The behavior of the uniform-field electromagnetic flowmeter with air-watertwo phase flow was studied both experimentally and theoretically. The gas holdup couldbe measured quite accurately in a bubbly flow. It can be considered that there is no effectof the axisymmetric gas holdup profile and liquid velocity profile on the output signal. Butin a slug flow, the sensitivity is lowered heavily. The largest case for the error is the violent fluctuation of the liquid velocity and gas holdup. The sensitivity is unit in a churn turbulent flow, because the intensity of the fluctuation is decreased rapidly with an increase of column diameter. It is assumed that the droplets, ripples and disturbance waves give rise to a decrease of sensitivity in an annular flow.
