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Viscosity Measurement Using Drop Coalescence in MicrogravityWe present in here validation studies of a new method for application in microgravity environment which measures the viscosity of highly viscous undercooled liquids using drop coalescence. The method has the advantage of avoiding heterogeneous nucleation at container walls caused by crystallization of undercooled liquids during processing. Homogeneous nucleation can also be avoided due to the rapidity of the measurement using this method. The technique relies on measurements from experiments conducted in near zero gravity environment as well as highly accurate analytical formulation for the coalescence process. The viscosity of the liquid is determined by allowing the computed free surface shape relaxation time to be adjusted in response to the measured free surface velocity for two coalescing drops. Results are presented from two sets of validation experiments for the method which were conducted on board aircraft flying parabolic trajectories. In these tests the viscosity of a highly viscous liquid, namely glycerin, was determined at different temperatures using the drop coalescence method described in here. The experiments measured the free surface velocity of two glycerin drops coalescing under the action of surface tension alone in low gravity environment using high speed photography. The liquid viscosity was determined by adjusting the computed free surface velocity values to the measured experimental data. The results of these experiments were found to agree reasonably well with the known viscosity for the test liquid used.
Document ID
Document Type
Preprint (Draft being sent to journal)
Antar, Basil N.
(Tennessee Univ. Space Inst. Tullahoma, TN United States)
Ethridge, Edwin C.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Maxwell, Daniel
(Tennessee Univ. Space Inst. Tullahoma, TN United States)
Curreri, Peter A.
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Space Processing
Distribution Limits
Work of the US Gov. Public Use Permitted.

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