• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.737-744
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• 2011

The success of continuous aluminum powder combustion with steam plasma is different from hydrocarbon ignition source. Ignition characteristics of aluminum powder with high temperature thermal plasma is studied with oxidizer-free environment. Experiment with argon plasma has same temperature conditions at 4500 K and particle feeding condition for previous combustion test with steam plasma and swirl combustor. The temperature of the plasma was measured using Optical Emission Spectroscopy method. Ignition characteristics were analyzed by SEM image and EDS. Aluminum powder with plasma has rapid evaporation mechanism contrast to hydrocarbon ignition source. It enhances to aluminum powder effective ignition characteristics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.134-137
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• 2009

Combustion tests of a low thrust rocket engine was performed to get combustion characteristics, which used a high concentrated hydrogen peroxide and kerosene as the oxidizer and fuel. The engine consisted of multi injector(six coaxial swirl injectors), chamber, nozzle and catalyst ignition system. The test was carried out by changing O/F ratio from 3.8 to 11.0. The experimental results showed that combustion efficiency was highest at O/F ratio from 5 to 6 and pressure fluctuations of all the range were lower than 5%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.119-122
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• 2009

The purpose of this study is to design of film-cooling ring for the small thrust rocket engine using green propellants(Hydrogen peroxide and kerosene). Cold flow test was carried out to measure the mass flow rate and atomizing characteristic. Required mass flow rate was obtained from thermal analysis of the engine, and measured flow rate 42.25g/s was in the range of permissible coolant flow rate. With the same mass flow rate, cooling ring with more hole and high velocity shows better spray pattern. The result of thermal analysis, cooling ring has enough cooling performance.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.197-207
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• 2004

The developing Smart UAV in KARI supposes high speed flight as like a conventional plane, as well as vertical takeoff and landing as like a helicopter. Therefore, the air intake system should be designed to provide the sufficient air flow to the engine and the maximum possible total pressure recovery at the engine intake screen over a wide range of flight conditions. For this purpose, we designed the intake system using a pitor type intake model and plenum chamber. In this paper, we designed the intake model and analyzed the performance of designed intake system using the general-purpose commercial CFD code, CFD-ACE+. The analysis results of the total pressure variation and the velocity distribution were illustrated in this paper. The pressure recovery and distortion coefficient at a plane coincident with the compressor inlet were calculated and streamline variation through the intake system was investigated at the worst flight condition as well as the standard flight condition.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.279-282
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• 2002

Recently, gas turbines for power generation adopt multistage DLN(Dry Low NOx) type combustion, where diffusion combustion is applied at low load and, with increase in load, the combustion mode is changed to lean premixed combustion to reduce NOx emissive concentration. However, during the mode changeover from diffusion to premixed flame, unfavorable phenomena, such as flashback, high amplitude combustion oscillations, or thermal damage of combustor parts could frequently occur. In the present study, to apply for the analysis of such unfavorable phenomena, three-dimensional CFD investigations are carried out to compare the detailed flow characteristics and temperature distribution inside the gas turbine combustor before and after combustion mode changeover. The fuel considered here is pure methane gas. A standard $k-{\varepsilon}$ turbulence model with wall function and a P-N type radiation heat transfer model, have been utilized. To analyze the complex geometric effects of combustor parts on combustion characteristics, fuel nozzles, a swirl vane f3r fuel-air mixing, and cooling air holes on the combustor liner wall, are included in this simulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.868-875
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• 2001

The objective of this study is to investigate the average droplet size distributions of a GDI spray by simultaneous fluorescence/scattering image technique. GDI engine is recently very popular because of high engine efficiency and low emissions. However, the injectors must have good spray characteristics because the fuel is directly injected into the cylinder. The fuel mixtures used in this study were 2% of fluorobenzene, 9% of DEMA(diethyl-methyl-amine) and 89% of hexane by volume. The system for obtaining 2-D fluorescence/scattering images of fuel spray was constituted of a laser sheet, a doubling prism, optical filters, and an ICCD camera. Using the ratio of the fluorescence to the scattering intensities, SMD distributions were obtained. SMD measured by the technique was compared with that obtained by PDA. It was found that average droplet size was bigger at spray center in the early stage of injection and at the outer periphery of the spray in the late stage of injection.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.35-41
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• 2014

The wood pellet, which is one of the woody biomass energy, has very high economic efficiency and combustion efficiency during their combustion. The existing pellet burner have many problems such as low combustion efficiency, flame stabilization, ash problem and ignition time etc. We developed cyclonic wood pellet burner aim to 20,000kcal/hr boiler and measured temperature profiles and exhaust gases in order to investigate the flame stability and optimum combustion condition at any air flow conditions. As results, we confirmed the reappearance and the isotropy of the experimental results in the burner. At the first air flow inlet condition of excess air ratio ${\alpha}=0.02$, second air flow $490{\ell}/min$ had the best combustion condition when pellet supplied 30g. This result means that we need much air supply only for the swirling of second air flow. So we tested various second air flux at first air excess air ratio ${\alpha}=0.7$ condition. At this condition, we could find out that we don't need much second air and total air flux compared to the former condition. We will continuously test this work of air flow distribution, and swirl effect of first air flow, and ash elimination.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.4027-4035
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• 1996

Accuracy of gas flow measurements using sonic nozzle and factors which influence on the discharge coefficients of sonic nozzle are investigated with high pressure gas flow standard measurement system. The gas flow measurement system comprises two compressors, storage tank, temperature control loop, sonic nozzle test section, weighing tank, gyroscopic scale and data acquisition system. The experiments are performed at various nozzle throat diameter and inlet pressure. Overall uncertainty of discharge coefficients is estimated to less than .+-.0.2% and most of experimental data fall into this range. Dependence of discharge coefficients on the Reynolds number is good agreement with those suggested in ISO document. The influence of swirl on the discharge coefficients becomes greater as the nozzle throat diameter is enlarged. The discharge coefficient of conical nozzle shows about 4.5% lower discharge coefficients than those of toroidal nozzle, but variation trend with Reynolds number is very similar each other and reproducibility of data is very good.

• Journal of ILASS-Korea
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• v.6 no.2
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• pp.16-21
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• 2001

This paper describes the macroscopic behavior and atomization characteristics of the high-pressure gasoline swirl injector in direct-injection gasoline engine. The global spray behavior of fuel injector was visualized by shadowgraph technique. The atomization characteristics of gasoline spray such as mean diameter and mean velocity of droplets were measured by the phase Doppler particle analyzer system. The macroscopic visualization and experiment of particle measurement on the fuel spray were investigated at 7 and 10 MPa of injection pressure under different spray cone angle. The results of this work show that the geometry of injector was more dominant over the macroscopic characteristics of spray than the fuel injection pressure and injection duration. As for the atomization characteristics, the increase of injection pressure resulted in the decrease of fuel droplet diameter and the atomization characteristics differed as to the spray cone angle. The most droplets had under $25{\mu}m$ diameter and for the large droplets(upper $40{\mu}m$) as the spray grew the atomization presses were very slow. Comparison results between the measured droplet distribution and the droplet distribution functions revealed that the measured droplet distribution is very closed to the Normal distribution function and Nukiyama-Tanasawa's function.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.18-25
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• 2007

제 2세대 직접분사식 가솔린 기관에서 6공 연료분사기의 연료분무특성을 관찰하였다. 실험에 사용한 직접분사식 가솔린 기관은 2개의 흡입밸브와 2개의 배기밸브를 갖는 텀블형 Spray Guided 연소실과 Quartz로 제작된 실린더 라이너와 실린더 헤드 창으로 구성되어 있다. 선회유동을 유도하기 위하여 흡입매니폴드에 선회유동 제어밸브를 부착하였다. 2차원 Mie 스캐터링 기법을 이용하여 연료분사시기, 연료분사압력과 실린더 내 유동 및 냉각수 온도가 연료분무에 미치는 영향을 관찰하였다. 실험결과로는 흡기과정동안 흡기 선회유동은 분사된 연료의 공간적 분포에 크게 작용하였고, 압축과정동안에는 텀블 및 선회유동의 영향이 흡기과정에 비해 크지 않음을 확인하였다. 또한 성층연소를 위해서 압축과정에서 연료를 분사하는 경우 고압의 연료분사압은 분무도달거리의 성장을 촉진시키나 상승하는 피스톤과 이로 인한 실린더 압력의 상승으로 분무도달거리의 성장이 억제됨을 확인할 수 있었다.