Non-intrusive measurements in dispersed, bubbly pipe flow

Document Type

Conference Proceeding

Publication Date

12-1-1995

Abstract

A phase-Doppler light-scattering method is used to measure liquid and bubble velocities and bubble size in vertical-upwards, dispersed, bubbly pipe flow. The measurements are non-intrusive and therefore the possible physical effects of probe insertion are not present. Bubble size measurements are obtained with the phase-Doppler method and a video imaging technique which is also non-intrusive. Optical distortion is eliminated, by using pipe material with index of refraction equal to that of water in combination with an index-of-refraction-matching box. Pure-liquid velocity and turbulence intensity test-measurements compare very well with existing data in pipe flow. Measurements of bubble velocity and size at two locations along the pipe are presented with emphasis on the near wall region. The experiments have been carried out at a Reynolds number of 12086 and a volumetric flow ratio of 2.7%. Bubble velocity fluctuation properties were found to be almost uniform in the core region. Bubble mean velocity was constant within one average bubble diameter from the wall and axial velocity fluctuations peaked at approximately half that distance. Velocity distributions near the wall were non-gaussian and skewed towards lower values. The average bubble size was found to be in the range between 1200 μm and 1400 μm with standard deviations of the order of 500 μm. Smaller bubbles were found to be in the neighborhood of the wall.

Publication Source (Journal or Book title)

American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD

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