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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 21, Issue 12 - Dec 1997
Volume 21, Issue 11 - Nov 1997
Volume 21, Issue 10 - Oct 1997
Volume 21, Issue 9 - Sep 1997
Volume 21, Issue 8 - Aug 1997
Volume 21, Issue 7 - Jul 1997
Volume 21, Issue 6 - Jun 1997
Volume 21, Issue 5 - May 1997
Volume 21, Issue 4 - Apr 1997
Volume 21, Issue 3 - Mar 1997
Volume 21, Issue 2 - Feb 1997
Volume 21, Issue 1 - Jan 1997
Selecting the target year
Numerical simulation of combustor afterward sprayed in hot product stream
Kim, Tae-Han ; Gwon, Hyeong-Jeong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 841~848
DOI : 10.22634/KSME-B.19126.96.36.1991
Combustion of gaseous fuel combustor in a high temperature vitiated air stream was studied with computer simulation. It is for application to afterburner of gas turbine engine which the exact mechanism is not yet clarified. As the jet velocity from fuel nozzle is very high and the geometry of combustor is three dimensional complex structure, many time and money are required to have good results. To consider this demerit, it is simplified to 2-dimensional and modified with the nozzle hole area to same area of annual status. As the thickness of annual is too thin, it is to divide with the many grids for reasonable results. Accordingly, new method which injected fuel mass, momentum and energy are added to source terms of each governing conservation equation as a source terms is introduced like as two phase analysis. Reaction rate is determined by taking into account the Arrhenius reaction based on a single step reaction mechanism. It is focused to temperature and product concentration distribution at each equivalence ratio of inlet hot product.
A numerical simulation on the effect of hole geometry for film cooling flow
Lee, Jeong-Hui ; Choe, Yeong-Gi ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 849~861
DOI : 10.22634/KSME-B.19188.8.131.529
In this study, the effect of hole geometry of the cooling system on the flow and temperature field was numerically calculated. The finite volume method was employed to discretize the governing equation based on the non-orthogonal coordinate with non-staggered variable arrangement. The standard k-.epsilon. turbulence model was used and also the predicted results were compared with the experimental data to validate numerical modeling. The predicted results showed good agreement in all cases. To analyze the effect of the discharge coefficient for slots of different length to width, the inlet chamfering and radiusing holes were considered. The discharge coefficient was increased with increment of the chamfering ratio, radiusing ratio and slot length to width and also the effect of radiusing showed better result than chamfering in all cases. In order to analyze the difference between the predicted results with plenum region and without plenum region, the velocity profiles of jet exit region for a various flow conditions were calculated. The normal velocity components of jet exit showed big difference for the low slot length to width and high blowing rate cases. To analyze the flow phenomena injected from a row of inclined holes in a real turbine blade, three dimensional flow and temperature distribution of the region including plenum, hole and cross stream with flow conditions were numerically calculated. The results have shown three-dimensional flow characteristics, such as the development of counter rotating vortices, jetting effect and low momentum region within the hole in addition to counter rotating vortex structure in the cross stream.
Analysis of cooling phenomenon of water with the supercooled
Chu, Mi-Seon ; Yun, Jeong-In ; Kim, Jae-Dol ; Kamata, Yoshinobu ; Kato, Toyofumi ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 862~872
DOI : 10.22634/KSME-B.19184.108.40.2062
Ice formation in a horizontal circular cylinder has been studied numerically. From the numerical analysis results, it was found that there were three types of freezing pattern and that freezing phenomenon was affected largely by density inversion and cooling rate. The type of freezing pattern largely depends on the secondary flow which is generated by density inversion. When supercooling energy is released before the development of the secondary flow, the annular ice layer grows. If the energy is released when the secondary flow is considerably developed and the supercooled region is removed to the upper half part of the cylinder, an asymmetric ice layer grows. And if the energy is released after perfect development of the secondary flow, instantaneous dendritic ice formation over the full region occurs. Furthermore, this secondary flow was found to have an effect on heat transfer characteristics. The heat transfer rate becomes small at the instant when the secondary flow is generated, but becomes large with the development of the flow. It's concluded that for the facilitation of heat transfer it is desirable to keep water in liquid phase until the secondary flow is perfectly developed. This study gave an instruction of performance improvement of capsule type ice storage tank.
Simulation of Three-Dimensional Turbulent Flows around an Ahmed Body-Evaluation of Turbulence Models-
Myeong, Hyeon-Guk ; Jin, Eun-Ju ; Park, Hui-Gyeong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 873~881
DOI : 10.22634/KSME-B.19220.127.116.113
A numerical simulation has been carried out for three-dimensional turbulent flows around an Ahmed body. The Reynolds-averaged Navier-Stokes equation is solved with the SIMPLE method in general curvilinear coordinates system. Several k-.epsilon. turbulence models with two convective difference schemes are evaluated for the performance such as drag coefficient, velocity and pressure fields. The drag coefficient, the velocity and pressure fields are found to be changed considerably with the adopted k-.epsilon. turbulence models as well as the finite difference schemes. The results of simulation prove that the RNG k-.epsilon. model with the QUICK scheme predicts fairly well the tendency of velocity and pressure fields and gives more reliable drag coefficient. It is also demonstrated that the large difference between simulations and experiment in the drag coefficient is due to relatively high predicted values of pressure drag from vertical rear end base.
Non-uniform wall temperature effect of the flow and heat transfer of a hot circular air jet impinging on a circular cylinder
Hong, Gi-Hyeok ; Gang, Sin-Hyeong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 882~890
DOI : 10.22634/KSME-B.1918.104.22.1682
A buoyant jet flow impinging on a circular cylinder is investigated including heat conduction through the cylinder. Temperature and flow fields are obtained by an iterative method, and the effects of the non-uniform wall temperature on the flow and heat transfer are analyzed. Effects of three-dimensionality and the traversing of the jet are also included. Nusselt number over the cylinder surface for the conjugate case is relatively small as compared with the constant wall temperature case due to the small temperature gradient. As the conductivity of the cylinder becomes lower, Nusselt number decreases due to the reduced temperature gradient. Increasing jet traversing speed causes the surface temperature of the cylinder to decrease, which increases local Nusselt number over the surface.
Turbulent flow in annuli depending on the position of roughness
An, Su-Hwan ; Kim, Gyeong-Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 891~899
DOI : 10.22634/KSME-B.1922.214.171.1241
This paper presents the results of a detailed experimental examination of fully developed asymmetric flows between annular tubes with square-ribbed surface roughness. The main emphasis of the research has been on establishing the turbulence structure, particularly in the central region of the channel where the two dissimilar wall flows interact. Measurements have included profiles of time mean velocities, turbulence intensities, turbulent shear stresses, triple velocity correlations, skewness, and flatness. The region of greatest interaction is characterized by strong diffusional transport of turbulent shear stress and kinetic energy from rough toward the smooth wall region, giving rise to an appreciable separation between the planes of zero shear stresses depending on positions of roughness on the walls.
A hypercube + + approach for multiblock structured grids
Park, Sang-Geun ; Lee, Geon-U ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 900~910
DOI : 10.22634/KSME-B.19126.96.36.1990
Multiblock structured grids are, to a large extent, capable of filling up topologically complex flow domains in an efficient way. The proposed approach enables to use different flow models in each different block and the easy incorporation of different grid refinement strategies for different blocks. Furthermore, it may be expected that this multiblock structured approach will naturally lead to the parallel executions of calculations per block on different vector processors. In this paper, the hypercube + + structure is proposed for topological informations on multiblock grids and the B-spline volume for geometrical informations. Three samples of the-three dimensional results are presented to demonstrate the capabilities of the present approach.
A study on the three dimensional turbulent flow analysis of wake flow behind rotating blade row between hub and midspan
No, Su-Hyeok ; Jo, Gang-Rae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 911~918
DOI : 10.22634/KSME-B.19188.8.131.521
The turbulent viscous wake flows behind a single airfoil, two-dimensional stationary blade row and three-dimensional rotating blade row were calculated, and the numerical results were compared with experimental ones. The numerical technique was based on the SIMPLE algorithm using three turbulent closure models, standard k-.epsilon. model(WFM), low Reynolds number k-.epsilon. model(LRN) and Reynolds stress model (RSM). In the case of a single airfoil, WFM, LRN and RSM presented fairly good velocity distributions in the wake compared with experimental data. In the case of the stationary blade row, LRN and RSM presented better results than WFM for wake velocity distribution, and especially LRN showed best results among these three turbulent models. In the case of the rotating blade row, WFM and LRN showed fairly good agreement with experimental data of the three-dimensional velocity component distributions in the range from hub to mid span region. LRN was also superior to WFM in accuracy of prediction for the wake velocity distribution as same with the cases of a airfoil and the stationary blade row.
Time-dependent natural convection in a glass melting furnace
Im, Gwang-Ok ; Lee, Gwan-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 919~927
DOI : 10.22634/KSME-B.19184.108.40.2069
The main purpose of this study is to determine bifurcation as the primary instability of a glass melting furnace. Steady-state and unsteady characteristics of natural convection in the partially open cavity as appeared in a glass melting furnace is investigated by using numerical analysis. Three types of convection, such as steady laminar, unsteady periodic or unsteady quasi-periodic convection may occur according to the temperature difference between upper two isothermal surfaces along the depth of cavity in a glass melting furnace. In the temperature difference of 150-900 K between batch and free surface, the larger the temperature difference, the weaker the convection strength and unsteadiness. Since the glass viscosity is increasing exponentially in the lower temperature, the batch freezes the thermofluidic field especially below the surface of it. If the depth of cavity is 0.5 m, the bifurcation to time-dependent natural convection may occur in the range of 60-650 K. If that is 1.0 m, it may occur in the whole range of temperature difference.
Rotor fan effects on end winding heat transfer in totally enclosed fan cooled induction motor
Yun, Myeong-Geun ; Go, Sang-Geun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 928~938
DOI : 10.22634/KSME-B.19220.127.116.118
The end winding is an important part in induction motor for thermal analysis. But there is little information on the heat transfer coefficient of that surfaces because of geometrical complexity. So our experimental object is to know the heat transfer coefficient of end winding and find the optimum design parameter of rotor fan. Carbon coated papers were used for a uniform heat generating surfaces which were easy to fabricate. The experiments of some parameters were performed as varying rotation speed of rotor fan. We obtained the local and average Nusselt number of the end winding surfaces by correcting radiation and conduction losses errors. The results showed that the average Nusselt number increased with rotor fan blade number and width but decreased with end winding length. However, the increasing limits existed in the case of rotor fan width and blade number. So optimum design value were obtained for rotor fan width and blade numbers.
Skin friction measurements using He-Ne laser
Choe, Seung-Ho ; Lee, Yeol ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 939~947
DOI : 10.22634/KSME-B.1918.104.22.1689
An experimental study of the skin friction measurement in a turbulent boundary-layer has been carried out. The skin friction measurements are made using the laser interferometer skin friction (LISF) meter, which optically detects the rate of thinning of an oil applied to the test surface. This technique produces reliable skin friction data over a wide range of flow situations up to 3-dimensional complicated flows with separation, where traditional skin friction measurement techniques are not applicable. The present measured data in a turbulent boundary-layer on a flat plate using the LISF technique shows a good comparison with the result from the previous velocity profile techniques, which proves the validity of the present technique. An extensive error analysis is carried out for the present technique yielding an uncertainty of about .+-.8%, which makes them suitable for CFD code validation purposes. Finally the measurements of the skin friction in a separated region after a surface-mounted obstacle are also presented.
A study on the effects of intake port eccentricity and a partition between the two intake ports on the in-cylinder swirl characteristics in a valve diesel engine
Lee, Ji-Geun ; Gang, Sin-Jae ; No, Byeong-Jun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 7, 1997, Pages 948~961
DOI : 10.22634/KSME-B.1922.214.171.1248
The effects of intake port eccentricity and a partition between the two intake ports on the incylinder swirl characteristics in a 4 valve diesel engine having the two intake ports, one is a helical intake port and the other is a tangential intake port, were investigated by using the impulse swirl meter(ISM) in a steady flow test rig. Mean flow coefficient (
, swirl ratio (
) and the mass flowrate through the two intake ports with and without intake port partition were measured. The results showed that the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by valve eccentricity ratio (
) and the existence of an intake port partition between the two intake ports. Mean flow coefficient (
) increases and swirl ratio (
) decreases in case of being the partition between the two intake ports. And also the mass flowrate through the tangential intake port is 19.0% and 7.7% more than that of the helical intake port in case of the two intake ports with and without partition respectively.ively.