Wind Energy

Ben Ralph

Optimisation and calibration of loading analysis models for a large-scale floating offshore two-bladed turbine with teetering hinge

Apostolos Reppas

Techno-economic analysis of the installation and O&M of far-offshore floating wind turbines coupled with hydrogen production

Sweder Reuchlin

Hybrid Power Plant Modelling and Sizing using Airborne Wind Energy Systems

Alberto Rottigni

Optimisation of Hybrid Renewable Energy Systems for Distributed Wind Applications

Akarsh Kidiyur Sathish

Detecting the occurence of atmosphreric gravity waves along with its effect on offshore wind farm performance

Georgios Spyridonos

Unsteady Aerodynamics of Floating Offshore Wind Turbines under Surge Motion

Ferran van Kan

Numerical and experimental simulation of X-rotor VAWT with tip-rotors
 

Ioannis Voultsos

Aerodynamic Design Optimisation of Floating Wind Turbines for in-situ Hydrogen Production

John Watchorn

Development of an Aeroelastic Simulation Framework for 3D Leading Edge Inflatable Wings in Airborne Wind Energy Operations

Flip van der Weijden

Performance comparison of independent forecast models and hybrid forecasting model for hybrid solar and wind systems.

Dmitrij Mordasov

Wind Farm Energy Yield Assessment of the ‘Wake-Diffusion’ Rotor Concept Using Computational Fluid Dynamics

A 'wake-diffusion' rotor concept for wake mitigation was recently proposed, which reduces thrust loads near the blade root, increasing the radial gradients of the wake flow downstream. This should contribute to higher turbulent mixing of the wake structure by enhancing sheargenerated turbulence, accelerating the diffusion of the wake momentum deficit, overall resulting in increased yields of downstream situated wind turbines in a wind farm. The objective of this master thesis project is to investigate the effect of this 'wake-diffusion' rotor wake-mitigation concept on wind farm yields using Computational Fluid Dynamics (CFD).

Supervisors

Paul van der Laan (DTU)/Mads Baungaard (DTU)/Simon Watosn (TUD) Andreas Knaue (EQUINOR)

Guillem Vergés i Plaza

Cross comparison and uncertainty quantification of aero-acoustic measurements performed in several wind tunnels

Trailing edge serrations have been widely used to reduce trailing edge noise of wind turbine blades. However, large uncertainties in terms of analytical and computational modelling as well as testing do persist. The challenges in wind tunnel testing are found in the low signal to noise ratio, because an aerofoil equipped with trailing edge serration is very quiet and background noise in the aeroacoustic test setup can become dominant. A benchmark test to evaluate the noise reduction properties of trailing edge serrations experimentally and to assess the uncertainties of the wind tunnel tests was conducted. Two NACA63018 aerofoil models with different chord length were manufactured together with three generic serration shapes for both models. The models were tested in five different wind tunnel facilities of TUD, DTU and DLR.

Objectives of the thesis:

The objective of the master's thesis is to investigate the uncertainty of the data derived from the different wind tunnel facilities and investigate the noise reduction mechanisms of the serration geometries for a wide range of Reynolds and Mach numbers.

In order to achieve these objectives the student will: Understand the concept of trailing edge noise and the dependencies with Re number/ Get acquainted with the measurement techniques and the data acquired/ Collect data in a coherent format/ Process and scale data for cross-facility comparison/ Conduct a sensitivity and uncertainty analysis/ Perform supporting simulations for flow and noise emissions/ Analysis of boundary layer flow properties/ Analysis of wind tunnel correction methods

DTU supervisor: Andreas Fischer

TU Delft supervisor: Daniele Ragni

External supervisor: Michaela Herr (DLR)

Joana Cardiff Aleu

Fast aeroservoelastic models for load simulation 

In this thesis, the wind turbine simulator developed in Siemens Gamesa, BHawC, will be used to obtain a fast response model. This will be done in three different work packages (WPs):

1. Isotropic case with low turbulence intensity In this WP the student will have to compute the steady state with BHawC, linearize the system and get the transfer function. The wind turbine response will be computed in the frequency domain. This approach has been proposed by Tibaldi in “Wind turbine fatigue damage evaluation based on a linear model and a spectral method”, and will form the basis for the subsequent steps.

2. Isotropic case with high turbulence intensity Here the challenge will be to capture the variations in operating point, and in particular the switch in control region. This might be done by approximating the system as a linear parameter-varying system. Some computational speed can be obtained by converting in discrete time and/or applying model reduction.

3. Anisotropic case, with low turbulence intensity In this case the system will be a linear time-periodic system. We will thus compute the harmonic transfer function, and get the response in the frequency domain. The applications will focus on efficiently evaluating the loads for several turbulence seeds, and on understanding the effect of gravity and wind shear. In all cases, the verification can be done against BHawC time simulation.

Super visors

DTU: Riccardo Riva ricriv/ TU Delft: Bianca Giovanardi B.Giovanardi/  External: Peter Fisker Skjoldan

Mathieu Pelle

Flow structure detection using a numerical LiDAR measurement model.

Light Detection and Ranging (LiDAR) technology is becoming a popular alternative to traditional methods for wind-field measurements and wind turbine control systems mostly due to its practicality and cost-effectiveness. Although LiDAR’s offer satisfactory mean wind speed predictions, this is mostly not the case for measurements of wind speed variance or turbulence and remains a subject of on-going research. The objective of this master thesis project is to take a closer look at the LiDAR measurement process by numerically emulating its operation and subsequent data processing steps, in order to investigate possible ways of detecting flow structures such as vortices, shear layers, gusts, etc. Evaluating the models’ performance will be performed with synthetically generated wind fields or gust/shear wind models with the end goal being to improve the wind turbine’s lifetime and durability.

TU Delft Supervisor: Wim Bierbooms

DTU Supervisor: Mickael Sjöholm

External Supervisor: Norbert Warncke (SGRE

Nils Joseph Gaukroger

Analytical solution for the cumulative wake of wind turbines

Wake steering has of late been a hot topic within the wind energy community due to its ability to mitigate wake losses within wind farms. Whilst fast, engineering models that can describe the shape and deflection of the wakes of individual turbines exist, the cumulative effects of these wakes within wind farms are still poorly detailed by the current generation of empirical superposition methods. (Bastankhah, et al. 2021) developed an analytical model which solves an approximate form of conservation of mass and momentum for the streamwise velocity within a wind turbine array. This project aims to extend that work to develop an analytical model for the lateral velocity component within a wind farm, which is of particular importance for wake steering effects such as secondary wake steering, as described by (King, et al. 2020). Model predictions are validated against Computational Fluid Dynamics simulations, namely RANS through PyWakeEllipSys and LES from SOWFA.

supervisors:

DTU supervisor Paul van der Laan / TU Delft supervisor Prof. Simon Watson/ External co-supervisor (Durham University) Dr. Majid Bastankhah 

Oriol Cayón Domingo

Fast aeroelastic model of a leading-edge inflatable kite for the design phase of airborne wind energy systems

Airborne Wind Energy shows the potential to become one of the pillars of sustainable energy production, as it can harvest energy from higher altitudes than wind turbines, where the wind resource is higher and more constant. Furthermore, it reduces the amount of material consumption significantly, 1-10% of the material used on modern wind turbines. The concepts that are closest to market are those that fly in the crosswind direction, with either on-board generation ( “drag mode”) or ground generation (“lift mode”). Although the potential advantages of these concepts are very attractive, there are still very few companies with concepts that are close to entering the market. This is because it is a very complex control problem, with an inherently unstable system that can fail in many ways, and where a failure is usually catastrophic. Currently, the most developed concepts are the so-called LEI (Leading Edge Inflatable) kites, which are made of fabrics. They are easier to control than the rigid wing concepts and it is less probable that a failure results in the destruction of the kite. The behavior of a soft kite is quite a complex phenomenon due to the strong coupling between the wing’s deformation and the flow pattern i.e., the wing deforms, which causes the flow around the wing to change, which changes the pressure distribution and again deforms the kite. This fluid-structure interaction is particularly important for AWE systems, as the kite has to fly in very different inflow conditions during its periodic flight path. One of the main problems is that there are not many existing models that are sufficiently accurate and computationally cheap at the same time. The objective of this project is to create a FSI model that couples an aerodynamic model, that resolves the flow behavior and pressure distributions around the wing, with a structural model that computes the deformation of the kite. The kite that is going to be analyzed for this study is the Kitepower Falcon, which has a rated power of 100kW and a planform area of XXXm^2.

To achieve this objective, the project is going to be divided into three parts:

1. Development of an aerodynamic model of the kite based on potential flow theory.

2. Coupling between the aerodynamic model and a structural model that computes the deformations of the kite caused by the reel out and reel in of the cables.

3. Development of a bridle system solver able to calculate the deformations caused by the aerodynamic forces

Supervision

Coordinator (TUDelft): Roland Schmehl/ Co-coordinator(DTU): Mac Gaunaa

Pramod Kashyap

Impact Assessment of Wind Farm Blockage in Complex Terrain

Measurement campaigns [1] and wind-tunnel experiments [2] have recently identified a large-scale flow phenomenon called wind-farm flow blockage, which is a significant and far-reaching reduction in wind speed upstream of a wind farm that cannot be attributed to the induction of a single turbine. Wind-farm flow blockage has important consequences for the energy production because it reduces the available kinetic energy in the incoming wind flow, causing leading wind turbines in a wind farm to produce less energy than they each would in isolated operating conditions. To date, the physics of this global blockage effect are not entirely understood, and they are therefore an active research topic. One open research question pertains to the impact of complex terrain on the amount of flow blockage induced by a wind farm. Some studies have found that very complex terrain conditions can reduce the magnitude of the blockage effect, while preliminary studies of other wind farm cases with particular topographical features found that the terrain can enhance the blockage effect. The objective of this master’s thesis is to perform Reynolds-Averaged Navier-Stokes (RANS) simulations to assess the impact of wind-farm flow blockage in complex terrain using the open source software OpenFOAM and to investigate how the topography affects the blockage effect. The project will focus on a row of wind turbines situated on top of a bell- shaped ridge.

Supervisions

DTU Supervisor Prof. Hamid Sarlak Chivaee/ TU Delft Supervisors Dr. Ir. Dries Allaerts/  Prof. Simon Watson/ External Co-Supervisor/ James Bleeg 

Mario Rodriguez. Francesco

Design of Martian Airborne Wind Energy System on Tharsis Bulge By Using Refined Wind Resource Estimations and Quasi-Steady Model

Using the Mars Climate Database (MCD), a detailed system design of an automated 10 kW airborne wind energy system was recently proposed by a TU Delft DSE group for later use on the Rhizome Mars habitat project. Due to the very coarse resolution of the MCD, local effects are not captured, which could have a decisive effect on the system performance. A new trade-off study considering more details such as the wing component masses and packing volume must be conducted in order to optimise the wing design. The objective of this master thesis project is to provide and validate a method to locally refine the wind resource estimation on a new habitat site and employ a quasi-steady model in order to revise the hybrid design of the wing.

Supervisors:

Roland Schmehl (TU Delft) and Mac Gaunaa (DTU).