A VIBRATING-WIRE VISCOMETER FOR DILUTE AND DENSE GASES

Citation
J. Wilhelm et al., A VIBRATING-WIRE VISCOMETER FOR DILUTE AND DENSE GASES, International journal of thermophysics, 19(2), 1998, pp. 391-401
Citations number
4
Categorie Soggetti
Physics, Applied","Chemistry Physical",Thermodynamics,Mechanics
ISSN journal
0195928X
Volume
19
Issue
2
Year of publication
1998
Pages
391 - 401
Database
ISI
SICI code
0195-928X(1998)19:2<391:AVVFDA>2.0.ZU;2-V
Abstract
The vibrating-wire technique has been applied to design a viscometer f or precise measurements on gases in the temperature range 25 to 250 de grees C at pressures from 0.1 to 40 MPa employing two Chromel wires wi th different radii. The technique has been improved to avoid the influ ence of higher harmonic modes and the degeneracy of perpendicular mode s, to eliminate electromagnetic noise From the signal, and to minimize the influence of the magnetic damping. The decrement and frequency of the oscillation have to be determined by extrapolation to zero displa cement, and wires with a perfectly smooth surface are needed to meet t he requirements of the measuring theory. The viscosity measurements ar e characterized by a precision of +/- 0.05% at ambient temperature. Co nsidering the uncertainty of the reference data used for calibration, the total uncertainty amounts to +/- 0.2% within the calibrated range of the boundary-layer thickness.