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CFD 해석을 통한 핀틀-노즐 조립체의 성능 특성 연구
진정근(Jungkun Jin),하동성(Dong Sung Ha),이정섭(Jeongsub Lee),기태석(Taeseok Ki) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5
고체 추진기관의 추력 조절을 위한 핀틀-노즐 밸브 조립체의 유동해석을 통하여 핀틀 스트로크 변화에 따른 노즐 성능 변화에 대한 연구를 수행하였다. OpenFOAM을 사용하였으며 유동 해석으로부터 획득한 유량, 추력을 이용하여 유량 배출 계수(CD), 추력 계수 (CF)의 거동을 확인하였다. 핀틀-노즐 조립체에서 기하학적으로 획득한 최소 면적을 이용하여 CD와 CF를 획득할 경우 스트로크에 따라 이론치와의 비율이 달라짐을 확인하였으며 핀틀 헤드부에 가해지는 압력 분포가 바뀜에 따라 핀틀에 가해지는 축하중의 방향이 스트로크에 따라 변화되는 것을 확인하였다. The pintle-nozzle performance was studied with CFD simulation using open source code, OpenFOAM. The mass flow rate and thrust obtained from CFD were used to get the discharge coefficient (CD) and thrust coefficient (CF) of the pintle nozzle for various pressure and stroke. Throat area used in the calculation of CD and CF were the geometrical minimum area which is bounded by the nozzle wall and the pintle wall. It was observed that the ratio of CD obtained with CFD and the value estimated theoretically depended on the pintle stroke. The results of CF were also similar with CD for various the pintle strokes The axial load on the pintle was also estimated and its direction change was observed as the pintle stroke increased.
진정근(Jungkun Jin),하동성(Dong Sung Ha),기태석(Taesoek Ki) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.5
핀틀 노즐 기술을 적용한 고체 추진기관의 지상 연소시험을 수행하였다. 고정된 핀틀에 대하여 연소시험을 수행한 결과 핀틀 팽창에 의한 압력 증가현상이 나타남을 확인하였으며 압력 측정 결과로부터 예측한 팽창량을 적용하면 핀틀 구동 시에도 압력 결과를 잘 예측할 수 있음을 확인하였다. 핀틀 구동 시 핀틀 기밀부의 열팽창에 따른 마찰력 증가에 의한 핀틀의 비정상 거동이 확인되었으며 기밀부 수정을 통하여 이러한 현상을 해결할 수 있음을 실험적으로 확인하였다. 또한 추진기관 내부에 위치한 중공을 통과하는 유량에 따라 중공 삭마 현상이 심해져 중공의 손실이 발생함을 확인하였다. Ground firing test of solid rocket motor with pintle-technology was carried out. using two different pintle-nozzles. The effects of thermal expansion of the pintle on the measured pressure and thrust were observed with fixed pintle stroke. Unstable actuation of pintle was observed through the ground firing test with actuator due to increase in friction force induced by the radial thermal expansion of pintle. This unexpected unstable actuation was removed by modifying pintle sealing part. In addition, it was observed that erosion of the central tube which was inserted to supply combustion gas to the pintle-nozzle attached on the back-side dome of the combustion chamber, was able to be enhanced due to the increase in mass flow rate passing through the central tube at a certain pintle stroke combination.
핀틀-노즐이 적용된 고체추진기관의 연소 시험 성능 분석
진정근(Jungkun Jin),하동성(Dong Sung Ha),오석진(Seokjin Oh) 한국추진공학회 2014 한국추진공학회지 Vol.18 No.5
Firing test of solid rocket motor with pintle-technology carried out and the measured pressure-time curve was compared with the values predicted by the internal ballistic and performance analysis. Without baffle, the measured combustion chamber pressure was similar with the predicted pressure at the beginning of combustion, but gradual increase in pressure, which was unexpected with the end-burning grain of which burning area is constant, was observed. A baffle was inserted to make uniform flow over the pintle. Unlike the thruster without baffle, the measured combustion chamber pressure was 1.4 times higher than the predicted value. Through the CFD simulation, 10% of total pressure loss of the flow was observed from combustion chamber to nozzle throat when the baffle was inserted. The measured pressure with baffle was predicted well by considering the total pressure loss in the internal ballistic modelling and performance analysis.
진정근(Jungkun Jin),오석진(Seokjin Oh),이지형(Ji Hyung Lee),하동성(Dong Sung Ha),박성한(Sunghan Park),양준서(Juneseo Yang) 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.12
핀틀 노즐 기술을 적용한 고체 추진기관의 지상 연소시험을 수행하여 내탄도 성능 해석과 비교하였다. Baffle이 없는 핀틀-노즐 추진기관 시험 결과 초기 압력은 내탄도 성능 해석 결과와 유사하였으나 점진적으로 압력이 증가하는 현상이 나타났다. 또한, 핀틀로 공급되는 유동을 균일하기 위하여 baffle을 추가하여 시험을 수행하였다. 시험 결과 예측되는 압력보다 40% 높은 압력이 측정되었으며 CFD 유동 해석을 통하여 baffle에 의한 전압력 손실이 발생하며 전압력 손실을 고려하여 예측된 연소실 압력이 측정 압력과 유사함을 확인하였다. Firing test of solid rocket motor with pintle-technology was carried out to compare the pressure-time curve obtained by internal ballistic and performance analysis. Without baffle, the measured combustion chamber pressure was similar with the predicted pressure and progressive burning was observed with end-burning grain. A baffle was inserted to make uniform flow over the pintle and tested. Unlike the thruster without baffle, the measured combustion chamber pressure was 1.4 times higher than the predicted value. In CFD simulation, 10% of total pressure loss was observed from combustion chamber to nozzle throat with the baffle. The measured pressure with baffle was predicted well by considering the total pressure loss in the internal ballistic modelling and performance analysis.