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초음속 유동 내 램프 탭의 형상적 특성에 따른 성능 연구
고재명(Jae-Myoung Ko),강민호(Min-Ho Kang),김진호(Jin-Ho Kim),이종훈(Jong-Hun Lee),박종호(Jong-ho Park) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the drawbacks. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. This paper studies the aerodynamic performance that the tapered ramp tabs showed its geometric characteristics. Numerical simulation was also performed to study flow characteristics and interactions between ramp tabs. This paper provides distribution of pressure in the region enclosed by the tapered ramp tabs.
김경련(Kyoung-Rean Kim),고재명(Jae-Myoung Ko),박순종(Soon-Jong Park),박종호(Jong-Ho Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the disadvantages. TVC is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. In this paper, the conceptual design and the performance study on the tapered ramp tabs of the thurst vector control has been carried out using the supersonic cold flow system and shadow graph. Numerical simulation was also performed to study flow characteristics and interactions between ramp tabs. This paper provides to analyze the location of normal shock wave and distribution of surface pressure on the region enclosed by the tapered ramp tabs.
초음속 노즐 출구에 비대칭적으로 설치한 램프 탭의 성능 연구
김경련(Kyoung-Rean Kim),고재명(Jae-Myoung Ko),박종호(Jong-Ho Park) 한국항공우주학회 2007 韓國航空宇宙學會誌 Vol.35 No.10
추력방향제어는 발사 직후 비행체를 임의의 방향으로 급선회해야 할 경우에 초음속 노즐의 배출가스 방향을 조절하여 측력과 모멘트를 형성시키는 방법이다. 본 연구에서는 압축공기를 이용한 비 연소시험으로 초음속유동 시험장치를 이용하여 기계적 편향판인 램프 탭의 설치위치에 따라 성능연구를 수행하였다. 밀도변화에 따라 유동장을 관찰할 수 있는 쉬리렌 장치를 이용하여 램프 탭 내부에서 발생하는 유동장 구조와 경사충격파의 위치 등을 가시화하였다. 아울러 각 방향에 작용하는 제어 힘, 추력손실 및 표면 압력 분포 등을 도시ㆍ분석하였다. Thrust vector control(TVC) is the method which generates the side force and moment by controlling the exhausting gas directly from the supersonic nozzle to change the trajectory of a missile quickly. In this paper, performance study on the tapered ramp tabs asymmetrically installed in the supersonic nozzle exhaust for the thurst vector control has been carried out using the supersonic cold flow system. To study the shock wave structure and location of the oblique shock wave produced by the ramp tab, the flow field visualization using the schlieren system is conducted. This paper provides the thrust spoilage, three directional forces and moments and distribution of surface pressure on the region enclosed by the tapered ramp tabs.
원통다관식 열교환기의 크기 및 형상 변화에 따른 설계 응력 연구
이용범(Yong-Bum Lee),한성건(Sung-Gun Han),고재명(Jae-Myoung Ko) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.7
The present work aims to evaluate theoretically the axial, bending and equivalent stress of tube sheet, shell and tube stress, according to size, thickness and dimension of shell and tube heat exchangers. In addition, effects of stress due to variations of tube side and shell side temperature are investigated. Our ultimate purpose is to ensure safety of design products and develop new products rapidly. According to our results, first of all, the effective pressure, and stress of tube sheet and shell increase with an increment of the shell diameter and a decrement of tube temperature under constant shell temperature. Next, these decrease with an increment of the number of tube, shell thickness and shell temperature under constant tube temperature. Finally, the stress of tube row decrease when the equivalent stress of tube increases. Stress knowledge related to various parameters will be helpful for designers and manufacturers.
김영준(Young-joon Kim),김상균(Sang-gyun Kim),이동근(Dong-keun Lee),박주영(Ju-young Park),고재명(Jae-myoung Ko) 한국유체기계학회 2009 유체기계 연구개발 발표회 논문집 Vol.2009 No.-
An experimental investigation has been carried out in order to evaluate the characteristic of wetted multi-path ultrasonic flowmeter. This knowledge has been gained from measurements in laboratory devices of K-water institute. The multi-path ultrasonic flowmeter was installed before and after various pipe fittings(straight, 90˚ elbow) and valve (gate valve, butterfly valve). We measured the flow-rate at each location. The distance between the flow disturbance factor and a flowmeter was important element of the test.