Abstract
Electromagnetic (e.m.) flowmeter systems are commonly used in physiological experiments. Little information, however, is available about their accuracy in a time-dependent flow field. In miniaturised sensors especially the magnetic flux density cannot be made uniform, which may result in a non-ideal response to axisymmetric flows. The measured flow rate may therefore differ from the actual flow rate owing to the varying shape of the velocity profile. To study this effect unsteady flow experiments were performed to relate the e.m. flowmeter reading to the flow rate deduced from laser-Doppler anemometry.
The experiments were performed in a straight circular tube with an internal diameter of 4 mm. The fluid (saline) flow was fully developed, laminar and pulsatile with flow reversal occurring near the wall in certain phases of the cycle. The frequency of the pulsations varied from 0·2 to 2 Hz. The fluid velocity was measured with a single component laser-Doppler system. The velocity profiles obtained were integrated to obtain the instantaneous flow rates and compared with those measured electromagnetically (Transflow 601).
The results show no significant differences in the mean volume flow rates (averaged during one cycle). For momentary flow rates the differences are hardly significant. Small but briefly significant differences were found in the instantaneous flow rates, the largest deviation (7·8%) being found at flow reversal. Variation of the pulsation frequency (by a factor 10) or the mean flow rate (by a factor 4) has no significant effect on these differences.
Similar content being viewed by others
References
Bevir, M. K. (1970) The theory of induced voltage electromagnetic flowmeters.J. Fluid Mech.,43, 577–590.
Bevir, M. K., O'Sullivan, V. T. andWyatt, D. G. (1981) Computation of electromagnetic flowmeter characteristics from magnetic field data.J. Phys. D: Appl. Phys.,14, 373–388.
Drain, L. E. (1980)The laser-Doppler technique. John Wiley & Sons, Chichester.
Edgerton, R. H. (1975) Experimental measurements of the radial conductivity of dog arteries in blood.Med. & Biol. Eng.,7, 531–533.
Faraday, M. (1832) Experimental researches in electricity. The Bakerian Lecture.Trans. R. Soc. London (biol. sci.),122, 163–177.
Hemp, J. andWyatt, D. G. (1981) A basis for comparing the sensitivities of different electromagnetic flowmeters to velocity distributions.J. Fluid Mech.,112, 189–201.
Oldengarm, J. andvan Krieken, A. H. (1973) Laser-Doppler velocimeter with optical frequency shifting.Optics and laser technology, 249–252.
Shercliff, J. A. (1962)The theory of electromagnetic measurement, Cambridge University Press, Cambridge.
Wyatt, D. G. (1977) InCardiovascular flow dynamics and measurements,Hwang andNormann (Eds.), Chapter 2, University Park Press, Baltimore.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Corver, J.A.W.M., Kuiken, G.D.C., van der Mark, F. et al. Response to pulsatile flow of a miniaturised electromagnetic blood flow sensor studied by means of a laser-Doppler method. Med. Biol. Eng. Comput. 21, 430–437 (1983). https://doi.org/10.1007/BF02442630
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02442630