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경험적 모델과 실험 자료 기반 하이브리드 로켓 신뢰성 분석
김완범(Wan-Beom Kim),문근환(Geun-Hwan Moon),이정표(JungPyo Lee),김진곤(JinKon Kim),최주호(Joo-Ho Choi) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Reliability evaluation is of paramount importance in the design of critical systems such as rocket motors. Numerical analysis technique that can predict the reliability during the design stage has been a viable solution, from which possible design changes to attain higher reliability, can be made in a fast manner. In the real practice, however, the approach relying solely on the numerical codes have found only a limited success due to the lack of knowledge to model the complex phenomena of propulsion or prohibitive computational cost for underlying physics. In this study, reliability analysis procedure is addressed for a hybrid rocket motor, which is currently developed by our research group. The advantages of hybrid rocket over the other systems are the on-off capability, lower development cost, less environmental impact, and more importantly, greater safety and reliability. The performance is characterized by the fact that the oxidizer and the fuel are in different phases; the fuel is a solid of cylindrical configuration, while the oxidizer is injected into its port as a liquid spray. In the hybrid rocket motor, high fidelity codes for the propulsion simulation are not readily available or almost useless unless validated via costly instrumentation. Instead, design procedure has been established based on the low-fidelity or empirical model supported and validated by greater number of experimental data for input parameters and responses. Despite the obvious presence of uncertainties associated with this procedure, however, the performance has mostly been assessed by a primitive regression technique. In this study, method for quantification of various uncertainties such as ignorance of probability distribution, limited number of data, bias in the validation experiment and inherent measurement error is explored. Bayesian approach plays the central role to this end, which can take care of various uncertainties in an integrated manner. Consequently, the propulsion performance will be given in the form of probability distribution, from which the reliability is computed and used for design evaluation.
몬테 카를로 시뮬레이션을 이용한 하이브리드 로켓의 신뢰성 분석
문근환,김완범,이정표,최주호,김진곤,Moon, Keunhwan,Kim, Wanbeom,Lee, Jungpyo,Choi, Jooho,Kim, Jinkon 항공우주시스템공학회 2013 항공우주시스템공학회지 Vol.7 No.4
In this study, probabilistic reliability analysis was conducted for hybrid rocket performance using Monte-Carlo Simulation. For the accuracy, reliability analysis was performed with experimental data. To simplify the analysis process, the oxidizer was supplied with constant pressure, so that pressure variation with time can be eliminated. And time-space averaged regression rate model was used. The regression rate is obtained with a series of experiments. For reliability analysis of thrust, constant exponent of regression rate is assumed that has probabilistic character. So, the efficiency of characteristic velocity has also probabilistic values. As a results, probability distribution of the thrust is obtained by Monte-Carlo simulation using random samples of the input parameter and validated under the 95% confidence level.
확률적 설계 기법을 적용한 하이브리드 로켓 모터의 신뢰성 분석
문근환(Keunhwan Moon),김완범(Wanbeom Kim),이정표(Jungpyo Lee),최주호(Jooho Choi),김진곤(Jinkon Kim) 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.5
본 연구에서는 확률적 설계 기법을 적용하여 하이브리드 로켓 모터의 신뢰성 분석을 수행하였다. 하이브리드 로켓 모터의 신뢰성 분석을 위해서 실험을 통해 측정된 실험값을 사용하여 입력 변수의 확률적 특성을 모델링 하였다. 이 결과 추력을 확률분포로 구할 수 있었으며, 실제 측정치가 예측한 확률분포의 95% 신뢰구간 내에 있는 것을 확인 할 수 있었다. In this study, reliability analysis is conducted for hybrid rocket motor performance using probabilistic design method. Experimental data are used to model the probability distributions of the input parameters of the equations in the performance evaluation. As a result, distribution of the thrust is predicted and validated by the measured thrust under the 95% confidence level.