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Numerical study for flame deflector design of a space launch vehicle
Oh, Hwayoung,Lee, Jungil,Um, Hyungsik,Huh, Hwanil Elsevier 2017 ADVANCES IN SPACE RESEARCH Vol.59 No.7
<P><B>Abstract</B></P> <P>A flame deflector is a structure that prevents damage to a launch vehicle and a launch pad due to exhaust plumes of a lifting-off launch vehicle. The shape of a flame deflector should be designed to restrain the discharged gas from backdraft inside the deflector and to reflect the impact to the surrounding environment and the engine characteristics of the vehicle. This study presents the five preliminary flame deflector configurations which are designed for the first-stage rocket engine of the Korea Space Launch Vehicle-II and surroundings of the Naro space center. The gas discharge patterns of the designed flame deflectors are investigated using the 3D flow field analysis by assuming that the air, in place of the exhaust gas, forms the plume. In addition, a multi-species unreacted flow model is investigated through 2D analysis of the first-stage engine of the KSLV-II. The results indicate that the closest Mach number and temperature distributions to the reacted flow model can be achieved from the 4-species unreacted flow model which employs H<SUB>2</SUB>O, CO<SUB>2</SUB>, and CO and specific heat-corrected plume.</P>
Hyungsik Ju,Eunsung Oh,Daesik Hong IEEE 2009 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.8 No.8
<P>This letter presents a new full duplex relay (FDR) system that features more efficient use of time resource and antennas. The proposed FDR system is constructed based on time and antenna-sharing and elimination of underlying interference. The underlying interference caused by time- and antenna-sharing is eliminated using precoding. We propose a design for the precoder and decoder, and investigate the achievable rate of the proposed FDR system when the precoder and decoder are applied. Simulation results show improved achievable rate and BER performances with the proposed FDR system compared to half duplex and conventional full duplex relay systems.</P>
고체추진기관의 Al<SUB>2</SUB>O<SUB>3</SUB>가 고무내열재에 미치는 영향을 평가하는 시험방법 연구
이형식(Hyungsik Lee),강윤구(Yoongoo Kang),임수용(Sooyong Lim),오종윤(Jongyun Oh),이경훈(Kyunghoon Lee) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11
고체추진기관의 연소 생성물 중 Al2O3는 노즐목으로 빠져나가지 않고 연소관내부에 침적될 수 있다. 침적된 슬래그에 의한 고무내열재의 열반응을 모사하기위하여 특별한 추진기관을 설계하여 시험하였다. 이 특별한 추진기관 시험 중 슬래그 침적양상을 Dynamic Radioscopy로 촬영함으로서 처음 설계한데로 원하는 위치에 슬래그가 침적된다는 것을 입증하였다. 본 논문에서 개발한 시험방법은 새롭게 설계하려는 추진기관내부의 온도와 압력을 그대로 모사할 수 있어 슬래그에 의한 고무내열재의 재료 특성평가 및 연소관의 내열고무두께를 결정하는 설계자료로 사용할 수 있는 모사시험 방법이다. 연소평균압력 770 psi이고 연소시간 50초인 추진기관의 EPDM내열재를 모사 시험한 결과 열량이 큰 슬래그에 의한 고무 열반응량이 연소가스 유속에 의한 삭마량보다 적음을 알 수 있었다. In solid propellant rocket motors, Al2O3 , one of combustion products, can be accumulated inside a combustion chamber. A special rocket motor was designed and tested to simulate thermal reaction of rubber insulator affected by the deposited slag. We successfully demonstrated through a dynamic radioscopy that the slag was deposited at the location as designed. In this paper we present a new test method which can simulate a high temperature and pressure environment in combustion chamber to evaluate material characteristics of rubber insulator and can provide design data to decide its thickness for a new solid rocket motor. The solid rocket motor, which has an average chamber pressure of 770 psia and a burning time of 50 seconds, was tested. The results show that erosion of EPDM insulator is more affected by a gas velocity rather than by the thermal reaction of slag with a high thermal capacity.
고체추진기관의 Al₂O₃가 고무내열재에 미치는 영향을 평가하는 시험방법 연구
이형식(Hyungsik Lee),강윤구(Yoongoo Kang),임수용(Sooyong Lim),오종윤(Jongyun Oh),이경훈(Kyunghoon Lee) 한국추진공학회 2011 한국추진공학회지 Vol.15 No.3
In solid propellant rocket motors, Al₂O₃, one of combustion products, can be accumulated inside a combustion chamber. A special rocket motor was designed and tested to simulate thermal reaction of rubber insulator affected by the deposited slag. We successfully demonstrated through a dynamic radioscopy that the slag was deposited at the location as designed. In this paper we present a new test method which can simulate a high temperature and pressure environment in combustion chamber to evaluate material characteristics of rubber insulator and can provide design data to decide its thickness for a new solid rocket motor. The solid rocket motor, which has an average chamber pressure of 770 psia and a burning time of 50 seconds, was tested. The results show that erosion of EPDM insulator is more affected by a gas velocity rather than by the thermal reaction of slag with a high thermal capacity.
이덕주,오형식 한국경영과학회 1994 經營 科學 Vol.11 No.1
B-ISDN(Broadband Integrated Services Digital Network)which is defined as a service or system requiring transmission channels capable of supporting rates above 1.5 Mbps has emerged as a new future telecommunication infrastructure. B-ISDN can integrate a wide range of services and the success of B-ISDN is crucially dependent on the development of user-needing application services. The purpose of this study is the conceptual development of B-ISDN application services. We survey on the kind of B-ISDN service, classify application areas by user groups, and develop B-ISDN application services. Finally we categorize B-ISDN application services by their application areas and necessary services.
오화영(Hwayoung Oh),강선일(Sunil Kang),김대래(Daerae Kim),이정일(Jungil Lee),엄형식(Hyungsik Um),허환일(Hwanil Huh) 한국추진공학회 2014 한국추진공학회지 Vol.18 No.6
The flame deflector should be constructed to minimize the induced environmental effects on the launch vehicle and to minimize the exhaust impingement effects on the launch complex structures during the lift-off operation. Therefore, it should be designed to avoid recirculation and reverse flow of rocket exhaust plumes. The circumstance around launch complex and characteristics of launch vehicle should be taken into consideration for the flame deflector design. In this paper, we designed the flame deflector reflecting KSLV-II 1st engine characteristics and analyzed the effect of exhaust plumes related to change geometry by means of computational flow analysis.
우주발사체 엔진 연소 후류에 따른 발사대 지상설비 영향성 분석
오화영(Hwayoung Oh),엄형식(Hyungsik Um),허환일(Hwanil Huh) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
발사대시스템은 조립시험시설에서 단별 총 조립과 기능 점검을 마친 우주발사체를 발사장으로 이송하여 최종 기능 점검과 추진제, 고압가스 충전을 통해 발사 운용을 수행하는 설비이다. 발사대 지상에 위치한 지상기계설비는 우주발사체 엔진 노즐 후단에서 배출되는 고온·고속의 연소가스에 견딜 수 있도록 구축되어야 한다. 본 논문에서는 전산유동해석을 활용하여 시험발사체 이륙 시 엔진 연소가스가 발사대 지상설비에 미치는 영향에 대해 검토하였다. The launch complex system is a facility that transports the launch vehicle, of which all the stages have been assembled and functionality has been checked at the assembly complex, and conducts the launch operation as it provides final functionality checkouts and charges propellant and high-pressure gases. The mechanical ground support equipment located on the ground should be constructed to bear up under the exhaust gas of high temperature and pressure emitted from the engine nozzle. In this paper, we analyzed the effect of exhaust gas on the ground equipment related to a lift-off of the Test Launch Vehicle by means of computational flow analysis.
오화영(Hwayoung Oh),강선일(Sunil Kang),이정일(Jungil Lee),엄형식(Hyungsik Um),허환일(Hwanil Huh) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12
화염유도로는 우주발사체 이륙 시 발생하는 연소 후류에 의한 발사체 및 발사대 구조물에 대한 손상을 방지하는 구조물이다. 화염유도로 설계는 엔진 노즐에서 배출되는 연소가스가 화염유도로 내부에서 역류하지 않는 구조적인 형상 설계가 필수이며, 발사장 주변 환경과 운용되는 발사체의 엔진특성이 반영되어야 한다. 본 연구에서는 한국형발사체 1단 엔진 특성과 나로우주센터 발사장 환경을 고려하여 3가지 화염유도로 기초 형상을 설계하였으며, 플룸을 추진제 연소가스 대신 공기로 가정한 3D 유동해석을 통해 화염유도로 형상에 따른 연소 가스 배출 형태를 분석하였다. A flame deflector is a structure that prevents damage to the launch vehicle and launch complex due to the exhaust plume of a lifting-off launch vehicle. The shape of a flame deflector should be designed to restrain the discharged gas from backdraft inside the deflector and to reflect the impact to the surrounding environment and the engine characteristics of the vehicle. This study presents the three preliminary flame deflector configurations which are designed for the first-stage rocket engine of the KSLV-Ⅱ and surroundings of the Naro space center. The gas discharge patterns of the designed flame deflectors are investigated via the 3D flow field analysis assuming that the air, in place of the exhaust gas, forms the plume.