Masters Theses

Date of Award

8-1987

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Gary V. Smith

Committee Members

W. R. Hamel, J. A. Euler

Abstract

A concept of a cantilever Coriolis mass flowmeter for gas flow measurement has been developed and tested. This work draws from original work performed by W. R. Hamel, who developed the cantilever Coriolis flowmeter concept. The concept has been developed as an in line device utilizing a null-type configuration for the use with gas flows where the Mach number remains less than approximately 0.3. This constraint was placed on the flowmeter to ensure that compressibility effects were minimized, so that the approximate, single-mode, analytical solution to the governing equation, which Hamel derived, could be used, since the governing equation was derived assuming incompressible flow.

The governing equation is a fourth-order, non-self-adjoint, homogeneous, partial differential equation; and the approximate solution mentioned above relates the unforced cantilever vibration characteristics to the density and mean velocity of the flow. The results given by the solution have been utilized along with a framework laid out by Hamel to establish a design methodology for systems of flows whose compositions are constant. This synthesis procedure centers on maximizing the sensitivity of the tube to the dissipative Coriolis forces with respect to the various tube parameters.

The analytical solution to the governing equation was also used to develop measurement and calibration algorithms for use in proof-of-principle testing. A bench-size prototype flowmeter was constructed and tested using an air circulation loop with a flow rate range of 0 - 0.3 SCMM ^Standard Cubic Meters per Minute), where the maximum air velocity reached approximately 100 m/s (300 ft/s). Three different sets of tubes were tested, comprising two materials and sizes. A laminar flow element was used to provide a comparison measurement. The results were in general promising, demonstrating measurable and repeatable trends in the comparison of the mass flow measurements, although a fair amount of scatter was present in the results. Future work should include the determination of ways to eliminate the scatter and improve the precision and rangeability of such a flowmeter.

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