Offene Themen für Semester- und Abschlussarbeiten am Lehrstuhl für Hubschraubertechnologie
Anwendung des Onera-Edlin „Dynamic Stall“-Modells auf Rotormodelle mit der Mehrkörpersimulationsumgebung Dymore (06.03.2023)
Am Lehrstuhl für Hubschraubertechnologie wurde ein Rotorprüfstand für die Untersuchung von Dynamic Stall im Schwebeflug sowie im Windkanal gebaut. Grundlage der Untersuchung bildet ein 2-Blatt-Rotor mit gelenklosem Blattanschluss und Pitch-Lager für die Ansteuerung der kollektiven und zyklischen Einstellwinkel. Mit Hilfe dieses Rotors wurden bereits erste dynamische Strömungsabrissversuche im Schwebeflug bei unterschiedlichen Steuerwinkeln durchgeführt. Dreidimensionale CFD-Simulationen zur Abbildung und Untersuchung der Auswirkungen dieses Phänomens auf die Steuerstangenlasten sind sehr rechenzeitaufwändig. Daher sollen herkömmliche „Dynamic Stall“-Modelle, wie z.B. das Onera-Edlin-Modell in der Mehrkörpersimulationsumgebung Dymore genutzt und deren Anwendbarkeit auf das bereits vorhandene UH60-Hauptrotor-Modell sowie den Versuchsrotor untersucht werden. Hierfür ist ein bestehendes Strukturmodell des Prüfstands zu erweitern, sodass auch Steuerstangenlasten ausgegeben werden können. Es sollen Abweichungen zwischen Experiment und Simulation identifiziert, lokalisiert und ggf. mit physikalisch sinnvoller Modellanpassung minimiert werden.
Bachelor/Semester/Master thesis: Fluid Structure Interaction Investigation of a Dynamically Camber Morphing and Pitching Rotor Airfoil (01.04.2023)
Active camber morphing airfoils have a major potential to improve the efficiency of rotor blades by adapting to the various inflow conditions occurring over a rotor revolution. In comparison to traditional trailing edge flaps the continuous changes in camber show improvements for the lift-to-drag ratios by maintaining a similar lift.
The Fish Bone Active Camber (FishBAC) device was shown to be a promising approach for implementation. Due to the highly flexible structure of the FishBAC, aeroelastic effects play a crucial role and can have a vast influence on the aerodynamic performance of the airfoil. In previous studies a high-fidelity fluid-structure interaction simulation was build up with the CFD-solver TAU, the FEM-solver Calculix and the coupling library preCICE.
High-Speed Vertical Takeoff and Landing (HSVTOL) Aircraft
40th Annual VFS Student Design Competition
Keywords: Preliminary Design, VTOL, Design, CAD, Aerodynamics, Aerospace Structures
Motivation: You want to work on an exciting, creative, and challenging research practice for your master's program? We are looking for motivated students to work in a group on the UseCase for this year's VFS Student Design Challenge, "High Speed Vertical Takeoff and Landing (HSVTOL) Aircraft". Develop a solution for this year's challenging requirements with your team and participate in the international competition. Work alongside the Helicopter Chair scientists and gain insight into the Preliminary Design of VTOLS. Implement your ideas into a detailed CAD program, calculate the flight physics, and optimize the aerodynamics and structure of your vehicle.
Course of the Group Project: The group work is an alternative to the term paper (Semesterthesis) required in the Aerospace program. We prepare you with theory sessions in all important subjects for the challenges ahead. In addition, you will receive regular support from our experienced scientific staff in all important subject-related questions. Furthermore, we want to offer you a varied working environment, including excursions and project days. Within six months, you work on the already published UseCase and make your own design proposal in the form of a final report and presentation. After that you are free to participate in VFS Student Design Competition with the chance to present your design in an international environment at the VFS Forum and win a prize money. Skills: High motivation and the ability to learn new topics independently. Experience with Preliminary Design of Helicopters is an advantage but not necessary. The willingness to familiarize yourself with programming tools is necessary
Preliminary Design and Teamwork. Additional personal topic like CFD, Free-Wake, FEM or other. Application: Send an email with a short motivation and resume at email@example.com. If you are applying as a group, please include your team members (Team size 5-10 People) If you have questions, feel free to write your question at all times or come by the Institute. Further Information: vtol.org/awards-and-contests/student-design-competition
Generic determination of the damping properties of composite materials for design application (20.09.22)
In the design of helicopters, the considerations of dynamic loads and vibrations are of great importance. This also affects the helicopter tail, which is dynamically excited by the Rotor Wake in forward-flight. Unfortunately, the decisive loads are difficult to predict in early design. As a result, problems with the tail boom are often only discovered in the flight test phase on the prototype, which results in expensive changes and lengthy delays in the development process, as the previous design processes from TUM Partners showed.
Since the exact frequencies and excitations in the early stages of development are unknown, one approach to reduce the risk is to increase the overall damping of the tail to counteract critical aeroelastic effects. The Institute of Helicopter Technology is investigating how to reinforce the composite structure of the horizontal tail with flax fibers. Natural flax fibers offer a significantly higher damping potential when used in hybrid composites than carbon fibers.
Rotorcraft Comprehensive Analysis Validation Framework
The goal of the thesis is to compare computational predictions based on a high fidelity rotorcraft model with experimental measurement data available from full-scale rotor wind tunnel tests. These measurements were only recently published and include blade loads, hub vibration, rotor acoustic noise, control loads etc, in the time and frequency domains – essentially a treasure trove of data for computational engineers! Comparison of computational predictions with a rich set of experimental measurements (at various operating conditions) provides the opportunity to identify, and attribute, mismatches to specific modelling strategies or physical phenomena. Working with a comprehensive analysis model and experimental data of this scale provides the unique opportunity to develop an overall understanding of the methods involved in analyzing rotorcraft loads and performance with high fidelity.
HiWi: Jupyter Notebook
The Hiwi position includes the task of creating Jupyter Notebooks based on existing course content available in the form of Powerpoint slides. These Notebooks have to simultaneously cater to in-class presentations as well as conform to a distribution-friendly format so that they can be easily shared and maintained without the need for any proprietary software. Accordingly, the Powerpoint slides will be primarily converted to ‘slides’ format in Jupyter Notebook and therafter formatted as a Jupyter Book – slides corresponding to each lecture comprise a chapter in the book. Images and other relevant media content is going to be heavily utilized in the creation of the Notebooks. HTML/Markdown experience would come in handy in order to construct templates that make this task simple for future iterations of the course notes.
CUDA-based Parallelisation of Rotor Aerodynamics Solver (11.02.2022)
Compared to fixed-wing aircraft, the rotational motion of rotor blades complicates their aerodynamics analyses.
Presence of more than one rotors in close proximity to each other can additionally lead to mixing of the rotor wakes,
further making conventional analysis difficult. A particle-based aerodynamic formulation is attractive for modelling
such flows since the discretization scheme is stable while analysing such scenarios. A novel rotor wake
aerodynamics solver based on viscous vortex particles formulation is currently being used for analysing a novel
rotor geometry at the Institute of Helicopter Technology. The solver is written in C++ and currently uses OpenMP
to achieve speed-up. However, this leaves room for improvement since rotor aerodynamics modelling routinely
uses vortex particles ~106 . From experience, speed-up using traditional ‘n-body’ algorithms such as Treecode or
Fast Multipole method can lead to unphysical results. Therefore, a straightforward implementation of the code, with
O(n2) particle interactions, that is capable of running on the GPU is desired to reduce overall helicopter simulation
Bachelor / Master Thesis: Simulator Flight Test Evaluation of OEI operations using Audio Cueing
This thesis investigates in evaluating simulated flight trials whereas an original Bo105 engine is connected to the Rotorcraft Simulation Environment (ROSIE), a fixed based high fidelity simulator. First, for the Human Machine Interface (HMI) extension regarding multimodal cueing aspects, an audio concept can be used as reference during enhanced OEI operations. Second, the enhanced OEI operations are supported by future-proof mechanisms enabling higher engine performance. The goal of the work is to discuss pilot workload in combination to OEI operations.
Externe Masterarbeit: Entwicklung einer generalisierten Methodik der Systemsicherheitsanalyse zur Bewertung von elektrischen Antriebssystemen im Luftfahrtbereich
Das elektrische Fliegen spielt eine bedeutende Rolle in der Mobilität der Zukunft, gerade im Hinblick auf die Bewältigung des Klimawandels. Dafür werden bestehende Systeme im Luftfahrtbereich schrittweise durch elektrische Antriebssysteme ersetzt, wobei vor allem die Faktoren Leistungsgewicht, Effizienz und Zuverlässigkeit entscheidend sind, um diese im Luftfahrtbereich zu etablieren. In der zu bearbeitenden Masterarbeit soll die Zuverlässigkeit von elektrischen Antriebssystemen näher untersucht werden. Die damit verbundenen Aufgaben gliedern sich wie folgt:
NFK/CFK Hybrid Composite Systems in Aerospace Industrie (13.08.2021)
Eine hybride Leichtbaustruktur aus bio-kompatiblen sowie konventionellen Werkstoffen (CFK) für die Luftfahrt soll weiterentwickelt werden. Hierfür dient eine Hubschrauber-Kabinentür als Demonstrator des Technologiekonzepts der Naturfaserverstärkten Kunststoffe (NFK) worauf Einflüsse aus der Luftfahrt-Umwelt getestet werden sollen. Aufgrund der hohen Anforderungen in der Luftfahrt hinsichtlich Festigkeit, Steifigkeit und operationeller Langlebigkeit sind NFK-Materialien wie Flachsfasern mit Bio-Epoxidharzen noch im Forschungstadium. Aus diesem Grund muss für den Einsatz im fliegenden System und für die Einhaltung von Luftfahrtzertifizierungsnormen die Widerstandsfähigkeit gegenüber Umwelteinflüssen untersucht werden.
CFD-based unsteady aerodynamic reduced-order model (ROM) for rotorcraft application (23.07.2021)
The unsteady motion of aerodynamic surfaces, such as blades on rotors in edgewise flight and wings on aircraft during turbulence, can significantly influence the aerodynamic loads. These loads cannot be represented accurately using steady or quasi-steady airfoil aerodynamic performance methods. Therefore, unsteady aerodynamic theories exist to model aerodynamics in such regimes. Classical unsteady models (e.g. those by Theodorsen and Wagner) are based on potential flow theory. To remedy this situation, the proposed problem statement seeks to obtain an improvement to these existing unsteady models using URANS-based 2D airfoil aerodynamics results (Cl, Cd, and Cm) to modify quantities within the potential flow theory-based models.
High-fidelity Rotorcraft Comprehensive Analysis Toolchain (21.06.2021)
The Institute of Helicopter Technology extensively works with a rotorcraft comprehensive analysis code called Dymore (http://www.dymoresolutions.com/), written in C, and is working on expanding it. The goal is to simulate the operation of an active rotor (see figure below) with a high degree of fidelity. The aerodynamics module currently within Dymore is incapable of carrying out such analysis with requisite fidelity. So, a higher-fidelity rotor aerodynamics solver is planned to be coupled with Dymore for this purpose. The challenges of coupling this new solver include Coupling – since the two solvers are independent codes, a coupling mechanism needs to be established whereby the structural solver (Dymore) accepts the aerodynamic loads and passes on the calculated
structural deformation to the aerodynamics solver, and vice versa.
Tutor for the Helicopter IFR Practical Course (31.05.2021)
• You are responsible for one or two groups of the Helicopter IFR Practical Course
• You assist the students with typical IFR procedures, checklists and flying in the simulator
• You assist in the seamless organization of the practical course
• (Optional: You like working with computer and software, or have experience in IT)
Bachelor/Semester/Master thesis: Robust Helicopter Rotor State Estimation for High-Bandwith Control Laws (26.03.2021)
We offer an exciting opportunity to work on a high-bandwidth helicopter flight control system for our rotorcraft simulation environment. The thesis will aim to study the theoretical frameworks on state estimation and apply it to higher-order linear state space models of a bearingless helicopter. The student will seek to answer the research question:
How can the rotor states be estimated robustly and accurately using only the measurements of the fuselage states and a higher-order state-space model?
How can the estimated rotor states be used in the feedback control laws to improve bandwidth and stability characteristics?
How do human pilots perceive rotor state feedback control laws?
Bachelor/Semester/Master thesis: Development and Validation of Helicopter Pilot-Controller-Vehicle Models (23.03.2021)
We offer an exciting opportunity to develop human biodynamic models for our rotorcraft simulation environment. The student will have the chance to study the factors influencing a human pilot’s actions in a helicopter cockpit with different autopilot modes.
The student will analyze data from a recent test campaign conducted with experimental pilots and different flight control modes. The student will study the relevant human pilot models given in the literature. The ultimate goal is to develop a suitable pilot-controller-vehicle system model that can replicate similar pilot behavior in helicopter flight tasks as the human pilots.