Practical trainings, student assistants and theses

A multiphase jet is the ejection of a fluid, in which different particles, bubbles and droplets are finely dispersed, from a small orifice. Examples of such systems are the ash clouds of volcanos, the liquid droplets from a spray can or the injection of bubbles in an underwater ramjet engine.

In our numerical and experimental studies of the bubbly jet [1], we encountered an interesting phenomenon that bubbles are pushed out of the jet centre into a thin layer at the jet boundary. This effect may be used to improve mass transfer or bubble-particle collisions in applications such as chemical reactors and mineral flotation. The task of this student work is to perform an experimental parameter study with an optical Doppler probe [2], measuring profiles of the bubble speed, size and volume fraction for different water and air flow rates. The results will elucidate the interaction of liquid flow with bubbles and how the bubble “hole” in the jet centre is affected by the process parameters.

The thesis subject includes…

• conducting and protocolling experiments with advanced optical measurement equipment
• evaluation and interpretation of the measurement data

[1] Zürner et al., Min. Eng. 211 (2024), DOI: https://doi.org/10.1016/j.mineng.2024.108699
[2] Lefebvre et al., Chem. Eng. Sci. 250 (2022), DOI: https://doi.org/10.1016/j.ces.2021.117359

• Field of study: Process engineering, mechanical engineering, fluid mechanics, physics or similar orientation
• Advantageous are experiences in laboratory work, evaluation of measurement data (e.g. programming skills) and optical measurement methods
• Ability for practical, accurate and independent work
• Good language skills in English and/or German

• Place of work: HZDR
• Start: from March 2026
• Duration: min. 4 months
• Remuneration according to HZDR internal regulations