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덕트 형상 연소기내의 연소 진동 감소를 위한 헬름홀츠 공진기의 적용
송재천(Jaecheon Song),송진관(Jinkwan Song),황정재(Jeongjae Hwang),윤영빈(Youngbin Yoon) 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.39
Combustion oscillations are caused by a coupling between acoustic waves and unsteady heat release. They can be eliminated using passive controller such as a Helmholtz resonator. But, Helmholtz resonator is normally only effective over a narrow frequency range. In this work, Helmholtz resonator is applied for reducing the combustion oscillations and we vary the Helmholtz resonator volume using piston in oder to tune in the wide range of operating conditions. As the result, it is found that the dominant combustion oscillations can be largely reduced by optimizing the size of resonator volume. And, interesting relation for phase difference of dynamic pressure both combustor and the Helmholtz resonator are presented in this paper. Also, we investigate tuned passive control using phase difference.
송재천 ( Jae Chun Song ),김상겸 ( Sang Kyum Kim ),김익성 ( Eak Seong Kim ),정인수 ( In Su Jung ),송영구 ( Young Goo Song ),유정식 ( Jeong Sik Yu ),박효진 ( Hyo Jin Park ) 대한소화기학회 2008 대한소화기학회지 Vol.52 No.4
We experienced a rare case of colonic cryptococcosis in an apparently immunocompetent individual. A 27-year-old woman admitted our hospital for intermittent melena. Initial abdominal CT scan revealed a mass lesion obstructing most of the lumen in ascending colon. Colonoscopy showed huge ulcerofungating mass in proximal ascending colon. Colonoscopic biopsy was performed and pathologic diagnosis was made as colonic cryptococcosis with positive PAS stain. Laboratory test evaluating immune status and bone marrow examination was normal. The patient was treated with intravenous amphotericin B for four weeks and six months of oral fluconazole afterwards. Follow-up abdominal CT scan and colonoscopy were taken at four weeks and seven months after the beginning of treatment. On completion of intravenous amphotericin B treatment, the mass lesion was decreased in abdominal CT and colonoscopy. After seven months, abdominal CT and colonoscopy showed near-complete resolution of the colonic lesion so the treatment ended. Cryptococcosis in a healthy individual is a rare disease and there have been only several sporadic case reports on pulmonary or central nervous system involvement. Hence, we report a case of colonic cryptococcosis in an apparently immunocompetent individual. (Korean J Gastroenterol 2008;52:255-260)
덕트 형상 연소기의 연소불안정에 대한 Semi-Active Control
송재천(Jae-Cheon Song),송진관(Jin-Kwan Song),황정재(Jeong-Jae Hwang),윤영빈(Young-Bin Yoon),이종근(Jong-Guen Lee) 한국항공우주학회 2009 韓國航空宇宙學會誌 Vol.37 No.11
연소불안정현상은 주로 음향파와 열방출률 섭동간의 상호작용에 의해 발생한다고 알려져 있다. 이러한 현상은 헬름홀츠 공진기와 같은 수동제어기를 사용하여 감소시킬 수 있다. 그러나 헬름홀츠 공진기는 일반적으로 좁은 주파수대역에 대해서만 효과가 있는 단점을 가진다. 따라서 본 연구에서는 다양한 작동 범위에서 효과를 가질 수 있도록 피스톤을 사용하여 헬름홀츠 공진기의 부피를 변화시켜가며 연소불안정현상에 적용하였다. 그 결과 피스톤을 최적 위치인 40mm에 동조시킴으로써 연소 불안정 모드의 진폭을 크게 감소시킬 수 있었다. 그리고, 연소기와 헬름홀츠 공진기 사이의 동압의 위상차가 흥미로운 관계에 있음을 나타내었다. 또한 헬름홀츠 공진식과 위상차를 이용한 능동적으로 동조되는 수동제어방식에 대해 알아보았다. Combustion Instabilities are caused by a coupling between acoustic waves and unsteady heat release. They can be eliminated using passive controller such as a Helmholtz resonator. But, Helmholtz resonator is normally only effective over a narrow frequency range. In this work, Helmholtz resonator is applied for reducing the combustion oscillations and we vary the Helmholtz resonator volume using piston in oder to tune in the wide range of operating conditions. As the result, it is found that the dominant combustion oscillations can be largely reduced by optimizing the size of resonator volume. And, interesting relation for phase difference of dynamic pressure both combustor and the helmholtz resonator are presented in this paper. Also, we investigate semi-active control using Helmholtz equation and phase difference.
연료온도 및 분사홀 크기에 의한 GDI 인젝터 유량 특성 연구
송재천 ( Song Jae-cheon ),정재호 ( Jung Jae-ho ),박정환 ( Park Jeong-hwan ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-
This study presents an experimental investigation of the flow characteristics according to fuel temperature and spray hole size for high pressure GDI injector, equipped with multi-hole type nozzle. For this purpose, injection rate measurements were performed with four different spray hole size over operating conditions from 100 to 300bar of fuel pressure and from -30 to +80℃ of fuel temperature. The test was conducted on FIE system bench similar to the actual engine operating conditions using the solenoid type injector.(Fig.1) Fuel injection rate was analyzed by using IAV injection rate system based on the Bosch method.
액체 램제트 엔진에서 Actively Tuned Passive Control 가능성의 실험적 연구
송재천(Jaecheon Song),송진관(Jinkwan Song),황정재(Jeongjae Hwang),윤영빈(Youngbin Yoon) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.5
연소불안정현상은 주로 음향파와 열방출률 섭동간의 상호작용에 의해 발생한다고 알려져 있다. 이러한 현상은 헬름홀츠 공진기와 같은 수동제어기를 사용하여 감소시킬 수 있다. 그러나 헬름홀츠 공진기는 일반적으로 좁은 주파수대역에 대해서만 효과가 있는 단점을 가진다. 따라서 본 연구에서는 다양한 작동 범위에서 효과를 가질 수 있도록 피스톤을 사용하여 헬름홀츠 공진기의 부피를 변화시켜가며 연소불안정현상에 적용하였다. 그 결과 피스톤을 최적위치에 동조시킴으로써 연소 불안정 모드의 진폭을 감소시킬 수 있었다. 또한 이러한 결과를 바탕으로 능동적으로 동조되는 수동제어방식의 가능성에 대해서 알아보고자 한다. Combustion oscillations are caused by a coupling between acoustic waves and unsteady heat release. They can be eliminated using passive controller such as a helmholtz resonator. But, helmholtz resonator is normally only effective over a narrow frequency range. In this work, helmholtz resonator is applied for reducing the combustion oscillations and we vary the helmholtz resonator volume using piston in oder to tune in the wide range of operating conditions. As the result, it is found that the dominant combustion oscillations can be reduced by optimizing the size of resonator volume. Also, from these results, we investigate feasibility of actively tuned passive control.
송재천(Song, J. C.),김재기(Kim, J. K.),신명섭(Shin, M. S.),박찬욱(Park, C. W.),안해성(Ahn, H. S.) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
This paper represents resistance and propulsion test results performed in order to verify the initial design(hull form, control fin, propeller, etc.) and improve performance of underwater vehicle with pre-twist angle of fin. These tests were carried out at a towing tank, KORDI and used large-scaled model with the law of dynamical similarity considering availability of VPMM equipment. Consequently, resistance and propulsion characteristics according to pre-twist angle of fin could be derived.
V-gutter 형 보염기를 장착한 모델 램제트 연소기의 화염 특성 및 연소 불안정 연구
송진관(Jinkwan Song),황정재(Jeongjae Hwang),송재천(Jaecheon Song),윤영빈(Youngbin Yoon) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.11
The goal of this study is to find flame dynamic behavior using a transverse fuel injection in a model combustor, and is to investigate main causes of unstable combustion in a liquid-fueled combustor.For transverse fuel injection into air cross flow, spray result shows similar tendency with Wu et al.[1998] until spray arrives at flame-holder. However, passing through flame-holder, fuel inflow into recirculation region of flameholder is not sufficient so it makes large difference between shear flame and recirculation flame behind flameholder. In combustion tests, the stable flame shows a kind of shear flames and low peaks of dynamic pressure frequencies. On the other hand, unstable flame shows periodic detached flame in recirculation zone and a strong peak of dynamic pressure frequency. The instability frequency is highly affected by influx air velocity, air temperature, equivalence ratio and wake or vortex shedding frequency behind the flameholder