Simulation and experiment of viscous torque for disengaged wet clutches of tracked vehicle

2018 ◽  
Vol 233 (4) ◽  
pp. 593-604 ◽  
Author(s):  
Wei Bin ◽  
He yongyong ◽  
Wang Wei ◽  
Luo jianbin
Keyword(s):  
Heat Dissipation ◽  
Friction Pair ◽  
High Mobility ◽  
Viscous Force ◽  
Viscous Drag ◽  
Computation Method ◽  
Drag Torque ◽  
Rotation Direction ◽  
Viscous Torque ◽  
Spiral Grooves

In order to predict the viscous drag loss for tracked vehicles, the drag torque of the friction pair with different grooves was investigated in this paper. The traditional computation method is difficult to adapt for the new kinds of friction plates with complex grooves. A numerical method with the help of CFD models is adopted to simulate the fluid flow status in the grooves and the drag torque was obtained by the accumulation of the discrete viscous force. The simulation results implied that the plates with different kinds grooves were provided with various characteristics of viscous torque and these characteristics could be affected by the rotation direction for the plate with spiral grooves, which are proved in experiment. Meanwhile, it was also found that the two kinds of plates with double arc or spiral grooves, which have different sensitive parameters in drag dissipation, have to perform accurate flow control and clearance design respectively. The simulations and experiments showed that the ‘positive spiral grooves’ friction plates had minimum drag torque in regular heavy-duty conditions. It can be used in transmission system with requirements of limited space and high mobility, which can lead to better heat dissipation and less power loss.

Dynamic transmission of oil film in soft-start process of HVD considering surface roughness

2018 ◽  
Vol 70 (3) ◽  
pp. 463-473 ◽  
Author(s):  
Fangwei Xie ◽  
Jie Zhu ◽  
Jianzhong Cui ◽  
Xudong Zheng ◽  
Xinjian Guo ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Friction Pair ◽  
Maximum Temperature ◽  
Force Model ◽  
Content Type ◽  
Oil Film ◽  
Soft Start ◽  
Viscous Torque ◽  
Start Process

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.

Experimental Research on Drag Torque for Single-plate Wet Clutch

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Hu Jibin ◽  
Peng Zengxiong ◽  
Wei Chao
Keyword(s):  
Contact Angle ◽  
Surface Tension Force ◽  
Transmission Efficiency ◽  
Viscous Drag ◽  
Drag Torque ◽  
Two Phase ◽  
Rotating Speed ◽  
Single Plate ◽  
Wet Clutch ◽  
Set Up

The relative motion between the friction and separate plates in a disengaged wet clutch causes viscous drag torque when the lubrication fluid flows through the clearance. Reduction of the drag torque is one of the important potentials for the improvement of transmission efficiency. The objective of this study is to set up an experimental rig to measure drag torque for a single-plate wet clutch. Visualization of the flow pattern in the clearance through transparent quartz was presented. Design factors and lubrication conditions were tested to evaluate the effects on drag torque. A comparison between the nongrooved plate and grooved plate was made. Plates made up of different materials were also tested to reveal the effects caused by the contact angle. Drag torque increases linearly at low rotating speeds and gradually decreases at high rotating speeds. It is confirmed that fluid completely covers the plate surface at a low rotating speed and air mixes with the fluid at a high rotating speed. A low feeding flow rate is useful to reduce drag torque. The reduction of the drag torque benefits from radial and deep grooves compared to a flat plate. A small contact angle near the stationary plate plays an important role in maintaining the oil film, however, it has little effect on the drag torque at the rotating side because the hydrodynamic force becomes dominant compared to the surface tension force. The test results help to build an accurate mathematical model based on two-phase flow lubrication.

scholarly journals Viscous Drag Torque on a Rotating Nanofabricated Cylinder Near an Infinite Plane Boundary

2009 ◽  
Vol 96 (3) ◽  
pp. 289a
Author(s):  
James Inman ◽  
Christopher Deufel ◽  
Scott Forth ◽  
Michelle D. Wang
Keyword(s):  
Plane Boundary ◽  
Viscous Drag ◽  
Infinite Plane ◽  
Drag Torque

Simulation and experimental study on the influence of oil groove structure on the drag torque of the wet clutch

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chengjun Wang ◽  
Wujian Ding ◽  
Xudong Zheng ◽  
Haiqiang Zhu ◽  
Zuzhi Tian ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Reference Object ◽  
Drag Torque ◽  
Content Type ◽  
Oil Film ◽  
Wet Clutch ◽  
Groove Structure ◽  
Dimensional Simulation

Purpose This paper aims to design a single and double throat oil groove structure, which can reduce the drag torque of the wet clutch. Design/methodology/approach A three-dimensional simulation model was established herein using the computational fluid dynamics method. The influence of oil groove structure on the oil film flow field and the drag torque is obtained by a simulation. Findings Compared with the traditional radial oil groove, the results show that the single throat oil groove structure reduces the drag torque by about 24.59%; the double throat oil groove reduces the drag torque by about 47.27%. As the speed difference increases, the average temperature rise of the oil film of the double throat oil groove is 4°C lower than that of the single throat oil groove, indicating that it has good heat dissipation performance. The analysis results were verified by experimental results. Originality/value In this paper, the radial oil groove is taken as the reference object, and the structure of the oil groove is designed and improved. The simulation analysis and experiment verify the rule of the influence of the oil groove structure on the drag torque, which provides a new design idea for reducing the drag torque of wet clutch.

Model for the prediction of drag torque characteristics in wet clutch with radial grooves

2018 ◽  
Vol 233 (12) ◽  
pp. 3043-3056 ◽  
Author(s):  
Lin Zhang ◽  
Chao Wei ◽  
Ji Bin Hu
Keyword(s):  
Flow Rate ◽  
Rotational Speed ◽  
Heat Dissipation ◽  
Maximum Speed ◽  
Drag Torque ◽  
Cross Sectional ◽  
Oil Film ◽  
Oil Supply ◽  
Wet Clutch ◽  
Film Lubrication

Drag torque can cut down the efficiency of the vehicle transmission system. So it should be reduced on the premise of normal vehicle lubrication and heat dissipation. The purpose of this paper is to analyze the variation rule of drag torque in single-plate wet clutch from the perspective of flow rate, density, and viscosity. In the theoretical model of drag torque, the flow field is divided into oil film area and cavitation zone. Based on the mass flow conservation and viscosity–pressure equation, the equivalent density and viscosity of each node in each region are obtained. Then the total drag torque is calculated through the sum of each node’s torque. Finally, the curves of drag torque with rotational speed under different working conditions are obtained by numerical calculation, and they have been tested and verified. Through this research, the following conclusions can be reached: the rotational speed of the peak of drag torque is near the maximum speed where full oil film lubrication is realized. While temperature declines, it will lead to higher viscosity, then the speed of the lubricant along the radial direction will decrease, resulting in the increase in maximum speed of full oil film lubrication under the same oil supply; accordingly, the peak of drag torque will rise. If the flow rate of oil supply is increased, the maximum speed where full oil film lubrication is realized will be higher; consequently, the maximum drag torque will be improved. When clearance becomes wider, the cross-sectional area of the radial flow will be larger, then the maximum speed of full oil film lubrication under the same oil supply will be decreased, thus the peak of drag torque will decline.

Calculating the Torques and Meter Factor of Turbine Flow Meter with Numerical Simulation

2015 ◽  
Vol 713-715 ◽  
pp. 164-168
Author(s):  
Yong Zhang Huang ◽  
Ying Tao Sun ◽  
Bao Sheng Zhang ◽  
Gang Chen ◽  
Bao Li Zhu
Keyword(s):  
Numerical Simulation ◽  
Viscous Drag ◽  
Drag Torque ◽  
Friction Drag ◽  
Flow Meter ◽  
Numerical Simulation Methods ◽  
Unsteady Numerical Simulation ◽  
Driving Torque ◽  
Turbine Flow Meter ◽  
Bearing Friction

The torque balancing equations and the torque equation of the turbine flow meter is deduced in the paper. The driving torque, the viscous drag torque and the bearing friction drag torque on the impeller is calculated by unsteady numerical simulation methods. The change rule of the various torques is gotten considering or not the influence of bearing drag torque. Also, the effect of different viscosity on the torque is calculated, which is used to explain the phenomenon of meter factor change law with the viscosity. It makes clear that the possibilities to improve the accuracy of the meter and to predicate the meter factor by unsteady numerical simulation.

Effect of Low Temperature and High Pressure on Deep-Sea Oil-Filled Brushless DC Motors

2016 ◽  
Vol 50 (2) ◽  
pp. 83-93 ◽  
Author(s):  
Minjian Cai ◽  
Shijun Wu ◽  
Canjun Yang
Keyword(s):  
Dynamic Viscosity ◽  
Deep Sea ◽  
Power Loss ◽  
Dynamic Performance ◽  
Viscous Drag ◽  
Oil Viscosity ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Dc Motors ◽  
Viscous Torque

AbstractThe principle of electronic commutation makes brushless DC motors suitable for deep-sea application by sealing the motor in an oil-filled housing. However, if the oil-filled actuator is not designed properly, it will malfunction in the deep sea in spite of its excellent performance on land. In this paper, oil viscosity variations with pressure and temperature are reviewed because both factors vary with the operating depth, and a practical approach to estimate the viscous torque is advanced based on a viscous drag model of the selected motor and the properties of the oil. An experimental rig that can simulate the deep sea environment was developed, by which a series of experiments to study the motor efficiency and dynamic performance in different conditions were conducted. The values of viscous torque obtained in the experiments agreed well with our estimation. The low efficiency in the 2°C experimental group confirmed the influence of temperature, while the dramatic difference in the dynamic performance of the motor when filled with different oils verified the importance of analyzing the properties of the oil and of making a deliberate selection.<def-list>Nomenclature<def-item><term>T0</term><def>Normal temperature</def></def-item><def-item><term>P0</term><def>Atmospheric pressure</def></def-item><def-item><term>μ</term><def>Dynamic viscosity</def></def-item><def-item><term>μ0</term><def>Dynamic viscosity at given temperature T0 and pressure P0</def></def-item><def-item><term>ρ</term><def>Density</def></def-item><def-item><term>P</term><def>Pressure</def></def-item><def-item><term>T</term><def>Temperature</def></def-item><def-item><term>α</term><def>Pressure-viscosity coefficient</def></def-item><def-item><term>η</term><def>Kinetic viscosity</def></def-item><def-item><term><inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mimetype="image" xlink:href="MTS50208e13.gif"/></term><def>Taylor number</def></def-item><def-item><term>Mv</term><def>Viscous drag moment</def></def-item><def-item><term>MC</term><def>Viscous drag moment acting on cylinder flank</def></def-item><def-item><term>CM</term><def>Moment coefficient</def></def-item><def-item><term>Ri</term><def>Rotor diameter</def></def-item><def-item><term>C</term><def>Air-gap clearance</def></def-item><def-item><term>L</term><def>Rotor length</def></def-item><def-item><term>B</term><def>Clearance between housing and end face of the motor</def></def-item><def-item><term>ω</term><def>Rotor angular velocity</def></def-item><def-item><term>Re</term><def>Reynolds number</def></def-item><def-item><term>k</term><def>Coefficient relating to the motor geometry</def></def-item><def-item><term>PeL</term><def>Input electric power</def></def-item><def-item><term>Pir</term><def>Iron power loss</def></def-item><def-item><term>Pme</term><def>Mechanical power</def></def-item><def-item><term>Pj</term><def>Joule power loss</def></def-item><def-item><term>R</term><def>Phase resistance</def></def-item><def-item><term>U</term><def>Input voltage</def></def-item><def-item><term>I</term><def>Input current</def></def-item></def-list>

Computational Simulation Study on the Viscous Drag of the Automotive Wet Clutch for Prediction and Control

2015 ◽  
Author(s):  
In-Ha Sung ◽  
Jin Seok Ryu
Keyword(s):  
High Speed ◽  
Simulation Analysis ◽  
Automatic Transmission ◽  
Computational Simulation ◽  
Viscous Drag ◽  
Drag Torque ◽  
Wet Clutch ◽  
Pattern Shape ◽  
Friction Plate ◽  
Groove Pattern

The reduction of drag torque is an important issue in terms of improving transmission efficiency. Drag torque in a wet clutch occurs because viscous automatic transmission fluid flow narrow gap between friction plate and separate plate. The main purpose of this study is to observe the effects of the various parameters on the drag torque using finite element simulation. In this study, the simulation analysis reveals that as the rotational speed increases, the drag torque generally increases to a critical point and then decreases sharply at a high speed regime. Depth of groove on the friction plate plays an important role in controlling drag torque peak. An increase in the depth of groove causes a decrease in shear stress; thus, the drag torque also decreases according to Newton’s law of viscosity. Also, an observation of the effect of the angle of groove pattern shape shows that the drag torque changes with groove pattern shape. Therefore, the optimum angle of the groove pattern should be determined carefully, considering both the clutch performance and drag reduction. It is expected that the results from this study can be very useful as a database for clutch design and to predict the drag torque for the initial design with respect to various clutch parameters.

Error Estimation for Neglecting Unsteady Hydrodynamic Forces in the Equation of Motion for an Immersed Pendulum

2012 ◽  
Vol 29 (1) ◽  
pp. 1-6 ◽  
Author(s):  
F.-L. Yang
Keyword(s):  
Solid Sphere ◽  
Added Mass ◽  
Unsteady Motion ◽  
Layer Growth ◽  
Viscous Force ◽  
Viscous Drag ◽  
Mass Force ◽  
Actual Error ◽  
History Force ◽  
Boundary Layer Growth

ABSTRACTThe unsteady motion of a fully immersed solid sphere at low to moderate particle Reynolds number, from 1 to about 1600, has been modeled by considering the quasi-steady viscous drag, the added mass force, and the history force. The last force results from unsteady boundary layer growth and is often neglected in multiphase flow applications due to its complex formula. However, it has been shown that this unsteady viscous force is more crucial than the widely employed added mass force to describe an unsteady sphere motion. Thus, targeting the flow regime when the quasi-steady viscous drag is dominating, this work proposes two simple formulae to approximate the errors of neglecting either the history force or the added mass force in describing a fully immersed spherical pendulum motion. The proposed formulae are shown to capture the actual error when the numerical solution of a partial model that omits one force component is compared to the full model prediction when the sphere density is not too close to the ambient liquid.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

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