Abstract

Over the past few decades considerable attention have been directed towards the development of different types of flow-metering techniques. High pressure drop after passing the metering device and partial obstruction of the flow represent the two most common problems for the majority of the existing flow-metering devices. The main intention of the current study was to overcome or minimize these two issues.
The principle objectives were developing a low-cost measurement system and setup to measure the flow in pipes of small diameters (0.5” to 4”), and performing an analytical / numerical model that enables to extract the distinction of the dynamic pressure throughout the flow.
Both analytical and numerical solutions of the fluid flow inside the pipe indicate forming of a parabolic velocity profile across the pipe in the fully developed flow region. Dynamic pressure variation due to velocity change across the pipe is used as the fundamental measurement principle in this work. The equipped cantilever beams with piezo-resistive materials are used as sensor for detecting the induced signals in three different levels across the pipe. The collected signals are used to reconstruct the parabolic velocity profile. Further, the integration of the parabolic profile in the cross-section area of the pipe will yield to the flow value.
The constructed sensors with strain gages are connected to a Wheatstone-Bridge. The resistance variation due to the strain changing in cantilever platform converts to voltage variation by the Wheatstone-Bridge. Signal amplification and filtering are carried out by a dedicated circuit board.
The work was extended to inkjet-printing of the conductive ink which is introduced as an alternative method for piezoresistive sensor fabrication. Easiness and fast-fabrication process are two important factors which give ability to mass production of low-cost piezoresistive sensors.