곡관덕트에서 LDV를 이용한 천이정상유동의 유동특성에 관한 연구(I)

봉태근,박길문 한국마린엔지니어링학회 2000 한국마린엔지니어링학회지 Vol.24 No.6

In this paper, an experimental investigation of characteristics of developing transitional steady flows in a square-sectional 180 urved duct is presented. The experimental study is carried out to measure axial velocity profiles by using Laser Doppler Velocimeter (LDV) system. The flow development is found to depend upon Dean number and curvature ratio. For transitional steady flows, the maximum velocity position of axial velocity profiles begins to incline toward the outer wall from $\phi$=$30^{\circ}$bended angle, velocity profiles in center of the duct have lower value than those of the inner and outer walls because of the centrifugal forces.

선박화재사고의 재해방지에 관한 연구

봉태근,조대환 木浦海洋大學校 2002 論文集 Vol.10 No.2

This study is a preparation for the application of FSA(Formal Safety Assessment) to the fire safety of ships. FSA is the new-fashioned methodology proposed to prevent ships from the accidents. To make a base of the fire safety assessment about ship's fire protection design and Classification Society rule, statistical informations for the fire safety engineering are investigated. From results, the necessity of new criterion for ship's fire safety design, the need to study the human behavior in the evacuation from fire, and the development of new fire progress model considering special situations in ships are acknowledged.

정방형 공기덕트 내부의 유동특성에 원심력이 미치는 영향에 관한 연구

봉태근,조대환,Bong, Tae-Keun,Cho, Dae-Hwan 해양환경안전학회 2012 海洋環境安全學會誌 Vol.18 No.5

이 연구에서는 정사각 단면을 갖는 덕트 내부에 원심력의 영향을 받는 유동의 천이특성을 실험 및 수치적으로 규명하였다. 실험적 연구로서 레이저도플러 속도계를 이용하여 축방향속도를 측정하였고, 상용소프트웨어인 플루언트를 이용한 전산유체 시뮬레이션으로 천이특성을 고찰하였다. 유동의 발달은 딘수와 굽힘각에 의존한다는 사실을 알 수 있었으며 덕트의 중앙에서의 속도분포는 원심력 때문에 내외벽보다 낮은 값을 나타내었다. In this paper, an experimental and numerical investigation of transition characteristics in a square-sectional curved duct flow under Centrifugal force is presented. The experimental study is carried out to measure axial velocity profiles by using Laser Doppler Velocimeter (LDV) system. Computational fluid dynamic (CFD) simulation was performed using the commercial CFD code FLUENT to investigate the transition characteristics. The flow development is found to depend upon Dean number and curvature ratio. The velocity profiles in center of the duct have lower value than those of the inner and outer walls because of the centrifugal forces.

遠心펌프의 캐비테이션에 의한 低사이클系 振動特性에 關한 考察

奉邰根 木浦海洋大學校 1993 論文集 Vol.1 No.1

It is known that low cycle system oscillation tends to occur in a piping system connected to a high-speed pump in which cavitation occuring. This paper is conducted with the aim of clarifying the cause of low-cycle system oscillation in flow modality, where cavitation in reverse flow periodically emerges and dissipates. The three types of low-cycle system oscillation are defined by synthetic studies. The effects of NPSH, pump flow rate, rotational speed, and pipe length are clarified experimentally.

소형어선의 동력인출장치 원격제어시스템 개발에 관한 연구

봉태근,조대환 한국기계기술학회 2014 한국기계기술학회지 Vol.16 No.5

This research was conducted to develop the system for a remote control operation for the existing power transfer unit. It was also conducted to supplement the shortcomings of the existing lever control operation, and to develop a system for applying the clutch mechanism and shut down equipment. The developed net hauler for coastal small vessels will result in better fishing with improved efficiency and lower manpower consumption by remote control of winch system.

石炭燃料를 使用하는 디젤機關의 排出가스의 特性과 制御에 관한 考察

奉邰根 木浦海洋大學校 1994 論文集 Vol.2 No.1

It is not enough that a prime mover be an effcient producer of power ; the engine must also be environmentally acceptable. If a new engine type is to replace a current engine successfully, the engine should produce no more and preferably less emission than the current engine type. Coal-fueled diesel engine are being developed with the goal of being environmentally superior to current technology. The major emission contaminant from conventional diesel engines has been NOx, although data to date suggest that a comparable CWS-fueled diesel engine will produce less than one-half the amount of NOx. SOx and particulates appear to be the major concern for CWS-fueled diesel engines.

틈새를 갖는 수직벽 후류특성에 관한 연구

봉태근,조대환 木浦海洋大學校 2004 論文集 Vol.12 No.-

The turbulent shear flow around a surface-mounted vertical wall was investigated by using the two-frame PIV(CACTUS 3.1) system. And mean velocity distributions have also been measured in the whole flow field. From this study, it is revealed that at least 500 instantaneous velocity field data are required for ensemble average to get reliable turbulence statistics. It. is found that the large eddy structure in the separated shear layer have significant influence on the development of the separated shear layer. The vertical wall with center gap ε=20% seems to be effective for attenuating the velocity fluctuations behind wall.

곡관덕트의 입구영역에서 천이정상유동의 유동특성에 관한 연구

봉태근 한국마린엔지니어링학회 1999 한국마린엔지니어링학회지 Vol.23 No.1

In this paper an experimenatal investigation of characteristics of developing ransitional steady flows in a square-sectional $180^{\circ}$ curved duct is presented, The experimental study is carried out to measure axial velocity profiles secondary flow velocity profiles and entrance length by using Laser Dopper Velocimeter(LDV) system. The flow development is found to depend upon Dean number and curvature ratio. Of special interest is the secondary flow generated by centrifugal effects in the plane of the cross-section of the duct. The secondary flows becomes strong from $120^{\circ}$ of bended angle on the duct. The entrance length of transitional steady flow is obtained to $120^{\circ}$ of bended angle of the duct in this experimental conditions.

곡관덕트내의 입구영역에서 난류 맥동유도의 유동특성

봉태근 한국마린엔지니어링학회 1999 한국마린엔지니어링학회지 Vol.23 No.4

In this study the flow characteristics of developing turbulent pulsating flows in a square-sec-tional 180。 curved duct are investigated experimentally. The experimental study of air flow in a square-sectional curved duct is carried out to measure axial velocity distribution secondary flow velocity profiles and wall shear stress distributions by using a Laser Doppler Velocimetry system with the data acquisition and processing system of Rotating Machinery Resolver (RMR) and PHASE software at the entrance region of the duct which is divided into 7 sections from the inlet(${{\o}}=0_{\circ}$) to the outlet (${{\o}}=180_{\circ}$) in $30_{\circ}$ intervals. The results obtained from the study are summarized as follows: (1) The time-averaged critical Dean number of turbulent pulsating flow(De ta, cr) is greater than $75{\omega}+$ It is understood that the critical Dean number and the critical Reynolds number are related to the dimensionless angular frequency in a curved duct. (2) Axial velocity profiles of turbulent pulsating flows are of an annular type similar to those of turbulent stead flows. (3) Secondary flows of trubulent pulsating flows are strong and complex at the entrance region. As velocity amplitudes(A1) become larger secondary flows become stronger. (4) Wall shear stress distributions of turbulent pulsating flows in a square-sectional $180_{\circ}$ curved duct are exposed variously in the outer wall and are stabilized in the inner wall without regard to the phase angle.

정방형 공기덕트 유동의 축방향 속도분포에 관한 전산모사 연구

봉태근,조대환,최지운 한국기계기술학회 2013 한국기계기술학회 학술대회논문집 Vol.2013 No.08