Liquid Metal Two-Phase Flows
Two-phase flows play an important role in a number of technological processes in metallurgical and chemical industries. Gas bubbles are injected into liquid baths in order to stirr the fluid, because often times a better homogeneization (temperature, concentration) or the generation of a distinct flow structure is desired.
One has to look for suitable methods to control the properties of such kind of flows. The utilization of magnetic fields seems to be an attractive way to affect the spatial distribution of bubbles or the momentum transfer between the gas and the liquid.
An actual example for the technical application of a mercury/helium bubbly flow is the concept of a liquid metal target for the Common European Project ESS (European Spallation Source). The controlled addition of tiny gas bubbles to the target flow should enhance the compressibility of the fluid to diminish the pressure wave effect arising from the interaction between the target and short period proton pulses with a high energy impact. Gas injection experiments in mercury and InGaSn, respectively, revealed some surprising features of the bubble formation process inside a liquid characterised by a high surface tension. Consequently, the practical solution to generate tiny bubbles with a diameter less than 1 mm at high gas flow rates of more than 1000 l/h is not straigthforward.
The interest of our investigations have been focussed on the following subjects: