Practical trainings, student assistants and theses

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

Immediate start possible
Duration according to the respective study regulations

Fine-grained solid particles from various industrial sources, which would otherwise be discarded, should ideally be processed to valuable products or inert residues. They contain valuable residuals, such as metals, that can be returned to the industrial cycle instead of being landfilled. This is one aim of the Helmholtz project FINEST in which this work is embedded.
The different finest powders need to be mixed and agglomerated for further processing. Our work in the project deals with the granular mixing. One aim is to describe particle flow based on the rheology of the bulk good while describing the mixing process among the particles using a transport equation.
The mixing process among particles is described by the transport equation. It needs to be coupled with the flow field of the particle bulk. The latter can be modelled by CFD, using e.g. FEM. Here, a rheologic model is required.
We are looking for someone with experience in CFD or other modelling to continue the implementation of this model.

• Student of e.g. Process Engineering, Chemical Engineering, Computational Engineering, Mechanical Engineering, …
• General interest in fluid mechanics and simulations
• Preliminary experience in CFD, ideally OpenFOAM
• Preliminary experience in code development (C++) optional

• Start after September 2024
• Duration of internship or thesis according to study regulations
• Remuneration available, scholarship holders (e.g. ERASMUS+) welcome

Data acquisition in large industrial vessels such as bio reactor, biogas fermenters or wastewater treatment plants is limited to local measurement points due to the limited access to the vessel and the non-transparent fluid. To optimize these kinds of plants the three-dimensional flow field and the spatial distribution of e.g. temperature and electrical conductivity inside the vessel needs to be known. This can be done by the autonomous flow following lagrangian sensor particles (LSP) developed at the HZDR. Equipped with a pressure sensor, an accelerometer, two gyroscopes and a magnetometer, the sensor particle can track the flow movement inside of the vessels. From this, the flow field can be reconstructed.

To achieve a good flow following behavior, the density of the LSP can be adjusted before they are released into the vessel. While this works well for non-aerated systems, the influence of aeration on the flow following capability is unknown. Another unknown is how the velocities of the rising bubbles and of the continuous phase relates to the velocity measured by the LSP.
Therefore, the aim of this master thesis is to investigate the influence of aeration on the LSPs theoretically and experimentally by tracking the LSP with a camera. This includes the following tasks:

• Literature research on flow following behavior of large particles in fluids
• Experiments in a bubble column (330 mm ID) with LSPs and camera
• Data evaluation to retrieve the fluid velocity, bubble rising velocity and LSP velocity
• Comparison and conclusions on the flow following capability of LSPs in aerated reactors and comparison to the non-aerated case.

• Studies in the area of chemical or mechanical engineering or similar
• Basic chemical and fluid engineering knowledge
• Data analysis in Python
• Independent and structured way of working

• Immediate start possible
• Duration according to the respective study regulations