scholarly journals Influence of Unbalanced Electromagnetic Force and Air Supply Pressure Fluctuation in Air Bearing Spindles on Machining Surface Topography

2020 ◽  
Vol 22 (1) ◽  
pp. 1-12
Author(s):  
Yazhou Sun ◽  
Quanhui Wu ◽  
Wanqun Chen ◽  
Xichun Luo ◽  
Guoda Chen
Keyword(s):  
Surface Topography ◽  
Pressure Fluctuation ◽  
Electromagnetic Force ◽  
Air Bearing ◽  
Supply Pressure ◽  
Air Supply

Air bearings in high precision systems

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
I. Cracaoanu ◽  
F. Bremer
Keyword(s):  
Surface Topography ◽  
High Precision ◽  
Air Bearing ◽  
Test Results ◽  
Air Bearings ◽  
Bearing Surface ◽  
Operational Parameters ◽  
Low Friction ◽  
Air Supply ◽  
Precision System

In high precision system applications low friction levels between components are desirable. Moving heavy parts at high speeds and accelerations without friction is possible by using air bearings. The main failure ofthe air bearings is the wear phenomenon (modification of surface topography) that occurs due to crash into the counterpart when air supply is interrupted. The aim of this research is to investigate different types of air bearings for a large number of crashes using real operational parameters from the field: speed, acceleration, load and supply air pressure. The real crash phenomenon in a high precision machine hasbeen replicated using a test setup. During testing, evolution of air bearing surface topography and air bearing characteristics (gap and flow) after different number of crashes are investigated. Test results showthat some air bearings are not reaching the specified number of crashes due to large defects that occur on the bearing surface. Some specific relations were found between crash defects and parameters such asthe air gap size and the direct contact between opposing surfaces. The preferred type of air bearings shows good performance even above the maximum specified number of crashes. This behavior can be explainedby low friction level during crash tests between the opposing surfaces. The test results from this investigation produced a reliable candidate for air bearings in the high precision system application.

Flow Characteristics of Fluid Droplet Obtained From Air Assisted Atomizer

2011 ◽  
Author(s):  
Pipatpong Watanawanyoo ◽  
Hirofumi Mochida ◽  
Hiroyuki Hirahara ◽  
Sumpun Chaitep
Keyword(s):  
Mass Flow ◽  
Cone Angle ◽  
Flow Ratio ◽  
Test Liquid ◽  
Solid Cone ◽  
Spray Cone ◽  
Supply Pressure ◽  
Liquid Mass ◽  
Air Supply ◽  
Mass Flow Ratio

Air assisted atomizer system was designed and developed for fuel injection. The present purpose is to utilize a low pressure in supplying of atomized fuel. Distilled water was used as test liquid on the experiments for the system of atomization. The results revealed air assisted atomizer had a capability to inject the test liquid in the range of the rates of 0.0019–0.00426 kg/s, with the use of air pressure supplied from 68.9 to 689 kPa. In this research, the test liquid supply pressure was kept constant and the air flow rate through the atomizer was varied over a range of air supply pressure to obtain the variation in air liquid mass flow ratio (ALR). The spray solidity was studied by taking pictures of the spray at different liquid air supply pressures. The experimental investigations suggest that spray cone angle tends to increase with increasing in air liquid mass flow ratio because the kinetic energy of the flow keeps on increasing. The solid cone spray has a pattern of penetration depth between 408–446 mm. and cone angle between 14.5–23.6°. It was observed that spray formed the solid cone at all the operating conditions.

scholarly journals Improved Atomization via a Mechanical Atomizer with Optimal Geometric Parameters and an Air-Assisted Component

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 584
Author(s):  
Inna Levitsky ◽  
Dorith Tavor
Keyword(s):  
Liquid Fuel ◽  
High Efficiency ◽  
Geometric Parameters ◽  
Supply Pressure ◽  
Swirl Chamber ◽  
Air Supply ◽  
Wide Range ◽  
Liquid Atomization ◽  
Atomization Characteristics ◽  
Geometrical Dimensions

Atomization of liquid media is a key aim in various technological disciplines, and solutions that improve spray performance, while decreasing energy consumption, are in great demand. That concept is very important in the development of liquid fuel spray atomizers in high-efficiency microturbines and other generator systems with low inlet pressure and a wide range of power supply. Here we present a study of the liquid atomization characteristics for a new mechanical atomizer that has optimal geometric parameters and a preliminary swirl stage. In our air-assisted atomizer, air is introduced through a swirl chamber positioned at the exit of the mechanical atomizer. The optimized mechanical atomizer alone can achieve D32 drop diameters in the range of 80 to 40 µm at water supply pressures of 2 to 5 bar, respectively. The addition of an air swirl chamber substantially decreases drop sizes. At an air–liquid ratio (ALR) equal to 1, water pressures of 2.5 to 3 bar and air supply pressures 0.35 to 1 bar, D32 drops with diameters of 20–30 µm were obtained. In an air-assisted atomizer the parameters of the mechanical atomizer have a much stronger influence on drop diameters than do characteristics of the air-swirl chamber. Using a mechanical atomizer with optimal geometrical dimensions allows limiting the liquid supply pressure to 5 bar; but when an air-assisted component is introduced we can recommend an ALR ≈ 1 and an air supply pressure of up to 1 bar.

Characteristics Analysis of Pneumatic Booster Valve With Energy Recovery

2016 ◽  
Author(s):  
Fan Yang ◽  
Kotaro Tadano ◽  
Gangyan Li ◽  
Toshiharu Kagawa
Keyword(s):  
Energy Efficiency ◽  
Energy Saving ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Energy Recovery ◽  
High Energy ◽  
State Equation ◽  
Conservation Equation ◽  
Local Pressure ◽  
Supply Pressure

Pneumatic booster valve is widely used in local pressure boost circuit for energy saving, a new booster valve with energy recovery (short for BVER) was proposed in this paper in order to further improve the energy efficiency. Firstly, the principle of BVER was introduced by comparing with the traditional booster. Based on flow-rate characteristics equation, gas state equation, energy conservation equation, etc., the mathematics model of BVER was established, and the flow-rate characteristics, boost ratio, pressure in tank and energy efficiency were systematically analyzed by simulation. Lastly, the model was verified by experiments. This study shows that: firstly, the pressure decreased sharply with the flow-rate’s increasing, and the pressure in tank is much lower than in BVER. Secondly, the boost ratio was affected by supply pressure, regulator coefficient and the diameter of recovery chamber. Thirdly, the pressure fluctuation in tank decreases with the tank volume increasing, and the pressure fluctuation is less than 1% when tank volume is larger than 10L. Lastly, the energy efficiency will increase 5∼10 percent with the boost ratio increases 15∼25 percent under different supply pressure. This study proves that BVER has better performance than VBA for its high boost ratio and high energy efficiency, and it provides a reference for booster valve’s design and energy saving.

Performance of Externally Pressurized Dry Gas Seal

2011 ◽  
Vol 335-336 ◽  
pp. 610-614 ◽  
Author(s):  
Wei Bing Zhu ◽  
Sheng Ren Zhou ◽  
He Shun Wang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Reynolds Equation ◽  
Dry Gas Seal ◽  
Supply Pressure ◽  
Lubrication Equation ◽  
Air Supply ◽  
Computer Numerical Simulation ◽  
Film Stiffness

By adding the flow rate of throttle orifice to conventional stable externally pressurized gas lubrication equation, the Reynolds equation for externally pressurized dry gas seal with orifice compensation is established. The solution of the equation is studied by functional extremum algorithm and finite element method, and the computer numerical simulation is carried out in Matlab software. The effects of air supply pressure, numbers and diameter of throttle orifice, on face opening force and gas film stiffness are discussed in detail.

An Externally Pressurized Air Bearing System, Journals and Thrust, for Application to Small Turbomachinery

1992 ◽  
Author(s):  
A. B. Turner ◽  
S. J. Davies ◽  
Y. L. Nimir ◽  
J. D. Richardson
Keyword(s):  
High Speed ◽  
Dynamic Test ◽  
Maximum Temperature ◽  
Air Bearing ◽  
Axial Thrust ◽  
Turbine Wheel ◽  
Air Supply ◽  
Gauge Pressure ◽  
Compressor Impeller ◽  
Bearing System

An aerostatic (externally pressurized) air bearing system for application to small high speed, low temperature turbomachinery has been designed and successfully tested at over 100,000 rpm using an air supply at a gauge pressure of 3.4 bar (50 psig). The test rig used a Holset turbocharger centrifugal compressor impeller and radial turbine wheel mounted at either end of a 150 mm long 40 mm diameter shaft with two 23 mm long inboard journal bearings mounted on either side of an integral 100 mm diameter tapered thrust collar. The turbine was driven by an independent air supply with a maximum temperature of 200°C, and the unit was operated with the shaft vertical. A static axial thrust capability of over 1000 N (225 lbf) has been demonstrated using a novel plenum chamber arrangement to overcome pneumatic instability (air hammer) problems. The paper presents details of the design, some static rig tests and the dynamic test conditions and results.

Influences of Surface Topography on the Flying Performances of a Sub-3 nm Air Bearing Slider

2010 ◽  
Vol 49 (12) ◽  
pp. 125202 ◽  
Author(s):  
Wei Hua ◽  
Bo Liu ◽  
Shengkai Yu ◽  
Weidong Zhu
Keyword(s):  
Surface Topography ◽  
Air Bearing ◽  
Air Bearing Slider

Measurements of Static and Dynamic Load Performance of a 102 mm Carbon-Graphite Porous Surface Tilting-Pad Gas Journal Bearing

2021 ◽  
Author(s):  
Luis San Andrés ◽  
Rachel Bolen ◽  
Jing Yang ◽  
Ryan McGowan
Keyword(s):  
Dynamic Load ◽  
Load Capacity ◽  
Stable Operation ◽  
Specific Load ◽  
Force Coefficients ◽  
Supply Pressure ◽  
Air Supply ◽  
Tilting Pad ◽  
Frequency Independent ◽  
Gas Bearing

Abstract Aerostatic journal bearings with porous tilting pads enable shaft support with minute drag power losses. To date archival information on the static and dynamic load performance of this bearing type is scant. Thus, the paper presents measurements conducted with an air lubricated bearing with diameter d = 102 mm and comprising four tilting pads made of porous carbon-graphite, each with length L = 76 mm. Two nested Belleville washers resting on spherical pivots support each pad. At ambient temperature of ∼ 21°C, as the air supply pressure into the bearing pads increases, so does the bearing aerostatic specific load (F/(L·d)) that reaches 58% of the pressure difference, supply minus ambient. With an air supply pressure of 7.8 bar(a), the test bearing static stiffness KS = 13.1 MN/m, is independent of both shaft speed and static load. KS is just 63% of the washers’ stiffness KP = 20.6 MN/m (during loading). While operating with shaft speeds equal to 6 krpm and 9 krpm (150 Hz) and under specific loads to 115 kPa and 101 kPa respectively, dynamic load experiments with excitation frequencies up to 342 Hz show the test bearing supplied with air at 7.8 bar(a) has frequency independent stiffness (K) and damping (C) coefficients. For rotor speeds equaling 0, 6 and 9 krpm, the bearing direct stiffnesses KXX ∼ KYY range from 13.6 MN/m to 32.7 MN/m as the specific load increases from 0 kPa to 115 kPa. The direct damping coefficients CXX ∼ CYY are as large as 5.8 kN·s/m, though having a large experimental uncertainty. Bearing cross-coupled force coefficients are insignificant. The test porous gas bearing reached its intended load capacity, demonstrated a dynamically stable operation and produced force coefficients mainly affected by the pads’ pivot supports and the magnitude of air supply pressurization.

Realization of Tubeless Stage in Semiconductor Exposure System

2008 ◽  
Vol 2 (2) ◽  
pp. 119-123
Author(s):  
Yuichi Shibazaki ◽  
Keyword(s):  
Center Of Gravity ◽  
Light Weight ◽  
Air Bearing ◽  
Direct Drive ◽  
Exposure System ◽  
Air Supply ◽  
Symmetry Structure ◽  
Force Ripple

We realized super fine positioning of the stage which is applied for the step and scan lithography apparatus using the following technologies. - Direct drive concept (not using “fine and coarse” stage configuration) - Newly developed air-bearing without moving tube for air supply. - Simple and light weight configuration - 3DOF (X Y Tz) counter-mass - Compensation of motor force ripple - Symmetry structure and driving at center of gravity

Development of Portable Energy-Saving Type Air Supply System – 1st Report: Effect of Variable Volume Tank –

2012 ◽  
Vol 24 (3) ◽  
pp. 464-471 ◽  
Author(s):  
Tatsuyuki Iwawaki ◽  
◽  
Daisuke Sasaki ◽  
Toshiro Noritsugu ◽  
Masahiro Takaiwa
Keyword(s):  
Energy Saving ◽  
Elastic Energy ◽  
Supply System ◽  
Pneumatic Actuator ◽  
Variable Volume ◽  
Flexible Materials ◽  
Supply Pressure ◽  
System A ◽  
Air Supply ◽  
Discharge Pressure

The purpose of this study is to develop a portable energy-saving type air supply system. A variable volume tank is developed in order to drive a pneumatic actuator with a low discharge pressure in a tank. The developed tank composed of flexible materials can store pneumatic energy by converting it to elastic energy. In this paper, the composition of the system, the structure and characteristic of a variable volume tank and experiment of driving actuator with constant and variable volume tanks are discussed. As a result, the variable volume tank can drive the actuator at a lower supply pressure than with the constant volume tank.

Sign in / Sign up

Export Citation Format

Share Document