Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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Performance Characteristics Under Non-Reacting Condition with Respect to Length of a Subscale Diffuser for High-Altitude Simulation

고고도 모사를 위한 축소형 디퓨저의 길이변화에 따른 비연소장에서의 성능특성

  • Jeong, Bonggoo (Dept. of Mechanical Engineering, Chungnam Nat'l Univ.) ;
  • Kim, Hong Jip (Dept. of Mechanical Engineering, Chungnam Nat'l Univ.) ;
  • Jeon, Junsu (Dept. of Aerospace Engineering, Chungnam Nat'l Univ.) ;
  • Ko, Youngsung (Dept. of Aerospace Engineering, Chungnam Nat'l Univ.) ;
  • Han, Yeoung-Min (Propulsion Test Team, Korea Aerospace Research Institute)
  • 정봉구 (충남대학교 기계공학과) ;
  • 김홍집 (충남대학교 기계공학과) ;
  • 전준수 (충남대학교 항공우주공학과) ;
  • 고영성 (충남대학교 항공우주공학과) ;
  • 한영민 (한국항공우주연구원 추진시험팀)
  • Received : 2013.09.17
  • Accepted : 2014.02.10
  • Published : 2014.04.01
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Abstract

The performance characteristics of a subscale diffuser under non-reacting conditions for high-altitude simulation were numerically investigated with respect to different lengths of the secondary throat diffuser. The ratio of the length of the diffuser entrance to the nozzle exit diameter was set to 0, 50, and 100%. In addition, flow characteristics were studied for a range of length-to-diameter ratios of the secondary throat diffuser. An insufficient diffuser entrance length caused contraction of the plume immediately after the nozzle exit. When the length-to-diameter ratio was less than 8, a strong Mach disk was formed inside the diffuser, resulting in a sharp increase in pressure. In addition, flow characteristics in the diverging part of the diffuser were investigated for a range of diverging part lengths. A short diverging part may lead to abrupt pressure recovery, resulting in the possible application of mechanical load to the diffuser.

고고도 모사를 위한 축소형 디퓨저의 비연소장 조건에서의 성능특성을 수치적으로 파악하였다. 디퓨저 입구길이를 노즐 출구직경과 비교해 0, 50, 100%로 변화 시켰고, 디퓨저 목의 길이는 2차목의 직경과 비교해 3, 5, 6, 7, 8, 12로 다양화하여 해석하고 실제 모사실험 값과 비교하였다. 그 결과 디퓨저의 입구길이가 짧아질수록 plume의 형상은 수축되었다. 또한, 디퓨저의 2차목 길이가 디퓨저 지름의 최소 8배보다 짧으면 내부에 마하디스크가 형성되어 압력의 급격한 상승을 일으킨다. 아음속 디퓨저의 길이는 설계치의 0, 50, 75, 100%로 변화시켜 유동의 변화를 관찰하였고, 길이가 짧아질수록 2차목 내부에 갑작스런 압력 상승을 야기함을 확인하였다.

Keywords

References

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