An adaptive magnetization structure and method for low field NMR two-phase flow measurement

Abstract In low field NMR multiphase flow measurement, the magnetization time and magnetization length are affected by the two-phase flow velocity and water fraction, so it is difficult to realize the complete magnetization of multiphase flow with fixed length magnet. In this paper, an adaptive magnetization structure for two-phase flow is proposed. The pre-magnetization model of the adaptive structure is established based on the magnetization theory of nuclear magnetic resonance. And parameters of the adaptive magnetization structure are determined by analyzing the influence of two-phase flow parameters such as velocity and water fraction on magnetic susceptibility. Finally, the simulation analysis shows that the adaptive magnetization structure can achieve complete magnetization effect for two-phase flow in the range of water fraction 0-36% and flow rate 0-4.66m/s, which provides the necessary conditions for the accurate measurement of NMR two-phase flow and provides a new idea for the design of NMR two-phase flow measurement sensor.