베인없는 디퓨저에서의 스톨 임계 유동각에 관한 연구

Stall Critical Flow Angle in a Vaneless Diffuser of a Centrifugal Compressor

  • 강정식 (한국항공우주연구원 터보기계연구그룹) ;
  • 강신형 (서울대학교 기계항공공학부)
  • 발행 : 2002.08.01

초록

Rotating stall in vaneless diffusers of centrifugal compressor occurs in the diffuser wall due to flow separation at large inlet flow angle. For this reason, the critical inlet flow angles are suggested by several researchers. Beyond this critical angle, flow separates in the diffuser, and develops into rotating stall. This paper studied this critical flow angle. Rotating stall is measured through eight fast-response pressure transducers which are equally spaced around the circumference at the inlet and exit of a vaneless diffuser. Experiments are done from 20000rpm to 60000rpm for the diffuser stall. Two-cell structure which rotates at $6{\~}l0{\%}$ of impeller speed is fully developed at $20000{\~}40000rpm$, and three-cell structure which rotates at $7{\~}9{\%}$ of impeller speed is fully developed at $50000{\~}60000rpm$. This paper shows that the critical inlet flow angle is not constant but related with tip speed of impeller. As tip speed increases, so does the critical inlet flow angle.

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