Void Fraction Measurements Using the Impedance Method

임피던스 방법을 이용한 기공율 측정에 대한 연구

  • 김무환 (포항공과대학교 기계공학과) ;
  • 양훈철 (포항공과대학교 기계공학과) ;
  • 송철화 (한국원자력연구소 열수력안전연구팀) ;
  • 정문기 (한국원자력연구소 열수력안전연구팀)
  • Published : 2000.04.20

Abstract

Impedance method was carried out to design the electrode that can measure the void fraction of the bubbly flow in pool reservoir. To find out the optimum electrode shape, Styrofoam-tests were performed in a specially designed acrylic reservoir. Three kinds of electrodes were designed to compare the characteristics of water-air flow. The resistance was increased as the void fraction increased and the capacitance was decreased as the void fraction increased. The resistance is a main parameter to express the nature of the water-air flow in impedance method. Almost all the values of impedance were involved in resistance. The degree of deviation from the mean-resistance values showed reasonable results. Electrode type-I expressed excellent results among the three electrode shapes. The impedance values in void fraction 0-10% were similar to those of Maxwell's equation. But the impedance values in void fraction 10-20% were not similar to those of Maxwell' equation because of the edge effect near electrode.

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