• 한국추진공학회지
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• 제6권4호
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• pp.1-6
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• 2002

소형 연소기의 냉각 유로 설계를 위하여 열전달 및 냉각 유로의 구조해석을 수행하였다. 연소기의 고온가스에서의 열전달에 관한 2차원 해석을 수행하여 연소실 벽으로의 열유속을 예측한 다음 이를 3차원 해석을 위한 열경계 조건으로 적용하였다. 위 방법으로 예측한 열 유속은 기존의 경험식과 비교하여 검증하였으며 냉각수의 유량에 둔감한 것으로 판명되어 냉각 조건이 변화하더라도 동일한 열경계 조건을 사용할 수 있었다. 단일 냉각 유로에 대한 3차원 해석을 수행하여 연소실 벽의 최대온도 변화를 예측하였으며 이는 재사용 연소기 개발에 적용될 것이다. 냉각 유로의 정적 구조 해석을 통해 응력 분포와 구조 안전성을 예측하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.149-152
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• 2008

30톤급 액체로켓엔진 실물형 연소기의 형상에 따른 연소특성속도에 대한 연구를 수행하였다. 본 연구에서 연소기의 형상은 연소기 헤드와 분리가 가능한 내열재 및 채널 냉각형 연소실(${\varepsilon}$=3.2), 그리고 일체형인 팽창비가 각각 3.5와 12인 재생냉각형 연소기이다. 연소압력은 약 53${\sim}$60 bar 그리고 추진제 유량은 약 89 kg/s이고, 적용된 분사기는 리세스수가 1.0인 동축 와류형이다. 설계점 연소시험에서 팽창비가 12인 일체형 재생냉각 방식의 연소기가 가장 큰 연소특성속도를 보였는데 이는 추진제인 케로신이 분무되기 전 챔버 냉각으로 인한 온도 상승에 따른 엔탈피의 증가 및 연소압력의 증가에 기인한 것이다.

• 한국분무공학회지
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• 제10권2호
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• pp.1-9
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• 2005

An experimental study was carried out to obtain the fundamental data about the effects of radical ignition on premixture combustion. A CVC(constant volume combustor) divided into the sub-chamber and the main chamber was used. Numerous narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in tile sub-chamber derives the simultaneous multi-point ignition in the main chamber. We have examined the effects of the sub-chamber volume, the diameter and number of passage holes, and the equivalence $ratio({\Phi})$ on the combustion characteristics by means of burning pressure measurement and flame visualization. In a CVC, the overall burning time including the ignition delay became very short and the maximum burning pressure was slightly increased by the radical ignition(RI) method in comparison with those by the conventional spark ignition(SI) method. Combustible lean limit by RI method is extended by ${\Phi}=0.25$ compared with that by SI method. Also, In cases of charging the number and the diameter for the fixed total cross section of the passage holes, combustion period increased significantly at a sub-chamber with a single hole, but those of the other conditions had almost a similar tendency in the sub-chamber with 4 or more holes. regardless of equivalence ratio. Therefore, it was Proved that a critical cross section exists with the number of passage holes.

• 한국전기전자재료학회논문지
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• 제29권8호
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• pp.510-515
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• 2016

Single-chamber solid oxide fuel cells (SC-SOFCs) consist of only one gas chamber, in which both the anode and the cathode are exposed to the same fuel-oxidant mixture. Thus, this configuration shows good thermal and mechanical resistance and allows rapid start-up and -down. In this study, the unit cell consisting of $La_{0.8}Sr_{0.2}MnO_3$ (cathode) / $Zr_{0.84}Y_{0.16}O_{2-x}$ (electrolyte) / $Ni-Zr_{0.84}Y_{0.16}O_{2-x}$ (anode) was fabricated and its electrochemical property was investigated as a function of temperature and the volume ratio of fuel and oxidant for SC-SOFCs. Impedance spectra were also investigated in order to figure out the electrical characteristics of the cell. As a result, the cell performance was governed by the polarization resistances of the electrodes. The cell exhibited an acceptable cell-performance of $86mW/cm^2$ at $800^{\circ}C$ and stable performance for 3 hs under 0.7 V.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.469-473
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• 2010

본 연구에서는 빠른 후퇴율을 갖는 용융성 고체연료를 사용한 연소 실험을 수행하여 연소 중 압력진동 특성을 분석하고 연소 불안정의 위해성을 검토하였다. 빠른 후퇴율을 가지는 용융성 고체연료는 기존의 폴리머계 연료에 비해 압력 진동의 진폭이 증가하였다. 그러나 연료 그레인 내부 직경의 증가가 연소실 압력 진동의 증폭을 제한하여 급격한 연소 불안정은 거의 일어나지 않았다. 축방향 인젝터를 사용하는 경우 연료 연소량의 큰 증가와 예연소실에서의 와류 진동이 큰 압력 진동을 유발하였다.

• 한국자동차공학회논문집
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• 제3권5호
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• pp.122-134
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• 1995

The present study was investigated combustion characteristics of methane-air mixtures at stratified charge in a constant volume combustion chamber. The main results obtained from this study can be summarized as follows. In case of ${\phi}_s=1.0$, total burning times greatly affected rather than initial time of pressure increase and maximum combustion pressure. In case of ${\phi}_t=1.0$, initial time of pressure increase and total burning times were affected considerably in comparison with the case of ${\phi}_s=1.0$. Also, even the very lean mixture which total equivalence ratio is ${\phi}_t=0.69$(${\phi}_s=1.0$, ${\phi}_m=0.65$), by changing configuration of the critical passage-hole and using a stratified mixture, it is possible to decrease substantially the initial time of pressure increase. total burning times and NOx concentration without deteriorating combustion characteristics such as maximum combustion pressure, rate of heat release etc. in comparison with the use of single chamber(in case of ${\phi}=1.0$) only. Specifically, our trends were revealed remarkably in the case of Type D which is reduced a flame contact area of sub-chamber side of the passage-hole.

• 한국기계가공학회지
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• 제18권5호
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• pp.1-8
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• 2019

Breath analysis using a portable device is better than the classical breath analysis system in terms of installation and operation. There is an increasing need to develop cost-effective equipment for testing gas sensors from the viewpoint of functionalities that can be applied applicable to portable devices. In the present study, an economical gas chamber for in-situ gas measurement is implemented with a single gas chamber without using expensive gas storage and control equipment; the gas response characteristics are analyzed using the above-described chamber. The main features of the implemented gas chamber are simple injection procedure, improved gas diffusion, easy measurement and cleaning, support for low-power mode measurement function for portable devices, and open source platform. Moreover, an analysis of gas response characteristics based on changes in sensor voltage show that the sensitivity and 90% response time are affected by the sensor voltage. Furthermore, the sensitivity graph has an inflection point in a specific range. The gas sensor applied in this study showed fast response speed and high sensitivity for sensor voltages of 3.0-3.5 V, regardless of the concentration of acetone gas, the target gas used in this study.

• International Journal of Automotive Technology
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• 제2권3호
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• pp.85-91
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• 2001

Characteristics of methane direct-injection spark-ignition stratified combustion in lean hydrogen mixture were analyzed both in a single cylinder engine and in a constant volume combustion chamber. Combustion pressure and Instantaneous combustion chamber wall temperature during the combustion process were measured with a thin-film thermocouple and used in analyses of combustion and cooling loss. Results in this research show that the premixed hydrogen increases cooling loss to combustion chamber wall while achieving combustion promotion, and the combustion system is effective especially in lean mixture conditions. Analysis of flame propagation was also done with Schlieren photography in the constant volume combustion chamber.

• 한국항공운항학회지
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• 제15권4호
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• pp.17-23
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• 2007

This paper describes the flow and performance characteristics inside the post-chamber of the multi-port hybrid rocket motor. Using the computational fluid dynamics (CFD) technique, the non reactive compressible flow fields in the downstream of the fuel grain was numerically calculated. The motor performance obtained from computational results were in agreement with that conducted by the ground motor firing test. Besides, the flow field characteristics inside the post-chamber were discussed under different port numbers (1 port and 3 ports) of the fuel grain. The flow pattern showed that the performance of multi-port hybrid rocket motor having three grain ports is higher than that of the single-port one due mainly to the difference of incoming mass flow rate irrespective to the pressure field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1011-1014
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• 1999

An on-board monitoring system for an automobile emission gas has a test chamber remote from the automobile's engine exhaust gas stream: apparatus for supplying the chamber with sampled exhaust gases. A single hydrocarbon sensor exposed to the exhaust gas in the chamber to render a signal responsive to the hydrocarbon. The conductive ions in emission gas was checked by the HC sensor in test chamber. A preferred application includes hydrocarbons in an automotive exhaust gas stream by exposing a transition porous alumina($Al_{2}O_{3}$) ceramic based sensor to the same exhaust gas stream. By combining the electrical signal, a measure of hydrocarbons can be provided.