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Numerical study on combustion characteristics of a pintle injector for liquid rocket engines
Kanmaniraja Radhakrishnan,Min son(손민),Kijeong Yu(유기정),Jaye Koo(구자예) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.11
The numerical study has carried on the pintle injector to analysis the characteristics and their performance of combustion in liquid rocket engine and get an optimized pintle shape by recirculation zone which is present near to the pintle opening. The effects of recirculation zone, flame structure, minimum heat transfer to pintle tip and combustion performance have been studied with the help of three different cases of pintle injector. We observed numerically that Case 2 has minimum heat transfer to pintle tip than remaining two different cases due to effects of re-circulation zone under given conditions. And also, the presence of re-circulation zone in the geometry which makes better blends of methane and oxygen to make the combustion complete.
Effect of injection conditions on mixing performance of pintle injector for liquid rocket engines
Radhakrishnan, Kanmaniraja,Son, Min,Lee, Keonwoong,Koo, Jaye Elsevier 2018 Acta astronautica Vol.150 No.-
<P><B>Abstract</B></P> <P>A movable pintle injector provides an effective throttling and high combustion stability in liquid rocket engines for performing space maneuvers safely. It has a movable pintle rod that causes a variable injection area. The mass flow of simulant and pintle opening affect the mixing performance of propellants, which is concerned in this paper. Therefore, the mixing performance is studied by the effect of mass flow rate of liquid, gas and pintle opening distance. The liquid is ejected radially from a center gap to form a thin liquid sheet which is broken by gas jet from an annular gap axially. To simulate this, the Lagrangian approach was employed. A 2D-axisymmetrical model is used in which Realizable K-epsilon model as a viscous model. Then, the primary and secondary breakup are performed by employing the single injection model and wave model based on Weber number. The spray angle and SMD are compared with the experimental data for validating the breakup model. The effect of increasing the mass flow rate of liquid at the lower pintle opening results a narrow dispersion angle that causes the poor mixing quality, which is recovered by increasing the mass flow rate of gas, where the dispersion angle is became wider. And, the effect of the pintle opening distance results a wider dispersion angle thereby the case with poor mixing quality at a lower opening distance is recovered. As a result, it is observed that the case with wider dispersion angle had a wide range of the mass fraction distribution of droplets along the radial position at X/D<SUB>pt</SUB> = 5.00 than the case with narrow dispersion angle. The dispersion angle, spray angle and mixing quality are compared with the correlating parameter <SUB> N K </SUB> . The comparison showed that the mixing quality, spray angle and dispersion angle are not changed largely after <SUB> N K </SUB> = 0.83.</P>
핀틀 인젝터의 팁 내부 유동 가이드가 연소 성능에 미치는 영향
이건웅(Keonwoong Lee),남정수(Jeonsoo Nam),칸마니라자(Kanmaniraja Radhakrishnan),구자예(Jaye Koo) 한국항공우주학회 2020 韓國航空宇宙學會誌 Vol.48 No.9
핀틀 인젝터는 LMDE의 인젝터로 채용되어 아폴로 계획의 성공적인 수행에 일조하였으며, 최근 SpaceX 사의 Merlin 엔진으로 다시 조명받고 있는 인젝터의 형태이다. 본 연구에서는 액체산소/기체메탄을 이용하는 500N 급 Lab-Scale 핀틀 인젝터 추력기를 제작하여 연소실험을 수행하였다. 그러나 초기 연소실험은 핀틀 팁의 용융과 낮은 연소효율이라는 문제를 노출하였다. 따라서 이를 해결하기 위하여 전산수치해석을 통한 시뮬레이션을 통해 유동 가이드가 추가된 핀틀 팁의 냉각 성능을 향상시킬 수 있는 설계를 채택하였으며, 연소실험을 통해 유동 가이드의 효용성을 확인하였다. Pintle injector is known to have been adopted as injector of Lunar Module Descent Engine (LMDE) and contributed to success of the Apollo program and recently used in merlin engine. In this study, 500N Lab-Scale pintle injector thruster was manufactured and the combustion experiment with LOx/GCH4 was conducted. However, the proto-type thruster was showed some problems, such as low combustion efficiency and melting of pintle tip. To solve these problems, the flow guide in pintle tip was suggested through the CFD simulation. After addition of flow guide module, the combustion efficiency increased and pintle tip did not melt until the end of combustion.
가변 추력용 핀틀 분사기에서 추진제 상에 따른 상압분무 특성
유기정 ( Kijeong Yu ),손민 ( Min Son ),( Kanmaniraja Radhakrishnan ),김희동 ( Heuy Dong Kim ),구자예 ( Jaye Koo ) 한국분무공학회 2016 한국액체미립화학회지 Vol.21 No.1
Atmospheric spray characteristics were experimentally compared between liquid-gas and liquid-liquid sprays of a pintle injector. In order to study spray characteristics, water and air were used as the simulants and the visualization technic was adopted. Spray images were acquired by using a backlight method by a high-resolution CMOS camera. As a result, when the pintle opening distance increased, liquid sheets became unstabled and fluttering droplets increased. In the liquid-gas case, the breakup performance increased as the pressure of gas injected from the annular orifice increased. In the liquid-liquid case, atomization efficiency decreased as the pressure of liquid injected from the annular orifice increased. Spray angles presented a similar trend between two cases. At the same momentum ratio, the spray angle of liquid-liquid case was lower than the angle of liquid-gas case.
발사체 인젝터 특별세션 : 액체-액체 모사추진제를 사용한 핀틀 인젝터의 분무 특성
유기정 ( Kijeong Yu ),손민 ( Min Son ),( Kanmaniraja Radhakrishnan ),구자예 ( Jayae Koo ) 한국액체미립화학회 2015 한국액체미립화학회 학술강연회 논문집 Vol.2015 No.-
Spray angle characteristics of a pintle injector using liquid-liquid phases were compared with the characteristics of the injector using liquid-air phases. The spray angles were measured from spray images captured by backlight method using a CMOS camera. The water and air were injected in the pressure range of 0.1 bar - 1.0 bar and pintle opening distances were controlled from 0.2 mm to 1.0 mm. The spray angles of liquid-liquid phase decreased linearly as the momentum ratios increased. While the spray angle characteristics of liquid-liquid phases had similar trend as the characteristics of liquid-gas, break up characteristics were different.