• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.53-54
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• 2012

In an IGCC plant, one of the most important issues on fuel flexibility in the lean premixed combustor is combustion instabilities. They are characterized by large amplitude pressure oscillations which are caused by unsteady heat release from the flames. The relationship between the unsteady heat release and flow oscillation can be qualitatively and quantitatively explained by flame transfer function. This paper introduces combustion instability modeling methods based on the flame transfer function approach.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2946-2951
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• 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.

• Journal of ILASS-Korea
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• v.26 no.4
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• pp.182-188
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• 2021

In this paper, using a transfer function-based analytical model, major factors influencing the acoustics and combustion instability in a two-stage duct system composed of a nozzle and a combustor were derived and their quantitative effects were evaluated. From the acoustic analysis, it was confirmed that the change in reflection coefficient and mean flow could have a great influence on the instability growth rate, and the area ratio and speed of sound ratio between the nozzle and the combustor are also key parameters to determine combustion instability as well as flame transfer functions.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.71-72
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• 2014

The current paper introduce the flame transfer function calculation results using CFD in order to quantify the heat release fluctuations in a lean premixed gas turbine combustor. Comparisons of the modeled and measured flame shapes were made using the optimized heat transfer conditions.

• Journal of ILASS-Korea
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• v.25 no.3
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• pp.119-125
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• 2020

In this paper, we used Helmholtz solver based on 3D finite element method to quantitatively analyze the effects of change of gain, time delay and time delay spread, which are the main variables of flame transfer function, on combustion instability in gas turbine combustor. The effects of the variable of flame transfer function on the frequency and growth rate, which are the main results of combustion instability, were analyzed by applying the conventional heat release fluctuation model and modified one considering the time spread. The analysis results showed that the change of gain and time delay in the same resonance mode affected the frequency of the given resonance modes as well as growth rate of the feedback instability, however, the effect of time delay spread was not relatively remarkable, compared with the dominant effect of time delay.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.8
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• pp.714-719
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• 2004

The objective of the present study is to investigate the convective instability driven by buoyancy and the heat transfer characteristics of nanofluids. Using the property relations of nanofluid expressed as a function of the volume fraction of nanoparticles, the ratio of nanofluid Rayleigh number to basefluid one, f is newly defined. The results show that the density and the heat capacity of nanoparticles act as a destabilizing factor. With an increase of ${\gamma}$ which is the ratio of thermal conductivity of nanoparticles to that of basefluid, the thermal instability of nanofluid decreases but the heat transfer rate increases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.65-67
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• 2017

Various combustion modeling approaches have been developed and verified in a combustion system such as rockets, gas turbines, and so on. This study introduces basic theory and recent research activities on 1D network model where a system is divided into a series of acoustic element and mass/momemtum/energy conservations are applied in the component. Each component is connected to the neighboring ones with proper jump conditions. Flame transfer function and acoustic transfer function are determined and effects of the each function on the system instability is investigated.

• Journal of the Korean Society of Combustion
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• v.22 no.1
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• pp.39-45
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• 2017

Combustion instability analysis of partially premixed model gas turbine combustor was conducted with 1D lumped method. Flame Transfer Function(FTF) was obtained with variation of fuel composition by Photo Multiplier Tube(PMT) and Hot Wire Anemometry(HWA). Decreasing instability frequency was observed when combustor length increased and multi-mode instability was confirmed. Instability frequency mode was changed while $H_2$ composition rate was increased and had agreement with experimental value. This work confirms that prediction of longitudinal combustion instability mode of partially premixed combustor is possible using 1D lumped method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.3
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• pp.156-164
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• 2010

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 not only the advantages of the transfer matrix method but also well established classic control theories. The approach is applied to a gas turbine combustion system, which shows the validity and effectiveness of the approach.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1449-1457
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• 2009

Combustion instability is a major issue in design of co-generation 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 co-generation 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 not only the advantages of the transfer matrix method but also well established classic control theories. The approach is applied to a simple co-generation gas turbine combustion system, which shows the validity and effectiveness of the approach.