Instrument for Simultaneous Measurement of Density and Viscosity

The speed of torsional stress waves transmitted in solid waveguides submerged in a liquid depends, among other things, on the liquid's density and viscosity and the waveguides' cross-sectional geometry. By measuring the speed of torsional stress waves in two waveguides of different cross-sectional geometries, one can obtain both the liquid's density and viscosity. An online, real-time sensor for the simultaneous measurement of density and viscosity is described. The article details the sensor's principles of operation and reports experimental results conducted using viscosity standard calibration liquids with wen-known thermophysical properties. For fluids with density ρf > 1 X 103 kg/m3 , it is estimated that the instrument can measure density with a precision better than 0.5%. For fluids with the product shear viscosity (μ) and density, ρfμ> 100 kg2/(m4s), it can measure the shear viscosity with a precision better than 1%. Disciplines Engineering | Mechanical Engineering Comments Suggested Citation: Kim, Jin O. and Haim H. Bau. (1989). Instrument for simultaneous measurement of density and viscosity. Review of Scientific Instruments. Vol. 60(6). Copyright 1989 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Review of Scientific Instruments and may be found at http://link.aip.org/ link/RSINAK/v60/i6/p1111/s1. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/meam_papers/203 Instrument for simultaneous measurement of density and viscosity Jin O. Kim and Haim H. Bau Department of Mechanical Engineering and Applied Mechanics. University of Pennsylvania, Philadelphia, Pennsylvania 19104-6315 (Received 30 September 1988; accepted for publication 7 February 1989) The speed of torsional stress waves transmitted in solid waveguides submerged in a liquid depends, among other things, on the liquid's density and viscosity and the waveguides' crosssectional geometry. By measuring the speed of torsional stress waves in two waveguides of different cross-sectional geometries, one can obtain both the liquid's density and viscosity. An online, real-time sensor for the simultaneous measurement of density and viscosity is described. The article details the sensor's principles of operation and reports experimental results conducted using viscosity standard calibration liquids with wen-known th"rmophysical properties. For fluids with density Pr > 1 X 10 kg/m , it is estimated that the instrument can measure density with a precision better than 0.5%. For fluids with the product shear viscosity (/1) and density, Pill> 100 kg /(m4 s), it can measure the shear viscosity with a precision better than 1 %.