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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
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 20, Issue 12 - Dec 1996
Volume 20, Issue 11 - Nov 1996
Volume 20, Issue 10 - Oct 1996
Volume 20, Issue 9 - Sep 1996
Volume 20, Issue 8 - Aug 1996
Volume 20, Issue 7 - Jul 1996
Volume 20, Issue 6 - Jun 1996
Volume 20, Issue 5 - May 1996
Volume 20, Issue 4 - Apr 1996
Volume 20, Issue 3 - Mar 1996
Volume 20, Issue 2 - Feb 1996
Volume 20, Issue 1 - Jan 1996
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The characteristics of laminar diffusion flame impinging on the wall
Park,Yong-Yeol ; Kim, Ho-Yeong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 979~987
DOI : 10.22634/KSME-B.1922.214.171.1249
A theoretical study for the laminar round jet diffusion flame impinging on the wall was carried out to predict the characteristics and structure of impinging jet flame and heat transfer to the wall. Finite chemistry via Arrhenius equation was adopted as the combustion model. All the transport properties were considered as the variable depending on the temperature and composition. For the parametric study, the distance from nozzle to perpendicular wall and Reynolds number at nozzle exit were chosen as the major parameters. As the results of the present study, the characteristics of flow field and the distributions of temperature, density and each chemical species were obtained. The heat transfer rate from flame to the wall and the effective heating area were calculated to investigate the influence of the major parameters on the heat transfer characteristics.
A numerical simulation of radiative heat transfer coupled with Czochralski flow in cusp magnetic field
Kim, Tae-Ho ; Lee, Yu-Seop ; Jeon, Jung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 988~1004
DOI : 10.22634/KSME-B.19126.96.36.1998
The characteristics of flow and oxygen concentration are numerically studied in Czochralski 8" silicon crystal growing process considering radiative heat transfer. The analysis of net radiative heat flux on all relevant surfaces shows growing crystal affects the heater power. Furthermore, the variation of the radiative heat flux along the crystal surface in the growing direction is confirmed and should be a cause of thermal stress and defect of the crystal. The calculated distributions of temperature and, heat flux along the wall boundaries including melt/crystal interface, free surface and crucible wall indicate that the frequently used assumption of the thermal boundary conditions of insulated crucible bottom and constant temperature at crucible side wall is not suitable to meet the real physical boundary conditions. It is necessary, therefore, to calculate radiative heat transfer simultaneously with the melt flow in order to simulate the real CZ crystal growth. If only natural convection is considered, the oxygen concentration on the melt/crystal interface decreases and becomes uniform by the application of a cusp magnetic filed. The heater power needed also increases with increasing the magnetic field. For the case of counter rotation of the crystal and crucible, the magnetic field suppresses azimutal flow produced by the crucible rotation, which results in the higher oxygen concentration near the interface.
A study on spray characteristics of the triplet impinging stream type injector for liquid rocket
Park, Seong-Yeong ; Kim, Seon-Jin ; Kim, Yu ; Park, Seung-Un ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1005~1014
DOI : 10.22634/KSME-B.19188.8.131.525
An experimental investigation has been carried out to examine the influence of injector design variables and operating conditions on the resultant drop size for triplet impinging streams injectors. The variables studied in this investigation are pressure drop, impinging angle, orifice length to diameter ratio, and impinging point distance. Droplet-size data are obtained using water as the propellant simulant by Malvern Particle Analyzer System. Drop size decreases with increasing impinging angle and pressure drop while other injector parameters remain constant at the same point. But it is found that there is no noticeable droplet-size change which results from change in orifice length to diameter ratio or impinging point distance within the investigated range.
Calculation of the incompressible Navier-stokes equations in generalized nonorthogonal body fitted coordinate system
Gang, Dong-Jin ; Bae, Sang-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1015~1027
DOI : 10.22634/KSME-B.19184.108.40.2065
In this paper, a numerical procedure for the calculation of the incompressible Navier-Stokes equations in a generalized nonorthogonal body fitted coordinate system is proposed and is validated through three test problems. Present numerical procedure derives the pressure equation by using the pressure substitution method on the regular grid system, and discretized momentum equations are based on the covariant velocity components. Cavity flow, backward facing step flow, and two dimensional channel flow with a sinusoidal wavy wall are chosen as three test problems. Numerical solutions obtained by present procedure shows a good agreement with previous numerical and/or experimental results. Convergence rate is also satisfactory.
An Experimental Study on Flame Structure and Combustion Characteristics of Turbulent Diffusion Flame(I)
Choe, Byeong-Ryun ; Jang, In-Gap ; Choe, Gyeong-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1028~1039
DOI : 10.22634/KSME-B.19220.127.116.118
This study was focused on the examination of the flame structure and the combustion characteristics of diffusion flame which was formed the turbulent shear flow of a double coaxial air jet system. The shear flow was formed by the difference velocity of surrounding air jet(U
s/) and center air jet (U
c/). So experimental condition was divided S-type flame (.lambda. > 1) and C-type flame (.lambda. < 1) by velocity ratio .lambda. (=U
c/). For examination of the flame structure and the combustion characteristics in diffusion flame, coherent structure was observed in flame by schlieren photograph method. We measured fluctuating temperature and ion current simultaneously and accomplished the statistical analysis of its. According to schlieren photograph, the flame was stabilized in the rim of the direction of lower velocity air jet, coherent eddy was produced and developed by higher velocity air jet. The statistical data of fluctuating temperature and ion current was indicated that reaction was dominated by higher velocity air jet. The mixing state of burnt gas and non-burnt gas was distributed the wide area at Z = 100 mm of C-type flame.
An experimental study on characteristics of mixture turbulence and flame scale
Choe, Byeong-Ryun ; Jang, In-Gap ; Choe, Gyeong-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1040~1049
DOI : 10.22634/KSME-B.1918.104.22.1680
The high loading combustion is accomplished by making the turbulent intensity strong and the scale small in the premixed combustor. The Da-mkoler number, which is decreased by short turbulent characteristic time or by long chemical reaction time, can make the distributed reaction flame. So we developed a doubled jet burner for high loading combustion. The doubled jet burner was designed to make the scale of the flame small by the effect of impingement and increasing shear stress with doubled jet. We investigated the turbulence characteristics of unburned mixture and visualized several flames with the typical schlieren photography. Then we studied the influence of several factors that related the scale of flame. Consequently, the doubled jet burner can make the eddy very small. And we can obtain the detail information of the flame scale through ADSF(the Average Distance between Successive Fringes) in the micro- schlieren photography. The ADSF is not a exact flame scale, but it has qualitative trend with increasing turbulent intensity. The ADSF is diminished remarkably with increasing turbulent intensity. The reason is that strong turbulent intensity makes the flame zone thick and flamelets numerous. We can confirm this fact by the signal analysis of ion currents.
An Experimental Study on Flame Structure and Combustion Characteristics of Turbulent Diffusion Flame(II)
Choe, Byeong-Ryun ; Jang, In-Gap ; Choe, Gyeong-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1050~1060
DOI : 10.22634/KSME-B.1922.214.171.1240
Recently, attention has been paid to the flame diagnostic by noncontact methods which dose not deform the flame shape. One of them is a method which is using the radical luminous intensity. Generally, this diagnostic method using radical luminous has been investigated its reliability by applying to laminar flame. This study, however, investigated each radical luminous signals through stocastical analysis like auto-correlation, cross-correlation, phase and coherence which were acquired from measuring radical luminous intensity of OH, CH,
, radicals in turbulent diffusion flame. To compare radical luminous intensity in flame with temperature, ion current and concentration , radious distribution of each properties was investigated and considered. In radical luminous intensity, correlation in the reaction zone of flame was higher than in correlation in combusted gas zone. And radious distribution of radical luminous intensity was corresponded with radious distribution of temperature, ion current and concentration. The result of the study confirms that a radical luminous flame diagnosis is possible in the turbulent diffusion flame.
An experimental study for cold end orifice of vortex tube
Yu, Gap-Jong ; Choe, Byeong-Cheol ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1061~1073
DOI : 10.22634/KSME-B.19126.96.36.1991
Vortex tube is a simple device which splits a compressed gas stream into a cold stream and a hot stream without any chemical reactions. The phenomena of energy separation taking place in a vortex tube has been investigated experimentally. Recently, vortex tube is widely used to local cooler of industrial equipments and air conditioner of special purpose. In this study, experimental study on vortex tube efficiency was performed with various cold end orifices and nozzles type. The experimental results indicate that there is an optimum diameter of cold end orifice and nozzle type for the best cooling performance. The variation of the maximum wall temperature along the vortex tube surface provides useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. The similarity relation for the prediction of the temperature of the cold exit air was obtained.
Influence of inducer inlet angle on cavitation flows and suction performance
Lee, Seon-Gi ; Jeong, Jin-Do ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1074~1082
DOI : 10.22634/KSME-B.19188.8.131.524
In order to understand the influence of the inducer inlet angle on cavitation and suction performance, experiments were carried out for two kindy o
A passive control on shock oscillations in a supersonic diffuser
Kim, Hui-Dong ; Matsuo, Kazuyasu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1083~1095
DOI : 10.22634/KSME-B.19184.108.40.2063
Shock wave/boundary layer interaction frequently causes the shock wave to oscillate violently and thus the global flow field to unstabilize. In order to stabilize the shock wave system in the diffuser of a supersonic wind tunnel, the present study attempted to control the shock oscillations by using a passive control. A porous wall with the porosity of 19.6% was mounted on a shallow cavity. Experiment was made by means of schlieren optical observation and wall pressure measurements. The flow Mach number just upstream the shock system and Reynolds number based on the turbulent boundary layer thickness were 2.1 and 1.8 * 10
6/, respectively. The results show that the present passive control method on the shock wave/boundary layer interaction in the supersonic diffuser can significantly suppress the oscillations of shock system, especially when the shock system locates at the porous wall.
The theoretical Model for predicting the behaviors of the frost formation
Lee, Gwan-Su ; Lee, Tae-Hui ; Heo, Jeong-Hei ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1096~1105
DOI : 10.22634/KSME-B.19220.127.116.116
A theoretical model of the frost formation has been presented to investigate the characteristics of the growth of frost layer by considering molecular diffusion of water vapor and heat generation caused by sublimation of water vapor in the frost layer. The present model was compared with existing experimental data as well as a previous model. The difference between the present model and existing experimental data was found to be about 6 percent. An analysis for the behavior of frost formation using present model shows a good agreement with the trend for a number of experimentally observed features. The present analysis can also provide the physical understanding on the phenomena of the frost formation.
Phase criterion of the feedback cycle of edgetones
Gwon, Yeong-Pil ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1106~1113
DOI : 10.22634/KSME-B.1918.104.22.1686
The phase criterion of the feedback cycle of low-speed edgetones has been obtained using the jet-edge interaction model which is based on the substitution of an array of dipoles for the reaction of the wedge to the impinging jet. The edgetone is produced by the feedback loop between the downstream-convected sinuous disturbance and upstream-propagating waves generated by the impingement of the disturbance on the wedge. By estimation of the phase difference between the downstream and the upstream disturbances, the relationship between the edge distance and the wavelength is obtained according to the phase-locking condition at the nozzle lip. With a little variation depending on the characteristics of jet-edge interaction, the criterion can be approximated as follows: h/.LAMBDA. + h/.lambda. = n - 1/4, where h is the stand-off distance between the nozzle lip and the edge tip, .LAMBDA. is the wavelength of downstream-convected wave, .lambda. is the wavelength of the upstream-propagating acoustic wave and n is the stage number for the ladder-like characteristics of frequency. The present criterion has been confirmed by estimating wavelengths from available experimental data and investigating their appropriateness. The above criterion has been found to be effective up to 90.deg. of wedge angle corresponding to the cavitytones.
Temperature field measurement of convective flow in a Hele-Shaw Cell with TLC and color image processing
Yun, Jeong-Hwan ; Do, Deok-Hui ; Lee, Sang-Jun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 3, 1996, Pages 1114~1122
DOI : 10.22634/KSME-B.1922.214.171.1244
Variation of temperature field in a Hele-Shaw convection cell was measured by using a HSI true color image processing system and TLC(Thermochromic Liquid Crystal) solution. The relationship between the hue value of TLC color image and real temperature was obtained and this calibration result was used to measure the true temperature. The temperature field in the Hele-Shaw convection cell shows periodic characteristics of 45 sec at Ra = 9.3 * 10
6/. The temperature field measurement technique developed in this study was proved to be a useful and powerful tool for analyzing the unsteady thermal fluid flows.