Practical trainings, student assistants and theses
Numerical investigation of particle mixing (Id 419)
Master theses / Diploma theses / Compulsory internship
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.
Department: Particle dynamics
Contact: Baecke, Anna Magdalena, Dr. Lecrivain, Gregory
Requirements
- 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
Conditions
- Start after September 2024
- Duration of internship or thesis according to study regulations
- Remuneration available, scholarship holders (e.g. ERASMUS+) welcome
Online application
Please apply online: english / german
Investigation of the flow following behavior of lagrangian sensor particles in aerated reactors (Id 398)
Master theses / Diploma theses / Compulsory internship
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.
Department: Efficient wastewater treatment
Contact: Buntkiel, Lukas, Marchini, Sara
Requirements
- 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
Conditions
- Immediate start possible
- Duration according to the respective study regulations
Links:
Online application
Please apply online: english / german
Internship on experimental investigation of aerosol propagation (Id 381)
Student practical training / Compulsory internship / Volunteer internship
Background:
Currently, there is a broad discussion whether ventilation by frequent window opening is sufficient for providing a sufficient amount of fresh air or if technical air purification devices based on e.g. HEPA filters are better solutions for public spaces. Furthermore, there is another discussion ongoing, whether a well-guided laminar flow or a high degree of mixing within a room is more beneficial. The latter, on the one hand distributes the potentially virus-laden aerosols in the whole room, but on the other hand reduces the peak concentrations of these aerosols clouds by magnitudes.
Objectives:
The objective is to perform aerosol propagation experiments and to estimate the potential aerosol inhalation of people in dynamic situations. To achieve this, an aerosol generator will be used in a demonstrator room under different flow conditions. The data from different scenarios will be processed in order to obtain a transference function that can relate the aerosol source with the aerosol receivers.
Tasks:
- Literature survey
- Aerosol experiments in different scenarios.
- Post-processing of the results.
Department: Experimental Thermal Fluid Dynamics
Requirements
- Student of natural sciences or engineering
- Willingness to conduct experimental work
Conditions
Duration:
4-6 months
Remuneration:
According to HDZR guidelines
Online application
Please apply online: english / german
Numerical simulation of particles in rising gas bubbles (Id 356)
Student practical training / Master theses / Student Assistant / Compulsory internship / Volunteer internship
The separation of aerosol particles by a moving gas-liquid fluidic interface is central to a wide variety of industrial and natural applications, among which stand out air purification systems and precipitation scavenging. The particle size significantly affects the separation rate. The diffusion of particles in the nanometer range is largely dominated by molecular diffusion. In this regime, predictive models accurately estimate the separation rates. Model inaccuracy increases, however, significantly when the particle size ranges from 0.1 μm to 2.5 μm. In this impaction-dominated regime, the complex interplay between the flow dynamics on both sides of the fluidic interface and the particle inertia makes it difficult to develop suitable models.
In this work, the student will numerically investigate whether enforcing bubble deformation into a non-spherical shape leads to a higher deposition rate, hereby making the particle separation process more efficient. The results will lead to the development of an improved and reliable separation model accounting for the deformation of the fluidic interface and the associated flow changes.
Department: Experimental Thermal Fluid Dynamics
Contact: Maestri, Rhandrey
Requirements
- General interest in fluid mechanics
- Preliminary experience in code development (C++) is desirable
- Good written and oral communication skills in either English or German
Conditions
- Either an immediate start or a start in 2024 is possible
- Duration of the internship is anticipated to be 6 months but can be modified according to study regulations
- Remuneration according to HZDR internal regulations