Offene Themen für Semester- und Abschlussarbeiten am Lehrstuhl für Hubschraubertechnologie

Numerical investigation of aerodynamic interference in rotor tests under Martian conditions

The next step in Martian exploration will be UAVs by NASA’s Ingenuity helciopter. The most critical component of such UAVs are the rotor blades which have to generate thrust in the thin atmosphere while being extremely light. This is why we plan to build and test blades for a larger UAV in an upcoming project.

For the testing a near vacuum of 8 mbar is necessary which means that the tests have to be performed in a special chamber normally used for space simulation in satellite tests. The largest chamber of its kind in Germany is the Weltraumsimulationsanlage (WSA) at iABG in Ottobrunn. Due to its shape and orientation the test rig will have the rotor flow not in the direction of the cylindric chamber but perpendicular to it. This will lead to aerodynamic effects that have not been studied yet, especially under these atmospheric conditions.

To investigate this you will setup a CFD simulation of the rotor as an actuator disk in the WSA and the isolated rotor as reference. The aim is to investigate the influence of the chamber on the flow and the rotor performance. The results will inform the decision which size of rotor can be tested in the WSA without skewing the test results due to interference.

 

More Information and prerequisites

Coupling and Mapping approach of a DLR Free-Wake Aerodynamic Code to an inhouse Structural Solver (13.08.21)

The objectives of this project fit into the aeromechanical helicopter design and specifically in the risk minimization of T-tail arrangements and new configurations by building aeroelastic computational tools on a mid-fidelity level. The primary goal is to build a strongly coupled, aeroelastic simulation chain to calculate interaction loads in early design and safeguard the design against aeroelastic instability phenomena (flutter) on aerodynamic surfaces (tails, wings) under the influence of rotor wake.

 

More Information

Generic determination of the damping properties of composite materials for design application (13.08.21)

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.

More Information

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.

More Information

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.

More information

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.

More information

Tutor for the Helicopter IFR Practical Course (31.05.2021)

Tasks
• 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)

More information

 

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?

More Information

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.

More Information

Bachelor/Semester/Master thesis: Fluid Structure Interaction Investigation of a Dynamically Camber Morphing and Pitching Rotor Airfoil (01.03.2021)

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.

More Information