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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers B
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 28, Issue 12 - Dec 2004
Volume 28, Issue 11 - Nov 2004
Volume 28, Issue 10 - Oct 2004
Volume 28, Issue 9 - Sep 2004
Volume 28, Issue 8 - Aug 2004
Volume 28, Issue 7 - Jul 2004
Volume 28, Issue 6 - Jun 2004
Volume 28, Issue 5 - May 2004
Volume 28, Issue 4 - Apr 2004
Volume 28, Issue 3 - Mar 2004
Volume 28, Issue 2 - Feb 2004
Volume 28, Issue 1 - Jan 2004
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A Study on Cooling of Hot Steel Surface by Water-Air Mixed Spray(I) -The Effect of Air Mass Flux on Film Boiling Heat Transfer-
Lee, Pil-Jong ; Jin, Sung-Tae ; Lee, Sung-Hong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 247~255
DOI : 10.3795/KSME-B.2004.28.3.247
The cooling characteristic of water-air mixed spray for high water mass flux is not well defined, compared to that of highly pressurized spray. A series of research program was planned to develop the boiling correlation for whole temperature range in case of water-air mixed spray with high water mass flux. The cooling experiments of hot steel surface with initial temperature of 820
were conducted in unsteady state with relatively high water mass flux. A computer program was developed to calculate the heat flux inversely from measured data by three inserted thermocouples. Finally the effects of water and air mass flux on the averaged film boiling heat flux and wetting temperature were studied. In this 1st report, it is found that the boiling curve was similar to that of highly pressurized spray and the decreased slope of heat flux in film boiling region with respect to surface temperature became steep by increasing air mass flux. Also it is shown that, by increasing air mass flux, the averaged heat flux in film boiling region was increased, and then saturated and the wetting temperature was increased, and then decreased. Finally when the heat flux in film boiling region is compared with that of highly pressurized spray, it is known that the cooling is improved by introducing air up to 60%.
Analysis of Granular Flow Using DEM
Sah, Jong-Youb ; Choi, Jeung-Wook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 256~264
DOI : 10.3795/KSME-B.2004.28.3.256
The granular flow has been numerically studied by using DEM(Discrete Element Method). The eve교 particle is checked if it collides neighbor particles, and the next motion of the particle is predicted. The computing time has been drastically reduced by improving the collision check against neighboring particles. The comparison of the present method with ail experiment for the vibrating floor problem shows the good accuracy. The broken tower problem has been calculated to show the good comparison with the other computational result. This DEM(Discrete Element Method) can be a useful tool for constructing the constitute equation of the continuum approach of the granular flow.
Experimental Study on Millimeter Scale Two Phase Catalytic Reactor
Cho, Chung-Hun ; Lee, Dae-Hoon ; Kwon, Se-JIn ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 265~270
DOI : 10.3795/KSME-B.2004.28.3.265
Experiment study on a down scaled two-phase catalytic reactor is presented. As a preliminary step for the development of catalytic reactor, nano-particulate catalyst was prepared. Perovskite La
is chosen and synthesized as a catalyst considering superior catalytic performance in reduction and oxidation process where oxygen is involved among the reagent. Reactor that has a scale of 2
25mm was made by machining of A1 block as a layered structure considering further extension to micro-machining. Hydrogen peroxide of 70wt% was adopted as reactant and was provided to the reactor loaded with 1.5 g of catalyst. Reactant flow rate was varied by precision pump with a range of 0.15cc/min to 17.2cc/min. Temperature distribution within reactor was recorded by 3 thermocouples and total amount of liquid product was measured. Temperature distribution and factors that affect temperature were observed and relation between temperature distribution and production rate was also analyzed. Relative time scale plays a significant role in the performance of the reactor. To obtain steady state operation, appropriate ratio of flow rate, catalyst mass and reactor geometry is required and furthermore to get more efficient production rate temperature distribution should be evenly distributed. The database obtained by the experiment will be used as a design parameter for micro reactor.
Assessment of Image Registration for Pressure-Sensitive Paint
Chang, Young-Ki ; Park, Sang-Hyun ; Sung, Hyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 271~280
DOI : 10.3795/KSME-B.2004.28.3.271
Assessment of image registration for Pressure Sensitive Paint (PSP) was performed. A 16 bit camera and LED lamp were used with Uni-FIB paint (ISSI). Because of model displacement and deformation at `wind-on` condition, a large error of the intensity ratio was induced between `wind-on` and` wind-off images. To correct the error, many kinds of image registrations were tested. At first, control points were marked on the model surface to find the coefficients of polynomial transform functions between the `wind-off` `wind-on` images. The 2nd-order polynomial function was sufficient for representing the model displacement and deformation. An automatic detection scheme was introduced to find the exact coordinates of the control points. The present automatic detection algorithm showed more accurate and user-friendly than the manual detection algorithm. Since the coordinates of transformed pixel were not integer, five interpolation methods were applied to get the exact pixel intensity after transforming the `wind-on` image. Among these methods, the cubic convolution interpolation scheme gave the best result.
Combustion Characteristics of a Turbulent Diffusion Flat Flame According to Oxygen Enriched Concentration of Combustion Air
Kwark, Ji-Hyun ; Jeon, Chung-Hwan ; Chang, Young-June ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 281~288
DOI : 10.3795/KSME-B.2004.28.3.281
Combustion using oxygen enriched air is an energy saving technology that can increase thermal efficiency by improving the burning rate and by increasing the flame temperature. Flame figures, OH radical intensities, temperature distributions and emissions concentration were examined according to oxygen enriched concentration(OEC) in a turbulent diffusion flat flame. As long as the oxygen enriched concentration was increased, the length and volume of the flat flame was decreased while OH radical intensity was raised and the flame temperature was increased. However, RMS of the fluctuating temperature was decreased, and more homogeneous temperature field was formed. Thermal NO also was increased with increase of oxygen enriched concentration, but CO was decreased due to the increase of chemical reaction rate.
Heat Transfer Characteristics During Gas Cooling Process of Carbon Dioxide in a Horizontal Tube
Son, Chang-Hyo ; Lee, Dong-Gun ; Oh, Koo-Kyu ; Jeong, Si-Young ; Kim, Young-Lyoul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 289~295
DOI : 10.3795/KSME-B.2004.28.3.289
The heat transfer coefficient and pressure drop during gas cooling process of carbon dioxide in a horizontal tube were investigated. The experiments were conducted without oil in the refrigerant loop. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flowmeter, an evaporator, and a gas cooler(test section). The main components of the water loop consist of a variable-speed pump, an isothermal tank, and a flowmeter. The gas cooler is a counterflow heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus. The test section consists of smooth, horizontal stainless steel tube of the outer diameter of 9.53mm and of the inner diameter of 7.75mm. The length of the test section is 6m. The refrigerant mass fluxes were 200∼300kg/(m2
s) and the inlet pressure of the gas cooler varied from 7.5㎫ to 8.5㎫. The main results were summarized as follows : Pressure drop of CO2 increases with increasing gas cooler pressure. The friction factors of CO2 in a horizontal tube show a relatively good agreement with the correlation by Blasius. The heat transfer coefficient of CO2 in transcritical region increases with decreasing gas cooler pressure and decreasing mass flux of CO2. Most of correlations proposed in a transcritical region showed significant deviations with experimental data except for those predicted by Gnielinski.
Optimal Shape of a Parallel-Flow Heat Exchanger by Using a Response Surface Method
Oh, Seok-Jin ; Lee, Kwan-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 296~303
DOI : 10.3795/KSME-B.2004.28.3.296
The heat and flow characteristics in a single-phase parallel-flow heat exchanger was examined numerically to obtain its optimal shape. A response surface method was introduced to approximately predict its performance with respect to the design parameters over the design domain. The inflow/outflow angle of the working fluid, the location of inlet/outlet, the protruding height of flat tube and the height of header were chosen as a design parameter The evaluation of the relative importance of the design parameters was performed based on a sensitivity analysis. An efficiency index was used as an evaluation characteristics value to simultaneously consider both the heat transfer and the pressure drop. The efficiency index of the optimum model, compared to that of the base model, was increased by 9.3%.
The Effects of Staggered Rows of Rectangular Shaped Holes on Film Cooling
Kim, Young-Bong ; Rhee, Dong-Ho ; Lee, Youn-Seok ; Cho, Hyung-Hee ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 304~314
DOI : 10.3795/KSME-B.2004.28.3.304
An experimental study has been conducted to measure the temperature fields and the local film cooling effectiveness for two and three staggered rows of the rectangular shaped-holes with various blowing rates. The hydraulic diameter of rectangular-shaped hole is 10mm. To compare with the film cooling performance of rectangular-shaped hole, two kinds of circular holes are tested. One has the same hydraulic diameter as the rectangular hole and the other has the same cross sectional area. Also, rectangular holes with expanded exit with same inlet area as rectangular ones are tested. Temperature fields are measured using a thermocouple rake attached on three-axis traversing system. Adiabatic film cooling effectiveness on the surface are obtained based on experimental results of thermochromic liquid crystals. The film cooling effectiveness is measured for various blowing rates and compared with the results for the cylindrical holes. In case of 2 rows, the rectangular holes has better performance than circular holes due to its slot-like geometry. In case of 3 rows, the effecta of hole shape is not clear.
Design and Performance Evaluation of a Faraday Cage and an Aerosol Charger
Ji, Jun-Ho ; Bae, Kwi-Nam ; Hwang, Jung-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 315~323
DOI : 10.3795/KSME-B.2004.28.3.315
An electrical cascade impactor is a multi-stage impaction device to separate airborne particles into aerodynamic size classes using particle charging and electrical detection techniques. A Faraday cage and an aerosol charger, which are basic components of the electrical cascade impactor, were designed and evaluated in this study. The low-level current response of the Faraday cage was investigated with changing particle size and air flow rate by using sodium chloride (NaCl) particles. The response of the prototype Faraday cage was very similar to that of a commercial aerosol electrometer (TSI model 3068) within
5% for singly-charged particles. The response linearity of the prototype Faraday cage could be extended up to flow rate of 30 L/min. For the performance evaluation of the aerosol charger the monodisperse liquid dioctyl sebacate (DOS) particles, with diameters of 0.1∼0.8
, were generated using spraying from an atomizer followed by evaporation-condensation process. Typical performance parameters of the aerosol charger such as P
n, wall loss, and elementary charges per particle were evaluated. The performance of the prototype aerosol charger was found to be close to that of the aerosol charger used in an electrical low pressure impactor (ELPI, Dekati).
A Study on the Emissions of Homogeneous Charge Compression Ignition Engine
Han, Sung-Bin ; Choi, Gyeung-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 324~329
DOI : 10.3795/KSME-B.2004.28.3.324
As a new concept in engines and a power source for future automotive applications, the HCCI(Homogeneous Charge Compression Ignition) engine has been introduced. Essentially a combination of spark ignition and compression ignition engines, the HCCI engine exhibits low NO
and PM emissions as well as high efficiency under part load. In this research, a 4 cylinder diesel engine was converted into a HCCI engine, and propane was used as the fuel. The main parameters for this research are fuel flow rate and the temperature of the intake manifold, and the effects of such on a HCCI engine`s performance and exhaust was investigated
Analysis of Flow Phenomena in a Centrifugal Compressor Impeller Operating near Stall
Eum, Hark-Jin ; Kang, Shin-Hyoung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 330~337
DOI : 10.3795/KSME-B.2004.28.3.330
Analysis of flow phenomena in a centrifugal compressor impeller has been carried out with numerical simulation to understand the physics of flow near stall. Near stall point, tip leakage flow spills ahead of the leading edge of adjacent blade and other leakage flow passes over the clearance of the adjacent blade instead of rolling up into vortex within the passage. The tip leakage flow at the mid chord of impeller blade impinges against the pressure surface of the adjacent blade and then rolls up into vortex within the passage, which blocks the flow passage and generates viscous loss. The spillage of leakage flow ahead of the adjacent blade generates the recirculation of flow entering the impeller, which causes the power transferred into the flow by the impeller to decrease and blocks the flow passage. Near diffuser hub wall, flow recirculation occurs. As operating point goes to stall point, the core of recirculation approaches the impeller exit The length rises to peak point and then drops with mass flow reduction, while the height steadily rises.
Heat/Mass Transfer Characteristics on Rib-roughened Surface for Impingement/Effusion Cooling System with Initial Crossflow
Rhee, Dong-Ho ; Nam, Yong-Woo ; Cho, Hyung-Hee ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 338~348
DOI : 10.3795/KSME-B.2004.28.3.338
The present study is conducted to investigate the effect of rib arrangements on an impingement/effusion cooling system with initial crossflow. To simulate the impingement/effusion cooling system, two perforated plates are placed in parallel and staggered arrangements with a gap distance of 2 times of tile hole diameter. Initial crossflow passes between the injection and effusion plates, and the square ribs (3mm) are installed on the effusion plate. Both the injection and effusion hole diameters are 10mmand Reynolds number based on the hole diameter and hole-to-hole pitch are fixed to 10,000 and 6 times of the hole diameter, respectively. To investigate the effects of rib arrangements, various rib arrangements, such as 90
transverse and 45
angled rib arrangements, are used. Also, the effects of flow rate ratio of crossflow to impinging jets are investigated. With the initial crossflow, locally low transfer regions are formed because the wall jets are swept away, and level of heat transfer rate get decreased with increasing flow rate of crossflow. When the ribs are installed on the effusion plate, the local distributions of heat/mass transfer coefficients around the effusion holes are changed. The local heat/mass transfer around the stagnation regions and the effusion holes are affected by the rib positions, angle of attack and rib spacing. For low blowing ratio, the ribs have adverse effects on heat/mass transfer, but for higher blowing ratios, higher and more uniform heat transfer coefficient distributions are obtained than the case without ribs because the ribs prevent the wall jets from being swept away by the crossflow and increase local turbulence of the flow near the surface. Average heat transfer coefficients with rib turbulators are approximately 10% higher than that without ribs, and the higher values are obtained with small pitch of ribs. However, the attack angle of the rib has little influence on the average heat/mass transfer.
Design and Performance Evaluation of a Low Pressure Impactor for Sampling Submicron Aerosols
Ji, Jun-Ho ; Cho, Myung-Hoon ; Bae, Gwi-Nam ; Hwang, Jung-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 349~358
DOI : 10.3795/KSME-B.2004.28.3.349
A low pressure impactor is an impaction device to separate airborne particles into aerodynamic size classes at low pressure condition. We designed a two-stage low-pressure impactor to classify submicron sized environmental aerosols. Performance evaluation was carried out for stages 1 and 2 by using an electrical method. Monodisperse liquid dioctyl sebacate (DOS) particles were generated using evaporation-condensation process followed by electrostatic classification using a DMA (differential mobility analyzer). The test particles were in the range of 0.08∼0.8
. For the evaluation of the impactor we used two electrometers; one was connected to the impaction plate of the impactor and the other was to the Faraday cage used as a backup filter. The effect of polydispersity of test aerosols on the performance was investigated. The results showed that the experimental 50-% cutoff diameters at each impactor`s operation pressure were 0.53 and 0.187
for stages 1 and stage 2, respectively. The effects of operation pressure on the cutoff diameter and the steepness of collection efficiency curves were also investigated.
Experiment on the Characteristics of Jet Diffusion Flames with High Temperature Air Combustion
Cho, Eun-Seong ; Ohno, Ken ; Kobayashi, Hideaki ; Chung, Suk-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 359~364
DOI : 10.3795/KSME-B.2004.28.3.359
For the development of high efficiency and low emission combustion systems, high temperature air combustion technology has been tested by utilizing preheated air over 1100 K and exhaust gas recirculation. In this system, combustion air is diluted with large amount of recirculated exhaust gases, such that the oxygen concentration is relatively low in the reaction zone, leading to low flame temperature. Since, the temperature fluctuations and sound emissions from the flame are small and flame luminosity is low, the combustion mode is expected to be flameless or mild combustion. Experiment was performed to investigate the turbulent flame structure and NO
emission characteristics in the high temperature air combustion focused on coflowing jet diffusion flames which has a fundamental structure of many practical combustion systems. The effect of turbulence has also been evaluated by installing perforated plate in the oxidizer inlet nozzle. LPG was used as a fuel. Results showed that even though NO
emission is sensitive to the combustion air temperature, the present high temperature air combustion system produce low NO
emission because it is operated in low oxygen concentration condition by the high exhaust gas recirculation.
A Study on the Turbulent Characteristics of Rushton Turbine Mixer by Simultaneous Measurement of Velocity and Concentration field with Stereo-PIV/PLIF Technique
Min, Young-Uk ; Kim, Yun-Gi ; Kim, Kyung-Chun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 3, 2004, Pages 365~370
DOI : 10.3795/KSME-B.2004.28.3.365
Simultaneous measurement with PLIF(Planar Laser-Induced Fluorescence) and Stereo-PIV(Stereo Particle Image Velocimetry) was performed to investigate the structural characteristics of flow field in Rushton Turbine Mixer. Instantaneous 3D velocity fields are measured by two 2K
2K CCD cameras focused on an object plane with the angular displacement methods while the concentration fields are obtained through the measurement of the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. Finally, the spatial structures of turbulent flow around Rushton turbine were identified by the calculation of synchronized data of the velocity field and concentration field.