Library Subscription: Guest
Home Archives Officers Future meetings American Society of Thermal and Fluids Engineering
Second Thermal and Fluids Engineering  Conference

ISSN: 2379-1748
ISBN: 978-1-56700-430-4

EFFECT OF BUBBLE SIZE PASSING THROUGH A RECTANGULAR ORIFICE USING PARTICLE SHADOW VELOCMETRY (PSV)

Hirad Soltani
University of Alberta, Department of Mechanical Engineering, Edmonton, T6G 2G8, Alberta, Canada

Faezeh Rasimarzabadi
University of Alberta, Department of Mechanical Engineering, Edmonton, T6G 2G8, Alberta, Canada

Michael Leitch
RGL Reservoir Management, Leduc, AB

David S. Nobes
University of Alberta, Department of Mechanical Engineering, Edmonton, T6G 2G8, Alberta, Canada

Abstract

Rise of single bubbles in a free fluid medium has been extensively studied. In this study, the passage of air bubbles of different sizes through narrow straight slots (rectangular orifices) was investigated. The slot dimensions were chosen to be in a range used for other studies in similar cases. Bubble sizes were varied from bubbles of smaller diameter than slot width up to relatively larger diameter. Particle shadow velocimetry (PSV) was used to investigate flow field around single bubbles as they pass through a mini-slot as well as measure bubble size and velocity. As the working fluid which flows along with a bubble in the flow cell, a water/glycerol mixture was used and viscosity and density were calculated using water/glycerol reference tables. As bubbles become larger and closer in diameter to the slot width, confinement should be taken into consideration as a resisting force on bubble passage. Results show that as bubble size increases the rising velocity data sees an upward trend up to a specific diameter. There is a downward trend of bubble rising velocity due to wall effects (confinement). Reynolds number analysis for bubbles show that the range is below what is essential to generate recirculation or a von Karman vortex behind passing bubbles. Results show that all bubble sizes decelerate as they enter the slot and they accelerate again after exiting. In the regions before and after the slot, bubbles of bigger sizes had higher rise velocity due to higher buoyancy force. However, rising velocity had a downward trend inside the slot for bubbles bigger than a certain diameter due to confinement. The vorticity map analysis showed that smaller bubble developed lower a value of vorticity in comparison to the large bubbles. This is because in a system of rising bubble for smaller bubbles the pressure difference between front and rear of the bubble is lower.

Purchase $20.00 Check subscription Publication Ethics and Malpractice Recommend to my Librarian Bookmark this Page