Measurement and characterization of fluid flow profile using electrical capacitance tomography

摘要

The concept of electrical capacitance tomography (ECT) was used to characterize the flow of water in a pipe. The technique is based on measuring capacitances from multiple electrodes alongside the surface of the fluid-containing pipe and correlating the measured capacitances to identify changes which could pinpoint the exact location of air bubbles positioned in the pipe. This enables the characterization of the flow of air bubbles along the horizontally flowing water. The innovativeness of the approach comes from the fact that the results could be used to measure and characterize the flow of water in pipes or ducts. Using the proposed technique, flow velocity of water in a pipe was measured to be 0.2936 m/s and the volumetric flow rate was 5.96*10 m/s. Comparing this result with conventional water flow rate measurement of bucket-and-timer method which resulted in flow velocity of 0.30699 m/s and volumetric flow rate of 6.22*10 m/s, the proposed technique had measured flow velocity and flow rate differences of below 5 %. Moreover, by applying tomographic techniques to the capacitive plates, the optimum number of electrodes required in an ECT setup was identified to properly characterize the flow of a given size of air bubble in a pipe. The results indicate that for air bubbles of size larger than 0.0127 m or 0.5 inches in diameter, four electrodes used in the tomographic setup give the required accuracy in identification and localization of air bubbles in water flow in the water pipe.