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전태준(Tae Jun Jeon),박태선(Tae Seon Park) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
초임계 상태의 연소해석은 단상의 유체로 가정이 가능하여 미립화나 분열과정을 고려할 필요가 없다는 장점이 있지만, 급격한 물성치 변화로 인해 해석이 쉽지 않은 상황에 있다. 따라서 초임계 상태의 연소해석을 위한 많은 연구들이 진행되었지만, 대부분 2차원 축대칭조건으로 해석되어 실제 연소기 조건에 대한 연구 결과로 타당하지 않다. 본 연구에서는 초임계 압력에서 수소, 산소의 실제유체 효과가 고려된 3차원 형상의 다중 분사기에 대해 분사기의 수 변화에 의한 영향을 수치적으로 연구하였다. The combustion analysis in the supercritical state can be assumed as a single-phase fluid, so there is no need to consider the atomization or break up process, but the analysis is difficult due to rapid changes in the material properties. So, many studies have been carried out for supercritical combustion analysis, but most of them have been applied as two-dimensional axisymmetric conditions and are not valid as a result of real combustor conditions. In this study, the effect of the number of injector on the three dimensional multi-injector considering the real fluid effect of hydrogen and oxygen at supercritical pressure was numerically investigated.
추력이 최적화된 노즐의 초음속 유동에 대한 노즐벽 초기 및 출구각도의 영향
전태준(Tae Jun Jeon),박태선(Tae Seon Park) 한국추진공학회 2021 한국추진공학회지 Vol.25 No.3
Effects of the nozzle wall angles on the supersonic flow field in a thrust optimized nozzle were numerically investigated. The combustor and operating condition of 30-tonf rocket engine was selected to study the optimum nozzle shape. The nozzle flow of combustion products was realized by the shifting equilibrium calculation for the propellant of kerosene-LOx. The change of nozzle wall angles induced different developing patterns of the internal and secondary shock wave. The optimum nozzle was obtained when the internal shock was in a specific position at the nozzle outlet. The nozzle wall angles of the optimum nozzle were very similar to those of the optimum nozzle which does not consider the shock wave.
초임계 압력조건에서 기체수소-액체산소 연소해석의 층류화염편 라이브러리에 대한 인공신경망 학습 적용
전태준(Tae Jun Jeon),박태선(Tae Seon Park) 한국추진공학회 2021 한국추진공학회지 Vol.25 No.6
To develop an efficient procedure related to the flamelet library, the machine learning process based on artificial neural network(ANN) is applied for the gaseous hydrogen/liquid oxygen combustor under a supercritical pressure condition. For hidden layers, 25 combinations based on Rectified Linear Unit(ReLU) and hyperbolic tangent are adopted to find an optimum architecture in terms of the computational efficiency and the training performance. For activation functions, the hyperbolic tangent is proper to get the high learning performance for accurate properties. A transformation learning data is proposed to improve the training performance. When the optimal node is arranged for the 4 hidden layers, it is found to be the most efficient in terms of training performance and computational cost. Compared to the interpolation procedure, the ANN procedure reduces computational time and system memory by 37% and 99.98%, respectively.
상변화가 있는 가변추력 액체로켓엔진의 재생냉각채널에 대한 수치해법 개발
전태준(Tae Jun Jeon),박태선(Tae Seon Park) 한국추진공학회 2023 한국추진공학회지 Vol.27 No.6
In order to analyze regenerative cooling channels of a variable thrust liquid methane engine with phase change, an ANSYS UDF(User-defined function) program was developed using the exact solution of the Stefan problem. The NASA CEV(Crew Exploration Vehicle) methane engine with the expander cycle was selected for the computational domain. The combustion chamber pressure is reduced from 5.86 ㎫ to 1.172 ㎫ where phase change can occur. The results of boiling heat transfer for phase change models and Nu correlations were investigated and the related problems were presented.