• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.327-330
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• 2006

Numerical simulations were carried out to investigate the base drag characteristics of a base bleed projectile with a central propulsive jet by considering the base homing process. Overall fluid dynamic process is modeled by Wavier-Stokes equations for reacting flows with two-equation $k-\omega$ SST turbulence closure. The combustion process is modeled by finite-rate chemistry with a given partially burned exit condition of the BBU (base-bleed unit). Besides the demonstrating the capability of the present CFD solver for the base drag and the interaction of the base flow with a rocket plume, present study gives an insight into the fluid dynamics and the combustion process of the hybrid-propulsion projectile.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.37-45
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• 2017

Extinguishment of a burning solid propellant is difficult, however, dynamic extinction can be induced by fast depressurization in combustion chamber. This paper describes experimental results for the characteristics of extinguishment for composite solid propellants by rapid depressurization. For various composition of solid propellants, depressurization ratio which can induce extinguishment of combustion was obtained using experimental apparatus with rupture disk. Experimental results showed that particle size of oxidizer, mixing ratio of oxidizers with different particle size and contents of metal fuel can affect on the characteristics extinguishement for solid propellant.

• Clean Technology
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• v.20 no.4
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• pp.398-405
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• 2014

In the treatment of spent high energetic materials, the issues such as environmental pollution, safety as well as working capacity should be carefully considered and well examined. In this regard, incineration has been recommended as one of the most promising processes for the disposal of such explosives. Due to the fact that high energetic materials encompass various types and their different characteristics, the technology development dealing with various materials is not an easy task. In this study, rigorous modeling and dynamic simulation was carried out to predict dynamic physico-chemical phenomena for research department explosive (RDX). Plug flow reactor was employed to describe the incinerator with 263 elementary reactions and 43 chemical species. Simulation results showed that safe operations can be achieved mainly by controlling the reactor temperature. At 1,200 K, only thermal decomposition (combustion) occurred, whereas increasing temperature to 1,300 K, caused the reaction rates to increase drastically, which led to ignition. The temperature further increased to 3,000 K which was the maximum temperature recorded for the entire process. Case studies for different operating temperatures were also executed and it was concluded that the modeling approach and simulation results will serve as a basis for the effective design and operation of RDX incinerator.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.136-148
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• 1999

Detailed mathematical models of hybrid drivertrain components are presented and numerical simulations are carried out to analyze the shift characteristics and to improve the driving comfortability when the hybrid drivetrain is applied at the vehicle . Theoretical results are compared with experimental ones from the dynamometer as same condition in order to prove the appropriateness of modeling . Adding the vehicle body modeling, included in the suspension and the engine mount, it is possible to predict the dynamic behavior and shift characteristics more actually when shifts are occurred by automated manual transmission(AMT). these additional results are also compared with the same simulation ones of internal combustion engined vehicle equipped conventional manual transmission. Hence, it can be expected that the hybrid vehicle with AMT has a good shift quality.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.109-115
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• 2004

The micro turbo generator is new portable power source based on the Brayton cycle, which consists of a compressor, a turbine, a generator, and a combustion chamber. In this paper, the thermodynamic analysis was performed to find the required condition for hundreds watts power in the micro turbo generator, and also the rotordynamic stability was predicted using the numerical analysis of air foil bearings which support the micro turbo generator. By experimental works, the rotordynamic stability of the micro turbo generator with foil bearings was verified. While various transient dynamic situation, the micro turbo generator had stable performances. From the result, it was demonstrated that air foil bearings could be adapted to the micro turbo generator as a excellent lubrication element.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.619-625
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• 2015

Swirl injectors are widely used for Liquid Rocket Engine(LRE) as fuel injection system and following researches are also being carried out throughout the world. Especially, solving combustion instability problem is essential for every type of LREs. In this study, cold test was carried out for open type swirl injector as a fundamental research to solve combustion instability problem. Pressure fluctuation was applied to the inlet flow coming into the injector and the following response characteristics were observed. The effect of swirl chamber geometry was also studied by changing both swirl chamber length and diameter.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.269-273
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• 2005

A practical, 30-tonf-class fullscale thrust chamber has been combustion tested using real propellants for the first time in the domestic technology scene. The very first combustion test was conducted at a low mass flow rate condition for the preliminary assessment of any problems associated with its function and performance while reducing risks from a high chamber pressure never achieved before. A test for the design condition achieved through a low-pressure stage shows stable characteristics of all the static pressures and thrust. Dynamic pressures measured in the manifolds and the chamber did not reveal any distinct wave coupled to a specific frequency and their intensities reside in the allowable range. Moreover, it is encouraging to find no physical failures with a thrust chamber hardware.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.8
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• pp.599-606
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• 2019

The pulse gun device is designed to identify the transverse pressure wave propagation/damping mechanism into the combustion flow field and in the combustion chamber according to the arrangement of multiple injectors. The manufactured pulse gun was tested to verify operability at the target combustion pressure and control of the pressure wave intensity. Gas nitrogen was used to pressurize the high-pressure tube and an OHP film of $100{\mu}m$ thickness was used for the diaphragm. To check the speed and intensity of the pressure waves, the dynamic and static pressure were measured using the pressure transducer. The performance test confirmed that the manufactured pulse gun can generate pressure waves with transverse characteristics that can be controled for strength depending on the supply pressure.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.44-51
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• 2017

An experimental results on the dynamic characteristics of hydrocarbon/air premixed flames with ultrasonic standing waves are presented and compared. Images of the propagating flames were acquired by using a high-speed camera, and the flame behavior of methane/air and propane/air premixed flame were closely scrutinized through the image post-processing. At the fuel-lean conditions, the flame propagation velocity increased due to the intervention of the ultrasonic standing wave and vice versa at the fuel-rich conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2280-2285
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• 1993

Many items, as internal pressure, thrust, temperature, strain, etc. are measured in Ground Firing Test (GFT) of rocket motors. But these items are influenced by various phenomena occurred during propellant combustion. In this study, natural frequencies of motor itself and system(motor+loadcell) on Stand were measured. Also motor responses were measured during burning and analyzed so that the vibration characteristics occurred during GFT and the causes and characteristics of vibration signal appearing on thrust curve were identified.