gear is measured, a finite line-contact mixed elastohydrodynamic lubrication model is established to perform the contact analysis, and, on this basis, the influence of tooth surface roughness on the subsurface stress field is studied. Results show that compared with the smooth surface, the overall level of subsurface stress is raised; maximum stress values and plastic zones occur in the close vicinity of tooth surface, which adds to the risk of surface failure; within sections in the valley regions of roughness, locations of maximum stresses are generally similar to the smooth surface situation, i.e. in relatively deep zones, while within sections in the peak regions, the majority of locations with maximum stresses shift much closer to the surface; contact pressure and stress status see only mild undulation between different sections distributed along the contact line, but intense changes between sections distributed along the entraining direction.

Effect of frictional heat generation on the temperature distribution in roller linear motion rail surface

2017 ◽  
Vol 31 (3) ◽  
pp. 1477-1487 ◽  
Author(s):  
De-Jun Cheng ◽  
Je-Hong Park ◽  
Jeong-Se Suh ◽  
Su-Jin Kim ◽  
Chun-Hong Park
Keyword(s):  
Temperature Distribution ◽  
Heat Generation ◽  
Frictional Heat ◽  
Linear Motion ◽  
Frictional Heat Generation

Brush Seal Temperature Distribution Analysis

2005 ◽  
Author(s):  
Yahya Dogu ◽  
Mahmut F. Aksit
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Operating Conditions ◽  
Frictional Heat ◽  
Distribution Analysis ◽  
Cfd Analysis ◽  
Oxidation Rates ◽  
Frictional Heat Generation ◽  
Brush Seal

Brush seals are designed to survive transient rotor rubs. Inherent brush seal flexibility reduces frictional heat generation. However, high surface speeds combined with thin rotor sections may result in local hot spots. Considering large surface area and accelerated oxidation rates, frictional heat at bristles tips is another major concern especially in challenging high temperature applications. This study investigates temperature distribution in a brush seal as a function of frictional heat generation at bristle tips. The two-dimensional axisymmetric CFD analysis includes the permeable bristle pack as a porous medium allowing fluid flow throughout the bristle matrix. In addition to effective flow resistance coefficients, isotropic effective thermal conductivity as a function of temperature is defined for the bristle pack. Employing a fin approach for a single bristle, a theoretical analysis has been developed after outlining the brush seal heat transfer mechanism. Theoretical and CFD analysis results are compared. To ensure coverage for various seal designs and operating conditions, several frictional heat input cases corresponding to different seal stiffness have been studied. Frictional heat generation is outlined to introduce a practical heat flux input into the analysis model. Effect of seal stiffness on nominal bristle tip temperature has been evaluated. Analyses show a steep temperature rise close to bristle tips that diminishes further away. Heat flux conducted through the bristles dissipates into the flow by a strong convection at fence height region.

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