TY - JOUR
T1 - Degassing of a decompressed flowing liquid under hypergravity conditions
AU - Oikonomidou, O.
AU - Evgenidis, S.P.
AU - Schwarz, C.J.
AU - van Loon, J.J.W.A.
AU - Kostoglou, M.
AU - Karapantsios, T.D.
PY - 2019/6/1
Y1 - 2019/6/1
N2 - The formation and growth of bubbles due to decompression degassing of a liquid has been extensively studied in the past, aiming to enhance the efficiency of specific industrial applications. Even though liquid decompression degassing may interfere with the performance of space processes (such as cooling and lubrication systems, combustion and storage of liquid propellants etc.), the phenomenon has never been studied in non-terrestrial gravity conditions. The present work investigates for the first time, bubbles dynamics of a degassing liquid under various hypergravity accelerations. Degassing bubbles form due to desorption of dissolved air upon decompression of a liquid jet partially saturated with air. Accelerations up to 12 g are applied artificially by means of the Large Diameter Centrifuge facility of the European Space Agency. A patented electrical impedance spectroscopy technique provides the distribution of desorbed gas along the flow. Analysis of high resolution images indicates changes of bubbles size. Residence time distributions using conductivity tracers reveal the flow pattern in the degassing vessel. The total extent of liquid degassing is derived from dissolved oxygen measurements. Hypergravity alters the bubbles velocity and, consequently, their residence time in the liquid. Therefore, it affects the gas fraction in the degassing vessel offering unique conditions for studying the impact of acceleration on bubble dynamics. Experimental findings are useful not only for the optimization of space processes during hypergravity phases, e.g., space vehicles launch and re-orbiting, but also for the construction of controlled degassing industrial applications.
AB - The formation and growth of bubbles due to decompression degassing of a liquid has been extensively studied in the past, aiming to enhance the efficiency of specific industrial applications. Even though liquid decompression degassing may interfere with the performance of space processes (such as cooling and lubrication systems, combustion and storage of liquid propellants etc.), the phenomenon has never been studied in non-terrestrial gravity conditions. The present work investigates for the first time, bubbles dynamics of a degassing liquid under various hypergravity accelerations. Degassing bubbles form due to desorption of dissolved air upon decompression of a liquid jet partially saturated with air. Accelerations up to 12 g are applied artificially by means of the Large Diameter Centrifuge facility of the European Space Agency. A patented electrical impedance spectroscopy technique provides the distribution of desorbed gas along the flow. Analysis of high resolution images indicates changes of bubbles size. Residence time distributions using conductivity tracers reveal the flow pattern in the degassing vessel. The total extent of liquid degassing is derived from dissolved oxygen measurements. Hypergravity alters the bubbles velocity and, consequently, their residence time in the liquid. Therefore, it affects the gas fraction in the degassing vessel offering unique conditions for studying the impact of acceleration on bubble dynamics. Experimental findings are useful not only for the optimization of space processes during hypergravity phases, e.g., space vehicles launch and re-orbiting, but also for the construction of controlled degassing industrial applications.
KW - Buoyancy
KW - Centrifuge
KW - Decompression
KW - Degassing
KW - Hypergravity
KW - bubble velocity
UR - http://www.scopus.com/inward/record.url?scp=85063868289&partnerID=8YFLogxK
UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85063868289&origin=inward
U2 - https://doi.org/10.1016/j.ijmultiphaseflow.2019.03.029
DO - https://doi.org/10.1016/j.ijmultiphaseflow.2019.03.029
M3 - Article
SN - 0301-9322
VL - 115
SP - 126
EP - 136
JO - International Journal of Multiphase Flow
JF - International Journal of Multiphase Flow
ER -
