Piezoelectric tiles for passive flow rate monitoring across a surface

TL;DR

This paper presents a non-invasive method using piezoelectric tiles to measure turbulent flow velocity in pipes by analyzing induced vibrations, achieving centimeter-per-second resolution.

Contribution

It introduces a novel vibration-based flow measurement technique that does not require pipe modification or penetration, applicable to both water and air flows.

Findings

Water flow velocity differences resolved to 1 cm/sec

Air flow velocity differences resolved to 15 cm/sec

Potential for external flow measurement and navigation applications

Abstract

We introduce a method for measuring the velocity of turbulent fluid flow passing through a pipe using piezoelectric tiles without penetrating the pipe, and without having previously designed the pipe to easily allow monitoring. To measure the flow, the vibrations induced on the pipe by the fluctuating pressure loading induced by the turbulent flow are measured and compared across flow speeds to establish effective invertible relationships from vibration to velocity. Measurements are reported for instrumented pipes transporting, in separate experiments, water and air. The water experiment was able to resolve linear velocity differences on the order of 1~cm/second, while the air experiment was able to resolve on the order of 15~cm/sec. Turned inside out, a similar system might be used to assess external flow velocity, determine differential velocities on opposite sides of a body traveling through air and water, and thus provide navigational data in the form of speed and attitude/angle of attack information. Although this approach is prototyped for a single sensor, it is likely to benefit substantially from the noise suppression possible when employing an array of sensors.