• Title/Summary/Keyword: 연소점

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동축형 분사기 분무특성 및 연소의 이론적 모델

  • 원영덕;윤웅섭;김영수;윤경택
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2000.04a
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    • pp.4-4
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    • 2000
  • 일반적인 액체추진제 로켓엔진의 연소는 분사제트의 미립화, 액적의 증발, 기상 추진제의 혼합, 화학반응 등, 일련의 물리적 과정들로 이루어지고, 여기서 특성속도 효율은 크게 분사특성 및 연소의 두 단계에서 결정되게 된다. 액체추진제 로켓엔진에 사용되는 여러 분무형태 중, 동축형 분사기에서는 액상과 기상 제트의 운동량 차에 의해 미립화가 이루어지며, 분무 액적들의 전개와 더불어 분사기 출구를 포함한 전 영역에서 연소가 발생되므로 매우 복잡한 물리적 특성들을 포함하게 된다. 본 연구에서는 기상 연료-액상 산화제의 동축형 분무연소를 JANNAF의 방법을 사용하여 수식화 하였으며, 이를 바탕으로 분무특성과 연소성능 예측을 위한 프로그램을 작성, 분사조건에 의한 분무특성과 그에 따른 연소성능을 계산하였다. 연속, 운동량, 에너지 및 혼합비 방정식의 지배방정식들을 바탕으로 기상 유동을 수식화 하였으며, 별도로 액적의 소산 및 연소과정을 모사하기 위한 별도의 수식들이 추가되었고, 이 식들을 결합하여 액적의 크기, 분포를 포함하는 액체 제트의 미립화 정도를 공간적으로 계산하였다. 미립화 모델의 검증을 위하여 계산 결과를 Reitz의 실험과 Giridharan의 모델 등과 비교하였으며 잘 일치하는 경향을 나타내었다. 또한 동축형 분사기에서의 분무 특성을 예측하기 위해 액체 산소, 기체 수소를 추진제 조합으로 하는 동축형 분무 연소장에서의 제트 길이, 액적의 크기, 액체 제트의 속도를 계산하였다. 계산 결과 액체 제트의 접촉길이는 분사공의 지름이 증가할수록 웨버수가 증가되므로 짧아지는 것으로 관찰되었으며 액적의 크기도 분사공의 지름이 증가할수록 작아지는 경향을 나타내었다. 액체 제트의 속도는 처음에는 일정하게 유지되다가 운동량을 보존하기 위해 가스로부터 운동량을 받아 점차 가속되어지는 것으로 나타났다.본 규격은 키, 총장, 어깨길이, 등길이, 머리길이, 머리둘레, 진동둘레, 목둘레, 가슴둘레, 허리둘레, 배둘레, 엉덩이둘레, 앞품, 뒤품, drop치를 포함하고 있고, 각 규격에서 호칭간 치수 간격도 함께 제시하고 있다. 본 연구 결과에서 보듯, 현행 8규격의 무진복의 각 호칭간 적정 허용범위를 고려해 합리적인 치수체계를 정립한다면 치수에 대한 적합도가 상당히 증가할 뿐 아니라 생산비용도 상당히 감축할 것으로 생각된다.나타났다. 4) 호감적 서비스능력 차원에서 세 독립변수간에 유의한 3원 상호작용이 존재하는 것으로 나타나( $F_{2,228}$=15.62, P<.001) 20대에 적합한 의복 착용시( $F_{2,228}$=3.98, P<.05)와 60대에 적합한 의복 착용시( $F_{2,228}$=16.55, P<.001) 점포유형과 격식차림간에는 유의한 상호작용이 존재하는 것으로 나타났다. 5) 호감을 구성하는 세 요인들이 구매의도에 미치는 영향을 조사한 결과 호감적 인상차원은 29%(P<.001), 호감적 서비스능력차원은 6%(P<.001)의 구매의도를 설명해 주는 것으로 나타났다. 본 연구결과 노년 소비자에게 호감을 주는 판매원의 외모는 구매의도에 영향을 주어 실버의류산업의 이익증대와 밀접한 연관을 갖는 서비스품질의 중요한 요인으로 밝혀졌다.중요한 요인으로 밝혀졌다.로운 단백질 EPSPS가 다른 여러 식물에 이미 존재하고 있는 단백질로서 우리가 이미 이러한 식품을 섭취할 때 이 단백질도 같이 섭취해오고 있었다는 점, 둘째. 이 단백질이 소화액 분해 실험에서 짧은 시간내에 분해가 되었다는 점, 셋째. 재조합 된 콩과 자연 콩이 성분 분석에서 차이를 나타내지 않았다는 점, 네 번째. 쥐를 통한 다양섭취 실험에서 아무런 이상 반응이 없었

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Prediction of Isothermal and Reacting Flows in Widely-Spaced Coaxial Jet, Diffusion-Flame Combustor (큰 지름비를 가지는 동축제트 확산화염 연소기내의 등온 및 연소 유동장의 예측)

  • O, Gun-Seop;An, Guk-Yeong;Kim, Yong-Mo;Lee, Chang-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.7
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    • pp.2386-2396
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    • 1996
  • A numerical simulation has been performed for isothermal and reacting flows in an exisymmetric, bluff-body research combustor. The present formulation is based on the density-weighted averaged Navier-Stokes equations together with a k-epsilon. turbulence model and a modified eddy-breakup combustion model. The PISO algorithm is employed for solution of thel Navier-Stokes system. Comparison between measurements and predictions are made for a centerline axial velocities, location of stagnation points, strength of recirculation zone, and temperature profile. Even though the numerical simulation gives acceptable agreement with experimental data in many respects, the present model is defictient in predicting the recoveryt rate of a central near-wake region, the non-isotropic turbulence effects, and variation of turbulent Schmidt number. Several possible explanations for these discrepancies have been discussed.

순환유동층 연소설비를 이용한 열병합설비의 특성 및 전망

  • 조재수
    • Journal of the KSME
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    • v.30 no.6
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    • pp.521-534
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    • 1990
  • 유동층 연소방식을 이용한 열병합설비는 상당수가 전세계적으로 성공리에 운전되고 있으며, 연료의 폭넓은 수용성, 저온연소에 기인한 저공해 특성으로 인해 기존연소 방식보다 월등한 강 점이 인정되고 있다. 따라서 에너지 활용의 극대화와 환경오염의 최소화라는 두가지 명제를 만족시키는 금세기 최대의 매력적인 석탄 연소 방법으로서 유동층 연소 기술은 지속적인 확산이 예상된다. 그러나 그 동안의 문제가 제작자와 사용자의 노력에 의해 거의 해결되었다고는 하나, 아직도 대형화 및 기본설계상의 문제가 부분적으로 해결되어야할 숙제로 남아 있다. 최근의 추세는 다양한 형태의 설계개념이 차츰 서로 비슷해지는 추세로서, 이는 구체적인 설계과정에서 최적 시스템으로 취합되는 경향을 나타내고 있다. 각공정에 맞는 최적 시스템/최적 설계를 도 입하기 위해서는 각 제작자의 독특한 시스템에 대한 검토 분석이 있어야 하며, 사용코자하는 연료와 석회석의 물리화학적 특성을 사전에 분석하여 선택코자 하는 유동층 시스템과의 적합성 여부에 대한 사전 검토가 요망된다.

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The Effect of Combustion Promotion in Constant Volume Combustion Chamber with Sub-chamber (부실붙이 정적연소실의 연소촉진 효과)

  • 이상준;김삼석;이종태;이성열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.3
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    • pp.569-577
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    • 1992
  • The effect of combustion promotion in a constant volume combustion chamber with sub- chamber located in the vicinity of spark plug, was analyzed for variables such as sub- chamber volume and diameter of orifice, and was also compared and evaluated with that of the chamber with sub-chamber which spark plug was located in the sub-chamber. Consequently, it was shown that decrease of duration of combustion in the latter case was larger than in the former case, but comparing by rate of overall combustion promotion that duration of combustion and pressure were both considered, the optimum configuration factor and the effect of combustion promotion were almost same in both cases.

A Study on Development of Reliability Assessment of GHG-CAPSS (GHG-CAPSS 신뢰도 평가 방법 개발을 위한 연구)

  • Kim, Hye Rim;Kim, Seung Do;Hong, Yu Deok;Lee, Su Bin;Jung, Ju Young
    • Journal of Climate Change Research
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    • v.2 no.3
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    • pp.203-219
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    • 2011
  • Greenhouse gas(GHG) inventories were reported recently in various fields. It, however, has been rarely to mention about the accuracy and reliability of the GHG inventory results. Some reliable assessment methods were introduced to judge the accuracy of the GHG inventory results. It is, hence, critical to develop an evaluation methodology. This project was designed 1) to develop evaluation methodology for reliability of inventory results by GHG-CAPSS, 2) to check the feasibility of the developed evaluation methodology as a result of applying this methodology to two emission sources: liquid fossil fuel and landfill, and 3) to construct the technical roadmap for future role of GHG-CAPSS. Qualitative and quantitative assessment methodologies were developed to check the reliability and accuracy of the inventory results. Qualitative assessment methodology was designed to evaluate the accuracy and reliability of estimation methods of GHG emissions from emission and sink sources, activity data, emission factor, and quality management schemes of inventory results. On the other hand, quantitative assessment methodology was based on the uncertainty assessment of emission results. According to the results of applying the above evaluation methodologies to two emission sources, those seem to be working properly. However, it is necessary to develop source-specific rating systems because emission and sink sources exhibit source-specific characteristics of GHG emissions and sinks.

The Visualization of Unstable Combustion in Hybrid Rocket (하이브리드 로켓의 불안정 연소 특성 가시화)

  • Koo, Won-Mo;Lee, Chang-Jin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.4
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    • pp.46-51
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    • 2007
  • The irregular fuel surface was observed by the visualization of hybrid rocket combustion. Even though the test condition maintained oxidizer rich environment, the irregular dark fuel surface was formed as the result of incomplete combustion. In order to investigate the correlation of the characteristics of oxidizer flow and the irregular fuel surface, various flow conditions were imposed such as swirl flow, induced swirl flow by helical fuel configuration and straight flow. Test results revealed no correlation was found between oxidizer flow condition and irregular fuel surface. And this can be a commonly observed phenomena in the tests with different fuel/oxidizer combination. Thus, the irregular fuel surface can be a result of the interaction of blowing flow of vaporized fuel and the boundary layer of oxidizer flow. A further study will be required to confirm the assumption for the formation of irregular fuel surface.

Numerical Study on the Process of Supersonic Flow Formation in a Direct-Connect Supersonic Combustor (Direct-Connect 초음속 연소기 내 초음속 유동 형성과정에 대한 수치해석)

  • Jeong, Seong-Min;Han, Hyunh-Seok;Sung, Bu-Kyeng;Lee, Eun-Sung;Choi, Jeong-Yoel
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.11
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    • pp.889-902
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    • 2020
  • In this study, a numerical analysis was performed to confirm the formation of supersonic flow and the stabilization time satisfying the design condition in a Direct-connect supersonic combustor. The process was examined in which the high-pressure gas of vitiation air heater propagates downstream to the supersonic combustor and forms a supersonic flow field. It was confirmed through the analysis of pressure and temperature that the supersonic flow field satisfies the design points of Mach number 2.0 and 1,000 K, and requires a minimum of 4.0 ms for stabilization. These results indicate that the time required for the supersonic flow field stabilization should be taken into account when testing for the supersonic combustion experiment.

Combustion and Spray Characteristics of Jet in Crossflow in High-Velocity and High-Temperature Crossflow Conditions (고온고속기류 중에 수직 분사되는 액체제트의 연소 및 분무특성)

  • Yoon, Hyun Jin;Ku, Kun Woo;Kim, Jun Hee;Hong, Jung Goo;Park, Cheol Woo;Lee, Choong Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.1
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    • pp.67-74
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    • 2013
  • A jet in a crossflow (JICF) has been extensively studied because of its wide applications in technological systems, including fuel injection into a ram-combustor. However, in the case of insufficient mixing performance of the liquid jet into the crossflow, the flame in a ram-combustor is unstable. In this study, the nonuniform flame and combustion instabilities due to lack of mixing performance were experimentally investigated. By performing correlations to predict the penetration height and break-up point, the spray and mixing characteristics of JICF have been studied. In particular, the improved correlations of penetration height are proposed in two distinctive domains depending on the X/d location of the crossflow.

Combustion Stability Rating Test of Liquid Rocket Engine Thrust Chamber (액체로켓엔진 연소기 연소안정성 평가시험)

  • Ahn, Kyubok;Kim, Jong-Gyu;Choi, Hwan-Seok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.18 no.2
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    • pp.60-66
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    • 2014
  • As a evaluation method of combustion stability in a liquid rocket engine thrust chamber, external disturbance devices are used. In the paper, the study on pulse-gun ignition tests for a combustion stability rating test of a thrust chamber was performed. Charging volume of pulse-guns was determined by confirming the intensities of the pressure waves from the ignition tests in the cold-flow conditions. While using same injector head, combustion instabilities were not encountered during 14 hot-firing tests without pulse-guns but combustion instabilities were triggered by pulse-gun ignition during 2 hot-firing tests. The results showed that the pulse-gun ignition test could be the evaluation method and could reduce the hot-firing test number for the stability rating of a thrust chamber.

Low Pressure Test Results of Regenerative Cooling Combustion Chamber for 30tonf-Class Liquid Rocket Engine (30톤급 액체로켓엔진 재생냉각 연소기 저압 연소시험 결과)

  • Han, Yeoung-Min;Kim, Jong-Gyu;Lee, Kwang-Jin;Lim, Byoung-Jik;Ahn, Kyu-Bok;Kim, Mun-Ki;Seo, Seong-Hyeon;Choi, Hwan-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.05a
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    • pp.71-75
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    • 2009
  • Test results of combustion chamber to verify the operation and the combustion performance at low pressure, design and off-design conditions for 30ton-class liquid rocket engine were described. The combustion chamber has nominal chamber pressure of 60 bar, propellant mass flow rate of 89 kg/s, and nozzle expansion of 12. Effects of chamber pressure on combustion characteristic velocity are largely affected by mixture ratio. The specific impulse of combustion chamber is proportional to the chamber pressure regardless of the mixture ratios. The present results can be used as the base to predict the combustion performance of large sized chamber at high pressure while demonstrating the possibility of low pressure firing test of large sized chamber.

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