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혼합기 공급방식에 따른 덤프연소기의 연소 불안정성에 관한 실험적 연구
홍정구,이은도,신현동,이민철,오광철 대한기계학회 2005 大韓機械學會論文集B Vol.29 No.8
The combustion instability of turbulent flames is the most important problem of the gas turbine combustor. Thus improved understanding of mechanisms of combustion instability is necessary for the design and operation of gas turbine combustors. In this study, the cause of the combustion instability in a rearward-step dump combustor was investigated with respect to the fuel flow modulation; choked fuel flow, unchoked fuel flow and fully premixed mixture flow. We observed various types of combustion instabilities with respect to the change of equivalence ratio, fuel flow conditions and fuel injection location. Particularly in the unchoked fuel flow condition, it was found that the oscillation time of combustion instability is strongly related to the convection time of the fuel and that the pressure fluctuation in a lab-scale combustor is highly related to the vortex and the equivalence ratio fluctuations due to fuel flow modulation and unmixedness of the fuel and air.
홍정구,김혁주,Hong, Jeong-Gu,Kim, Hyeok-Ju 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.8
The present study conducted experimental study of spray combustion to investigate the effect of the inlet conditions of fuel and air on the flame structure, the flame stability and the characteristics of emission in the can-type model of a gas turbine combustor. In the experiment, the diameter of fuel droplet was measured using Malvern particle size analyser and temperatures in the combustion chamber were measured with R-type shielded thermocouple. In addition, flame structure was taken picture with camera and analysed. Gas analyser was also used to analyse the concentration of each components of exhausting gas. The experimental results showed that the flame condition was optimal with swirl number, 0.63 and equivalence ratio, 0.5 for controlling the flame stability, the combustion temperature and the NOx concentration. The present study concluded that both the flame structure and the emission formation were strongly affected by the swirl intensity, which selection was found as an important parameter for either stabilizing flame or lowering the quantity of NOx.
열-음향에 의한 난류희박 예혼합연소의 불안정성에 관한 실험적 연구
홍정구(Jung Goo Hong),이민철(Min Chul Lee),신현동(Hyun Dong Shin) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The combustion instability acts as a serious obstacle for the lean premixed combustion of gas turbine and even causes the fatal damage to the combustor and whole system. In this experiment, the pressure fluctuation is highly related to the stabilizing position of flame and fuel injection location. The fuel injection location is connected with the convection time of the fresh mixture, which is important time scale to refresh the mixtures near the flame stabilization location. The flame is extremely unstable when the alternative stabilization occurs and bulk mode frequency (~10Hz) of pressure fluctuation is observed in this condition. It was found that the convection time scale of the fresh reactant coincided with the time scale of the bulk mode fluctuation. Hence this phenomenon results from the local equivalence ratio change caused by the pressure fluctuation induced by thermo-acoustic effects.
Urea-SCR 시스템 적용을 위한 스월 인젝터의 분무특성
홍정구(Junggoo Hong),구건우(Kunwoo Ku),김성열(Sungyoul Kim),이충원(Choongwon Lee),강명권(Myungkweon Kang),김경남(Kyungnam Kim),김재경(Jaekyoung Kim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.4
??In this study, a swirl hollow cone injector, which has a good atomization performance at the low injection pressure relatively, was designed to apply the Urea-SCR. In order to investigate the spray pattern and SMD of a swirl injector, the spray visualization was conducted by using the simple swirl injector, and the images of the spray cross-section were obtained from a sheet beam of Nd-Yag laser and CCD camera. The SMD of the swirl injector was measured with the axial of stance from the nozzle exit. The shape of the spray was converted from the hollow cone to solid cone along the distance from the injector exit. The spray angle is increased and the SMD is decreased with increasing injection pressure respectively.
헬름홀츠 공진기에 따른 버너내의 음향장에 관한 수치해석
홍정구(Jung Goo Hong),조한창(Han Chang Cho),신현동(Hyun Dong Shin) 한국연소학회 2007 KOSCOSYMPOSIUM논문집 Vol.- No.-
A study was performed to understand self-excited pressure fluctuations in the lean premixed flames and to evaluate the effect of Helmholtz resonator on the pressure fluctuations. As low-frequency pressure fluctuations have been reported to cause fatal damage to the combustor and the entire system, Helmholtz-type resonators, which reduce the damage by low-frequency pressure fluctuation in the combustor, are attached to the channel of unburned mixture flow. It is found that the range of low-frequency pressure fluctuations of flame mode 2 is narrowed by the attachment of Helmholtz resonators. From this result, if Helmholtz-type resonators are applied to actual gas turbine combustor, it is confirmed that Helmholtz resonators attached on the fuel discharge hole are also effective for narrowing the range of flame mode 2
당량비 변동과 와동이 덤프연소기내의 연소 불안정성에 미치는 영향
홍정구(Jung Goo Hong),이민철(Min Chul Lee),이은도(Uen Do Lee),오광철(Kwang Chul Oh),신현동(Hyun Dong Shin) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The combustion instability of turbulent flames, together with the emission of combustion products, is the most important problem of the gas turbine combustor. Thus improved understanding of mechanisms of combustion instability is necessary for the design and operation of gas turbine combustors. In this study, we investigated the cause of the combustion instability in a rearward-step dump combustor with respect to the fuel flow modulation choked fuel flow, unchoked fuel flow and fully premixed mixture flow. We observed various types of combustion instabilities with respect to the variation of equivalence ratio, fuel flow conditions and fuel injection location. We found that the pressure fluctuation of turbulent combustion in a lab-scale combustor is highly related to the vortex structure and the equivalence ratio fluctuations due to fuel flow modulation and unmixedness of the fuel and air.
덤프연소기내의 압력 변동과 당량비 변동에 관한 실험적 연구
홍정구(Jung Goo Hong),곽영태(Young Tae Guahk),오광철(Kwang Chul Oh),신현동(Hyun Dong Shin) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The flame behavior and the pressure fluctuations were measured in a dump combustor. Various types of combustion modes occurred in accordance with the equivalence ratio and the fuel supplying conditions. The fluctuations of pressure and equivalence ratio were measured by piezoelectric pressure sensor and gas chromatography respectively. Two representative modes were self-excited pressure oscillations at the resonance of combustion chamber (200 ㎐) and instabilities related to the modulated fuel flow rate through the fuel holes (10 ㎐). It is found that, especially in an unchoked fuel flow condition, the modulation of the fuel flow rate affects the characteristics of flame behavior and pressure fluctuations in a lean premixed flame.
Urea-SCR 시스템 적용을 위한 스월 인젝터의 분무특성
홍정구(Junggoo Hong),구건우(Kunwoo Ku),김성열(Sungryoul Kim),이충원(Choongwon Lee),강명권(Myungkweon Kang),김경남(Kyungnam Kim),김재경(Jaekyoung Kim) 한국자동차공학회 2011 한국자동차공학회 지부 학술대회 논문집 Vol.2011 No.4
In this study, a swirl hollow cone injector, which has a good atomization performance at the low injection pressure relatively, was designed to apply the Urea-SCR. In order to investigate the spray pattern and SMD of a swirl injector, the spray visualization was conducted by using the simple swirl injector, and the images of the axial of stance from the nozzle exit. The shape of the spray was converted from the hollow cone to solid cone along the distance from the injector exit. The spray angle is increased and the SMD is decreased with increasing injection pressure respectively.
커먼레일 디젤 인젝터의 분사압력과 분위기압력에 따른 분무 특성
홍정구(Jung Goo Hong),구건우(Kun Woo Ku),김준희(Jun Hee Kim),이충원(Choong Won Lee) 한국자동차공학회 2012 한국자동차공학회 지부 학술대회 논문집 Vol.2012 No.4
본 연구에서는 디젤 인젝터의 거시적 분무특성을 실험적으로 알아 보았다. 커먼레일 디젤 인젝터의 본사를 위해 보쉬 커먼레일 시스템을 사용하였다. 본 연구를 위한 대상 인젝터는 6-hole 보쉬 디젤 인젝터였다. 다양한 분사 조건에서 디젤 인젝터의 거시적 분무특성인 분무도달거리 및 분무각을 측정하였다. 본 연구에 따르면, 인젝터의 분사압력이 높을수록 분무달거리는 증가 하였다. 또한 동일 분사압력에서 분사되는 곳의 분위기 압력이 증가 할수록 분무도달거리는 감소하였고, 분무각은 증가하였다. In this study, we conducted the experimental study to investigate the macroscopic spray characteristics with a CRDI injector. A Bosch common rail system has been equipped for this study. We used a Bosch injector with 6 holes for nozzle in this study. The spray tip penetration and sprat angle was measured with the various test conditions. According to this study, the spray tip penetration increased with increase of the injection pressure. Furthermore, as the ambient pressure increase, the spray tip penetration decreased and the spray angle increased although the injection pressure was same.