• Journal of Mechanical Science and Technology
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• v.18 no.10
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• pp.1819-1828
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• 2004

The purpose of this paper is to investigate the effects of slits and swirl vanes on the turbulence augmentation in the flow fields of a gun-type gas burner using an X-type hot-wire probe. The gun-type gas burner adopted in this study is composed of eight slits and swirl vanes located on the surface of an inclined baffle plate. Experiment was carried out at a flow rate of 450 ι/min in burner model installed in the test section of subsonic wind tunnel. Swirl vanes playa role diffusing main flow more remarkably toward the radial direction than axial one, but slits show a reverse feature. Consequently, both slits and swirl vanes remarkably increase turbulence intensity in the whole range of a gun-type gas burner with a cone-type baffle plate.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1890-1901
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• 2022

We have assessed the applicability of the thermal-hydraulic system analysis code, SPACE, to a small modular reactor called SMART. For the assessment, the experimental data from a scale-down integral-test facility, SMART-ITL, were used. It was conformed that the SPACE code unrealistically calculates the safety injection flow rate through the CMT and SIT during a small-break loss-of-coolant experiment. This unrealistic behavior was due to the overprediction of interfacial heat transfer at the steam-water interface in a vertically stratified flow in the tanks. In this study, a special thermal-hydraulic component model has been developed to realistically calculate the interfacial heat transfer when a strong non-equilibrium two-phase flow is formed in the CMT or SIT. Additionally, we developed a special heat structure model, which analytically calculates the heat transfer from the hot steam to the cold tank wall. The combination of two models for the tank are called the special component model. We assessed it using the SMART-ITL passive safety injection system (PSIS) test data. The results showed that the special component model well predicts the transient behaviors of the CMT and SIT.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.97-100
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• 2009

Cold flow and ignition tests were performed for a technology demonstration model of a 75-tonf thrust chamber which is a candidate liquid rocket engine for a next Korea Space Launch Vehicle. The test facility was modified to support the new concepts of the thrust chamber such as ignition system, film cooling and LOx leading supply. The hydrodynamic characteristics of the supply pipelines, thrust chamber and igniter as well as the filling time of the propellants were obtained through the cold flow tests on the LOx and kerosene and the ignition cyclogram was determined using the results. The ignition test was successfully accomplished according to the cyclogram and therefore, a basic information was obtained for further hot firing tests.

• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.405-414
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• 1996

In this paper, the unsteady 2-dimensional turbulent flow model for thermal stratification in a pressurizer surge line of PWR plant is proposed to numerically investigate the heat transfer and flow characteristics. The turbulence model is adapted to the low Reynolds number K-$\varepsilon$ model (Davidson model). The dimensionless governing equations are solved by using the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The results are compared with simulated experimental results of TEMR Test. The time-dependent temperature profiles in the fluid and pipe nil are shown with the thermal stratification occurring in the horizontal section of the pipe. The corresponding thermal stresses are also presented. The numerical result for thermal stratification by the outsurge during heatup operation of PWR shows that the maximum dimensionless temperature difference is about 0.83 between hot and cold sections of pipe well and the maximum thermal stress is calculated about 322MPa at the dimensionless time 28.5 under given conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.4
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• pp.466-475
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• 2003

The gun-type gas burner adopted in this study is generally composed of eight slits and swirl vanes. Thus, this paper is studied to investigate the effect of slits and swirl vanes on the turbulent flow fields in the horizontal plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 $\ell$/min in the test section of subsonic wind tunnel. The axial mean velocity component in the case of burner model with only swirl vanes shows the characteristic that spreads more remarkably toward the radial direction than axial one, it does, however, directly opposite tendency in the case of burner model with only slits. Consequently. both slits and swirl vanes composing of gun-type gas burner play an important role in decrease of the speed near slits and increase of the flow speed in the central part of a burner because the biggest speed spurted from slits encircles rotational flow by swirl vanes and it drives main flow toward the axial direction. Moreover, the turbulent intensities and turbulent kinetic energy of gun-type gas burner are distributed with a fairly bigger size within X/R<0.6410 than burner models which have only slits or swirl vanes because the rotational flow by swirl vanes and the fast jet flow by slits increase flow mixing, diffusion, and mean velocity gradient effectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.417-420
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• 2009

The hot forming process of a CAM for vessel engine was designed by finite element (FE) simulation and experimental analysis. An aim of process design was to achieve the near-net shaped CAM forgings by hot forging process. Based on the compression test results of the low alloy steel, deformation processing map was generated using the superposition approach between the dynamic materials model (DMM) and flow stability and/or instability criteria. From the processing map, the initial heating temperature was determined as $1200^{\circ}C$. FE analysis was simulated to predict the formation of rolling defects and deformed shape with different forging designs. Optimum process design suggested in this work was made by comparing with the CAM for vessel engine manufactured by actual forging process.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.31-34
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• 2007

Performance tests of supersonic exhaust diffuser were conducted by using hot combustion gas for simulating high-altitude environment. The test rig consists of a combustion chamber, a vacuum chamber, water cooling ring and diffuser. Before combustion experiments, the preliminary leak tests were carried out on the liquid rocket engine and diffuser by using high pressure nitrogen(30barg) and a vacuum pump. The leak test results showed that there was no leaks at high pressure and vacuum pressure conditions.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.6
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• pp.21-27
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• 2023

Modern naval ships install an Infra-Red Signature Suppression system (IRSS) in their exhaust pipe to reduce infrared signature emitted to the outside. In addition, naval ships are strategic assets with a very long life cycle, so high reliability of the performance of the equipment on board must be guaranteed. Therefore, equipment such as IRSS is evaluated for performance through model testing at the design stage. A variety of measuring instruments are used in IRSS model testing, and the reliability of these instruments must also be guaranteed. In this paper, a study was conducted to evaluate the reliability of measurement equipment used in IRSS model testing. The test equipment and instruments used were a hot gas wind tunnel, pitot tube, digital differential pressure gauge, thermocouple sensor, and digital recorder. As the fan speed of the hot gas wind tunnel increased, the measurement deviation of the flow decreased, and the temperature output of the thermocouple sensor showed differences in response time and stability depending on the method used.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.2
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• pp.85-91
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• 2017

A wind tunnel test for 1/86 scaled down model of the NREL 5 MW offshore wind turbine was conducted to investigate the wake and flow fields. Deficit of flow speed in the wake region and variations of the turbulence intensity were measured using a hot wire anemometer at rated tip speed ratio of 11.4 m/s and a rotational speed of 1,045 rpm. According to the test results, velocity deficits along both of lateral and vertical directions were recovered within 2 rotor radii downstream from the rotating disc plane. The tip vortices effect was negligible after 5 rotor radii downstream from the rotating plane. Turbulence intensities showed maximum value around the blade tip, and decreased rapidly after one radius apart from the rotating plane, and those values were preserved until 6 rotor radii downstream.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.7
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• pp.567-573
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• 2001

A real-time HVAC system is proposed which implements real-time control of thermal environment for virtual reality. It consists of a pair of hot and cold loops that serve as thermal reservoirs, and a mixing box to mix hot and cold air streams flowing if from loops. Their flow rates are controlled in real-time to meet a set temperature and flow rate. A cascade control algorithm along with gain scheduling is applied to the system and test results shows that the closed-loop response approached set values within 3 to 4 seconds.