Measurement techniques for liquid metals

The measurement of flow properties of liquid metals, such as flow rate, flow structure and gas distribution, is a challenging task due to the opaqueness, the high temperatures (e. g. 1500 C for liquid steel or liquid silicon) and the corrosiveness of those fluids. In this paper, a short review about the recent developments of measurement techniques in the framework of the Helmholtz Alliance Liquid Metal Technologies (LIMTECH) is presented. It focuses on the development of contactless inductive measurement techniques exploiting the high electrical conductivity of those melts. These measurement techniques include the contactless inductive flow tomography (CIFT), which is able to reconstruct the mean three-dimensional velocity structure in liquid melts, local Lorentz force velocimetry (local LFV), which enables the local assessment of flows close to the wall, and inductive methods for bubble detection, which are based on mutual inductance tomography (MIT). Additionally, a short overview of contactless inductive flow rate measurement techniques is given. Furthermore, an ultrasound technique called ultrasound transit-time technique (UTTT) will be presented which enables the measurement of position and size of bubbles in large vessels.