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Institut für Strömungsmechanik
Time Evolution of Oblique Droplet Impact on Wetted
Surfaces
This work focuses on experimental investigations of droplet impacting on thin film flows using
high-speed visualization techniques. A flywheel experiment has been developed to investigate
different impact configurations at the Multiphase Flow and Icing department of the Institute of
Fluid Mechanics. This flywheel experiment allows the study of droplet impacting at very high
velocities and therefore it is necessary the usage of a high-speed camera (up to 1,000,000
frames per second) to visualize the different splashing phases. In this work we aim to describe
the asymmetrical lamella using a combination of different dimensionless parameters.
Contact:
Institute of Fluid Mechanics (ISM)
David Burzynski, M.Sc.
Figure 1: Vertical droplet impact on a thin film
Institut für Strömungsmechanik
Droplet Impact on Gaps and Sharp Edges
In this work we aim to analyse the secondary droplets generated by the impact of a single drop
on a dry surface with different gaps and edges configurations. Using a shadowgraph
technique, the student has to investigate the formed crown and the secondary droplets with
statistical methods. For this propose a flywheel experiment has been developed at the
Multiphase Flow and Icing department of the Institute of Fluid Mechanics. In order to detect all
the small droplets, the experiments have to be performed using high resolution CCD cameras,
a long distance microscope and PIV lasers with diffusor optics.
Contact:
Institute of Fluid Mechanics (ISM)
David Burzynski, M.Sc.
Fig. 1: Corona and secondary droplets formed after the impact of a droplet on a thin gap
Institut für Strömungsmechanik
Numerical calibration of extended eddy viscosity
turbulence model for vortical and separated flows
At the Institute of Fluid Mechanics, the prediction capabilities of Menter-SST turbulence model
along with Rotation/Curvature correction extension are investigated. Delta wings are the
predominant test cases due to the existence of vortical flow. Standard two dimensional
validation cases are also analysed. Deterministic optimization and Uncertainty Quantification
will be used for model calibration. The primary objective of this investigation is to exploit the
maximum potential of the two equation eddy viscosity model. The DLR TAU-Code, a three-
dimensional RANS-solver, is used for the numerical simulations.
Contact:
Institute of Fluid Mechanics (ISM)
Gokul Subbian, M.Sc.
Fig. 1: Vortex breakdown on the suction side of a delta wing with sharp leading
Parameterisation of Turboprop S-Duct Intake for Aerodynamic Design by CFD
Analysis
A regional passenger aircraft with high-lift capability is the design objective of the SFB880
project, in which IFAS has the research focus on the integration of the engine and the design
of its intake. The intake becomes a critical component of the integration due to the high power
demand considering the active high-lift and the high subsonic cruise mission. The focus of this
work is on the parametric analysis of the turboprop S-duct intake to define its aerodynamic
design space. The project starts with the parameterization of the basis intake model by its
cross-sections. An interface program in Matlab will be written to convert the parametric model
to the numerical simulation model. Verification will be done using CFD methods on 2D
meridional plane in comparison to turboprop S-ducts from literature (Little, 1982). In the second
phase, the model will be simulated using 3D RANS, which will serve as the initial estimation
for the S-duct design.
Contact:
Institute for Jet Propulsion and Turbomachinery (IFAS)
Caglar Atalayer, M.Sc.
Figure 2: (left) Wrap-around S-duct intake from Little, 1982; (right) wrap- around S-duct model for simulation grid generation
Modelling Microcracking in a Composite Laminate
There are several models of microcracking in special laminates like cross-plies available in
literature. Codes for their use are only partly open for use. It is the aim of this project to extend
an existing tool to more interesting laminate types. This has to be validated by literature results.
Contact:
Institute of Aircraft Design and Lightweight Structures (IFL)
Prof. Dr. Peter Horst
Fig. 1: Typical laminate (non-crimp fabric) with microcracking
Experiments and simulations for Electro Impulse Deicing
(EIDI)
The Electro Impulse Deicing (EIDI) removes ice from lightweight structures by loading a coil
with a short high-voltage impulse which induces eddy currents in the structure. The resulting
magnetic forces lead to a vibration of the structure which causes the ice layer to crack and
detach from the structure. At the Institute of Aircraft Design and Lightweight Structures (IFL)
the dynamic behavior of the EIDI system is studied using a simple test rig and electro-
mechanical coupled simulations. Furthermore, the mechanical properties of different types of
ice are investigated.
Contact:
Institute of Aircraft Design and Lightweight Structures (IFL)
Hannah Sommerwerk, M.Sc.
Fig. 1: EIDI test rig
Simulation of Thermal Barrier Coatings in Rocket Engines
The gas temperature inside a rocket engine can reach values of more than 3000°C. To protect
the rocket chamber from the resulting thermal load, it is cooled from the inside using liquid
hydrogen and made of copper alloys that have a high thermal conductivity. Although the
surface temperature of the copper liner can be reduced to temperatures of about 700°C, failure
may still occur. In this project, thermal barrier coatings are developed that can reduce the
temperature of the copper alloy and thus improve its temperature resistance. The effects of
these coating systems are studied using finite element simulations.
Contact:
Institut für Werkstoffe (IfW)
Dr. Martin Bäker
Fig. 1: Finite element simulation of a thermal barrier coating system in a rocket engine.
Improvement of the Oxidation Resistance of Titanium
Alloys
Even if Titanium alloys show outstanding specific fatigue properties, their application in aircraft
engines is limited due to their poor oxidation resistance. Above 550°C the protective TiO2 oxide
layer becomes permeable for Oxygen leading to severe oxidation at the oxide-metal-interface.
The addition of Niobium and Silicon to Titanium alloys leads to reduced oxidation whereas the
underlying mechanisms are not yet well understood.
In the current work, different binary and ternary Titanium alloys will produced and analysed
with respect to their oxidations resistance by means of optical microscopy, scanning electron
microscopy and micro-focused hard X-ray phase analyses, see figure 1.
Please not that for reasons of work security, knowledge of the German language is required
for experimental work.
Contact:
Institut für Werkstoffe (IfW)
Carsten Siemers
Fig. 1: Micro-focused hard X-ray experiment carried out at the synchrotron PETRA III of
HASYLAB, DESY. Different zones are detected by phase analyses at Ti 2Nb alloy after
oxidation at 800°C for 96 hours.
Automated maintenance of critical space debris modelling parameters
One of the research areas of the Institute of Space Systems is the modelling and simulation of
the space debris environment. One of the core aspects is the derivation of object spatial density
and flux density in orbital regions from LEO up to GEO. In addition, collision probabilities
between operational payload missions and space debris are calculated. These algorithms are
based on the different spatial densities in Earth orbit. The modelling incorporates the number
of TLE objects which belong to certain fragmentation events such as on-orbit explosions and
collisions. The number of those tracked objects is increasing over time, since observation
campaigns take time in order to observe the complete number of fragments. The goal of this
topic is to develop a software routine to maintenance the event database, which is used to
model the space debris environment. More precisely, the routine shall update the DC-value,
which indicates the recent number of TLE debris cataloged, belonging to the same
fragmentation. Based on this value, the NASA breakup model is calibrated. The NASA breakup
model generates the debris distribution which is caused by an on-orbit event. Updating the DC
value on a regular basis is essential in order to provide the community with the latest
informations on recent and past fragmentation which might pose danger to all operational
spacecraft.
Contact:
Institute of Space Systems (IRAS)
André Horstmann, M.Sc.
Enhancements to satellite models used in a free-floating test environment
During Active Debris Removal (ADR) or On-Orbit Servicing (OOS) missions, usually a small
servicer satellite approaches a bigger target and docks via a dedicated mechanism. This
process is highly challenging, as the target object is usually non-cooperative. The Institute of
Space Systems is currently investigating various technologies in the scope of ADR and OOS.
For this purpose, IRAS is setting up a free-floating test-environment based on an air-bearing
table. On this table, satellite models move on an air cushion with three degrees of freedom.
The test environment allows the investigation of different GNC algorithms for close approach,
formation flight, docking or detumbling, as well as contact dynamics of docking mechanisms.
This projects aims at enhancing the existing satellite models to better meet the requirements
of the test environment and the test campaigns. Enhancements might address different
subsystems, for example the propulsion, attitude control or navigation system, onboard data
handling or structure. The work to be conducted includes an analysis of the existing system, a
search for potential improvements, the development and integration of the improved
subsystems and tests to verify the functionality.
Contact:
Institute of Space Systems (IRAS)
M.Sc. Christopher Trentlage Dipl.-Ing. Mohamed Khalil Ben Larbi
[email protected] [email protected]
Fig. 1: A typical on orbit servicing mission: The ViViSat Mission Extension Vehicle attaches to a satellite
that is running out of propellant and takes over stationkeeping to extend the target satellite life
(Source: space.com)
Development of a quantitative measure of resilience in air
traffic management
Over the past decades, the term resilience was introduced in a variety of scientific domains
such as, psychology, ecology, economy or safety science. The different perspectives lead to
a vast amount of definitions available today. Though, three important schools of thought can
be distinguished. In that regard, different properties of the particular systems are examined in
the face of disturbances such as absorption, restoration or adaptivity and reflected in the
concepts of engineering resilience, ecological resilience and resilience engineering. The latter
is focusing on the human contribution in order to maintain the safety of the system in the
aftermath of disturbances. The other concepts address different aspect such as the effect of
disturbances on populations or networks.
Given that, different forms of measurement of resilience evolved, encompassing a wide range
of qualitative and quantitative descriptions. Furthermore, diverse approaches are applied as
well, such as viability theory, network based methods or agent based modeling, using insights
from complexity science and addressing emergent behavior respectively.
The task will contribute to the further development of a quantitative description of resilience in
the context of air traffic management (ATM). Current research investigates the socio-technical
ATM system with respect to its interaction with other critical infrastructure systems, such as
the health system. Due to the various involved stakeholders, acting at different hierarchical
levels under resource limitations and delays, the ATM system represents a complex system.
Here the need for new quantitative dynamical models arises. A challenging research objective
constitutes the integration of the “engineering” and the “sociological” perspective, since the
first one provides aforementioned quantitative descriptions, which allows for incorporating
measurement quantities of the ATM domain, such as performance indicators, whereas the
latter one tends to qualitative depictions of resilience.
The task will be based on the works of Francis and Bekera and might include procedures such
as literature research or investigation into the applicability of approaches to investigate
resilience in the ATM system such as bayesian networks or ecological viability theory.
Contact:
Institute of Flight Guidance (IFF)
Dipl.-Ing. Peter Förster
Francis, R., & Bekera, B. (2014). A metric and frameworks for resilience analysis of engineered and
infrastructuresystems. Reliability Engineering and System Safety, 121, 90–103
Structure integrated adaptive systems for flow control
The project focuses on improving the conformable integration of complex sensor and actuator
systems into highly loaded structures for effective flow control in high-lift devices. For this
purpose, innovative methods for design and manufacturing of functional components and the
transition zone between functional component and composite are investigated. The goal is to
maintain the strength of the composite as much as possible and to reduce stress
concentrations. The scalability of the developed systems is studied using a full-scale
demonstrator with a functional CFRP-skin and integrated functional components.
Active research tasks:
Simulation and characterization of structure integrated sensor systems in highly loaded
composites
Development of gradient composites with flowing stiffnesses
Contact:
Institute of Adaptronics and Function Integration (iAF)
Dipl.-Ing. Christian Behr
Fig. 1: full-scale demonstrator (left), tensile sample with integrated pressure sensor (right)
Experiments and Simulation of an Low Frequency De-icing
System based on harmonic excitation
The Low Frequency De-icing system is a mechanical system based on structural vibrations of
the unstiffened sections. Due to a suitable actuator and its position the skin is excited at its
natural frequency. The applied actuators are piezoelectric patch actuators based on the d31-
effect, which are placed at the inner side of the leading edge. This excitation allows large
deformations with a small energy input, since the actuator only has to overcome the structural
damping. In addition to the experiments a finite element model was developed to identify
suitable actuator positions and eigenmodes of the test specimen. For a better understanding
of the de-icing mechanism and to improve the finite element model further studies are
necessary.
Contact:
Institute of Adaptronics and Function Integration (IAF)
Dipl.-Ing. Matthias Endres
Figure 3: Before and after De-icing of a NACA0012-Profil, tested in an icing wind tunnel
