Journal of the Korean Society for Aeronautical & Space Sciences (한국항공우주학회지)

The Korean Society for Aeronautical and Space Sciences (한국항공우주학회)
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Simulations of Axisymmetric Transition Flow Regimes Using a CFD/DSMC Hybrid Method

CFD/DSMC 혼합해석기법을 이용한 축대칭 천이영역 유동 해석

  • Choi, Young-Jae (Department of Aerospace Engineering, Korea Advanced Institute of Science and Technology) ;
  • Kwon, Oh-Joon (Department of Aerospace Engineering, Korea Advanced Institute of Science and Technology)
  • Received : 2018.10.20
  • Accepted : 2019.02.01
  • Published : 2019.03.01
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Abstract

In the present study, a CFD/DSMC hybrid method performed by a coupled analysis between the CFD method and the DSMC method was developed to obtain the flow information on the rarefied gas flows effectively. Flow simulations around the high speed vehicles on the transition flow regimes were conducted by using the developed method. The FRESH-FX vehicle made of cone and cylinder shapes was considered for the simulations. The results of the hybrid method were compared with the results of the pure CFD and the pure DSMC method to confirm the reliability and efficiency of the hybrid method. It was found that the gradient and the intensity of the shock waves were weakened due to the relatively low density on the transition flow regime. It was confirmed that the results of the hybrid analysis were different to those of the pure CFD analysis and almost identical to those of the pure DSMC analysis. In addition, the computational time of the hybrid method was reduced than that of the pure DSMC method. As a result, it was obtained that the validity and the efficiency of the CFD/DSMC hybrid method.

본 연구에서는 희박기체 환경의 유동 정보를 효과적으로 계산하기 위해 CFD 해석기법과 DSMC 해석기법 간 연계 해석을 수행하는 CFD/DSMC 혼합해석기법을 개발하였으며, 개발된 해석기법을 이용하여 천이영역에서의 고속 비행체 주위 유동에 대한 해석을 수행하였다. 해석 형상으로는 콘과 실린더 형태로 이루어진 FRESH-FX 형상으로 고려하였고, 혼합해석기법의 결과는 순수 CFD 및 DSMC 해석 결과와 비교하였다. 천이영역의 대기가 상대적으로 희박하여 초음속 유동에서 발생하는 충격파의 구배 및 세기가 약화된 것을 확인하였다. 순수 CFD 해석 결과와는 차이를 보였고, 순수 DSMC 해석 결과와 거의 일치하는 결과를 도출하는 것을 확인하였다. 또한, 순수 DSMC 계산시간보다 해석 시간이 감소하였다. 이를 통해 혼합해석기법의 결과에 대한 신뢰성 및 해석 시간에서의 효율을 확인하였다.

Keywords

References

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