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고고도 모사를 위한 축소형 디퓨저의 성능 특성에 대한 수치적 연구
정봉구(Bonggoo Jeong),임경진(Kyungjin Yim),조성휘(Seonghwi Jo),김홍집(Hongjip Kim),전준수(Junsoo Jeon),고영성(Youngsung Ko),김승한(Seung-han Kim),한영민(Yeoung-Min Han) 한국추진공학회 2012 한국추진공학회 학술대회논문집 Vol.2012 No.5
고고도 모사를 위한 축소형 디퓨저의 성능특성을 파악하기 위해 수치적 연구를 수행하였다. 입구길이를 노즐 출구직경과 비교해 0%, 50%, 100%로 변화시켰고, 디퓨저 목의 길이는 디퓨저 목의 직경과 비교해 3, 5, 7, 8, 12로 다양화하여 수치해석하고 실제 모사실험 값과 비교하였다. 그 결과 디퓨저의 입구길이가 짧아질수록 plume의 형상은 수축되었다. 또한, 디퓨저의 이차목 길이가 디퓨저 지름의 최소 7~8배보다 작으면 내부에 마하디스크가 형성되어 압력의 급격한 상승을 일으킨다. Performance characteristics of subscale diffuser for high-altitude simulation have been numerically investigated. The length of diffuser entrance with respect to nozzle exit diameter was changed to 0, 50, 100%, respectively. In addition, flow characteristics have been studied for various length to diameter ratio of secondary throat diffuser. As a result, the shape of plume was contracted for insufficient length of diffuser entrance. Also, if the length to diameter ratio of secondary throat diffuser were less than 7 or 8, mach disk has been formed inside the diffuser.
축소형 모델 연소기에서 상온상압기상연소시험을 통한 FOOF 충돌형 분사기의 연소안정성 평가
정봉구(Bonggoo Jeong),김홍집(Hong Jip Kim) 한국연소학회 2013 KOSCOSYMPOSIUM논문집 Vol.2013 No.12
The objective of present study is to investigate the combustion stability boundaries of FOOF impinging injectors. For model tests. subscale chamber was adopted. Gaseous oxygen and methane/propane mixture are used to simulate actual propellants like liquid oxygen and kerosene. Experimental tests were performed under conditions of ambient temperature and pressure. Major instability region was determined and extrapolated by the parameters of combustion-chamber pressure and mixture ratio. This methodology can be used to quantify the stability margin of various injectors.
고고도 모사를 위한 축소형 디퓨저의 길이변화에 따른 비연소장에서의 성능특성
정봉구(Bonggoo Jeong),김홍집(Hong Jip Kim),전준수(Junsu Jeon),고영성(Youngsung Ko),한영민(Yeoung-min Han) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.4
고고도 모사를 위한 축소형 디퓨저의 비연소장 조건에서의 성능특성을 수치적으로 파악하였다. 디퓨저 입구길이를 노즐 출구직경과 비교해 0, 50, 100%로 변화 시켰고, 디퓨저 목의 길이는 2차목의 직경과 비교해 3, 5, 6, 7, 8, 12로 다양화하여 해석하고 실제 모사실험 값과 비교하였다. 그 결과 디퓨저의 입구길이가 짧아질수록 plume의 형상은 수축되었다. 또한, 디퓨저의 2차목 길이가 디퓨저 지름의 최소 8배보다 짧으면 내부에 마하디스크가 형성되어 압력의 급격한 상승을 일으킨다. 아음속 디퓨저의 길이는 설계치의 0, 50, 75, 100%로 변화시켜 유동의 변화를 관찰하였고, 길이가 짧아질수록 2차목 내부에 갑작스런 압력 상승을 야기함을 확인하였다. The performance characteristics of a subscale diffuser under non-reacting conditions for high-altitude simulation were numerically investigated with respect to different lengths of the secondary throat diffuser. The ratio of the length of the diffuser entrance to the nozzle exit diameter was set to 0, 50, and 100%. In addition, flow characteristics were studied for a range of length-to-diameter ratios of the secondary throat diffuser. An insufficient diffuser entrance length caused contraction of the plume immediately after the nozzle exit. When the length-to-diameter ratio was less than 8, a strong Mach disk was formed inside the diffuser, resulting in a sharp increase in pressure. In addition, flow characteristics in the diverging part of the diffuser were investigated for a range of diverging part lengths. A short diverging part may lead to abrupt pressure recovery, resulting in the possible application of mechanical load to the diffuser.
DFSS 기법을 이용한 EPS 소음/진동 인자 분석 및 강건 설계 방안
정태구(Taegu Jung),조기순(Kisoon Cho),정봉구(Bonggoo Jeong),임태서(Taeseo Lim) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
Recently, most of the steering system applied to vehicle is the EPS system using a motor. EPS can make the driver comfort and safe by providing proper steering performance on various driving condition. As the role and function of the EPS rises, the necessity of the EPS optimization design will be considered as an important task to increase the vehicle performance and customer satisfaction. But there are many EPS system during development due to mismatch among sub-systems and it causes extra resources such as cost and time. So steering system requires systematic design strategy and also to meet the requirement of functional safety(ISO 26262). Firstly, we analyzed issue histories such as vibration and noise by using DFMEA, then derived factors which influence on EPS system. The scope for each factors was determined by the tuning parameter of the EPS Module, Operation logic, and Performance calibration which are sub-system of EPS. The selected factors were derived by DFSS and were able to come up with a Robust Design for the EPS system by optimizing the main factor.