• Title/Summary/Keyword: 공기연료 혼합비

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Investigation of the Mixedness of Fuel and Air in MEMS Gas Turbine Engine According to Change of Fuel Injectors and Equivalence Ratio (연료 분사구 형상 변화 및 당량비 변화에 따른 MEMS 가스터빈 내 연료-공기 혼합에 관한 연구)

  • Hwang, Yu-Hyeon;Jung, Dong-Ho;Kim, Sun-Min;Kim, Dae-Joong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.9
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    • pp.835-841
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    • 2010
  • The design of the fuel injector is one of the important operating factors that determine the extent of mixing of air and fuel in an MEMS gas turbine engine. In this study, we consider a system with three inlet ports with each port having multiple injectors. We perform a parametric study by varying the arrangement of fuel injectors and difference of ratio of fuel supply. The results are presented in terms of the premixed flow distribution and equivalence ratio.

A Numerical Study on the Characteristics of Combustion for Hydrogen/Liquid Fuel/Air Mixture (수소/액체연료/공기의 연소특성에 관한 수치해석적 연구)

  • 임복빈;백승원;김광선
    • Proceedings of the KAIS Fall Conference
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    • 2002.11a
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    • pp.293-296
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    • 2002
  • 본 논문에서는 수소/액체연료/공기의 연소특성에 대해 CFD상용프로그램을 사용하여 수치해석을 수행하였다. 먼저 프로그램을 검증하기 위하여 수소/공기의 난류 비예혼합 화염에 대한 반응물과 생성물의 몰분율을 Barlow실험 결과와 비교하였고, X축 방향의 온도분포를 Flury의 실험 값과 비교하여 값이 물리적으로 근사함을 확인하였다. 혼합분율(Mixture Fraction)과 확률밀도함수(PDF)의 접근 방법을 이용하여 화염진단과 오염물질발생에 중요한 역할을 하는 중간 종들의 몰분율을 확인하였다. 수소/액체연료/공기에 대해서는 화염형성에 있어서 가장 중요한 연료와 산화제의 속도비 변화(100,10,1,0.1)로부터 산화제속도가 연료속도 보다 클 경우 고속 측인 산화제에 의해 연료의 확산이 지배되는 현상으로 인하여 화염의 온도분포가 최고가 됨을 확인하였다. 또한, 연소과정 중 발생하는 오염물질의 농도를 수치적으로 해석하여 최저의 오염농도를 가질 수 있는 속도 비를 찾아 낼 수 있었다. 수소/공기와 수소/액체연료/공기의 온도 장 비교를 통하여 수소/액체연료/공기의 혼합물이 대체에너지로서의 가능성을 확인하였다.

Effect of Engine Operating Conditions on Combustion and Exhaust Emission Characteristics of a Gasoline Direct Injection(GDI) Engine Fueled with Bio-ethanol (직접분사식 가솔린엔진에서 운전조건에 따른 바이오에탄올의 연소 및 배기배출물 특성)

  • Yoon, Seung Hyun;Park, Su Han
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.7
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    • pp.609-615
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    • 2015
  • In this study, the combustion and exhaust emission characteristics in a gasoline direct injection engine with variations of the bio-ethanol-gasoline blending ratio and the excess air factor were investigated. To investigate the effects of the excess air factor and the bio-ethanol blends with gasoline, combustion characteristics such as the in-cylinder combustion pressure, rate of heat release (ROHR), and the fuel consumption rate were analyzed. The reduction of exhaust emissions such as carbon monoxide (CO), unburned hydrocarbon (HC), and nitrogen oxides ($NO_x$) were compared with those of gasoline fuel with various excess air factors. The results showed that the peak combustion pressure and ROHR of bio-ethanol blends were slightly higher and were increased as bio-ethanol blending ratio is increased. Brake specific fuel consumption increased for a higher bio-ethanol blending ratio. The exhaust emissions decreased as the bio-ethanol blending ratio increased under all experimental conditions. The exhaust emissions of bio-ethanol fuels were lower than those of gasoline.

Numerical Analysis of Supersonic Combustion Flows according to Fuel Injection Positions near the Cavity (공동주위 분사위치에 따른 초음속 연소 유동해석)

  • Jeong Eunju;Jeung In-Seuck
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.368-373
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    • 2005
  • To achieve efficient combustion within a manageable length, a successful fuel injection scheme must provide rapid mixing between the fuel and airstreams. The aim of the present numerical research is to investigate the mixing enhancement combustion phenomena according to fuel injector location near the cavity in supersonic flow. Fuel injector location changes the actual length to depth ratio of the cavity in the supersonic combustor. Therefore fuel injector location near the cavity effects different fuel/air mixing efficiency and combustion efficiency.

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A Study on the Effect of Mid Layer on Supersonic 2D Double Shear Layer (초음속 2차원 2단 혼합층에서 중간층의 역할)

  • Kim, Dongmin;Baek, Seungwook
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.1
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    • pp.9-17
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    • 2015
  • The basic flow configuration is composed of a plane, double shear layer where relatively thin mid gas layer is sandwiched between air and fuel stream. The present study describes numerical investigations concerning the combustion enhancement according to a variation of mid layer thickness. In this case, the effect of heat release in turbulent mixing layers is important. For the numerical solution, a fully conservative unsteady $2^{nd}$ order time accurate sub-iteration method and $2^{nd}$ order TVD scheme are used with the finite volume method including k-${\omega}$ SST model. The results consists of three categories; single shear layer consists of fuel and air, inert gas sandwiched between fuel and air, cold fuel gas sandwiched between fuel and air. The numerical calculations has been carried out in case of 1, 2, 4 mm of mid layer thickness. The height of total gas stream is 4 cm. The combustion region is broadened in case of inert gas layer of 2, 4 mm thickness and cold fuel layer of 4 mm thickness compared with single shear layer.

Effects of Partial Premixing on Flame Structure and NOx Emission Characteristics in an Unstable Gas Turbine Combustor (불안정 가스 터빈 연소기에서 부분 예혼합이 화염구조와 NOx 배출 특성에 미치는 영향)

  • Lee Jae-Ho;Lee Jong-Ho;Kim See-Hyun;Chang Young-June;Jeon Chung-Hwan
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.437-444
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    • 2005
  • Experiments were carried out in an atmospheric pressure, lab-scale gas turbine combustor to see the effect of partial premixing on unstable flame structure and Nox emission characteristics. The swirl angle is 45 deg., fuel-air mixing degrees were varied 0, 50 and 100% respectively at equivalence ratio ranging from 0.53 to 0.79. The evolution of phased-locked OH chemiluminescence images were acquired with an ICCD. NOx emission characteristics were also investigated at each experimental condition. The effect of the fuel-air mixing degree on the flame structure was obtained from phase-locked $OH^*$ images. And it was obtained from local heat release characteristics that the information about the region which the combustion instability was amplified or damped. It also could be confirmed that $\sigma$ has greatly influence on NOx emission characteristics at lean regimes. It would be expected that it could provide invaluable data for understanding the mechanism of combustion instability.

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A study on performance improvement of natural gas fueled engine (천연가스 기관의 성능 향상에 관한 연구)

  • 정동수;정진도;서승우;최교남
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.1
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    • pp.175-179
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    • 1992
  • Generally speaking, natural gas possesses several characteristics that make it desirable as an engine fuel : for example (1) lower production cost, (2) abundant commodity and (3) cleaner energy source than gasoline. Due to the physical characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of 10-20% when compared to a convensional gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of air/fuel ratio, spark timing advance and supercharging effect by forced air supply method.

Fuel Distribution Measurements in ATR Combustor using PLIF (PLIF를 이용한 ATR 연소기 내부의 연료분포 측정)

  • Yang In-Young;Jin You-In;Yang Soo-Seok;Park Seung-Jae
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.10a
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    • pp.274-277
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    • 2004
  • Fuel/air mixing in air turbo ramjet(ATR) combustor is a significant parameter of combustion stability and efficiency. In this study, fuel distribution in the ATR model combustor was measured to compare the degree of mixing with respect to the velocity ratio$(r=v_a/v_f)$ between fuel gas and air. Planar laser-induced fluorescence(PLIF) and image processing method were used to obtain two dimensional fuel distribution. Fuel mixing went bad with approaching to r=1.

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A Numerical Study on the Combustion Characteristics in a Liquid Rocket Engine with Film Cooling Effect (막냉각 효과를 고려한 액체로켓 엔진의 연소 특성에 관한 연구)

  • Byeon,Do-Yeong;Kim,Man-Yeong;Baek,Seung-Uk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.8
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    • pp.69-76
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    • 2003
  • For stable combustion and safety of a structure of the propulsion system, a cooling system to the liquid rocket engine should be incorporated. In this study, Eulerian-Lagrangian scheme for two phase combustion, nongray radiation and soot formation effect, and film-wall interaction have been introduced to study the effect of film cooling. After briefly introducing the governing equation, combustion characteristics with change of wall temperature has been investigated by varying such parameters as fuel mass fraction for film cooling, diameter of the fuel droplet, overall mixture fraction of oxygen to fuel. Also, radiative heat flux is compared with the conductive one at the combustor wall.

Experimental Study on Fuel/Air Mixing using Inclined Injection in Supersonic Flow (경사 분사에 의한 초음속 유동 연료-공기 혼합에 관한 실험적 연구)

  • Lee, Dong-Ju;Jeong, Eun-Ju;Kim, Chae-Hyoung;Jeung, In-Seuck
    • Journal of the Korean Society of Propulsion Engineers
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    • v.13 no.4
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    • pp.9-15
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    • 2009
  • The flow of combustor in scramjet engine has supersonic speed so that the residence time and mixing ratio are very important factors for the efficient combustion. This study used open cavity(L/D=4.8) as a fuel/air mixing model. Laser schlieren visualization and pressure measurement were carried out to observe the flow characteristics around a jet orifice and a cavity at the time of fuel injection. As a result of 10ns laser schlieren, unsteady flow which was around the cavity could be observed effectively. Pressure was measured that momentum flux ratio(J) was changed. And the change of critical ignition point could be observed by the momentum flux ratio changed.