• 소음진동
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• 제6권6호
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• pp.819-825
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• 1996

Nonlinear dynamic characteristics of rubbing phenomenon in rotor dynamics are investigated experimentally and numerically. Rubbing phenomenon occurs when rotor contacts with stator during whirling and causes the large amplitude of vibration, high whirl frequencies, and possibly catastrophic failure. Rubbing has various types of forward whirl, backward rolling, backward slipping, and partial rub depending on the system parameters of rotating machinery and running speed. Experiments are performed for forward whirl and backward whirl. And numerical analysis are conducted to explain the changes between backward rolling and backward slipping. Experimental and numerical results show that the types of whirling motion depends on the friction coefficient between rotor and stator and the eccentricity of rotor.

• 한국추진공학회지
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• 제17권5호
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• pp.60-69
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• 2013

마이크로 가스터빈용 하이브리드/이중 선회 제트 연소기의 형상 최적화에 대한 실험연구가 수행되었다. 고정된 열부하에서 pilot 버너의 위치 및 선회기 베인의 방향이 주요 변수로 검토되었다. 주요 결과로서, pilot 버너 및 연료 노즐의 위치변화는 버너 출구 근처의 최소 유동면적 및 재순환 유동패턴의 변화를 발생시키며, 이로 인하여 선회강도 및 화염형상이 큰 영향을 받게 된다. 선회기 베인 각도의 증가($30^{\circ}$에서 $45^{\circ}$)는 희박가연한계 근처에서 CO 배출량을 크게 저감시킨다. 추가로 정방향 선회형상이 역방향 선회형상에 비해 보다 낮은 CO 및 NOx 배출량을 갖게 됨을 확인하였다.

• 대한기계학회논문집B
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• 제25권1호
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• pp.78-86
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• 2001

The Gasoline Direct Injection(GDI) system has been highlighted due to the improvement of fuel consumption and the control of exhaust emission from gasoline engines. The GDI system includes a high injection pressure, smaller mean diameter, good spray characteristics and stability. We were interested in the development for gasoline direct swirl injector(GDSI) in which the swirler is specially designed with an incident angle. Nymerical analysis was utilized to investigate the internal flow of GDSI with a goal to determine the swirl incident angle and needle lift. Accordingly, it describes characteristics of a GDSI in which the flowrate and spray characteristics are satisfied. especially the spray tip penetration decreases, compared with other type GDI, mean diameter of droplets is from 20${\mu}{\textrm}{m}$ to 25${\mu}{\textrm}{m}$ and spray angle ranges from 64$^{\circ}$to 66$^{\circ}$.