• Fire Science and Engineering
• /
• v.19 no.4 s.60
• /
• pp.18-25
• /
• 2005

In this study, numerical analysis of two-dimensional unsteady natural convection of air in a square enclosure heated from below, was performed as a basic research of fire science. SIMPLE algorithm was used to the pressure term of momentum equations in the numerical analysis. The numerical analysis were studied for the two model cases and two heat conditions, respectively, which are different with insulation of enclosures and position of heat applied. Also, the ceiling temperatures of enclosure were measured to compare the accuracy of numerical analysis, and it is found that the temperature predicted by numerical analysis were agreed well with the measurements. Streamline and isotherm of the each model case were acquired for each time step.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.22 no.3
• /
• pp.97-108
• /
• 2018

It is definitely important to measure thrust during ground test when developing air-breathing engine, and in case of air-breathing engine, gross thrust should be calculated considering not only the measured thrust but also the force induced by the air flow of engine intake. Also, side thrust like yaw and pitch should be measured and analyzed using multi-component thrust measurement system. Engine performance was accurately evaluated by calculating the gross thrust of air breathing engine precisely which is analyzed from below serial procedure: labyrinth seal isolation, 1-axis gross thrust calculation, develop multi-component thrust measurement system, and side thrust analysis.

• Solar Energy
• /
• v.12 no.3
• /
• pp.70-83
• /
• 1992

The interaction between the surface radiation and the mixed convection transport from an isolated thermal source, with a uniform surface heat flux input and located in a rectangular enclosure, is stuied numerically. The enclosure simulates a practical system such an air cooled electric device, where an air-stream flows through the openings on the two vertical walls. The heat source represents an electric component located in such an enclosure. The size of this cavity is $0.1[m]{\times}0.1[m]$. The inlet velocity is assumed as 0.07[m/s] and the inlet temperature is maintained as $27^{\circ}C$. The inflow is kept at a fixed position. Laminar, two dimensional flow is assumed, and the problem lies in the mixed convection regime, governed by buoyancy force and surface readiation. The significant variables include the location of the out-flow opening, of the heat source and the wall emissivity. The basic nature of the resulting interaction betwwn the externally induced air stream and the buoyancy-driven flow generated by the source is investigated. As a result, the best location of the heat source to make the active heat transfer is 0.075[m] from the left wall on the floor. The trends observed are also discussed in terms of heat removal from practical systems such as electric circuitry.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.2
• /
• pp.223-232
• /
• 2018

Bird screen meshes are installed at the air inlet and outlet ducts of spent fuel storage casks to inhibit the intrusion of debris from the external environment. The presence of these screens introduces an additional resistance to air flow through the ducts. In this study, a porous media model was developed to simplify the bird screen meshes. CFD analyses were used to derive and verify the flow resistance factors for the porous media model. Thermal analyses were carried out for concrete storage cask using the porous media model. Thermal tests were performed for concrete casks with bird screen meshes. The measured temperatures were compared with the analysis results for the porous model. The analysis results agreed well with the test results. The analysis temperatures were slightly higher than the test temperatures. Therefore, the reliability and conservatism of the analysis results for the porous model have been verified.

• Journal of Energy Engineering
• /
• v.25 no.2
• /
• pp.86-93
• /
• 2016

The existence of high temperature equipment such as steam pipe, deaerator, steam storage tanks and main steam stop valves makes relatively higher workplace temperature in a power plant of the turbine building. In order to cool down the air temperature in the turbine building, the outside air flow with lower temperature passes through the window and the hotter air in the building is extracted to the outside by installing the ventilation fan on the roof. Nevertheless, higher temperature regions near the high temperature equipment still exist in the turbine building and additional fans for the temperature reduction in the higher temperature region should be examined for the optimal location and mass flow rate. The purpose of the present study is to suggest the optimized location and capacity of the additional ventilation fans for a comfortable working environment. From the present study, it has been elucidated that the additional ventilation fans might be located near the high temperature deaerator and it could reduce the mean temperature in the turbine building by $3.0^{\circ}C$ and the temperature near the deaerator could be reduced by $4.2^{\circ}C$.