Optimal design of spiral electromagnetic sensor for phase holdup measurement

Electromagnetic sensors can obtain the distributions of the medium through excitation and sensing coils distributed on the boundary. In this paper, a novel spiral electromagnetic sensor was proposed for phase holdup measurement. The sensitivity matrices of the spiral sensors of 180 and 360 degrees rotation were derived based on field theory and the design was optimized based on sensitivity analysis. The trends and rules for selecting the optimum parameters were obtained. The optimized spiral electromagnetic sensors have better and more homogenous sensitivity distributions. The experiment showed that the electric signals obtained were good indicators of the phase holdup. The correlation curves between phase holdup and the relative change ratio of the phase angle of spiral sensors were obtained which proved the feasibility and accuracy of the phase holdup measurement by the spiral electromagnetic sensors.