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차동진,Jay H. Kim,주용진 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.6
Combustion instability is a major issue in design of gas turbine combustors for efficient operation with low emissions. A transfer matrix-based approach is developed in this work for the stability analysis of gas turbine combustors. By viewing the combustor cavity as a one-dimensional acoustic system with a side branch, the heat source located inside the cavity can be described as the input to the system. The combustion process is modeled as a closed-loop feedback system, which enables utilization of well-established classic control theories for the stability analysis. Due to the inherent advantage of the transfer matrix method and control system representation, modeling and analysis of the system becomes a straightforward task even for a combustor of the complex geometry. The approach is applied to the stability analysis of a simple combustion system to demonstrate its validity and effectiveness.
차동진 대한설비공학회 2011 International Journal Of Air-Conditioning and Refr Vol.19 No.3
Combustion instability is a major issue in designing gas turbine combustors for an efficient operation with low emissions. Combustion instability is induced by the interaction of the unsteady heat release of the combustion process and changes 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 was 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.
Calibration of Raman spectroscopy signals for measurements of methane-air tubular flames
차동진 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
This paper addresses a challenging approach to calibrating visible Raman spectroscopy data when investigating laminar methane-air tubular flames, which struggles against low signal levels, signal interferences, etc. The literature study considers only the crosstalks between the CO 2 and O 2 vibrational Raman lines. This study will expand the coverage of the crosstalks from H 2 rotational Raman lines onto CO 2 , O 2 , N 2 , and H 2 O by employing four more off-diagonal elements in a calibration matrix. The matrix elements are determined using proper calibration flames and calculated compositions in their post-flame zone. The polynomials represent the calibrated temperature dependence of the non-zero matrix elements. Temperaturedependent response curves of each calibration element of this study and the literature study are then compared. It also found that most of the matrix elements in this study, when normalized by their values at room temperature, behaved very closely to those previously reported by another researcher group.
차동진,S. S. Cha 대한설비공학회 1999 설비공학 논문집 Vol.11 No.6
Holographic interferornetric tomography can provide reconstruction of instantaneous three dimensional gross flow fields. The technique however confronts ill-posed reconstruction problems in practical applications. Experimental data are usually limited in projection and angular scanning when a field is captured instantaneously or under the obstruction of test models and test section enclosures. An algorithm, based on a series expansion method, has been developed to improve the reconstruction under the ill-posed conditions. A three-dimensional natural convection flow around two interacting isothermal cubes is experimentally investigated. The flow can provide a challenging reconstruction problem and lend itself to accurate numerical solution for comparison. The refractive index fields at two horizontal sections of the thermal plume with and without an opaque object are reconstructed at a limited view angle of 80" The experimental reconstructions are then compared with those from numerical calculation and thermocouple thermometry. It confirms that the technique is applicable to reconstruction of reasonably complex, three-dimensional flow fields.elds.
온라인 개방코드 OSCILOS를 이용한 모델 희박 예혼합 가스터빈 연소기의 연소불안정 해석 사례
차동진(Dong Jin Cha),송진관(Jin Kwan Song),이종근(Jong Geun Lee) 한국연소학회 2015 한국연소학회지 Vol.20 No.4
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.