Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Transactions of the Korean Society of Mechanical Engineers B
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
Volume & Issues
Volume 35, Issue 12 - Dec 2011
Volume 35, Issue 11 - Nov 2011
Volume 35, Issue 10 - Oct 2011
Volume 35, Issue 9 - Sep 2011
Volume 35, Issue 8 - Aug 2011
Volume 35, Issue 7 - Jul 2011
Volume 35, Issue 6 - Jun 2011
Volume 35, Issue 5 - May 2011
Volume 35, Issue 4 - Apr 2011
Volume 35, Issue 3 - Mar 2011
Volume 35, Issue 2 - Feb 2011
Volume 35, Issue 1 - Jan 2011
Selecting the target year
Effect of Injection Pressure and Injection Timing on Combustion Characteristics of Spray-Guided Direct-Injection Spark-Ignition Engine under Lean Stratified Combustion Operation
Oh, Hee-Chang ; Lee, Min-Seok ; Park, Jung-Seo ; Bae, Choong-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 981~987
DOI : 10.3795/KSME-B.2011.35.10.981
In this study, single cylinder engine experiment was carried out to investigate combustion characteristics spray guided direct injection spark ignition engine. In the result of engine experiment, it was shown that flammable window of injection timing was existed. The combustion efficiency increased with retarding injection timing, reaching a peak value, subsequent to decrease again. These results were likely due to the effect of ambient pressure on stratified-premixed mixture preparation. 150 bar injection pressure condition and retarded injection timing from the best combustion efficiency injection timing showed the highest IMEP value due to the advanced combustion phase of the maximum combustion efficiency condition. HC emission showed same trend of combustion efficiency, and smoke emission was increased as injection timing was retarded due to the increased locally rich area in the high ambient pressure. NOx emission showed decreasing trend as injection timing was retarded. This is likely due to the maximum in-cylinder temperature was decreased with retarded combustion phase.
Heat-Flux Analysis of Solar Furnace Using the Monte Carlo Ray-Tracing Method
Lee, Hyun-Jin ; Kim, Jong-Kyu ; Lee, Sang-Nam ; Kang, Yong-Heack ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 989~996
DOI : 10.3795/KSME-B.2011.35.10.989
An understanding of the concentrated solar flux is critical for the analysis and design of solar-energy-utilization systems. The current work focuses on the development of an algorithm that uses the Monte Carlo ray-tracing method with excellent flexibility and expandability; this method considers both solar limb darkening and the surface slope error of reflectors, thereby analyzing the solar flux. A comparison of the modeling results with measurements at the solar furnace in Korea Institute of Energy Research (KIER) show good agreement within a measurement uncertainty of 10%. The model evaluates the concentration performance of the KIER solar furnace with a tracking accuracy of 2 mrad and a maximum attainable concentration ratio of 4400 sun. Flux variations according to measurement position and flux distributions depending on acceptance angles provide detailed information for the design of chemical reactors or secondary concentrators.
An Experimental Study on the Devolatilization Kinetics of Ashless coal in Fixed and Entrained Conditions
Yu, Da-Yeon ; Lee, Byoung-Hwa ; Song, Ju-Hun ; Lee, Si-Hyun ; Jeon, Chung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 997~1003
DOI : 10.3795/KSME-B.2011.35.10.997
In order to investigate devolatilization characteristics for ashless coal with relatively low ash content and high heating value, an experiment was performed in different bed configurations of TGA and DTF(Drop Tube Furnace) at atmospheric pressure condition. The heating rate was
/min up to
in TGA, while the temperatures of DTF varied from 500 to
in step of
. A weight loss and particle temperature were obtained to determine devolatilization kinetics. The kinetic parameters including an activation energy and pre-exponential factor for ashless coal were obtained using Coats-Redfern method in TGA and single step method in DTF. Furthermore, the devolatilization kinetics of the ashless coal were compared with the results of different kinds of conventional coal such as sub-bituminous and bituminous. The results show that the activation energy of devolatilazation for ashless coal is lower than those of others in fixed and entrained conditions.
Cavitating Flow in Circular and Elliptical Nozzles
Ku, Kun-Woo ; Hong, Jung-Goo ; Lee, Choong-Won ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1005~1012
DOI : 10.3795/KSME-B.2011.35.10.1005
The purpose of this study was to investigate the internal nozzle flow and cavitation characteristics numerically in both circular and elliptical nozzles. The program FLUENT 6.2 was used to perform the numerical simulation of the cavitating flow in the nozzles. A comparison was made between the cavitation shapes predicted numerically and those found experimentally in order to validate the numerical solution. This study showed that the cavitation in the circular nozzle had a cylindrical shape that was symmetrical with the nozzle axis. However, the cavitation in the elliptical nozzles had a horseshoe-like shape. In addition, the radial velocity distribution varied between the major and the minor axis planes when the working fluid was flowing into the inlet.
Characteristics of Charging and Collection of 10-nm-Class Ultrafine Nanoparticles in an Electrostatic Precipitator
Han, Bang-Woo ; Kim, Hak-Joon ; Kim, Yong-Jin ; Song, Dong-Keun ; Hong, Won-Seok ; Shin, Wan-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1013~1018
DOI : 10.3795/KSME-B.2011.35.10.1013
The charging of 10-nm-class nanoparticles in an electrostatic precipitator (ESP) according to particle charging ratio has been investigated and compared to the diffusion effect of the nanoparticles. The competition between the charging probability and the diffusion loss effect determines the collection efficiency of nanoparticles in the ESP. The collection efficiency of nanoparticles decreased continuously with decreasing particle diameter. This indicates that the partial charging effect of 10-nm-class nanoparticles is more dominant than their diffusion loss effect in the ESP for nanoparticles in the particle size range of less than 10 nm. The charging ratios based on unipolar diffusion charging calculations were in good agreement with the experimental collection efficiencies for nanoparticles less than 10 nm in diameter.
Fluid Network Analysis for the Fuel-Supply Systems of Gaseous-Injection-Type LPG Engines
Yun, Jeong-Eui ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1019~1024
DOI : 10.3795/KSME-B.2011.35.10.1019
The gaseous fuel injection(GFI) type of LPG fuel-supply system is more advantageous than liquefied fuel injection(LFI) from the viewpoint of durability and cost reduction. However, compared with LFI types of LPG fuel-supply systems, in the GFI systems it is difficult to achieve precision fuel metering because of the compressible characteristic of the gaseous fuel. In this study, a Helmholtz resonator is proposed as an appropriate system for precision fuel metering in GFI systems, and the effects of the Helmholtz resonator on the fuel metering are simulated by the commercial flow-network-analysis package Flowmaster.
Effect of Ignition Delay Time on Autoignited Laminar Lifted Flames
Choi, Byung-Chul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1025~1031
DOI : 10.3795/KSME-B.2011.35.10.1025
Autoignition characteristic is an important parameter for designing diesel or PCCI engines. In particular, diesel spray flames are lifted from the nozzle and the initial flame is formed by an autoignition phenomenon. The lifted nature of diesel spray flames influences soot formation, since air will be entrained into the spray core by the entrainment of air between the nozzle region and the lifted flame base. The objective of the present study was to identify the effect of heat loss on the ignition delay time by adopting a coflow jet as a model problem. Methane (
), ethylene (
), ethane (
), propene (
), propane (
), and normal butane (n-
) fuels were injected into high temperature air, and the liftoff height was measured experimentally. As the result, a correlation was determined between the liftoff height of the autoignited lifted flame and the ignition delay time considering the heat loss to the atmosphere.
A Study on the Combustion Characteristics of Flat-Plate Premixed Burner for Various Flame Surface Media and Heat Exchangers
Cho, Eun-Seong ; Park, Chang-Kwon ; Choi, Kyung-Suhk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1033~1040
DOI : 10.3795/KSME-B.2011.35.10.1033
The premixed burner is a very strong candidate for using household boiler burner system because it has high efficiency, low emission and can be used in compact boiler system. Usually, household boiler burner systems use a Bunsen burner, which consists of an inner rich premixed flame and fuel burned completely by a secondary air supply. It has a relatively long flame length and operates in a high excess of air, so it is difficult to fit such a burner into a high efficiency compact boiler. In this paper, the characteristics of a premixed combustion burner for surface media such as metal fiber, ceramic, and SUS fin were evaluated. In particular, the flow velocity over the burner surface for the cold flow characteristics of the surface material were measured and adjusted. The combustion tests were carried out by taking pictures of the flame and measuring the flame temperature. The amounts of CO and NO were measured and the characteristics of the surface burner materials, combustion chamber, and heat exchangers were evaluated for various excess air ratios and heating values.
Micro-Shockwave Measurement and Evaluation of Laser Shock Peening
Kim, Joo-Han ; Lee, Woo-Ram ; Kim, Teak-Gu ; Cheong, Seong-Kyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1041~1046
DOI : 10.3795/KSME-B.2011.35.10.1041
Micro shockwaves are induced in laser shock peening and their effect on metal samples is presented. Laser shock peening produces maximized internal compressive stress on metal surfaces. This research evaluated the effects of micro shockwaves from laser shock peening with a pulsed Nd:YAG laser on steel samples, through the analysis of the mechanical properties of the samples. In the experiments, a piezo material was applied to measure the micro shockwaves and the hardnesses and micro tensile strengths of the samples were evaluated.
Vibration Analysis and Reduction for Large-scale Diesel Engines
Bae, Yong-Chae ; Kim, Hee-Soo ; Lee, Wook-Ryun ; Lee, Doo-Young ; Kim, Bong-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1047~1052
DOI : 10.3795/KSME-B.2011.35.10.1047
Diesel engines are widely used as power supplies for isolated islands as well as emergency power supplies for large-capacity power plants because of their rapid response to operation, high reliability, and good durability. However, diesel engines are also vulnerable to damage or degradation of reliability when high levels of vibration are generated in them. This paper shows experiments and analysis for the determination of the causes of high-vibration phenomena in large-scale diesel engines, which have experienced various power decreases over several years because of the high levels of vibration. The main cause of the vibration is identified as the resonance created by the torsional vibration of its crank axis, and the appropriate countermeasures that were designed worked well when applied in field tests.
Numerical Study of Flow Pattern and Drug Deposition in Drug-Eluting Stent
Seo, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1053~1060
DOI : 10.3795/KSME-B.2011.35.10.1053
This study is performed to determine the drug concentration profiles of drug-eluting stents (DES) for an ideal circular ring stent and intertwined stent models for various Reynolds numbers (Re = 200, 400, and 800). The Navier.Stokes equations coupled with the advection-diffusion equation are solved numerically in order to determine how the flow patterns and drug deposition are affected in the in-stent and post-stent regions where flow separation and recirculation occur. The presence of DES within the arterial segment affects the local drug distribution in the flow field. As a result, the drug concentration for the intertwined stent is higher over the in-stent region in comparison with the ideal stents. For a given stent geometry, the local drug concentration in the in-stent region decreases with Reynolds number, while for a given Reynolds number, the local drug concentration is relatively insensitive to the stent geometry. The results show that drug concentration along the arterial wall is significantly higher within the in-stent and post-stent regions for the intertwined stent geometry than for the ideal stent geometries.
Numerical Analysis of the Flow Characteristics of High-Pressure Injection Nozzle for Machine Tools
Yi, Chung-Seob ; Yun, Ji-Hun ; Jeong, In-Guk ; Song, Chul-Ki ; Suh, Jeong-Se ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1061~1066
DOI : 10.3795/KSME-B.2011.35.10.1061
In this study, the flow characteristics of an injection nozzle installed in a high-pressure holder for improving productivity were determined. The inlet velocity, nozzle inflow angle, and nozzle outlet diameter were selected as design factors having an influence on the flow characteristics, and numerical analysis was conducted for these factors. As the inlet velocity is high and the nozzle outlet diameter is small, the pressure and velocity of the injected flow are high. In the case of the nozzle inflow angle, the variation of flow characteristics according to angle was slight, but the highest pressure and velocity were found at
. In addition, the possibility of chip elimination by the injected flow was analyzed on the basis of the numerical results.
Performance Analysis of a Centrifugal Fan with Splitters
Jang, Choon-Man ; Choi, Ka-Ram ; Yang, Sang-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1067~1073
DOI : 10.3795/KSME-B.2011.35.10.1067
This paper describes the performance of a centrifugal fan used for refuse collection systems according to the chord length of the splitters installed near the blade suction and pressure surface sides. The fan performance is analyzed by three-dimensional Navier.Stokes analysis and is compared to the results obtained experimentally. Throughout the numerical simulation of the fan with splitters, it is found that the reverse-flow region observed near the suction side of the blade can be reduced by installing a splitter. The fan performance is successfully improved by controlling the chord length of the splitter installed near the blade suction side. Under the designed flow condition, the efficiency and pressure of a fan with splitters increase by up to 4% and 18%, respectively, compared to the reference fan.
Comparison of the Friction-Loss Coefficient for the Gap of Two Contact Surfaces and a Crack
Nam, Ho-Yun ; Choi, Byoung-Hae ; Kim, Jong-Bum ; Lee, Young-Bum ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1075~1081
DOI : 10.3795/KSME-B.2011.35.10.1075
A leak-detection method has been developed by measuring the pressure variation between the inner and outer heattransfer tubes of a double-wall tube steam generator. An experiment was carried out to measure the leak rate in the gap between two surfaces pressed with a hydraulic press in order to simulate the phenomena, and a correlation was determined for the leak rate in a micro gap. However, in the correlation, the gap width and friction coefficient were coupled with the surface roughness, which affects the two parameters. The two parameters were separated using a surface-contact model to develop a correlation for the friction coefficient. The correlation was compared with the existing correlations used for crack analysis. Although the applied ranges of Reynolds numbers were different, the developed correlation for Reynolds numbers of 0.1.0.35 showed similar tendencies to existing correlations used for higher Reynolds numbers.
Effects of Impellers and Floating Ring Seals on Performance of Centrifugal Pumps
Kim, Dae-Jin ; Choi, Chang-Ho ; Hong, Soon-Sam ; Kim, Jin-Han ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1083~1088
DOI : 10.3795/KSME-B.2011.35.10.1083
The effects of an impeller and floating ring seals on the performance of centrifugal pumps are investigated on the basis of their test results using water. The pumps are single-staged centrifugal pumps developed for 30-ton- and 75-ton-class liquid rocket engines, and are components of a turbopump that supplies propellants (liquid oxidizer and kerosene) to the combustion chamber. The exit width of the impellers and the numbers and exit angles of the impeller blades are found to have influences on the pump heads. In addition, the pumps have different efficiencies according to the gaps between the floating ring seals and the impellers, whereas the pump size seems to have less effect on the efficiency.
Numerical Study of Bubble Motion During Nucleate Boiling on a Micro-Finned Surface
Lee, Woo-Rim ; Son, Gi-Hun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1089~1095
DOI : 10.3795/KSME-B.2011.35.10.1089
Numerical simulation is performed for nucleate boiling on a micro-finned surface, which has been widely used to enhance heat transfer, by solving the equations governing the conservation of mass, momentum, and energy in the liquid and vapor phases. The bubble motion is determined by a sharp-interface level-set method, which is modified to include the effect of phase change and to treat the no-slip and contact-angle conditions, as well as the evaporative heat flux from the liquid microlayer on immersed solid surfaces such as micro fins and cavities. The numerical results for bubble formation, growth, and departure on a microstructured surface including fins and cavities show that the bubble behavior during nucleate boiling is significantly influenced by the fin-cavity arrangement and the fin-fin spacing.
Study on Design Change of a Pipe Affected by Liquid Droplet Impingement Erosion
Hwang, Kyeong-Mo ; Lee, Chan-Gyu ; Bhang, Keug-Jin ; Yim, Young-Sig ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1097~1103
DOI : 10.3795/KSME-B.2011.35.10.1097
Liquid droplet impingement erosion (LDIE) is caused by the impact of high-velocity droplets entrained in steam or air on metal. The degradation caused by the LDIE has been experienced in steam turbine internals and high-velocity airplane components (particularly canopies). Recently, LDIE has also been observed in the pipelines of nuclear plants. LDIE among the pipelines occurs when two-phase steam experiences a high pressure drop (e.g., across an orifice in a line to the condenser). In 2011, a nuclear power plant in Korea experienced a steam leak caused by LDIE in a pipe through which a two-phase fluid was flowing. This paper describes a study on the design change of a pipe affected by LDIE in order to mitigate the damage. The design change has been reviewed in terms of fluid dynamics by using the FLUENT code.
Evaluation of Liquid Droplet Impingement Erosion through Prediction Model and Experiment
Yun, Hun ; Hwang, Kyeong-Mo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 10, 2011, Pages 1105~1110
DOI : 10.3795/KSME-B.2011.35.10.1105
Flow-accelerated corrosion (FAC) is a well-known phenomenon that may occur in piping and components. Most nuclear power plants have carbon-steel-pipe wall-thinning management programs in place to control FAC. However, various other erosion mechanisms may also occur in carbon-steel piping. The most common forms of erosion encountered (cavitation, flashing, Liquid Droplet Impingement Erosion (LDIE), and Solid Particle Erosion (SPE)), have caused wall thinning, leaks, and ruptures, and have resulted in unplanned shutdowns in utilities. In particular, the damage caused by LDIE is difficult to predict, and there has been no effort to protect piping from erosive damage. This paper presents an evaluation method for LDIE. It also includes the calculation results from prediction models, a review of the experimental results, and a comparison between the UT data in the damaged components and the results of the calculations and experiments.