Student Theses

The efficiency of fuel cell systems can be drastically increased by using a turbocharger. Operation with humid air as the working fluid leads to a condensing two-phase flow in the turbine. Depending on the operating point, the number and size of the droplets as well as the location of droplet formation vary. While primary droplets mainly lead to a reduction in efficiency, coarse water (secondary) droplets can cause erosion damage to the turbine. 
Optical measuring systems for determining droplet distributions are being developed and used at the ITSM. Current systems can measure small (primary) droplets in the range of 0.1 - 10 µm. As larger (secondary) droplets are also expected, a new laser-based system is currently being developed that can measure droplets from 10 - 500 µm. Calibration is essential for this. 
In this work, an existing calibration system is to be redesigned and optimized for the present application.

Supervisor: Dominik Bezler

Type of work: experimental

The ITSM develops and uses optical measuring systems to determine droplet distributions. These systems are based on the light extinction method, which uses the wavelength-dependent attenuation of light to determine the droplet size and number of droplets. Complex numerical methods are used to evaluate such measurements, which can lead to uncertainties and is associated with high manual effort. 
In this work, a new algorithm for the evaluation of droplet measurements is to be developed at the ITSM. This is to be developed using mathematical surrogate models in MATLAB. Various surrogate models such as Kriging or ANN (artificial neural networks) are to be generated and compared on the basis of their prediction accuracy.

Supervisor: Dominik Bezler

Type of work: theoretical, numerical

The flow near the stability limit shows unstationary phenomena. The aim of the investigations is to calculate these phenomena using CFD and to compare the results with experimental data.

Supervisors: Maiken Günther, Daniel Nagel

Type: Numerical

The aim of this thesis is to investigate the influence of mistuning on the flow of an axial compressor blisk. Mistuning is a specific effect that can occur in blade vibrations due to manufacturing inaccuracies in the rotor. This effect will be transferred to transient CFD simulations using Ansys CFX and compared with experimental data. Experience with Ansys FE and CFX is recommended but not essential.

Supervisors: Maiken Günther

Type: Numerical

A screen mesh module is used to generate a correct flow profile in a channel of a test rig. Due to the size of the cells, this can not be directly simulated. In scope of the work the approach models will be investigated.

Supervisors: Anastasia Fomina, Manuel Maqueo

Type: Numerical