An experimental study on the characteristics of electromagnetic flowmeters in the liquid metal two-phase flow

Abstract

Based on the previous study for the water-air mixture, the characteristics of AC electromagnetic flowmeter were investigated in the liquid metal two-phase flow. Two-phase flow experiments, encompassing bubbly to slug flow regimes, were conducted with the liquid sodium-nitrogen mixture. The simple relation DeltaU(TP) = DeltaU(SP)(1-alpha), relating flowmeter signal between single-phase flow and two-phase flow, was verified with measurements of the potential differences and the void fraction a for a bubbly flow regime in water-air loop. Whereas there was no difference in the shape of the raw signal between single-phase flow and bubbly flow, the signal amplitude of bubbly flow was greater than that of single-phase flow under the same liquid flow (sodium or water) rates, since the passage area of the liquid flow was reduced. In the case of slug flow, the phase and the amplitude of the flowmeter output showed a change in the flow characteristics around each slug bubble and the position of a slug bubble itself. Therefore, the electromagnetic flowmeter shows a good potential as a useful device for identifying the flow regimes. The void fraction can be simply measured with two electromagnetic flowmeters for a low-void fraction flow such as bubbly flow. Thus, the flowmeters can be used to measure the void fraction for a liquid sodium. (C) 2003 Elsevier Ltd. All rights reserved.