Ultrasonic Doppler Velocimetry in Liquid Aluminum

Available techniques for the experimental study of flow patterns and velocities are difficult to apply to liquid metals because of the high temperatures generally involved. Thus, no velocity measuring technique for liquid metal flows is commercially available. In most cases, water models with particle velocity tracking measurements are used to estimate the local metal velocity. Ultrasound Doppler Velocimetry (UDV) is a non-invasive way of measuring the velocity in fluid depth, which can be used in opaque liquid and deliver velocity profiles in real-time. This paper describes the principle of the technique. It also presents recent UDV experiments performed at Constellium, in molten aluminum on lab equipment and at industrial scale. The breakthrough technology developed by Constellium for the wettability of the ceramic waveguides is introduced. It is essential for signal stability and continuous measurement. 2D UDV measurements in a trough and the liquid sump of a DC cast slab are presented together with numerical modeling results.