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초폭굉 모드 램가속기의 혼합기 강도 특성에 대한 수치적 연구
성근민(Kunmin Sung),정인석(In-Seuck Jeung) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.5
ISL의 초폭굉 모드 램 가속기 실험을 바탕으로 하여 혼합기 강도를 조정하여 수치해석을 수행하였다(3.0CO2 희석과 2.5CO2 희석). 계산결과 3.0CO2 희석의 경우는 초기 점화가 이루어지지 않아 탄체가 가속되지 않은 반면 2.5CO2 희석을 한 경우에는 점화가 이루어지고 높은 가속을 보임을 알 수 있었다. 이것은 탄체의 가속성능이 혼합기의 강도에 단순히 비례하지 않으며 점화가 가능한 최소한의 혼합기 강도 이상에서만 초폭굉 모드 램 가속기가 정상적으로 작동함을 알 수 있었다. Based on ISL" S225 superdetonative mode ram accelerator, numerical simulation is conducted for strong mixture cases (2H2+O2+3CO2, 2H2+O2+2.5CO2). For 3.0CO2 case, projectile is not acclerated, but 2.5CO2 case has sucessful acceleration. It shows that superdetonative mode ram accelerator can be operated when using mixture which strong enough to ignition.
희석 기체의 종류에 따른 초폭굉모드 램가속기의 화염특성
성근민(Kunmin Sung),김채형(Chae-hyoung Kim),이승복(Seung-bok Lee),박지현(Ji-hyun Park),정인석(In-Seuck Jeung) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.42
An numerical study was conducted on superdetonative mode ram accelerator for stoichiometric H₂/O₂ mixture which is diluted with CO₂, O₂, Ar. The computation case was based on ISL’s RAMAC30 Ⅱ experiment. Each computational cases was follows same Mach number and over-driven factor. Computational results showed similar flame structures. However, each case shows different ignition characteristics because reaction mechanism can be affected in the case of CO₂ or O₂ dilution. Moreover, specific heat ratio is also affected by dilution gases. If Ar is selected as dilution, specific heat ratio is increased and total temperature also increase. As result, ignition is affected by dilution. These characteristics with various dilution gases should be considered when design superdetonative mode ram accelerator.
초폭굉 모드 램 가속기의 연소실 길이에 따른 화염유지특성에 대한 수치적 연구
성근민(Kunmin Sung),정인석(In-Seuck Jeung) 한국연소학회 2007 KOSCOSYMPOSIUM논문집 Vol.- No.-
An numerical study was conducted on superdetonative mode ram accelerator with extended combustor. The computation case was based on ISL's RAMAC30 Ⅱ experiment. For 50% length increased combustor, flame is not sustained. For the case of 60% and 70% increase, flame is successfully sustaind. But detonation wave is oscillating and acceleration is fluctuating. Increasing of combustor length is helpful for sustaing detonation wave but it may cause unstart.
성근민(Kunmin Sung),정인석(In-Seuck Jeung) 한국연소학회 2014 한국연소학회지 Vol.19 No.1
An analytical study on performance evaluation of superdetonative mode ram accelerator was conducted for understanding the experimental result. The quasi-one dimensional continuum, momentum, energy equations were solved under the assumption of inviscid flow. It would be noticeable that experimental result could be analytically simulated with the assumptions of inlet shockwave, temperature dependent specific heat, and additional aluminum combustion due to ablation of aluminum projectile in superdetonative operation mode. The acceleration of ram accelerator was comparable to experimental result with the consideration of the additional aluminum combustion energy by ablation of projectile. As result, the experimental result with the aluminum projectile could be affected by heat of aluminum.
초폭굉 모드 램 가속기의 연소실 길이에 따른 화염유지특성에 대한 수치적 연구
성근민(Kunmin Sung),정인석(In-Seuck Jeung) 한국연소학회 2007 한국연소학회지 Vol.12 No.4
An numerical study was conducted on superdetonative mode ram accelerator with length extended combustor. The computation condition was based on ISL's RAMAC30 Ⅱ S225 experiment. For 50% length increased combustor, flame is not sustained. For the case of 60% and 70% increase, flame is successfully sustaind. But detonation wave is oscillating and acceleration is fluctuating. Extention of combustor is helpful for sustaing detonation wave but it may cause unstart.
성근민(Kunmin Sung),정인석(In-Seuck Jeung) 한국연소학회 2013 KOSCOSYMPOSIUM논문집 Vol.- No.46
An analytical study on performance of superdetonative mode ram accelerator was conducted for understanding the S225 experimental result of ISL. It would be noticeable that ISL S225 experimental result could be analytically simulated with the assumptions of inlet shockwave, equilibrium combustion chemistry, temperature dependent specific heat, and C-J oblique detonation in superdetonative operation mode. As result, the S225 experiment could be affected by heat of aluminum. Also, this study showed that the improper assumption, like isentropic assumption on shockwave, or constant specific heat on combustion, might cause misunderstanding about experimental result.
김채형(Chae-hyoung Kim),성근민(Kunmin Sung),정인석(In-Seuck Jeung),최병일(Byoungil Choi),Toshinori Kouchi,Goro Masuya 한국항공우주학회 2009 韓國航空宇宙學會誌 Vol.37 No.9
일반적으로 초음속 유동 실험 장치에는 축대칭형 노즐이나 이차원 대칭형 노즐이 사용되고 있다. 하지만, 이차원 비대칭형 초음속 노즐은 상대적으로 가공비용이 저렴하며 노즐의 결합부에서 생기는 불필요한 충격파 생성을 줄일 수 있는 이점이 있다. 본 논문에서는 초음속 혼합기의 연소 실험을 위해 마하수 2의 비대칭 초음속 노즐을 설계하였다. 특성곡선해법을 이용하여 설계된 노즐에 대하여 수치해석을 수행하여 경계층보정을 하였으며 최종적으로 가공된 노즐에 대하여 마하파를 가시화 하는 실험을 통하여 노즐의 성능을 검증하였다. 이를 통하여 2차원 비대칭형 초음속 노즐의 설계와 검증 방법을 제시하였다. Most supersonic-flow test facility has axisymmetric nozzles or two-dimensional symmetric nozzles. Compared to these nozzles, a two-dimensional asymmetric nozzle has advantages of reducing low cost for various Mach number testing and undesirable flow structure such as shock wave reflection because the nozzle part can be directly connected to the test section part in this type of nozzle. The two-dimensional asymmetric nozzle, which was Mach number 2, was designed for supersonic combustion experiment. And it was verified with the numerical analysis and visualization of Mach wave. This study suggested the practical method for design and verification of supersonic two dimensional asymmetric nozzles.