마이크로가스터빈용 환형연소기 설계 기법

조주형,Cho, Ju Hyeong 한국연소학회 2014 한국연소학회지 Vol.19 No.4

MGT (micro gas turbines) have been gaining particular attentions with a variety of commercial and military applications due to their advantages such as compact size, simple operability, easy maintenance, and low emissions. This study deals with development processes of an annular combustor applied to MGT. Preliminary design methodologies are used to size the main components of the combustor. Key design features such as liner temperatures and pressure losses are evaluated. Results show that the estimated liner temperatures are within acceptable range. Dominant factors for pressure losses are estimated to be air admission holes and burner swirlers.

유동 섭동에 의한 난류예혼합화염의 열발생 모델에 관한 연구

조주형(Ju Hyeong Cho),백승욱(Seung Wook Baek) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.6

The unsteady heat release characteristics play a significant role in combustion instabilities observed in low emissions gas turbine combustors. Such combustion instabilities are often caused by coupling mechanisms between unsteady heat release rates and acoustic perturbations. A generalized model of the turbulent flame response to acoustic perturbations is analytically formulated by considering a distributed heat release along a curved mean flame front and using the flame's kinematic model that incorporates the turbulent flame development. The effects of the development of flame speed on the flame transfer functions are examined by calculating the transfer functions with a constant or developing flame speed. The flame transfer function due to velocity fluctuation shows that, when a developing flame speed is used, the transfer function magnitude decreases faster with Strouhal number than the results with a constant flame speed at low Strouhal numbers. The flame transfer function due to mixture ratio fluctuation, however, exhibits the opposite results: the transfer function magnitude with a developing flame speed increases faster than that with a constant flame speed at low Strouhal numbers. Oscillatory behaviors of both transfer function magnitudes are shown to be damped when a developing flame speed is used. Both transfer functions also show similar behaviors in the phase characteristics: The phases of both transfer functions with a developing flame speed increase more rapidly than those with a constant flame speed.

난류예혼합화염이 음파의 산란에 미치는 영향에 관한 연구

조주형(Ju Hyeong Cho),백승욱(Seung Wook Baek) 한국연소학회 2007 한국연소학회지 Vol.12 No.1

Analytical investigation of acoustic wave scattering from turbulent premixed flames was conducted to evaluate the acoustic energy amplification/damping. Such acoustic energy change is attributed to the acoustic velocity jump due to flame’s heat release. Small perturbation method up to second order and stochastic analysis were utilized to formulate net acoustic energy and the energy transfer from coherent to incoherent energy. Randomly wrinkled flame surface is responsible for the energy transfer from coherent to incoherent field. Nondimensional parameters that govern net acoustic energy were determined: rms height and correlation length of flame front, incident wave frequency, incidence angle, and temperature ratio. The dependence of net acoustic energy upon these parameters is illustrated by numerical simulations in case of Gaussian statistics of flame front. Total net energy was amplified and the major factors that affect such energy amplification are incidence angle and temperature ratio. Coherent (incoherent) energy is damped (amplified) with rms height and correlation length of flame front.

A Heat Release Model of Turbulent Premixed Flame Response to Acoustic Perturbations

조주형(Ju Hyeong Cho),백승욱(Seung Wook Baek) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

The unsteady heat release characteristics play a significant role in combustion instabilities often observed in low emissions gas turbine combustors. Such combustion instabilities are often caused by coupling mechanisms between unsteady heat release rates and acoustic perturbations. A generalized model of the flame response to acoustic perturbations, including mixture ratio perturbations, is analytically formulated to extend the prior models by considering a distributed heat release along the mean flame front and using the flame’s kinematic model that incorporates the turbulent flame development. A specific example for the flame transfer function due to flame area fluctuation showed that, when a developing flame speed is used, the transfer function magnitude decreases faster at low Strouhal number and the transfer function phase increases more rapidly, as compared to the results with a constant flame speed. The results from both types of flame speed observe a well known n-τ model.

An Extended Heat Release Model of Turbulent Premixed Flame Response to Flow Perturbations

Ju-Hyeong Cho(조주형),Kook-Young Ahn(안국영),Seung Wook Baek(백승욱) 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.39

A generalized model of the turbulent flame response to acoustic perturbation, including mixture ratio perturbation, was analytically formulated by accounting for a distributed heat release along the mean flame front with a kinematic model that incorporates turbulent premixed flame development. The effects of turbulent flame development were evaluated on two types of flame transfer functions: one is due to velocity fluctuation, the other is due to equivalence ratio fluctuation. A developing turbulent flame speed plays a significant role in both cases. A developing turbulent flame reduces the magnitude of the flame transfer function due to velocity fluctuation particularly at low frequency regime while it enhances the transfer function magnitude due to equivalence ratio perturbation. Both transfer functions show similar behaviors in the phase characteristics: the phases of both transfer functions with a developing flame speed increase more rapidly than those with a constant flame speed, which implies that the time delay between flow perturbations and the corresponding heat release response increases with a developing turbulent flame.

동축 버너를 이용한 순산소 연소특성에 관한 실험적 연구

조주형(Ju Hyeong Cho),최원석(Won Seok Choi),김한석(Han Seok Kim),안국영(Kook Young Ahn) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

Oxy-fuel combustion has been gaining its significance as a means of migrating the green house effects. Some experimental measurements were conducted to investigate the characteristics of oxy-fuel combustion and to aid a fundamental design of a lab-scale oxy-fuel combustor with a coaxial burner. CO emission was measured along the combustor centerline while combustion of methane and oxygen diluted by CO2 took place. Substitution of CO2 with N2 indicates a possibility that some CO is formed by dissociation of CO2. Some parametric tests were also performed to see the mixing effects of reactant gases on CO emission by changing the gas injection velocity at the burner nozzles with various heat loads. The overall results indicate that CO emission was reduced when the reactants are injected at higher velocities of similar magnitude.

스월-예혼합 버너의 출구 형상 변화에 따른 연소 특성 분석

주해지(Hae-ji Ju),조주형(Ju Hyeong Cho),황정재(Jeongjae Hwang),김민국(Min Kuk Kim),김한석(Han Seok Kim),이원준(Won June Lee) 한국연소학회 2020 KOSCOSYMPOSIUM논문집 Vol.2020 No.9

이중 콘형 부분예혼합 GT 연료노즐의 연소특성 및 발전플랜트 실증

김한석(Han Seok Kim),조주형(Ju Hyeong Cho),김민국(Min Kuk Kim),황정재(Jeongjae Hwang),이원준(Won June Lee),민경욱(Kyungwook Min),강도원(Do Won Kang) 한국가스학회 2021 한국가스학회지 Vol.25 No.6

발전용 가스터빈에 사용되는 이중 콘형 예혼합 연소기의 성능 개선 및 검증을 위하여 기존 노즐에서 연료 분사 특성을 개선한 노즐(분사구 직경 증가, 분사구 수 감소, 총 분사면적 유지)을 이용하여 고압 및 다중화염조건에서 실험 연구를 수행하였으며 배기가스 특성을 기존 노즐과 비교하였다. 실험 결과로는 노즐의 연료 직경을 크게 한 경우 연소용 공기로 연료의 침투 거리가 증가하기 때문에 콘 내부에서 연료와 공기의 혼합특성이 개선되어 상압뿐만 아니라 압력 상승 시 NOx 배출 농도는 감소하며 다중 화염의 경우 화염간 연소영역의 중첩이 감소하게 되어 NOx 배출은 감소하지만 화염 안정성은 저하된다. 연료 분사구를 개선한 노즐의 발전 플랜트 실증 결과는 실험 결과와 같이 기존 노즐에 비하여 NOx 농도가 낮게 배출되었다. Combustion characteristics were examined experimentally for a swirl-stabilized double cone premixed burner nozzle used for industrial gas turbines for power generation. An original model and a variant with a different fuel injection pattern are tested to compare their combustion characteristics such as NOx, CO and stability in pressurized conditions with single burner-flame and in an ambient multi-flame conditions with multi-burners. Test results show that NOx emissions are smaller for the variant, whose number of fuel holes is reduced with the same total area of fuel holes, in ambient and pressurized single-flame conditions with single burner, which results from enhanced fuel/air mixing due to a higher penetration of fuel into the air stream. The multi-burnerflame test results show that NOx emissions are smaller for the variant due to reduced flame interactions, which, on the contrary, slightly reduces the stability margin. On-site test results fromin an actual power plants also show that NOx emissions are reduced for the variant, compared with the original one, which is in agreement with the lab test results stated above.

우주시험동의 궤도환경시험실

최석원(Seok-Weon Choi),조주형(Ju-Hyeong Cho),서희준(Hee-Jun Seo),이상설(Sang-Seol Lee),김진철(Zeen-Chul Kim) 한국항공우주학회 2001 韓國航空宇宙學會誌 Vol.29 No.3

이중 연료 분사구조를 갖는 희박-예혼합 버너의 연소특성 연구

장재환(Jae Hwan Jang),조주형(Ju Hyeong Cho),김한석(Han Seok Kim),이상민(Sang Min Lee),김민국(Min Kuk Kim),안국영(Kook Young Ahn) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.1

본 연구에서는 가스터빈 연소기에 적용하기 위한 예혼합 스월버너의 배기가스 및 화염안정성 최적화를 위하여 버너의 구조변경에 따른 연소특성을 실험적으로 분석하였다. 버너의 연료분사구조에 따른 배기가스 배출 특성을 파악하고자 단일연료분사구조와 이중연료분사구조를 갖는 예혼합 버너의 연소특성을 비교 분석하였으며 이중연료분사구조 적용 시 연료/공기 혼합특성이 향상되어 CO와 NOx의 배출농도가 감소하는 경향을 나타내었다. 또한, 노즐출구와 라이너의 지름 비(confined ratio)에 따른 연소부하 및 배기가스 특성을 분석한 결과 confined ratio 감소 시 연소부하 감소로 인해 NOx 배출농도가 감소되었으며, 체류시간의 증가로 인해 CO의 산화 반응이 증가하여 CO 배출농도가 감소하였다. 노즐분출속도는 30 ㎧에서 배기가스특성이 우수하며, 속도 증가(40 ㎧) 시 배가스특성이 저하되고 속도 감소(20 ㎧) 시 화염안정성이 저하되었다. This study aims to experimentally investigate the combustion characteristics of a lean premixed swirl-stabilized burner with dual-stage fuel injection arrays. The results show that a variation in the fuel distribution to fuel stages 1 (upstream) and 2 (downstream) produces a noticeable change in the NOx and CO emissions. Reducing the confined ratio, defined as the ratio of the nozzle exit diameter to the liner diameter, may reduce NOx and CO emissions owing to reduced combustion loading and longer residence time, respectively. A nozzle exit velocity of 30 ㎧ shows the optimum characteristics in terms of NOx and CO emissions and flame stability: increasing or decreasing the nozzle exit velocity leads to a degradation in emissions or flame stability, respectively.