DEVELOPMENT OF TECHNIQUE BASED ON FLUORESCENCE TO MEASURE TWOPHASE SLUG FLOW / DESENVOLVIMENTO DE TÉCNICA BASEADA EM FLUORESCÊNCIA PARA MEDIÇÃO DE ESCOAMENTO BIFÁSICO EM REGIME DE GOLFADA

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

This work presents the implementation of a non-intrusive optical technique for measuring the hydrodynamic characteristics of liquid- gas, two-phase flows. The work was limited to the study of air-water slug flows. The technique implemented, already described in the literature, combines Particle Image Velocimetry - PIV, Laser Induced Fluorescence - LIF, and pulsed background illumination, known as Pulsed Shadow Technique - PST. The combination of these techniques allows the simultaneous measurement of the instantaneous flow field generated in the liquid by the passage of the air bubble, together with the shape and velocity of the bubble. The technique was employed in the study of an air bubble rising in a stagnant liquid layer. The PIV technique was employed in the determination of the instantaneous flow field in the liquid using fluorescent particles illuminated by a pulsed laser sheet. An optical high-pass filter was used to block the light scattered by the air-water interfaces and by the pipe walls, allowing the digital camera employed to only capture the particle positions. A LED panel furnished back illumination at a wave length that passed through the high-pass filter and allowed an accurate determination of the bubble shape. A digital image processing procedure was employed to determine the bubble shape, velocity and liquid flow field. The results obtained revealed, with excellent resolution, the details of the liquid flow at the wake, wall film and nose of the rising bubble, thereby attesting to the quality of the technique implemented.

ASSUNTO(S)

escoamento bifasico lighting fluorescencia velocimetria velocimetry iluminacao fluorescence two-phase flow

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