Contactless viscosity measurement by oscillations of gas-levitated drops

Abstract

International audienceA recently demonstrated aerodynamic levitation technique is used to perform contactless viscosity measurements. Classical models dealing with free oscillations of droplets without gravity cannot correctly describe the correspondence between damping coefficient and viscosity. An energetic approach taking into account the shape of the drop, and the velocity field of the liquid inside the drop, is introduced, leading to good agreement between experimental measurements and known viscosities of glycerol-water mixtures. Nonlinear effects are also investigated and experimental results are compared with the theory of anharmonic oscillations

Linear shape oscillations and polymeric time scales of viscoelastic drops

“…Liquid characterization by the oscillating drop method The oscillating drop method has been developed and used in the past for measuring various physical liquid properties. The dynamic viscosity of aerodynamically levitated drops was measured by Perez et al (2000) making use of the resonance behaviour of the oscillating drop with account for the spheroidal drop shape. The dynamic viscosity follows from a correlation with the width of the resonance peak, which the authors derive.…”

The oscillating drop method for measuring the deformation retardation time of viscoelastic liquids

“…At the eutectic temperature of 1033 K, the measured dynamic viscosity was found to agree with results from the literature. Similarly Perez et al measured the Newtonian liquid dynamic viscosity making use of the resonance behaviour of the oscillating drop with account for the spheroidal drop shape [8]. The dynamic viscosity follows from a correlation with the width of the resonance peak, which the authors derive.…”

Measurement of Vacuum Residue and Asphaltene Fluid Properties at Process Conditions

“…(8) was proportional to the capillary number, defined in this case as: (11) The Reynolds number was less then 2; therefore, inertial effects were not significant. Allowing for empirical dependence on the thickness of the liquid film, δ, and the length of the liquid bridge, D, Aminu et al 10) proposed the following semi-empirical expression: (12) where k1, k2 and k3 were empirical constants. The total force on a liquid bridge for D ≥ b was (13) The coefficients were determined from a series of experiments with calibration oils of known viscosity (1-22 Pa s), giving best-fit values of k1 = 400.0, k2 = 0.752 and k3 = 0.677.…”

“…Temperatures of up to 2000°C can be handled without contamination using the gasfilm levitation method, which examines the deformation of a liquid drop suspended on a film of gas 12) .…”