• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.272-275
• /
• 2008

One of the important operating factors for the air-fuel pre-mixed conditions in an HCCI engine is an in-cylinder flow. In this study, unsteady in-cylinder air flow characteristics in a diesel engine as a reference engine of an HCCI engine development were numerically analysed. Unsteady flow analyses were conducted with the combination of 3 intake port inlets, then the in-cylinder air flow distribution and swirl ratio results from a case were compared with the results from the other cases.

• Journal of the Semiconductor & Display Technology
• /
• v.17 no.4
• /
• pp.91-96
• /
• 2018

In this study temperature distribution and gas flow inside a planetary type reactor in which a number of satellites on a spinning susceptor were rotating were analyzed using numerical simulation. Effects of flow rates on gas flow and temperature distribution were investigated in order to obtain design parameters. The commercial computational fluid dynamics software CFD-ACE+ was used in this study. The multiple-frame-of-reference was used to solve continuity, momentum and energy conservation equations which governed the transport phenomena inside the reactor. Kinetic theory was used to describe the physical properties of gas mixture. Effects of the rotation speed of the satellites was clearly seen when the inlet flow rate was small. Thickness of the boundary layer affected by the satellites rotation became very thin as the flow rate increased. The temperature field was little affected by the incoming flow rate of precursors.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.28 no.7
• /
• pp.269-274
• /
• 2016

This paper aims to suggest the water curtain installation guideline for prevention of fire spread. The water curtain systems play a role in preventing fire spread which is caused by fire flames and radiation heat release from a fire source. The radiation attenuation ratio is affected by the water droplet size, vertical distance from the nozzle and flow rate. This study suggests the water curtain installation guideline as follows : (1) Investigation of a reference store array (2) Calculation of the number of drencher heads (3) Review of the relationship between droplet size and attenuation factor depending on the height of the drencher head (4) Review of a drencher head array and spray overlapping. The reference traditional market in which a fire compartment is installed using a water curtain can be predicted to have a radiation attenuation ratio of 50%.

• Nuclear Engineering and Technology
• /
• v.52 no.1
• /
• pp.51-58
• /
• 2020

Despite the recent growth of interest in molten salt reactor technology and the crucial role which heat transfer plays in the design of power reactors, specific studies on the design of heat exchangers for the Molten Salt Fast Reactor have not yet been performed. In this work we deliver a preliminary but quantitative analysis of the intermediate heat exchangers, based on reference design data from the SAMOFAR H2020-Euratom project. Two different promising reference technologies are selected for study thanks to their compactness features, the Printed Circuit and the Helical Coil heat exchangers. We present preliminary design results for each technology, based on simplified design tools. Results highlight the limiting effects of the compactness constraints imposed on the fuel salt inventory and the allowed size. Large pressure drops on both flow sides are to be expected, with negative consequences on pumping power and natural circulation capabilities. The small size required for the flow channels also represents possible fabrication issues and safety concerns regarding channel blockage.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2004.11a
• /
• pp.105-105
• /
• 2004

• The KSFM Journal of Fluid Machinery
• /
• v.6 no.1 s.18
• /
• pp.44-50
• /
• 2003

Flow through a turbine flow meter is simulated by solving the incompressible Navier-Stokes equations. The solution method is based on the pseudo-compressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. The equations are solved steadily in rotating reference frames, and the centrifugal force and the Coriolis force are added to the equation of motion. The standard $k-{\epsilon}$model is employed to evaluate turbulent viscosity. Computational results yield quantitative as well as qualitative information on the design of turbine flow meters by showing the distributions of pressure and velocity around the turbine blades.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.573-578
• /
• 2000

Flow through turbine flow meter is simulated by solving the incompressible Navier-Stockes equations. The solution method is based on the pseudocompressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. The equations are solved steadily in rotating reference frames and the centrifugal force and tile Coriolis force are added to the equation of motion. The standard $k-{\varepsilon}$ model is employed to evaluate turbulent viscosity. At first the stability and accuracy of the program is verified with the flow through a square duct with a $90^{\circ}$ bend and on the flat plate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.08a
• /
• pp.366-372
• /
• 1999

The deformation behavior of commercial stainless steels under hot rolling conditions was investigated by means of hot compression tests performed in the temperature range 800$^{\circ}C$ to 1200$^{\circ}C$. The measured flow stress-strain curves were analyzed by using a simple flow stress model. It was found that the reference strength of stainless steels are much higher than that of carbon steel and that nitrogen and molybdenum alloying greatly increases flow stress of austenitic stainless steel. Ferritic and duplex stainless steel showed comparatively low flow stresses. The flow stress model, which correlates the flow stress with temperature and strain rate, was applied to predict roll forces during hot-plate rolling of stainless steels.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.526-529
• /
• 2008

Air Conditioner has become a popular comfort providing device since two decades, whether in an office or home especially for warm and wet climate countries. The RAC (Room Air Conditioner) is widely used in various working spaces and residences. It composed of heat exchager, cross-flow fan, stabilizer, rearguider and blade of diffuser region, etc. In this study, numerical analyses based on the prediction of transient phenomena were carried out to investigate the flow characteristics in the RAC, including the impeller, the rearguider, the stabilizer and the blade of the diffuser region. Using a commercial code, FLUENT, the velocity, pressure and streamlines were obtained with unsteady, turbulent flow and no-slip condition. The angular velocities of impeller are located in the 900 rpm. Turbulent closure was achieved using a standard k-${\varepsilon}$ model. A moving reference frame (MRF) approach was adopted to simulate the flow field generated by impeller in the RAC. Results were graphically depicted with various geometrical configurations and operating conditions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.12
• /
• pp.1898-1904
• /
• 2001

Measurement uncertainty should be evaluated according to ISO/IEC 17025. In Flow measurement area, uncertainty evaluation scheme was applied to the reference flow meter, sonic nozzle. Uncertainty was calculated by evaluating various uncertainty factors affected in flow measurement. The expanded uncertainty(U) of the sonic nozzle was 2.1$\times$ 10$^{-3}$ (confidence level of 95 %). This evaluation example will be useful in flow measurement uncertainty determination of other flow meters.