Development of New Groove Design for Reduction of Drag Torque or Spin Loss of Disengaged Wet Clutches in the High Speed Region

2018 ◽  
Author(s):  
Shahjada A. Pahlovy ◽  
Syeda Mahmud ◽  
Makoto Ogawa
Keyword(s):  
High Speed ◽  
Drag Torque ◽  
Groove Design

Evaluation of Windage Losses for High-Speed Disc Machinery

1992 ◽  
Vol 206 (3) ◽  
pp. 149-157 ◽  
Author(s):  
M R Etemad ◽  
K Pullen ◽  
C B Besant ◽  
N Baines
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Air Gap ◽  
Drag Torque ◽  
Torque Measurement ◽  
Air Mass ◽  
Temperature Changes ◽  
Insignificant Effect ◽  
Air Jets ◽  
Experimental Apparatus

Design and development of experimental apparatus is detailed for stator drag torque measurement as well as a method to evaluate rotor windage losses directly from air mass flow and temperature changes. Effects of air jets at the rotor rim were also investigated. Results are presented for air windage losses associated with ultra-high-speed machinery. These show that within the range investigated the air gap length between the rotor and the stator has an insignificant effect on windage losses. The lowest windage losses were encountered when air was forced through the rotor/stator gap from the direction of rim to bore.

The aerodynamic resistance to a sphere rotating at high speed

1963 ◽  
Vol 271 (1345) ◽  
pp. 143-153 ◽  
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Aerodynamic Resistance ◽  
Point Of View ◽  
Magnetic Suspension ◽  
Gas Flows ◽  
Drag Torque ◽  
Rotating Sphere ◽  
Theoretical Predictions

An attempt has been made to adapt the technique of magnetic suspension of steel rotors to the study of high-speed aerodynamic problems. Surface speeds up to ca. 800 m/s are possible. The advantages and shortcomings of the technique from the aerodynamic point of view are discussed together with the different regimes of flow at present attainable with the apparatus. The particular case of a rotating sphere in the boundary-layer regime is considered and some results obtained with this technique are presented. Observations with smoke and with schlieren photographs show that the gas flows from the poles to the equator where it is thrown off as a narrow plane radial jet. These results are in accord with Howarth’s theoretical predictions. The measured drag torque on the sphere is however somewhat higher than the predicted value and possible reasons for this are considered. The work is now being extended to other regimes of flow.

scholarly journals Performance Analysis of High-Speed Deep/Shallow Recessed Hybrid Bearing

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Lei Wang ◽  
Shuyun Jiang
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Load Capacity ◽  
Width Ratio ◽  
Drag Torque ◽  
Inertia Effects ◽  
Half Angle ◽  
Bearing Design ◽  
Hybrid Bearing

The present paper proposes a theoretical analysis of the performance of deep/shallow recessed hybrid bearing. It is intended that, on the basis of the numerical results drawn from this study, appropriate shallow recess depth and width can be determined for use in the bearing design process. By adopting bulk flow theory, the turbulent Reynolds equation and energy equation are modified and solved numerically including concentrated inertia effects at the recess edge with different depth and width of shallow recess. The results indicate that the load capacity, drag torque increases as the depth of shallow recess is shallower and the width ratio (half angle of deep recess versus half angle of shallow recess) is smaller. In contrast, the flow rate decreases as the depth of shallow recess is shallower and the width ratio is smaller. Nevertheless, the appropriate design of the depth and width of shallow recess might well induce the performance of high-speed deep/shallow recessed hybrid bearing.

Development of an Analytical Model for Prediction of Drag Torque Characteristics of Disengaged Wet Clutches in High Speed Region

2017 ◽  
Author(s):  
Shahjada A. Pahlovy ◽  
Syeda Mahmud ◽  
Masamitsu KUBOTA ◽  
Makoto Ogawa ◽  
Norio Takakura
Keyword(s):  
Analytical Model ◽  
High Speed ◽  
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.

Experimental Investigation on Unstable Vibration Characteristics of Plates and Drag Torque in Open Multiplate Wet Clutch at High Circumferential Speed

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Shiyang Hou ◽  
Jibin Hu ◽  
Zengxiong Peng
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Characteristic Curve ◽  
Dominant Frequency ◽  
Drag Torque ◽  
Viscous Shear ◽  
Clearance Flow ◽  
Friction Plate ◽  
Unstable Vibration ◽  
Torque Values

The drag torque caused by the viscous shear in open multiplate wet clutches has been studied in most available literature whose focus is placed on low circumferential speed. However, the drag torque increases drastically in the high circumferential speed range. The underlying physical principles and the influencing factors of the drag torque at high speed are still indeterminate. The present study aims to experimentally investigate the characteristics of the wobbling vibrations of plates and to characterize the effects of average clearance, flow rate of lubricant, shifting condition, and the number of friction interfaces on the drag torque at high circumferential speed. The result of the experiment reveals that the friction plate (FP) starts to wobble periodically at low circumferential speed, though the effect is insignificant. The dominant frequency of plate wobbling movements increases with the input speed. When wobbling vibrations of plates become unstable, the wobble gradually becomes nonlinear. The experiments confirm that the mechanical contacts between plates during the unstable wobbling vibration result in the drag torque rise at high circumferential speed. At high speed, the supplying flow rate of the lubricant influences the drag torque values. The rotation of separator plates (SPs) brings forward the torque rise and makes the drag torque rise smoother. By reducing the number of interfaces, the drag torque rise is delayed and the magnitude becomes smaller. Finally, a four-stage drag torque characteristic curve is illustrated to show the dominant factors of drag torque at different stages.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

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