Practical trainings, student assistants and theses

Flowing foam is relevant to many different industrial applications, such as froth flotation in mineral processing, fire-extinguishing systems, or brewing beer and beverage production. In a scientific context, the rheological properties of foams are very complex and significantly different from those of Newtonian fluids such as water. As a result, despite numerous experimental and theoretical studies, the fluid dynamics of foams remain poorly understood.

This project focuses on a classical benchmark experiment: the flow around a cylindrical obstacle. To identify key parameters of flowing foam in this configuration, we use two unique radiographic measurement techniques. First, neutron radiography provides imaging measurements of the local liquid fraction of the flowing foam. Second, X-ray radiography with foam-tailored tracer particles allows to perform local velocity measurements in the flowing foam.

The following subtasks are mainly to be worked on:

• Assistance in preparing and performing the foam flow experiment in the X-ray laboratory at HZDR
• Analysis of the measurement data, including image processing and machine learning if applicable
• Documentation of the experiment and measurement results in written form

• Field of study: process engineering, fluid mechanics, or similar focus in chemistry or physics
• Experience with laboratory work, imaging measurement techniques or measurement data analysis is beneficial (e.g. using ImageJ, Matlab, Python)
• High motivation and interest in the subject
• Careful, structured and independent way of working
• Good oral and written communication skills in English or German
• Enjoyment of scientific work

• Working in a multi-disciplinary and international team
• Place of work: HZDR or TU Dresden
• Start: from March 2025
• Duration: min. 3 months
• Remuneration according to HZDR internal regulations

The development of a multi-channel flow body sensor according to patent WO 2010/069307 A1 aims to quantify the gas content in flow-carrying components. A decisive advantage of this sensor lies in its optical measuring principle, which is based on fiber-optic coupling and the analysis of the light output signal. This avoids electrical potentials in the measuring area, offering significant advantages over electrical measuring methods (intrinsic safety), especially for explosive mixtures.

Preliminary tests at the Institute for Experimental Fluid Dynamics at the Helmholtz Center Dresden-Rossendorf on gas-liquid flows showed that a clear binarization of the sensor output signal can be achieved due to the capillary effects in narrow channels and the different refractive indices of the gas and liquid phases. Building on previous work with a single-channel sensor prototype based on a polymer optical fiber (POF) with a diameter of 1 mm, the following tasks must be completed as part of further research.

Tasks:

• Adjusting the POF diameter to 1.5 mm in the single-channel configuration.
• Conducting experimental investigations of the new single-channel prototype using the already developed test system and evaluation programs.
• Designing a multi-channel sensor body for gas content measurements in the system.
• Developing a transition adapter to optimize the flow distribution between the DN10 flow pipe and the sensor body.

• Students majoring in fields such as process engineering, mechanical engineering, or chemical engineering.
• Interest in fluid mechanics and the development of measurement technology.
• Experience with 3D CAD tools.
• Basic knowledge of Python programming

Start date: 01.01.2025
Duration: according to the respective study regulations