• Title/Summary/Keyword: Combustion instability

Search Result 480, Processing Time 0.026 seconds

A Experimental Study on Combustion-Stability Rating in a Subscale Chamber (모형 연소실에서 분사기 연소 안정성 평가에 관한 실험적 연구)

  • Kim, Chuljin;Sohn, Chae Hoon
    • 한국연소학회:학술대회논문집
    • /
    • 2012.04a
    • /
    • pp.77-78
    • /
    • 2012
  • To predict combustion instability in actual full-scale combustion chamber of rocket engines, air-injection test is proposed with scaling techniques. From the data, damping factors have been obtained as a function of hydraulic parameter and the data give us instability map. Two instability regions are presented and it is found that they coincide reasonably with them from hot-fire test with full-scale flow rates. Accordingly, the proposed approach can be applied cost-effectively to stability rating of jet injectors when mixing of fuel and oxidizer jets is the dominant process in instability triggering.

  • PDF

Note on Nonlinearity of Combustion Instability (연소 불안정 현상의 비선형적 특성 고찰)

  • 서성현
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2003.05a
    • /
    • pp.240-243
    • /
    • 2003
  • Combustion instability phenomena have been observed in various different combustion systems. For each specific combustion system, pressure fluctuations measured during high frequency combustion instability presented many different characteristics. High frequency instability occurring in a lean premixed gas turbine combustor mar be dominantly affected by a nonlinear relation between pressure oscillations and heat release rate fluctuations, and gas dynamics plays a crucial role in determining an amplitude of a limit cycle for a liquid rocket thrust chamber. Combustion instability phenomena manifest their inherent nonlinear characteristics. One is a limit cycle and the other bifurcation described by nonlinear time series analysis.

  • PDF

A Case Study on Combustion Instability of a Model Lean Premixed Gas Turbine Combustor with Open Source Code OSCILOS (온라인 개방코드 OSCILOS를 이용한 모델 희박 예혼합 가스터빈 연소기의 연소불안정 해석 사례)

  • Cha, Dong Jin;Song, Jin Kwan;Lee, Jong Geun
    • Journal of the Korean Society of Combustion
    • /
    • v.20 no.4
    • /
    • pp.10-18
    • /
    • 2015
  • Combustion instability is a major issue in design and maintenance of gas turbine combustors for efficient operation with low emissions. With the thermoacoustic view point the instability is induced by the interaction of the unsteady heat release of the combustion process and the change in the acoustic pressure in the combustion chamber. In an effort to study the combustion dynamics of gas turbine combustors, Morgans et al (2014) have developed OSCILOS (open source combustion instability low order simulator) code and it is currently available online. In this study the code has been utilized to predict the combustion instability of a reported case for lean premixed gas turbine combustion, and then its prediction results have been compared with the corresponding experimental data. It turned out that both the predicted and the experimental combustion instability results agree well. Further the effects of some typical inlet acoustic boundary conditions on the prediction have been investigated briefly. It is believed that the validity and effectiveness of the open source code is reconfirmed through this benchmark test.

Turing, Turing Instability, Computational Biology and Combustion (Turing, Turing 불안정성 그리고 수리생물학과 연소)

  • Kim, J.S.
    • Journal of the Korean Society of Combustion
    • /
    • v.8 no.1
    • /
    • pp.46-56
    • /
    • 2003
  • The present paper is concerned with the development of the computational biology in the past half century and its relationship with combustion. The modem computational biology is considered to be initiated by the work of Alan Turing on the morphogenesis in 1952. This paper first touches the life and scientific achievement of Alan Turing and his theory on the morphogenesis based on the reactive-diffusive instability, called the Turing instability. The theory of Turing instability was later extended to the nonlinear realm of the reactive-diffusive systems, which is discussed in the framework of the excitable media by using the Oregonator model. Then, combustion analogies of the Turing instability and excitable media are discussed for the cellular instability, pattern forming combustion phenomena and flame edge. Finally, the recent efforts on numerical simulations of biological systems, employing the detailed bio-chemical knietic mechanism is discussed along with the possibility of applying the numerical combustion techniques to the computational cell biology.

  • PDF

Numerical Simulation of Self-excited Combustion Oscillation in a Dump Combustor with Bluff-body (둔체를 갖는 연소기에서 자려 연소 진동에 관한 수치해석)

  • Kim, Hyeon-Jun;Hong, Jung-Goo;Kim, Dae-Hee;Shin, Hyun-Dong
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.32 no.9
    • /
    • pp.659-668
    • /
    • 2008
  • Combustion instability has been considered as very important issue for developing gas turbine and rocket engine. There is a need for fundamental understanding of combustion instability. In this study, combustion instability was numerically and experimentally investigated in a dump combustor with bluff body. The fuel and air mixture had overall equivalence ratio of 0.9 and was injected toward dump combustor. The pressure oscillation with approximately 256Hz was experimentally obtained. For numerical simulation, the standard k-$\varepsilon$ model was used for turbulence and the hybrid combustion model (eddy dissipation model and kinetically controlled model) was applied. After calculating steady solution, unsteady calculation was performed with forcing small perturbation on initial that solution. Pressure amplitude and frequency measured by pressure sensor is nearly the same as those predicted by numerical simulation. Furthermore, it is clear that a combustion instability involving vortex shedding is affected by acoustic-vortex-combustion interaction. The phase difference between the pressure and velocity is $\pi$/2, and that between the pressure and heat release rate is in excitation range described by Rayleigh, which is obvious that combustion instability for the bluff body combustor meets thermoacoustic instability criterion.

Characteristics of High-Frequency Combustion Instabilities Occurring in Combustion Devices (연소장치에서 발생하는 고주파 연소 불안정 특성)

  • Seo, Seong-Hyeon
    • Journal of the Korean Society of Combustion
    • /
    • v.17 no.1
    • /
    • pp.30-36
    • /
    • 2012
  • Dynamic characteristics of combustion occurring in various combustion devices have been extensively studied since most of high-performance combustion devices are susceptible to hazardous, unstable combustion that deteriorates combustor's lifetime. One of the most severe unstable combustion phenomena is high-frequency combustion instability in which heat release fluctuations from combustion are coupled to resonant modes of the combustor. Here in this study, characteristics of high-frequency combustion instabilities observed in three different combustion devices have been presented. Lean-premixed combustion instability occurs mainly due to equivalence ratio fluctuations which induce large heat release oscillations at lean conditions. Liquid-fueled combustion also shows high-frequency instability from energy coupling between pressure and heat release oscillations.

Domestic and Foreign Research Trends in Rocket Combustor Instability (국내외 로켓연소기의 연소불안정 연구동향 분석)

  • Bae, Jinhyun;Jeong, Seokgyu;Yoon, Youngbin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2017.05a
    • /
    • pp.47-53
    • /
    • 2017
  • One of the most common causes of failure of space launch vehicles is combustion instability. Combustion instability is a phenomenon that the pressure perturbation inside the combustion chamber is greatly amplified due to the interaction of the pressure perturbation inside the combustion chamber and the heat release perturbation. When this phenomenon becomes worse, an engine failure or launch vehicle crash occurs. In order to predict and avoid such combustion instability, understanding of the phenomenon is indispensable, and numerical, theoretical, and experimental approaches to combustion instability have been carried out worldwidely.

  • PDF

Combustion Instability Mechanism of a Lean Premixed Gas Turbine Combustor

  • Seo, Seonghyeon
    • Journal of Mechanical Science and Technology
    • /
    • v.17 no.6
    • /
    • pp.906-913
    • /
    • 2003
  • Lean premixed combustion has been considered as one of the promising solutions for the reduction of NOx emissions from gas turbines. However, unstable combustion of lean premixed flow becomes a real challenge on the way to design a reliable, highly efficient dry low NOx gas turbine combustor. Contrary to a conventional diffusion type combustion system, characteristics of premixed combustion significantly depend on a premixing degree of combusting flow. Combustion behavior in terms of stability has been studied in a model gas turbine combustor burning natural gas and air. Incompleteness of premixing is identified as significant perturbation source for inducing unstable combustion. Application of a simple convection time lag theory can only predict instability modes but cannot determine whether instability occurs or not. Low frequency perturbations are observed at the onset of instability and believed to initiate the coupling between heat release rate and pressure fluctuations.

A Combustion Instability Analysis of a Model Gas Turbine Combustor by the Transfer Matrix Method

  • Cha, Dong-Jin;Kim, Jay-H.;Joo, Yong-Jin
    • Proceedings of the KSME Conference
    • /
    • 2008.11b
    • /
    • pp.2946-2951
    • /
    • 2008
  • Combustion instability is a major issue in design of gas turbine combustors for efficient operation with low emissions. Combustion instability is induced by the interaction of the unsteady heat release of the combustion process and the change in the acoustic pressure in the combustion chamber. In an effort to develop a technique to predict self-excited combustion instability of gas turbine combustors, a new stability analysis method based on the transfer matrix method is developed. The method views the combustion system as a one-dimensional acoustic system with a side branch and describes the heat source as the input to the system. This approach makes it possible to use the advantages of not only the transfer matrix method but also well-established classic control theories. The approach is applied to a simple gas turbine combustion system to demonstrate the validity and effectiveness of the approach.

  • PDF

Combustion Instability of Gas Turbine with Segmented Dynamic Thermo-Acoustic Model under Load Follow-Up (이산형 열-음향 모델을 이용한 부하 변동시 가스터빈 연소 불안정 특성)

  • JEONG, JIWOONG;HAN, JAEYOUNG;JEONG, JINHEE;YU, SANGSEOK
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.29 no.5
    • /
    • pp.538-548
    • /
    • 2018
  • The thermo-acoustic instability in the combustion process of a gas turbine is caused by the interaction of the heat release mechanism and the pressure perturbation. These acoustic vibrations cause fatigue failure of the combustor and decrease the combustion efficiency. This study is to develop a segmented dynamic thermo-acoustic model to understand combustion instability of gas turbine. Therefore, this study required a dynamic analysis rather than static analysis, and developed a segmented model that can analyze the performance of the system over time using the Matlab/Simulink. The developed model can confirm the thermo-acoustic combustion instability and exhaust gas concentration in the combustion chamber according to the equivalent ratio change, and confirm the thermo-acoustic combustion instability for the inlet temperature and the load changes. As a result, segmented dynamic thermo-acoustic model has been developed to analyze combustion instability under the operating condition.