Journal of the Korean Society of Propulsion Engineers (한국추진공학회지)

The Korean Society of Propulsion Engineers (한국추진공학회)
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Temperature Distribution of Liquid Nitrogen Jet at Sub- and Supercritical States

아임계 및 초임계에서 액체 질소 분류의 온도 분포

  • Lee, Hyunchang (Department of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Kim, Haisol (Department of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Cho, Seongho (Department of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Sung, Hong-Gye (School of Aerospace and Mechanical Engineering, Korea Aerospace University) ;
  • Yoon, Youngbin (Department of Mechanical and Aerospace Engineering, Seoul National University)
  • Received : 2017.03.15
  • Accepted : 2017.07.05
  • Published : 2018.02.01
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Abstract

Temperatures of cryogenic nitrogen jet inside an injector and at three different downstream positions (0.9, 10.6, and 28.1d) were measured with thermocouples in sub- and supercritical states. The jet temperature decreased while cooling the supply line and injector. The jet experienced from flash boiling, boiling and then no boiling according to decreasing temperature. As an analogy to flash-boiling at the subcritical state, pseudo-flash boiling has been assumed considering the existence of pseudo-boiling at the supercritical state. By showing an area where the temperature did not increase downstream, the plausibility of pseudo-flash boiling is proposed.

아임계 및 초임계에서 액체질소 분류의 온도가 분사기 내부와 세 개의 축방향 하류 위치(0.9, 10.6, 28.1d)에서 열전대를 이용하여 측정되었다. 액체질소는 공급라인과 분사기를 냉각하며 분사되므로, 분류의 온도는 시간에 따라 감소한다. 이때 챔버와 분사기 사이에 분사 차압이 존재하므로, 아임계에서 분류는 감압비등에서 비등 그리고 비등이 일어나지 않는 상태로 변화한다. 초임계에서 가짜끓음이 존재함에 착안하여, 가짜 감압비등의 존재에 대해 가정하였으며, 실제로 초임계에서도 아임계와 유사하게 일정 온도 영역에서 하류에서 온도의 변화가 없는 구간이 확인되었으며, 이를 바탕으로 가짜 감압비등이 존재할 수 있음을 보였다.

Keywords

References

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