Search

The complex resonance frequency of a vibrating edge supported plate fabricated by the methods of MicroElectroMechanical Systems (MEMS) has been described by Goodwin et al. (J. Chem. Eng. Data 2006, 51, 190−208) and can be used to determine the density and viscosity of fluids. Working equations are required to relate the measured and desired quantities. In this article, two decoupled equations are used: one for density, the other for viscosity. For density, two expressions were evaluated. The first has been reported by Harrison et al. (Proc. SPIE 2006, 6111, 61110D) and contains three adjustable parameters, while the second is a purely empirical expression with two coefficients. For viscosity, the expression reported by Goodwin et al. (J. Chem. Eng. Data 2006, 51, 190−208) was used. The complex resonance frequency was measured for nitrogen, methylbenzene, water, 1-propene,1,1,2,3,3,3-hexafluoro-oxidized-polymd, polydimethylsiloxane, and four certified reference materials at temperatures between (313 and 37...

This article studies the fluid reaction on a vibrating disc immersed in a viscous fluid. The fluid is considered incompressible and Newtonian. The disc which is of negligible thickness vibrates harmonically in the direction perpendicular to its surface with an amplitude much smaller than the radius of the disc, in such a way that the non-linear terms can be neglected. The flow is axisymmetric and the velocity tends to zero away from the disc. Different approaches to this problem are presented. The first method consists in solving numerically an integral equation obtained from the Navier–Stokes equation. The second method calculates in an analytic fashion the asymptotic series for the pressure differential across the plate for large values of the dimensionless parameter β , equal to the frequency times the radius squared divided by the kinematic viscosity. The limit when β tends to zero is also studied. The analytical expressions give more reliable results when approaching the limits β large and β small than the numerical solution.

In the petroleum industry, measurements of the density and viscosity of petroleum reservoir fluids are required to determine the value of the produced fluid and production strategy. These thermophysical properties are also useful for the design of separators and process equipment and to control production processes. To measure the density and viscosity of petroleum fluids requires a transducer that can operate up to reservoir conditions and, to guide value and exploitation calculations with sufficient rigor, provide results with an accuracy of about ± 1 % in density and ± 10 % in viscosity. Necessarily, these specifications place robustness as a superior priority to accuracy for the design. In this paper, we describe a Micro Electrical Mechanical System (MEMS) that is capable of providing both density and viscosity of fluids in which it is immersed at the desired operating conditions. This transducer is based on a vibrating plate, with dimensions of about 1 mm and mass of about 0.12 mg, clamped along one ...