06 Fakultät Luft- und Raumfahrttechnik und Geodäsie
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/7
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Item Open Access Create a fluid-structure simulation framework for cycloidal rotors(2021) Schließus, JulianThe deformation of cyclorotor blades caused by aerodynamic forces and its effect on the rotor efficiency is not well understood. Therefore the aim of this thesis is to set up coupled Fluid Structure Interaction (FSI) simulations of cycloidal rotors. Furthermore, the results of this work shall create a base for prospective refinements of current cyclorotor CFD models in using a coupled simulation. For the FSI setup, the Computational Fluid Dynamics (CFD) simulation software OpenFOAM and the Multibody Dynamics (MBD) simulation software MBDyn are coupled using the coupling library preCICE. During this thesis, MBDyn models are set up and the advantages and limits of the currently existing preCICE OpenFOAM- and MBDyn-Adapter are discussed. To extend the coupling possibilities into the territory of rotating bodies, the creation of a custom OpenFOAM class is explained in this work. In addition, the influence of the cell displacement tolerance on mesh deformation is investigated and issues in OpenFOAM such as unwanted scaling or nonphysical motions are solved. Further, 2D and 3D setup cases are run and tested successfully on a High Performance Computing (HPC) cluster. Finally, certain coupling methods are reviewed and evaluated for the considered case.Item Open Access Optimizing automated postprocessing of point clouds for accurate wind turbine blade CFD analysis(2024) Schollenberger, KaiItem Open Access Experimental validation of a cycloidal rotor URANS CFD model and geometric parameter optimization(2022) Donners, LeonardCycloidal rotors offer many properties that are beneficial to VTOL rotor concepts. Two examples are high manoeuvrability and low aerodynamic noise emission. These rotors use cyclically pitched axial blades to generate thrust and operate in highly unsteady flow regimes, including curvilinear flow and dynamic stall phenomena. The current work develops an unsteady, incompressible 3D URANS CFD simulation setup that models a given small-scale experimental rotor. Measurements and simulation are conducted at a relatively low and slim Reynolds number range of 12x10^3 ≤ Re ≤ 76x10^3. By comparison of simulation results and experimental data, the CFD setup is validated. The validated setup is used to investigate flow phenomena on the initial rotor configuration and further conduct multiple separate parametric studies to optimise the rotor's energy efficiency. The investigated parameters are the blades' pitch profile, the number of blades, blade span and the addition of endplates at the blade tips. The highest efficiency increase of 14% compared to the experimental rotor is hereby found when adding endplates. The most efficient pitch profile results with a pitch rod length of l_opt=87 mm. The optimal blade span aspect ratio is 6 and a four-blade rotor is most efficient. Further research may aim at conducting this optimisation in a wider Reynolds number range or finding an optimum of multiple variable parameters combined.Item Open Access Investigation of the Reynolds Number on the performance of a cycloidal rotor(2021) Zimmer, FlorianThe Reynolds number has great influence on the provided lift and requested power of a cycloidal rotor. The aim of the present paper is to determine lift, power and efficiencyof a three bladed cycloidal rotor in relation to the Reynolds number. The investigated range of Reynolds numbers reaches from Re=10x10^3 to Re=600x10^3. For the parameter study, a cycloidal rotor under stationary hovering conditions, using a instationary, incompressible 2D URANS CFD simulation has been investigated. To interpret the rotation averaged data, field solutions are provided. Two different flow regimes can be distinguished: For the first regime (10x10^3≤Re≤100x10^3), two dynamic flow detachments occur, the first one at a maximum pitch angle of Ψ=270° and the second shortly afterwards. The second flow regime (200x10^3≤Re≤600x10^3) avoids the first detachment due to the increased Reynolds number. Both detachments are perceptible in the flow field solution as well as in the azimuthal lift distribution. The rotation averaged lift and power follow the proportionalities obtained by momentum theory.Item Open Access Create an automated structured mesh generation method for rotor blades using exclusively open source software(2023) Heider, Michael AndreasThe generation of high-quality CFD meshed wings for wind energy turbines currently requires either a very laborious process of building each wing by hand or requires the purchase of very expensive software. With university budgets and the advantages of open-source in mind, an open-source solution is desirable. The following thesis tackles this problem via a grid generation code in Python with Gmsh and extrusion via Pyhyp. However, designing software that has all of the features of commercial software with open source software leads to situations in which the intended way of usage is not the best way for the given task. An example of another open-source approach is the MACH-AERO framework which is an aerodynamic shape optimization tool that creates a grid along the way and extrudes it. However, this does not cover the intended usage of openblademesh for purely structured grid generation for predefined wings. Here we show one way to achieve an open-source solution with Gmsh and Pyhyp. All the necessary software, the versions needed, and installation instructions are described. Also how the wing generation process is achieved with special concentration on the wing-tip is part of the following thesis. The thesis also describes how to use the presented software Openblademesh and how to achieve the best results. The tool uses various automatisms to take the workload off of the user and helps to achieve the best mesh. Finally, the advantages and limitations of the tool are assessed and future extensions are described.Item Open Access Study on constraining turbulence to met mast data from the WINSENT complex terrain test site for use as inflow for CFD simulations(2025) Müller, CarstenThis work presents a method for generating time-resolved, three-dimensional turbulent inflow conditions for URANS/DDES simulations using the flow solver FLOWer. Turbulent inflow fields are generated using the Mann Turbulence Model via python’s Hipersim package and are applied as boundary conditions in the solver. The inflow is to reproduce both the absolute values and spectral characteristics of single-point time series and 3D velocity fields represented in atmospheric turbulence. A dedicated toolchain, InFlow, was developed to process and adapt turbulence input data from the WINSENT test site near Stötten, Germany. The approach is designed to be computationally efficient, straightforward to apply, and accurate enough for use in practical wind energy simulations. Its performance and limitations are evaluated across varying inflow scenarios and setups.