• 한국추진공학회지
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• 제25권2호
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• pp.66-78
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• 2021

본 연구에서는 환형연소기에서 연소불안정성이 발생하는 당량비 조건과 노즐 개수에 따라서 대칭성파괴(Symmetry Breaking) 효과를 비교하였다. 일반적으로 환형연소기에서는 연소실의 길이가 짧으므로 종-방향 연소불안정성이 잘 발생하지 않으나, 발전용 가스터빈시스템의 트랜지션피스(Transition piece) 같은 덕트가 존재하였을 때는 연소불안정성이 발생하였다. 이 경우 덕트로 인하여 종-방향의 불안정성 모드만 관찰되었다. 5개의 희박노즐 개수와 당량비 조건에 따라서 대칭성파괴 특성을 조사하였는데, 당량비가 감소할수록 대칭성파괴 효과가 빠르게 발생하여 불안정성이 극적으로 사라지면서 진폭이 크게 감소하였다. 또한, 희박노즐 개수가 증가할수록 당량비 감소와 같은 현상이 나타나는 것을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.802-806
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• 2004

For the protection of the local air quality and the global atmosphere, the emissions of trace species including nitric oxides (NO and NO$_2$) from gas turbines are regulated by local governments and by the International Civil Aviation Organization. In-situ measurements of such species are needed not only for the development of advanced low-emission combustion concepts but also for providing emissions data required for the sound assessment of the effects of the emissions on environment. We have been developing a laser absorption system that has a capability of simultaneous determination of NO and NO$_2$concentrations in the exhaust jets from aero gas turbines. A diode laser operating near 1.8 micrometer is used for the detection of NO while a separated visible tunable diode laser operating near 676 nanometers is used for NO$_2$. The sensitivities at elevated temperature conditions were determined for simulated gas mixtures heated up to 500K in a heated cell of a straight 0.5 m optical path. Sensitivity limits estimated as were 30 ppmv-m and 3.7 ppmv-m for NO and NO$_2$, respectively, at a typical exhaust gas temperature of 800K. Experiments using the simulated exhaust flows have proven that $CO_2$ and $H_2O$ vapor - both major combustion products - do not show any interference in the NO or NO$_2$ measurements. The measurement system has been applied to the NO/NO$_2$ measurements in NO and NO$_2$ doped real combustion gas jets issuing from a rectangular nozzle having 0.4 m optical path. The lower detection limits of the system were considerably decreased by using a multipass optical cell. A pair of off-axis parabola mirrors successfully suppressed the beam steering in the combustion gas jets by centralizing the fluctuating beam in sensor area of the detectors.