• Title, Summary, Keyword: Combustion oscillation

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Combustion Control and Symptom Detection on Self-excited Combustion Oscillation (자려 연소진동에 관한 연소제어와 징후의 검출)

  • Yang Young-Joon
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.7
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    • pp.1111-1122
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    • 2004
  • An idea to suppress the self-excited combustion oscillation was applied to the flames. The characteristics of unsteady combustion were examined and the unsteady combustion was driven by forced pulsating mixture supply that can modulate its amplitude and frequency. The self-excited combustion oscillation having weaker flow velocity fluctuation intensity than that of the forced pulsating supply can be suppressed by this method. The effects of the forced pulsation amplitude and frequency on controlling self-excited combustion oscillations were also investigated comparing with the steady mixture supply. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillation. Symptoms of self-excited combustion oscillation were also studied in order to predict the onset of combustion oscillation before it proceeded to a catastrophic failure For the purpose, the unique measures to observe the onset of self-excited combustion oscillations based on the careful statistics of fluctuating properties in flames, such as pressure or emission of OH radicals, have been proposed.

Symptoms of Self-excited Combustion Oscillation and their Detection

  • Yang, Young-Joon;Akamatsu, Fumiteru;Katsuki, Masashi;Bae, Suk-Tae;Kim, Si-Pom
    • Journal of Mechanical Science and Technology
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    • v.18 no.10
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    • pp.1859-1868
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    • 2004
  • Monitoring of OH chemiluminescence through an optical fiber was demonstrated to be a useful method in detecting self-excited combustion oscillations. OH chemiluminescence intensity detected by the optical fiber showed mostly excellent agreement with those obtained by high speed CCD camera measurements when combustion oscillations were strong. Symptoms of self-excited combustion oscillation were also studied in order to predict the onset of combustion oscillation before it proceeded to a catastrophic failure. For the purpose, we have found and proposed unique measures to tell the onset of self-excited combustion oscillations based on the careful statistics of fluctuating properties in flames, such as pressure or emission of OH radicals.

Characteristics of Self-excited Combustion Oscillation and Combustion Control by Forced Pulsating Mixture Supply

  • Yang, Young-Joon;Fumiteru Akamatsu;Masashi Katsuki;Lee, Chi-Woo
    • Journal of Mechanical Science and Technology
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    • v.17 no.11
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    • pp.1820-1831
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    • 2003
  • Characteristics of self-excited combustion oscillation are experimentally studied using confined premixed flames stabilized by a rearward-facing step. A new idea to suppress combustion oscillation was applied to the flames. The characteristics of unsteady combustion were examined, which is driven by forced pulsating mixture supply that can modulate its amplitude and frequency. The self-excited combustion oscillation having weaker flow velocity fluctuation intensity than that of the forced pulsating supply can be suppressed by the method. The effects of the forced pulsation amplitude and frequency on controlling self-excited combustion oscillations were also investigated comparing with the steady mixture supply. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations, and it also exhibits desirable performances, from a practical point of view, such as high combustion load and reduced pollutant emissions of nitric oxide.

Analysis of Combustion Oscillation and its Suppression in a Silo Type Gas Turbine Combustor (Silo 형 가스터빈 연소기에서 발생하는 연소진동 분석 및 저감)

  • Seo, Seok-Bin;Ahn, Dal-Hong;Cha, Dong-Jin;Park, Jong-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.2
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    • pp.126-130
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    • 2009
  • The present study describes an investigation into the characteristics of combustion oscillation and its suppression instability of a silo type gas turbine combustor in commercial power plant. Combustion oscillation is occurred the combustor in near full load during operation. As a result of FFT analysis of the combustion dynamics, the frequency of the oscillation is analyzed as the 1'st longitudinal mode of acoustic resonance of the combustor. For suppress of the instability, combustion tuning with adjust of fuel valve schedule is carried out, which changes equivalent ratio of each burners. As the result, the oscillation is successfully reduced with meeting the level of NOx emission regulation.

Characteristics of Low-Frequency Combustion-driven Oscillation in a Surface Burner (표면연소기의 저주파 연소진동음의 특성)

  • 한희갑;이근희;권영필
    • Journal of KSNVE
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    • v.10 no.6
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    • pp.991-997
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    • 2000
  • The objective of this study is to examine the onset condition and the frequency characteristics of the low-frequency combustion oscillation in a surface burner. For this purpose, extensive parametric studies have been performed experimentally and the effects of size of each section, the equivalence ratio, and the entrance velocity on oscillatory behavior explored. The experimental results were discussed in comparison with the other combustors associated tilth the low-frequency combustion oscillation. The combustion mode is driven at high combustion rate by the lift of unstable flame near the lower limit of the combustible equivalence ratio. The oscillation frequency is dependent not on the burner geometry but on the equivalence ratio and the combustion load. Low-frequency combustion mode was formed to be divided into two different modes, named C1 and C2 respectively. Two modes occurred individually, simultaneously or transitionally according to the equivalence ratio and combustion load. The characteristics of low-frequency oscillation is different from each other depending on the type of combustors. The surface burner has also its own characteristics of low -frequency oscillation.

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Experimental Installation of Pressure Oscillation based on Pulse-driving Technique

  • YANG, Tian-hao;LIU, Pei-jin;JIN, Bing-ning
    • International Journal of Aerospace System Engineering
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    • v.2 no.1
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    • pp.58-61
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    • 2015
  • Under the background of combustion instability in solid rocket motor, to study the relationship between pressure oscillations and dynamic process of propellant flames, it is necessary to simulate an oscillation environment with certain frequency, amplitude and duration. This paper presents an experimental installation of pressure oscillation based on pulse-driving technique, with which pressure oscillations features under different pulse-driving conditions were compared and analyzed. For the pulse-driver applied in this paper, a pressure oscillation with 0.15s-0.5s duration, 179Hz-210Hz first order frequency, 0.04MPa-0.35MPa amplitude is simulated. The test results show that an oscillation with higher frequency and lager amplitude can be obtained when pulse-driver is installed on the top of the installation cavity, while on the side, an oscillation with a longer duration and approximate cavity natural frequency can be simulated.

A cause analysis of Noise & Vibration of Gas Heater (가스히터의 소음 진동 원인 분석)

  • Koh, Jae-Pil;You, Hyun-Seok
    • Journal of the Korean Institute of Gas
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    • v.13 no.1
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    • pp.9-13
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    • 2009
  • A cause of noise and vibration which come from a Combustion of gas heater are a combustion roar and Combustion oscillation. A character of a combustion roar is that sound pressure is distribute with broad band frequency. otherwise, The presence of combustion oscillation caused by positive Feed Back in Combustion Chamber break out a noise and vibration. Accordingly, The method that be solved a noise and vibration is to make each natural frequency different frequency. first, in order to solve problem, we control ratio of fuel and air. that is, Keep away resonance. second, in order to changing natural frequency of Combustion Chamber, We changed the shape of Economizer.

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Characterization of Combustion Oscillation and Reduction of Abnormal Oscillation in a Power Generation Gas Turbine (발전용 가스터빈에서 발생하는 연소진동 특성 및 이상연소진동의 저감)

  • Seo, Seok-Bin;Ahn, Dal-Hong;Chung, Jae-Hwa
    • Proceedings of the KSME Conference
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    • pp.1682-1685
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    • 2004
  • Gas Turbine combustors for power plant can be reduced NOx emissions using lean premixed combustion technology. But the combustors are likely to occur combustion oscillations which damage operation reliability and mechanical life of the gas turbines. In this paper, characterizations of oscillation in a gas turbine combustor for power plant are presented. Combustion dynamics occur $1{\sim}1.5$ psi in amplitude with low frequency less than 140Hz during normal operation. An abnormal high level dynamics, 2.0 psi amplitude occur at 125 Hz frequency. Abnormal combustion oscillation is reduced by modulation of fuel supply valve control schedule.

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Numerical Simulations for Combustion and NOx Emission Characteristics in Oscillating Combustion Burner (수치해석을 이용한 맥동연소과정 및 NOx 배출특성 해석)

  • Kim, Hoo-Joong;Cho, Han-Chang
    • Journal of the Korean Society of Combustion
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    • v.14 no.3
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    • pp.37-44
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    • 2009
  • An experimental study was conducted to reduce NOx emission in RT(radiant tube)burner by using oscillating combustion processes in RIST. A solenoid valve gives the various oscillating conditions, such as oscillation frequency, duty ratio of fuel flow. In this study, we used commercial software, CFD-ACE+ to predict combustion and NOx emission characteristics for various experimental oscillation conditions. The effect of oscillation frequency and duty ratio on NOx emission will be discussed in terms of flow field, temperature and equivalence ratio distributions in detail.

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