An Unsteady Flowmeter for Pulsatile Flow

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  • This paper outlines the design of an unsteady flowmeter for ex-vivo heart perfusion applications. In order to determine the performance of a given heart, the flowrate in the system must be recorded. The proposed design is based on an orifice plate flowmeter comprising three pressure transducers and in which the flow measurement is obtained by numerically solving a modified version of the unsteady Bernoulli equation. As an intrinsic characteristic, pulsatile flows have acceleration and deceleration phases, so the flowmeter must account for these unsteady effects to produce accurate measurements. In addition to measuring laminar and turbulent bi-directional flows, the operational context also imposes several restrictions on the design, such as being disposable, low cost, easy handling and small in size. Three prototypes were experimentally tested by applying sinusoidal flows using a peristaltic pump at a frequency range of 15 - 30 Hz and then verified by applying physiological-like flow with a ventricular assist device (VAD) at a frequency of 1 Hz. The device was experimentally calibrated by means of a gravimetric procedure. The results showed that oscillatory flows can be measured with an accuracy of approximately 1% for the range from 1 to 2.5 L/min, while for lower flow rates (< 0.5 L/min) the accuracy was around 5%. It was found that the average discharge coefficient among the three manufactured flowmeters was Cd = 0.7119.

    Part of the Proceedings of the Canadian Society for Mechanical Engineering International Congress 2022

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    Attribution-NonCommercial 4.0 International