The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Yong-sik Song - One of the best experts on this subject based on the ideXlab platform.
-
A Study on the Various Characteristics of Ultrasonic-Energy-Added W/O Type Emulsified Fuel ( I ) - attaching importance to stability and spray characteristics -
2004Co-Authors: Yong-sik SongAbstract:This study is concerned about the characteristics of ultrasonic-energy-added W/O type emulsified fuel. The distilled water was mixed with diesel oil by using ultrasonic energy fuel feeding system and then the SMD of sprayed droplets was measured to find out atomization characteristics of emulsified fuel by using the Malvern 2600 system. The capacitance value was measured to verify stability of the same specimen by using the digital LCR meter, EDC1630 additionally. The main results are as follows; 1) The more measuring distance increases between one hole Nozzle Tip and analyser bearm, the more SMD increases. 2) The more water content increases, the more capacitance value increases depending on the time. Main Parameters of the study are the amount of water content by 5% in emulsified fuel, and the measurement distance, by 10mm or 20mm between Nozzle Tip and analyser beam.
-
A Study on the Various Characteristics of Ultrasonic-Energy-Added W/O Type Emulsified Fuel ( I ) - attaching importance to stability and spray characteristics -
2004Co-Authors: Yong-sik SongAbstract:This study is concerned about the characteristics of ultrasonic-energy-added W/O type emulsified fuel. The distilled water was mixed with diesel oil by using ultrasonic energy fuel feeding system and then the SMD of sprayed droplets was measured to find out atomization characteristics of emulsified fuel by using the Malvern 2600 system. The capacitance value was measured to verify stability of the same specimen by using the digital LCR meter, EDC1630 additionally. The main results are as follows; 1) The more measuring distance increases between one hole Nozzle Tip and analyser bearm, the more SMD increases. 2) The more water content increases, the more capacitance value increases depending on the time. Main Parameters of the study are the amount of water content by 5% in emulsified fuel, and the measurement distance, by 10mm or 20mm between Nozzle Tip and analyser beam.
J. Duan - One of the best experts on this subject based on the ideXlab platform.
-
Design and characteristic analysis of supersonic Nozzles for high gas pressure laser cutting
Journal of Materials Processing Technology, 1999Co-Authors: J. DuanAbstract:Abstract A new method for the design of a supersonic Nozzle Tip for high gas pressure laser cutting is presented. The design is based on the theory of gas dynamics in that the potential energy of high stagnation pressure is converted totally into effective velocity energy so that a high momentum of the exit jet can be obtained for improving the capability of removing molten debris quickly and minimizing the heat-affected zone of the cut edges. Another purpose is to increase the cutting speed and minimize gas consumption under high pressure cutting conditions. The behavior of the exit jet under the condition of stagnation gas pressure ranging from 4 – 16 bar are investigated by means of a computer simulation test. The results of theoretical analysis and of the simulation test show that for a supersonic jet, each sectional diameter and curve contour of the supersonic Nozzle must be designed strictly according to the theory of gas dynamics. An exit jet with high momentum, good uniform and a tidy boundary can be obtained and the tolerance of the working distance between the Nozzle Tip and the workpiece can be incresed.
-
Analysis of the dynamic characteristics of gas flow inside a laser cut kerf under high cut-assist gas pressure
Journal of Physics D, 1999Co-Authors: J. DuanAbstract:The behaviour of the cut-assist gas jet inside a simulating laser cut kerf for a supersonic and a conical Nozzle Tip were studied by a shadowgraphic technique under conditions of inlet stagnation pressure from 3 to 7 bar. The effects of the stand-off distance, kerf width, material thickness and the inlet stagnation pressure upon the dynamic characteristics and momentum thrust of the gas flow inside the cut kerf were investigated. It was found that under a gas pressure of 7 bar, the gas jet from a conical Nozzle Tip expands radially and the jet momentum deteriorates rapidly inside the kerf. The behaviour of the jet is strongly influenced by the stand-off distance and thickness of the workpiece. On the other hand, the gas jet from a supersonic Nozzle inside the cut kerf has tidy boundary and uniform distribution of pressure and thrust. The sensitivity to the stand-off distance and the workpiece thickness of the supersonic Nozzle are much less as compared with the conical Nozzle. With the supersonic Nozzle, a dross free clean cut on 5 mm stainless steel can be achieved at an inert cut-assist gas pressure as low as 5 bar instead of the normal operating range of 10 bar or above for the conical Nozzle.
-
Design of supersonic Nozzle for laser cutting with high pressure gas
International Congress on Applications of Lasers & Electro-Optics, 1997Co-Authors: J. Duan, P. DongAbstract:This paper presents the theoretical results of our investigation on the design of a supersonic Nozzle Tip for high pressure gas laser cutting. The design is based on the theories of gas dynamics and the aim is to convert the potential energy of high stagnation gas pressure into effective kinetic energy such that a high momentum gas jet with uniform and tidy boundary could be obtained. The designed supersonic Nozzle consisted of four sections: stable, convergent, throat and divergent. Each of these sections are designed strictly based on gas dynamic theories. The behavior of the exit jet and the distance of normal shock under condition of stagnation gas pressure ranging from 4 to 16 bar were investigated by computer simulation. The behavior of the exit jet in boundaryless condition as well as in slots of controlled dimensions were observed by Shadowgraphy. The slots that simulate laser cut kerf in practice were created by assembling two sheets of clear perspex with controlled gap width in between. Compared with the commonly used subsonic and transonic Nozzle Tips, this design of supersonic Nozzle Tip for high pressure gas laser cutting can reduce the gas consumption rate and improve the working distance tolerance.This paper presents the theoretical results of our investigation on the design of a supersonic Nozzle Tip for high pressure gas laser cutting. The design is based on the theories of gas dynamics and the aim is to convert the potential energy of high stagnation gas pressure into effective kinetic energy such that a high momentum gas jet with uniform and tidy boundary could be obtained. The designed supersonic Nozzle consisted of four sections: stable, convergent, throat and divergent. Each of these sections are designed strictly based on gas dynamic theories. The behavior of the exit jet and the distance of normal shock under condition of stagnation gas pressure ranging from 4 to 16 bar were investigated by computer simulation. The behavior of the exit jet in boundaryless condition as well as in slots of controlled dimensions were observed by Shadowgraphy. The slots that simulate laser cut kerf in practice were created by assembling two sheets of clear perspex with controlled gap width in between. Compared...
-
Design of supersonic Nozzle for laser cutting with high pressure gas
International Congress on Applications of Lasers & Electro-Optics, 1997Co-Authors: J. Duan, P. DongAbstract:This paper presents the theoretical results of our investigation on the design of a supersonic Nozzle Tip for high pressure gas laser cutting. The design is based on the theories of gas dynamics and the aim is to convert the potential energy of high stagnation gas pressure into effective kinetic energy such that a high momentum gas jet with uniform and tidy boundary could be obtained. The designed supersonic Nozzle consisted of four sections: stable, convergent, throat and divergent. Each of these sections are designed strictly based on gas dynamic theories. The behavior of the exit jet and the distance of normal shock under condition of stagnation gas pressure ranging from 4 to 16 bar were investigated by computer simulation. The behavior of the exit jet in boundaryless condition as well as in slots of controlled dimensions were observed by Shadowgraphy. The slots that simulate laser cut kerf in practice were created by assembling two sheets of clear perspex with controlled gap width in between. Compared with the commonly used subsonic and transonic Nozzle Tips, this design of supersonic Nozzle Tip for high pressure gas laser cutting can reduce the gas consumption rate and improve the working distance tolerance.This paper presents the theoretical results of our investigation on the design of a supersonic Nozzle Tip for high pressure gas laser cutting. The design is based on the theories of gas dynamics and the aim is to convert the potential energy of high stagnation gas pressure into effective kinetic energy such that a high momentum gas jet with uniform and tidy boundary could be obtained. The designed supersonic Nozzle consisted of four sections: stable, convergent, throat and divergent. Each of these sections are designed strictly based on gas dynamic theories. The behavior of the exit jet and the distance of normal shock under condition of stagnation gas pressure ranging from 4 to 16 bar were investigated by computer simulation. The behavior of the exit jet in boundaryless condition as well as in slots of controlled dimensions were observed by Shadowgraphy. The slots that simulate laser cut kerf in practice were created by assembling two sheets of clear perspex with controlled gap width in between. Compared...
-
Behaviour of supersonic and subsonic gas jets inside laser cut kerfs
International Congress on Applications of Lasers & Electro-Optics, 1997Co-Authors: J. DuanAbstract:A supersonic Nozzle Tip for high pressure gas assist laser cutting was designed based on the gas dynamic theories and the characteristics of its exit jet at free space were reported in last year’ s conference. More investigations have been carried out since. The effect of stand-off upon the jet momentum was studied using shadowgraphic technique. The behaviour of the gas jet inside the cut slot at different stand-off distance and inlet pressure were investigated. Cutting experiments were carried out using a 3.5 kw CO2 laser.A supersonic Nozzle Tip for high pressure gas assist laser cutting was designed based on the gas dynamic theories and the characteristics of its exit jet at free space were reported in last year’ s conference. More investigations have been carried out since. The effect of stand-off upon the jet momentum was studied using shadowgraphic technique. The behaviour of the gas jet inside the cut slot at different stand-off distance and inlet pressure were investigated. Cutting experiments were carried out using a 3.5 kw CO2 laser.
Jaekeun Yu - One of the best experts on this subject based on the ideXlab platform.
-
infleunce of Nozzle Tip size on the preparation of nano sized tin oxide powder by spray pyrolysis process
Korean Journal of Materials Research, 2013Co-Authors: Jaekeun YuAbstract:In this study, using a tin chloride solution as the raw material, a nano-sized tin oxide powder with an average particle size below 50 nm is generated by a spray pyrolysis process. The properties of the tin oxide powder according to the Nozzle Tip size are examined. Along with an increase in the Nozzle Tip size from 1 mm to 5 mm, the generated particles that appear in the shape of droplets maintain an average particle size of 30 nm. When the Nozzle Tip size increases from 1 mm to 2 mm, the average size of the generated particles is around 80-100 nm, and the ratio of the independent particles with a compact surface structure increases significantly. When the Nozzle Tip size is at 3 mm, the majority of the generated particles maintain the droplet shape, the average size of the droplet-shaped particles increases remarkably compared to the cases of other Nozzle Tip sizes, and the particle size distribution also becomes extremely irregular. When the Nozzle Tip size is at 5 mm, the ratio of droplet-shaped particles decreases significantly and most of the generated particles are independent ones with incompact surface structures. Along with an increase in the Nozzle Tip size from 1 mm to 3 mm, the XRD peak intensity increases, whereas the specific surface area decreases greatly. When the Nozzle Tip size increases up to 5 mm, the XRD peak intensity decreases significantly, while the specific surface area increases remarkably.
-
The effects of reaction factors on the fabrication of nano-sized indium tin oxide powder by spray pyrolysis process.
Journal of Nanoscience and Nanotechnology, 2012Co-Authors: Jaekeun YuAbstract:: In this study, waste ITO target is dissolved into hydrochloric acid to generate a complex acid solution. Nano-sized ITO powder with the average particle size below 50 nm is generated from this complex solution by spray pyrolysis process. This study also examines the influences of reaction parameters such as Nozzle Tip size and air pressure on the properties of the generated ITO powder. When the Nozzle Tip size is at 1 mm, the particle size distribution becomes more uniform in contrast to the case of other Tip sizes, and the average particle size is around 50 nm. When the Nozzle Tip size increases up to 5 mm, the average particle size increases slightly, yet the particle size distribution becomes extremely irregular. Along with the change of Nozzle Tip size, the changing tendencies of XRD peak intensity and specific surface area are almost consistent with that of average particle size. Along with the increase of air pressure, the average particle size of the ITO powder gradually decreases, and the particle size distribution becomes more uniform. When the air pressure is at 0.1 kg/cm2, the particle size distribution appears extremely irregular, yet the average particle size is around 70 nm. When the air pressure is at 3 kg/cm2, the average particle size decreases down to 40 nm. Along with the increase of air pressure, the XRD peak intensity gradually decreases and the specific surface area increases.
-
Preparation of Nano-Sized Tin Oxide Powder by Spray Pyrolysis Process
Journal of the Korean Institute of Resources Recycling, 2008Co-Authors: Jaekeun Yu, Cha Kwang Yong, Kim Myung-choun, Jaebum Jang, Lee Yung-hwaAbstract:In this study, nano-sized indium oxide powder with the average particle size below 100 nm is prepared from the indium chloride solution by the spray pyrolysis process. The effects of the concentration of raw material solution, the Nozzle Tip size and the air pressure on the properties of powder were studied. As the indium concentration of the raw material solution increased from 40 g/l to 350 g/l, the average particle size of the powder gradually increased from 20 nm to 60 nm, yet the particle size distribution appeared more irregular, the intensity of a XRD peak increased and specific surface area decreased. As the Nozzle Tip size increased from 1 nm to 5 nm, the average particle size of the powder increased from 40 nm to 100 nm, the particle size distribution was much more irregular, the intensity of a XRD peak increased and specific surface area decreased. As the air pressure increased from 0.1 kg/cm to 0.5 kg/cm, the average particle size of the powder varies slightly upto 90~100 nm. As the air pressure increased from 1 kg/cm to 3 kg/cm, the average particle size decreased upto 50~60 nm, the intensity of a XRD peak decreased and the specific surface area increased.
Chen S. Tsai - One of the best experts on this subject based on the ideXlab platform.
-
Characterization of 0.5 MHz Silicon-Based Ultrasonic Nozzles Using MulTiple Fourier Horns
MRS Proceedings, 2011Co-Authors: Shirley C. Tsai, Yu L. Song, Yuan F. Chou, Terry K. Tseng, J. W. Chen, W J Chen, J. H. Yang, Chen S. TsaiAbstract:ABSTARCTThis paper presents the experimental results of impedance analysis and longitudinal vibration measurement of micro-fabricated 0.5 MHz silicon-based ultrasonic Nozzles. Each Nozzle is made of a piezoelectric drive section and a silicon-resonator consisting of mulTiple Fourier horns each with half wavelength design and twice amplitude magnification. The experimental results verified the simulation prediction of one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude gain at the Nozzle Tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical value of 2n. Using this design, very high vibration amplitude at the Nozzle Tip can be achieved with no reduction in the Tip cross sectional area. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.
-
Silicon-based megahertz ultrasonic Nozzles for production of monodisperse micrometer-sized droplets
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2009Co-Authors: Shirley C. Tsai, Chih H. Cheng, Yu L. Song, Ning Wang, Chen S. TsaiAbstract:Monodisperse ethanol droplets 2.4 mum and water droplets 4.5 mum in diameter have been produced in ultrasonic atomization using 1.5- and 1.0-MHz microelectromechanical system (MEMS)-based silicon Nozzles, respectively. The 1.5- and 1.0-MHz Nozzles, each consisting of 3 Fourier horns in resonance, measured 1.20 cm times 0.15 cm times .11 cm and 1.79 cm times 0.21 cm times 0.11 cm, respectively, required electrical drive power as low as 0.25 W and could accommodate flow rates as high as 350 mul/min. As the liquid issues from the Nozzle Tip that vibrates longitudinally at the Nozzle resonance frequency, a liquid film is maintained on the end face of the Nozzle Tip and standing capillary waves are formed on the free surface of the liquid film when the Tip vibration amplitude exceeds a critical value due to Faraday instability. Temporal instability of the standing capillary waves, treated in terms of the unstable solutions (namely, time-dependant function with a positive Floquet exponent) to the corresponding Mathieu differential equation, is shown to be the underlying mechanism for atomization and production of such monodisperse droplets. The experimental results of Nozzle resonance and atomization frequencies, droplet diameter, and critical vibration amplitude are all in excellent agreement with the predictions of the 3-D finite element simulation and the theory of Faraday instability responsible for atomization.
-
High-frequency, silicon-based ultrasonic Nozzles using mulTiple Fourier horns
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2004Co-Authors: S.-c. Tsai, Yuan F. Chou, Terry K. Tseng, Y.l. Song, B J Chen, Chen S. TsaiAbstract:This paper presents the design, simulation, and characterization of microfabricated 0.5 MHz, silicon-based, ultrasonic Nozzles. Each Nozzle is made of a piezoelectric drive section and a silicon resonator consisting of mulTiple Fourier horns, each with half wavelength design and twice amplitude magnification. Results of finite element three-dimensional (3-D) simulation using a commercial program predicted existence of one resonant frequency of pure longitudinal vibration. Both impedance analysis and measurement of longitudinal vibration confirmed the simulation results with one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude sit the Nozzle Tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical values of 2/sup n/. Using this design, very high vibration amplitude gain at the Nozzle Tip can be achieved with no reduction in the Tip cross-sectional area for contact of liquid to be atomized. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.
-
Simulation and characterization of silicon-based 0.5 MHz ultrasonic Nozzles
Proceedings of SPIE, 2004Co-Authors: Y.l. Song, Shirley C. Tsai, Yuan F. Chou, Terry K. Tseng, W J Chen, Chen S. TsaiAbstract:This paper compares the simulation results with the experimental results of impedance analysis and longitudinal vibration measurement of micro-fabricated 0.5 MHz silicon-based ultrasonic Nozzles. Impedance analysis serves as a good diagnostic tool for evaluation of longitudinal vibration of the Nozzles. Each Nozzle is made of a piezoelectric drive section and a silicon-resonator consisting of mulTiple Fourier horns each with half wavelength design and twice amplitude magnification. The experimental results verified the simulation prediction of one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude gain at the Nozzle Tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical value of 2 n . Using this design, very high vibration amplitude at the Nozzle Tip can be achieved with no reduction in the Tip cross sectional area. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.
-
Flow visualization of Taylor-mode breakup of a viscous liquid jet
Physics of Fluids, 1999Co-Authors: Shirley C. Tsai, G. Roski, Chen S. TsaiAbstract:We recently reported a new spray technique called ultrasound-modulated two-fluid (UMTF) atomization and the pertinent “resonant liquid capillary wave (RLCW) theory” based on linear models of Taylor-mode breakup of capillary waves. In this article, flow visualizations of liquid jets near the Nozzle Tip are presented to verify the central assumption of the RLCW theory that the resonant liquid capillary wave in UMTF atomization is initiated by the ultrasound at the Nozzle Tip. Specifically, a bright band beneath the Nozzle Tip was seen in ultrasonic and UMTF atomization separately, but not in two-fluid atomization. The bright band can be attributed to scattering of laser light sheet by the capillary waves generated by the ultrasound on the intact liquid jet. As the capillary wave travels downstream in the direction of airflow, it is amplified by the air blowing around it and eventually collapsed into drops. Therefore, the jet breakup time can be determined by dividing the measured band length with the capill...
István Sztachó-pekáry - One of the best experts on this subject based on the ideXlab platform.
-
Influence of Fan Nozzle Tip Orifice Wear on Spray Pattern
Progress in Agricultural Engineering Sciences, 2006Co-Authors: István Sztachó-pekáryAbstract:The effects of orifice wear on the spray patterns and orifice dimensions of fan Nozzles made of different materials, types and capacities were investigated. A wear stand and a patternator system were developed to rapidly evaluate artificial wear effect and the spray deposit distribution, respectively. Theoretical analysis showed, that the percentage increase of orifice area is identical to the percentage increase of minor axis of Tip orifice. Results indicated that there were some differences between spray deposit distributions of new and worn fan Nozzles. The width of the spray pattern remained nearly constant but worn Nozzles delivered larger volumes of liquid in the center of the spray boom.
