• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.69-73
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• 2009

Combustion test results of 1/2.5-scale thrust chamber for 75tonf-class liquid rocket engine were described. The thrust chamber has chamber pressure of 60 bar, propellant mass flow rate of 89 kg/s, and nozzle expansion ratio of 12. The combustion tests were conducted to verify the combustion performance, the regenerative cooling performance and the durability of thrust chamber at design point condition, and then were performed to confirm the operation and the combustion performance at low combustion pressure condition. All the tests had been successfully executed without the damage of the hardware. These test results present a possibility of hot firing test at low combustion pressure condition, and can be used as fundamental data to predict the combustion performance at design point condition for 75 tonf thrust chamber.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.33-38
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• 2012

The aim of this experimental study was to analyze the effect of the shape parameters and chamber pressure of a land-based oscillating water column (OWC) in regular incident waves. The magnitude of the free surface elevations inside the chamber was measured in a two-dimensional wave tank for various chamber skirt drafts and bottom slope angles. The surface elevations were also measured under both open chamber and partially open chamber conditions. From these measurements, the optimum shape of the OWC device could be predicted for the maximum wave energy conversion efficiency. It was found that the resonance frequency of the OWC system associated with incident waves moved toward the long wave region with increments of the draft of the chamber skirt and bottom slope. The behavior of the free surface elevation inside the chamber was also found to be dependent on the chamber pressure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.4
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• pp.233-239
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• 2002

The technology of joining BT (Biotechnology) with NT (Nanotechnology) must be rapidly arranged in 21c. Specially, the technical value is important more and more since the research about MEMS, which synthesizes BT and NT, is variously proceeding on the wide fields. This study by simulation shows the Fluid-Flow within micro Pump used in Bio-MEMS technology through Fluent Program. Namely, this experiment shows the most suitable external conditions and Pump Model within micro Pump by observing the flow of fluids as to the conditions of pressure, temperature and Model when the Fluid flows within micro Pump. We saw the variousness of pressure and temperature as to the existence of Chamber through examining by reference of Fluid-Flow. In the case of the existence of Chamber, the variousness of pressure and temperature is less than in the case of the non-existence of Chamber. By this simulation, we know that the Pump, which has a Chamber, affects the Fluid-Flow less than that. So we can say that it is necessary for us to design the Pump which has a Chamber.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.72-78
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• 2012

The position effect of the solid propellant in the combustion chamber on the decrease of the differential pressure has been investigated using the IBcode. Generally the metallic cartridge or CCC (combustible cartridge case) are used to load the propellant of the gun propulsion system. The position of the cartridge(propellant) is, therefore, a major factor for the interior ballistics in case the combustion chamber is larger than the cartridge. In this study, three different positions in the empty space of the chamber have been considered. As results, the case of the propellant located in the region near the base and breech has shown that the negative differential pressure and the difference between the breech pressure and the base pressure are much higher than those of the case of the propellant located in the center of the chamber. The case of the propellant in the center of the chamber is, therefore, more profitable to improve the performance of the interior ballistics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.236-241
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• 2011

The position effect of the solid propellant in the combustion chamber on the decrease of the differential pressure has been investigated using the IBcode. Generally the metallic cartridge or CCC (combustible cartridge case) as the propellant for the cannon has been loaded. The position of the propellant(cartridge) is, therefore, a major factor for the interior ballistics in case the combustion chamber is larger than the cartridge. In this study, three cases of the existence of empty space in the chamber has been considered. As results, the case of the propellant located in the region near the base and breech has shown that the negative differential pressure and the difference between the breech pressure and the base pressure are much higher than those of the case of the propellant located in the center of the chamber. The case of the propellant in the center of the chamber is, therefore, more profitable to improve the performance of the interior ballistics.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.6
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• pp.34-42
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• 2022

A correlation between propellant supply condition and chamber pressure in GCH₄-LOx small rocket engine was explored and hot-firing tests were conducted to analyze the engine performance characteristics according to the equivalence ratio variation at a constant chamber pressure. Correlation studies have shown that chamber pressure is linearly proportional to oxidizer supply pressure. As a result of the test, the thrust, specific impulse and characteristic velocity that are the main performance parameters of a rocket engine, were found to be enhanced as the equivalence ratio starting from a fuel-lean condition approached the stoichiometric ratio, but the efficiencies of characteristic velocity and specific impulse were on the contrary, in their dependency on the equivalence ratio.

• Journal of Drive and Control
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• v.15 no.4
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• pp.11-16
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• 2018

Pilot operated control valve for $CO_2$ refrigerant is a valve that can perform various functions according to the user's intention by replacing pilot units, widely used for flow rate, pressure, and temperature control of refrigeration and air conditioning systems. In addition, $CO_2$ refrigerant, that requires high pressure and low critical temperature, can be installed and used in all positions of the refrigeration system, regardless of high or low pressure. In this paper, response characteristics are modeled and analyzed based on behavior of the main piston of the pilot-operated control valve. Although various factors influence operation of the main piston, this paper analyzes the effect of equilibrium pressure depending on valve installation position and application, and inlet and outlet orifice size of the load pressure feedback chamber to determine feedback characteristics of the main piston. As a result, it was possible to quantitatively analyze the effect of change in equilibrium and load pressure feedback chamber flow path size on the change in main piston dynamic and static characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.237-243
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• 2010

In this study, the effect of the shape of a pintle(obstacle) on thrust-modulation performance and drag in a pintle rocket was investigated by a cold flow test and by computational fluid dynamics. Pintle movement caused a monotonic increase in the chamber pressure. Thrust generated by the pressure distribution on the pintle body was linearly changed to the chamber pressure, and this thrust was greater than that generated by the nozzle-wall pressure distribution. Because the shock pattern in the nozzle changes with the shape of the pintle body and pressure ratio, the thrust generated by the nozzle-wall pressure is not directly affected by chamber pressure. The drag due to the pintle(obstacle) can be minimized for a fully linear pintle shape, regardless of chamber pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.970-972
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• 2011

The vacuum chamber pressure was investigated according to the second throat exhaust diffuser entrance diameter. The sizes of diffuser entrance were changed three cases, and each case was computed by using CFD. Also in order to relatively compare the vacuum chamber pressure the Euler equation was adopted. According to the results, as the size of diffuser entrance was increased it was observed that the vacuum chamber pressure was decreased.

• Journal of the Korean Society of Combustion
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• v.13 no.3
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• pp.9-16
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• 2008

In this study, a cylindrical constant volume combustion chamber is used to investigate the flow and combustion characteristics of methane-air homogeneous mixture under various initial charge pressure, excess air ratios and ignition times. The flame and burning speed, mean gas speed are calculated by numerical analysis to analyze the combustion characteristics. It is found that the mean gas velocity during combustion has the maximum value around 300 ms and then decreased gradually on the condition of 10000 ms, and that the combustion duration is shorten and flame speed and burning velocity have the highest value under the conditions of an excess air ratio 1.1, an initial charge pressure of 0.2 MPa and an ignition time of 300 ms in the present study. And, the initial pressure and burning speed are in inverse proportion, so that it is in agreement with Strehlow who presented that the initial pressure and burning speed are in inverse proportion when the burning speed is under 50cm/s.