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Optimization Study of the Efficient Spindle

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Journal of Thermal Science 2008年第3期17卷 243-246页

作者： Y.d.kim d.h.Chun M.S.Kang h.d.kim Korea Textile Machinery Research Institute School of Textiles Yeungnam University School of Mechanical Engineering Andong National University

In the field of yarn dyeing, the most generally employed method is a type of package dyeing which uses a package of cheese stacked on a spindle made of a perforated tube. Spindles up to now, have been designed without considering the characteristics of dyeing liquid, focusing only on the geometric configuration which cause many problems such as lack of level dyeing. To improve the level dyeing and find the appropriate spindle configuration for the most effective dyeing process, this study examines the spindle flow-field in detail, using a computational method. Flow characteristics inside the spindle have been investigated with varying in porosity, porous diameter and the velocity of the flow. The results show that the total pressure of the flow through the spindle is used to overcome body force. The characteristics of the flow from the porous spindle could also be observed. Based on the results from this study, an effective spindle configuration for level-dyeing has been proposed.

关键词： Porosity Spindle Yarn dyeing Computational Fluid dynamics

Computational Analysis of the Compressible Flow driven by a Piston in a Ballistic Range

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Journal of Thermal Science 2007年第4期16卷 360-369页

作者： G.Rajesh R.Mishra h.G.Kang h.d.kim School of Mechanical Engineering Andong National University388Songcheon-DongAndong-760 749Korea

The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics and aeroballistics, since it can create an extremely high-pressure state in very short time. Since the operation of the ballistic range includes many complicated phenomena, each process should be understood in detail for the performance enhancement of the device. One of the main processes which have significant influence on the device performance is the compression process of the driver gas. Most of the studies available in this field hardly discuss this phenomenon in detail and thus lack a proper understanding of its effect on the whole system performance. In the present study, a computational analysis has been made to investigate the fluid dynamic aspects of the compression process in the pump tube of a ballistic range and to assess how it affects the performance of the ballistic range. The results obtained are validated with the available experimental data. In order to evaluate the system performance, several performance parameters are defined. Effect of a shock tube added in between the pump tube and launch tube on the performance of the ballistic range is also studied analytically. Performance of the ballistic range could be significantly improved by the proper selection of the pump tube and high-pressure tube parameters and the addition of the shock tube.

关键词： Ballistic range compressible flow piston shock tube chimera mesh

Optimization Study of a Coanda Ejector

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Journal of Thermal Science 2006年第4期15卷 331-336页

作者： h.d.kim G.Rajesh T.Setoguchi S.Matsuo School of Mechanical Engineering Andong National University388Songcheon-dongAndongGyeongbuk 760-749Korea department of Mechanical Engineering Saga University1HonjoSaga 840-8502Japan

The Coanda effect has long been employed in the aerospace applications to improve the performances of various devices. This effect is the ability of a flow to follow a curved contour without separation and has well been utilized in ejectors where a high speed jet of fluid emerges from a nozzle in the ejector body, follows a curved surface and drags the secondary flow into the ejector. In Coanda ejectors, the secondary flow is dragged in the ejector due to the primary flow momentum. The transfer of momentum from the primary flow to the secondary flow takes place through turbulent mixing and viscous effects. The secondary flow is then dragged by turbulent shear force of the ejector while being mixed with the primary flow by the persistence of a large turbulent intensity throughout the ejector. The performance of a Coanda ejector is studied mainly based on how well it drags the secondary flow and the amount of mixing between the two flows at the ejector exit. The aim of the present study is to investigate the influence of various geometric parameters and pressure ratios on the Coanda ejector performance. The effect of various factors, such as, the pressure ratio, primary nozzle and ejector configurations on the system performance has been evaluated based on a performance parameter defined elsewhere. The performance of the Coanda ejector strongly depends on the primary nozzle configuration and the pressure ratio. The mixing layer growth plays a major role in optimizing the performance of the Coanda ejector as it decides the ratio of secondary mass flow rate to primary mass flow rate and the mixing length.

关键词： Coanda ejector compressible mixing layer flow dragging mixing length induced flow

A Study on the Gas-Solid Particle Flows in a Needle-Free drug delivery device

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Journal of Thermal Science 2013年第4期22卷 340-344页

作者： Md.Alim Iftekhar Rasel Md.Abu Taher h.d.kim department of Mechanical Engineering Andong National University

different systems have been used over the years to deliver drug particles to the human skin for pharmaceutical effect. Research has been done to improve the performance and flexibility of these systems. In recent years a unique system called the transdermal drug delivery has been developed. Transdermal drug delivery opened a new door in the field of drug delivery as it is more flexible and offers better performance than the conventional systems. The principle of this system is to accelerate drug particles with a high speed gas flow. Among different transdermal drug delivery systems we will concentrate on the contour shock tube system in this paper. A contoured shock tube is consists of a rupture chamber, a shock tube and a supersonic nozzle section. The drug particles are retained between a set of bursting diaphragm. When the diaphragm is ruptured at a certain pressure, a high speed unsteady flow is initiated through the shock tube which accelerates the particles. Computational fluid dynamics is used to simulate and analyze the flow field. The dPM (discrete phase method) is used to model the particle flow. As an unsteady flow is initiated though the shock tube the drag correlation proposed by Igra et al is used other than the standard drag correlation. The particle velocities at different sections including the nozzle exit are investigated under different operating conditions. Static pressure histories in different sections in the shock tube are investigated to analyze the flow field. The important aspects of the gas and particle dynamics in the shock tube are discussed and analyzed in details.

关键词： Shock tube drug delivery Contoured shock tube Unsteady flow Biolistics

A Study of the Weak Shock Wave Propagating over a Porous Wall/Cavity System

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Journal of Thermal Science 2005年第4期14卷 329-333页

作者： h.d.kim S.J.JUNG T.AOKI T.SETOGUChI School of Mechanical Engineering.Andong National University Songchun-dongAndong 760-746Korea department of Energy and Environmental Engineering Kyushu University6-1Kasuga-kouenKasugaFukuoka 816-8580Japan department of Mechanical Engineering Saga University1HonjoSaga 840-8502Japan

The present computational study addresses the attenuation of the shock wave propagating in a duct, using a porous wall/cavity system. In the present study, a weak shock wave propagating over the porous wall/cavity system is investigated with computational fluid dynamics. A total variation diminishing scheme is employed to solve the unsteady, two-dimensional, compressible, Navier-Stokes equations. The Mach number of an initial shock wave is changed in the range from 1.02 to 1.12. Several different types of porous wall/cavity systems are tested to investigate the passive control effects. The results show that wall pressure strongly fluctuates due to diffraction and reflection processes of the shock waves behind the incident shock wave. From the results, it is understood that for effective alleviation of tunnel impulse waves, the length of the perforated region should be sufficiently long.

关键词： compressible flow perforated wall railway tunnel shock wave.

A Study of the Critical Nozzle for Flow Rate Measurement of high-Pressure hydrogen Gas

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Journal of Thermal Science 2007年第1期16卷 28-32页

作者： h.d.kim J.h.Lee K.A.Park T.Setoguchi S.Matsuo School of Mechanical Engineering Andong National University388Songchun-dongAndong 760-749Korea dynamics Group Korea Research Institute of Standards and SciencePO Box 102YusongTaejon 305-606Korea department of Mechanical Enginering.Saga University 1Honjo—machiSaga-shiSaga 840—8502Japan

The mass flow rate measurement using a critical nozzle shows the validity of the inviscid theory, indicating that the discharge coefficient increases and approaches unity as the Reynolds number increases under the ideal gas law however, when the critical nozzle measures the mass flow rate of a real gas such as hydrogen at a pressure of hundreds bar, the discharge coefficient exceeds unity, and the real gas effects should be taken into account. The present study aims at investigating the flow features of the critical nozzle using high-pressured hydrogen gas. The axisymmetric, compressible Navier-Stokes computation is employed to simulate the critical nozzle flow, and a fully implicit finite volume method is used to discretize the governing equation system. The real gas effects are simulated to consider the intermolecular forces, which account for the possibility of liquefying hydrogen gas. The computational results are compared with past experimental data. It has been found that the coefficient of discharge for real gas can be corrected properly below unity adopting the real gas assumption.

关键词： critical nozzle compressible flow hydrogen gas ideal gas law real gas effect

A Parametric Study for high-Efficiency Gas-Liquid Separator design

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Journal of Thermal Science 2008年第3期17卷 238-242页

作者： S.Nagdewe J.K.Kwoon h.d.kim d.S.kim K.M.Kwak Toshiaki Setoguchi School of Mechanical Engineering Andong National University FMTRC Daejoo Co. department of Mechanical Engineering Saga University

A gas liquid centrifugal separator is widely used in industry on account of its simple geometry and little maintenance. These separators have considerable advantages over filters, scrubbers or precipitators in term of compact design, lower pressure drop and higher capacity. A gas liquid centrifugal separator is a device that utilizes centrifugal forces and low pressure caused by rotational motion to separate liquid from gas by density differences. Efficient and reliable separation is required for the optimum operation. These separators are often operated at less than peak efficiency due to the entrainment of separated liquid through an outlet pipe which is closely associated with the very complicated flow phenomena involved. design parameters such as length of the separation space, vane exit angle, inlet to outlet diameter ratio, models for separation efficiency and pressure drop as a function of physical dimensions are not available in literature. This leaves the designer with very little to go on except known designs and experimentation. The aim of present study is to perform a parametric study to get higher efficiency for gas-liquid separator. A parametric study has been carded out with the help of CFd tools to analyze a separation performance of a centrifugal separator by varying the length of separator space. The best design parameters are analyzed based upon obtained results, tangential velocities, vortices, total pressure losses. From the present study several attempts are made to improve the performance of conventional centrifugal separators.

关键词： Centrifugal separator Gas-liquid two-phase flow Swirl vane k-c RNG turbulence model Tangentialvelocity

Internal Flow Simulation of high-Performance Solid Rockets using a k-ω Turbulence Model

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Journal of Thermal Science 2005年第2期14卷 114-119页

作者： V.R.SANAL KUMAR h.d.kim B.N.RAGhUNANdAN T.SETOGUChI S.RAGhUNAThAN Andong National University Andong 760-749 KoreaAndong National University Andong 760-749KoreaIndian Institute of Science Bangalore-560 012IndiaSaga University Honjo-machiSaga 840-8502JapanThe Oueen's University of Belfast Northern IrelandUK

For technological reasons many high-performance solid rocket motors are made from segmented propellant grains with non-uniform port geometry. In this paper parametric studies have been carried out to examine the geometric dependence of transient flow features in solid rockets with non-uniform ports. Numerical computations have been carried out in an inert simulator of solid propellant rocket motor with the aid of a standard k-ω turbulence model. It was seen that the damping of the temperature fluctuation is faster in solid rocket with convergent port than with divergent port geometry. We inferred that the damping of the flow fluctuations using the port geometry is a meaningful objective for the suppression and control of the instability and/or pressure/thrust oscillations during the starting transient of solid rockets.

关键词： solid rockets pressure spike instability thrust oscillation turbulent separation.

Effect of Si Content on Mechanical Properties of a Mo and V Free Low Alloy Cast Steel for Automobile Cold Pressing die

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Journal of Materials Science & Technology 2008年第3期24卷 313-316页

作者： B.h.kim J.S.Shin S.M.Lee B.M.Moon h.d.kim S.Y.Ju O.Y.Choi Advanced Materials R＆d division Korea Institute of Industrial Technology Incheon 406-840 Korea Tooling Center GM Daewoo Auto ＆ Technology Co. Incheon 403-714 Korea

The effects of Si content on combinations of important properties such as hardness, hardenability, and weldability in addition to strength increment were systematically investigated to develop a Mo and V free low alloy cast steel for automobile cold pressing die insert. For the evaluation of the applicability as the die insert, the mechanical properties were measured after spheroidization annealing （SA）, quenching and tempering （Q/T）, and flame hardening （Fh） treatments, respectively. The developed 0.8%-1.6%Si containing Mo and V free alloy cast steels showed excellent matrix strengthening effect, hardenability, and weldability, fulfilling the industrial criterion of the mechanical properties for the die insert.

关键词： Low alloy cast steel Cold pressing die die insert Matrix hardening Flame hardening