Pressure Measurement Using Multi-Mode Self-Oscillating Cylinder Resonator

Abstract

A new technique for a mechanical resonator self-oscillating at its multiple natural frequencies has been developed. This technique has been applied for vibrating cylinder pressure transducers to eliminate temperature coefficient and influences of fluid density, cylinder surface contamination and elastic relaxation.
In this article it has been cleared that the pressure sensitivity of natural frequency is a function of vibrating mode numbers and the shape of cylinder, but the temperature sensitivity is independent of vibrating mode numbers. Then two vibrating modes have been selected. One of them is the most sensitive and the other is the least sensitive for pressure. An adequate function consisting of these two frequecies has high sensitivity for pressure but very low sensitivity for temperature, fluid density, cylinder surface contamination and elastic relaxation.
The system of pressure transducer consists of a cylinder pressure sensor, a frequency counter and a micro-computer. The microcomputer calculates the values of measuring pressure from the function of the two natural frequencies.
The accuracy of this pressure transducer is less than 0.01% F.S.