Journal of the Korean Society of Propulsion Engineers (한국추진공학회지)

The Korean Society of Propulsion Engineers (한국추진공학회)
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Direct Numerical Simulation of Low Frequency Instability in a Hybrid Rocket with Equivalence Ratio Effects

하이브리드 로켓의 저주파불안정성에 미치는 당량비 영향 직접수치해석

  • Choi, Hyosang (Department of Mechanical Engineering, Sejong University) ;
  • Lee, Changjin (Department of Aerospace Engineering, Konkuk University) ;
  • Kang, Sang Hun (Department of Aerospace System Engineering, Sejong University)
  • Received : 2018.09.27
  • Accepted : 2019.03.04
  • Published : 2019.04.01
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Abstract

To understand the low frequency instability(LFI) characteristics in hybrid rockets combustion, effects of equivalence ratio variations on the phase shift between pressure and heat release oscillations were investigated by using the direct numerical simulation. The change in the equivalence ratio of the main chamber was simulated by the temperature and composition variation of the combustion gas introduced into the post-combustion chamber. In the results, additional combustion appeared along with vortex generation at the backward step, and combustion pressure and heat release oscillations were observed as the vortex moved. In addition, the results confirmed that the phase difference between the pressure and heat release oscillation shifts because of the changes in the propagation velocity of pressure wave as the temperature of combustion gas changes.

하이브리드로켓의 저주파수 연소불안정(LFI) 특성을 이해하기 위해, 주연소실의 연소 당량비 변화가 500 Hz대역의 압력 및 열방출 진동의 위상변화에 미치는 영향에 대해 직접수치해석을 수행하였다. 주연소실의 당량비 변화는 후연소실로 유입되는 연소가스의 온도 및 조성 변화로 모사하였다. 수치해석 결과, 후향 계단 하류에 와류 생성과 함께 추가적인 연소가 나타나며, 와류가 이동함에 따라 연소 압력 및 반응률의 진동이 관찰되었다. 또한, 유입유동의 온도가 변화하면 압력파의 전파속도도 함께 변화하므로 압력 및 반응률 진동 사이의 위상차가 천이하게 됨을 확인하였다.

Keywords

References

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