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Generation of Bubbly Suspensions in Low GravityGeneration of a uniform monodisperse bubbly suspension in low gravity is a rather difficult task because bubbles do not detach as easily as on Earth. Under microgravity, the buoyancy force is not present to detach the bubbles as they are formed from the nozzles. One way to detach the bubbles is to establish a detaching force that helps their detachment from the orifice. The drag force, established by flowing a liquid in a cross or co-flow configuration with respect to the nozzle direction, provides this additional force and helps detach the bubbles as they are being formed. This paper is concerned with studying the generation of a bubbly suspension in low gravity in support of a flight definition experiment titled "Behavior of Rapidly Sheared Bubbly Suspension." Generation of a bubbly suspension, composed of 2 and 3 mm diameter bubbles with a standard deviation <10% of the bubble diameter, was identified as one of the most important engineering/science issues associated with the flight definition experiment. This paper summarizes the low gravity experiments that were conducted to explore various ways of making the suspension. Two approaches were investigated. The first was to generate the suspension via a chemical reaction between the continuous and dispersed phases using effervescent material, whereas the second considered the direct injection of air into the continuous phase. The results showed that the reaction method did not produce the desired bubble size distribution compared to the direct injection of bubbles. However, direct injection of air into the continuous phase (aqueous salt solution) resulted in uniform bubble-diameter distribution with acceptable bubble-diameter standard deviation.
Document ID
20000057304
Acquisition Source
Glenn Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Nahra, Henry K.
(NASA Glenn Research Center Cleveland, OH United States)
Hoffmann, Monica I.
(NASA Glenn Research Center Cleveland, OH United States)
Hussey, Sam
(NASA Glenn Research Center Cleveland, OH United States)
Bell, Kimberly R.
(Pennsylvania State Univ. University Park, PA United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2000
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
AIAA Paper 2000-0854
Meeting Information
Meeting: Aerospace Sciences
Location: Reno, NV
Country: United States
Start Date: January 10, 2000
End Date: January 13, 2000
Sponsors: American Inst. of Aeronautics and Astronautics
Distribution Limits
Public
Copyright
Public Use Permitted.
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