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 Numerical Simulation of Evaporating Two-Phase Flow in a High-Aspect-Ratio Microchannel with Bends

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Adam Girard ◽  
Seung M. You ◽  
Suresh V. Garimella
Keyword(s):  
Heat Flux ◽  
Contact Angle ◽  
Flow Boiling ◽  
Vertical Component ◽  
Hydrophobic Surface ◽  
Surface Tension Force ◽  
Heat Fluxes ◽  
Vertical Force ◽  
Two Phase ◽  
Hydrophobic Contact

Flow boiling was investigated on a hydrophobic surface by coating Teflon® onto a 1×1 cm2 copper surface, resulting in contact angle of 118°. The images depicted were taken using distilled water flowing at 299 kg/m2s with 3°C subcooling. In the first series, the number of active nucleation sites increased as heat flux increased. For lower values of heat flux (< 80 kW/m2), vapor bubbles remained almost stationary on the surface. The hydrophobic contact angle makes the horizontal component of surface tension force act radially outward, causing the bubble interface to grow. This leads to increased triple contact line and increased vertical component surface force. The buoyancy force due to the vapor bubble volume appears to be insufficient to overcome this vertical force for liftoff. This explains the stationary bubbles observed at the lower heat fluxes. The bubbles show an increase in size and number with heat flux. After this increasing trend, the bubble continues to grow larger when heat flux is higher than 80 kW/m2, eventually leading to the dryout at 117.5 kW/m2. The later bubble growth at high heat fluxes is caused primarily by the coalescences of neighboring bubbles. These larger bubbles are more affected by flow induced drag forces and move downstream. This can be seen in the lower sequential series at 100 kW/m2. The larger vapor masses slide across the surface, continue to absorb smaller bubbles as they move downstream, and are swept off the surface.

Combined Numerical and Experimental Study on Drag Torque in a Wet Clutch

2011 ◽  
Author(s):  
Youhei Takagi ◽  
Yasunori Okano ◽  
Masatoshi Miyagawa ◽  
Nobuyuki Katayama
Keyword(s):  
Experimental Study ◽  
Volume Fraction ◽  
Rotation Speed ◽  
Automatic Transmission ◽  
Rotating Disk ◽  
Open Boundary ◽  
Drag Torque ◽  
Two Phase ◽  
Frictional Material ◽  
Wet Clutch

The effect of flow field on drag torque in a wet clutch was examined through a combined numerical and experimental study. Three-dimensional hydrodynamic numerical simulations were carried out, and the drag torque was measured experimentally for a single wet clutch pack. Two-phase flow induced by aeration was visualized in the experiment. In the present drag torque test, the main section was consisted of two parallel circular plates. The plate with the frictional material was rotated. The frictional material was divided into some sections, and radial or circumferential grooves were made on the rotating disk. Automatic Transmission Fluid (ATF) was supplied from the axial center, and ejected into the surrounding open boundary. At low rotation speeds, it was found that the oil flow is of single-phase, and the drag torque is linearly proportional to the rotation speed since the shear stress on the clutch plate increased monotonically. In the single-flow regime, the slope of drag torque curve was controlled with the clearance between the clutch plates. The drag torque reached a peak value at a certain rotation speed, and it decreased gradually after the peak. These observed phenomena were due to the aeration from the inner gap on the disk, and the bubble volume fraction was directly related to the drag torque. The peak of drag torque was controlled by both the flow rate of supplied ATF and the arrangement of grooves on the frictional material. It also was found that the smooth ejection of ATF and the enhancement of aeration led to a reduction in the drag torque.

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.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

Pump Performance Improvement by Restraining Back Flow in Screw-Type Centrifugal Pump

2005 ◽  
Vol 127 (4) ◽  
pp. 755-762 ◽  
Author(s):  
Yasushi Tatebayashi ◽  
Kazuhiro Tanaka ◽  
Toshio Kobayashi
Keyword(s):  
Pressure Fluctuations ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Simple Method ◽  
Back Flow ◽  
Pump Performance ◽  
Impeller Outlet ◽  
Pump Head ◽  
The Difference ◽  
Set Up

The authors have been investigating the various characteristics of screw-type centrifugal pumps, such as pressure fluctuations in impellers, flow patterns in volute casings, and pump performance in air-water two-phase flow conditions. During these investigations, numerical results of our investigations made it clear that three back flow regions existed in this type of pump. Among these, the back flow from the volute casing toward the impeller outlet was the most influential on the pump performance. Thus the most important factor to achieve higher pump performance was to reduce the influence of this back flow. One simple method was proposed to obtain the restraint of back flow and so as to improve the pump performance. This method was to set up a ringlike wall at the suction cover casing between the impeller outlet and the volute casing. Its effects on the flow pattern and the pump performance have been discussed and clarified to compare the calculated results with experimental results done under two conditions, namely, one with and one without this ring-type wall. The influence of wall’s height on the pump head was investigated by numerical simulations. In addition, the difference due to the wall’s effect was clarified to compare its effects on two kinds of volute casing. From the results obtained it can be said that restraining the back flow of such pumps was very important to achieve higher pump performance. Furthermore, another method was suggested to restrain back flow effectively. This method was to attach a wall at the trailing edge of impeller. This method was very useful for avoiding the congestion of solids because this wall was smaller than that used in the first method. The influence of these factors on the pump performance was also discussed by comparing simulated calculations with actual experiments.

On-demand Electrohydrodynamic Jetting of an Ethylene Glycol and Water Mixture—System of Controlled Picoliter Fluid Deposition

2021 ◽  
Author(s):  
J. F. Dijksman ◽  
U. Stachewicz
Keyword(s):  
Fluid Flow ◽  
Power Amplifier ◽  
Large Diameter ◽  
Electrical Circuit ◽  
Viscous Drag ◽  
Water Mixture ◽  
Electrical Field ◽  
On Demand ◽  
Flat Substrate ◽  
Set Up

On-demand electrohydrodynamic jetting also called electrohydrodynamic atomization (EHDA) is a method to jet small amounts of fluid out of a nozzle with a relatively large diameter by switching on and off an electrical field between the nozzle and the substrate. The total amount of volume deposited is up to 5 pL. The set-up consists of a vertically placed glass pipette with a small nozzle directed downward and a flat substrate placed close to the end of the nozzle. Inside the pipette, an electrode is mounted close to the entrance of the nozzle. The electrode is connected to a high voltage power amplifier. Upon switching on the electrical field, the apparent surface tension drops, the meniscus deforms into a cone and fluid starts to flow toward the nozzle deforming the meniscus. At a certain moment the cone reaches the Taylor cone dimensions and from its tip a jet emerges that decomposes into a stream of charged fL droplets that fly toward the substrate. This process stops when the pulse is switched off. After switching off, the meniscus returns slowly to its equilibrium position. The process is controlled by different time constants, such as the slew rate of the power amplifier and the RC time of the electrical circuit composed of the electrical resistance in the fluid contained in the nozzle between the electrode and the meniscus, and the capacitance of the gap between the meniscus and the flat substrate. Another time constant deals with the fluid flow during the growth of the meniscus, directly after switching on the pulse. This fluid flow is driven by hydrostatic pressure and opposed by a viscous drag in the nozzle. The final fluid flow during droplet formation is governed by the balance between the drag of the charge carriers inside the fluid, caused by the current associated with the charged droplets leaving the meniscus and the viscous drag. These different phenomena will be discussed theoretically and compared to experimental results.

scholarly journals Two Phase Separation using Liquid Level Control System using PLC and SCADA

2019 ◽  
Vol 9 (2) ◽  
pp. 2389-2391
Keyword(s):  
Supervisory Control ◽  
Programmable Logic ◽  
Level Control ◽  
Fluid Level ◽  
Two Phase ◽  
Two Fluids ◽  
Control Framework ◽  
Set Up ◽  
The Individual ◽  
Fluid Levels

Activity of the plant requires a great deal of work and human asset and requires a ton of diligent work and persistence as the individual needs to take note of every single an incentive at various occasions by taking readings physically. With the advancement of Industrial Automation, fluid level control framework has been generally utilized in different fields. In this paper, in light of PLC a control framework is set up by PID calculation and this control framework can alter two diverse fluid levels consequently. On the off chance that there are two distinct kinds of fluids with various densities in an equivalent tank and so as to isolate those two fluids, Level control framework dependent on SCADA and PLC is actualized. This framework satisfies splendidly the need of various fluid level control framework in industry, and it brings advantageous and exact for controlling. The proposed framework gives the fluid Level control, with the assistance of Programmable Logic Controllesr (PLCs), and Supervisory Control and Data Acquisition (SCADA).

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