Steady Reynolds-Averaged Navier-Stokes (RANS) simulations utilizing the k-ω SST turbulence model are conducted to investigate the aerodynamic performance of a wing-integrated ram-air duct housing a heat exchanger for propeller-driven aircraft, including its impact on wing-body junction flow. The research is conducted in two stages: first, a 2D aerodynamic analysis employing a Design of Experiment (DoE) methodology to assess the sensitivity of key geometrical parameters–including stagger angle, leading-edge droop, duct gap, and heat exchanger characteristics–on lift, drag, and duct mass flow rate; and second, a 3D investigation of the junction flow behavior in the nacelle/ducted-wing configuration. The heat exchanger pressure drop is modeled as a porous media zone using the Darcy-Forchheimer quadratic drag law. Heat transfer is incorporated through a variable energy source term applied via a userdefined function (UDF) based on the ε-NTU correlation. Findings from the 2D aerodynamic analysis indicate that heat exchanger characteristics, particularly porosity and thickness, have a more pronounced impact on aerodynamic performance than external duct geometry. However, intake stagger angle and leading-edge droop play critical roles in mitigating flow separation and optimizing the wing pressure distribution. In addition, the redistribution of pressure due to flow restriction alters the stagnation point location, inlet-velocity ratio, and static pressure distributions, all of which influence the aerodynamic loading of the ducted wing. The optimal ducted airfoil configuration, featuring a lower-surface outlet aft of the maximum thickness and a thin heat exchanger, minimizes aerodynamic penalties while maximizing duct mass flow rate. However, thermal feasibility assessments reveal that meeting the cooling demands of fuelcell systems necessitates a thicker heat exchanger to accommodate sufficient heat transfer area within the constrained wing volume. This increase in thickness impairs aerodynamic performance through increased pressure drop and resultant drag. Although higher porosity mitigates flow resistance, the required thickness offsets this advantage, reinforcing the inherent trade-off between aero-thermal performance. In 3D, the presence of the heat exchanger inside the duct fundamentally alters the local aerodynamics by modifying boundary layer interactions at the wing-body junction. The flow resistance imposed by the heat exchanger directly affects the strength and topology of secondary flow structures, particularly the horseshoe vortex (HSV), which governs junction flow behavior and whose strength scales with the Reynolds number based on the momentum thickness of the incoming boundary layer. At low porosity levels, the stronger HSV , with an increased vertical extent above the wing, entrains high-momentum freestream flow into the chordwise and spanwise boundary layers, mitigating corner flow separation. Conversely, at high porosity levels, lower flow resistance alters HSV topology, reducing its vertical extent and allowing part of the vortex to enter the duct, inducing a secondary vortex at the lower lip. This weakens the HSV’s ability to stabilize the boundary layer, leading to earlier separation, increased pressure losses, and higher drag. A moderate porosity level provides an optimal balance between HSV strength, vertical positioning, and junction flow stability, reducing corner flow separation and associated pressure losses. Collectively, these findings yield critical insights into integrating ram-air cooling ducts within the wings of propeller-driven aircraft, offering a compelling approach to achieving efficient thermal management systems with minimal aerodynamic penalty. This investigation provides unprecedented detail in visualizing and understanding the intricate coupling between ducted wing aerodynamics and heat exchanger-induced flow interactions, while emphasizing the need for further research to validate and expand upon these findings

The transition to renewable energy sources is essential to mitigate climate change, and floating wind turbines (FOWTs) present a promising solution to harness offshore wind resources. Light Detection and Ranging (LiDAR) systems mounted on nacelles provide a cost-effective and efficient means to measure wind fields, critical for turbine performance, control and load simulation. However, FOWT's motion introduces complexities in LiDAR measurements due to velocity and positional changes. This thesis focusses on developing a correction method for LiDAR measurements on FOWTs, addressing the influence of motion on wind velocity, position, and direction. The accuracy and uncertainty of these corrected measurements are quantified.

Simulated six degrees of freedom (6DOF) motion and a power law wind field are inserted in a numerical LiDAR model, in which corrected and uncorrected measurement position, direction and line of sight velocity are constructed. The corrected outputs are validated through reconstructed wind fields and the uncertainty of the correction is quantified. In this study, significant motion-induced bias is identified in the reconstructed wind fields. The dominant motion affecting measurement accuracy was identified as pitch motion, especially when it exhibits a non-zero mean. The relative error of the reconstructed power law wind field parameters is reduced by 3 orders of magnitude. Despite an increase in uncertainties associated with the correction method applied, the correction remains effective in reducing the error in LiDAR measurements induced by FOWT motions. The findings highlight the necessity and feasibility of motion correction for LiDAR measurements, offering substantial improvements in the accuracy and reliability of reconstructed wind fields for floating wind turbine applications.

Goal-oriented reduced-order models (GOROM) have the potential to represent complex dynamics in an interpretable way. In the GOROM procedure, modes are found which when used in a Galerkin projection of the governing equations, return the desired goal function with minimum error. Determining such models leads to a high-dimensional optimisation problem, which may have multiple extrema, making purely local optimisation inapplicable.
In this thesis, a global optimisation algorithm was derived for GOROM. The optimisation response surface was approximated with a surrogate model, built using the Kriging technique. In each iteration, the surrogate model was improved by including the objective function of the three points with the highest expected improvements. This iterative process was stopped when the expected improvement fell below a threshold.
First, the performance of the algorithm was confirmed for a simple non-GOROM optimisation. Then the algorithm was applied to GOROM optimisation for the forced Burgers equation, initially using a complex forcing function giving multiple minima and later to a forcing function derived from a DNS of a turbulent channel flow. The initial forcing required on the order of tens of degrees of freedom to be optimised. The corresponding response surface proved similar to that of the simple problems, showing these optimisations to be tractable.
For the DNS forcing, hundreds of coefficients needed to be optimised. Using the developed algorithm a better optimal was found than with the local algorithm, although substantially more computational resources would be required to confirm global optimality.

This thesis aims to study the effects of enhanced flow entrainment in a VAWT wind farm. This is achieved by advection of low momentum wake into the free-stream flow via lateral forces, and these forces are introduced by pitching the rotor blades.
For this study, scaled down VAWT models have been designed and setup in a wind farm layout. This wind farm model has been tested in the Open Jet Facility (OJF) of the Delft University of Technology to gather insight into the farm's flow behaviour. The wake is acquired using Tomographic Particle Tracking Velocimetry (PTV) measurement technique, where the flow is measured by acquiring images of Helium Filled Soap Bubbles (HFSB), suspended in the flow-stream. The performance of individual turbines is characterized by taking the load measurements, and comparing the thrust coefficients.

This thesis proposes techniques to produce wall-shear stress estimates from three-dimensional Lagrangian particle tracking (LPT). Several works have already faced the problem of determining near-wall velocity and in particular skin friction for the case of a flat surface. Here, the problem is translated to generic three-dimensional objects. The work makes use of an experimental database, recently produced, with LPT (Hendriksen et al. 2024), that provides in-situ registration of the object, for three shapes of increasing complexity: a cube, an airfoil and a cyclist. Four techniques are examined and compared, including interpolation method as well as local data regression. The uncertainty is evaluated a-posteriori, comparing the results with a local coin-stacking technique, where applicable. All techniques yield accurate and robust representations of the skin friction lines around three-dimensional objects, allowing for an insightful inspection of the near-surface flow topology. Instead, distinct differences are found when the skin-friction magnitude is estimated.

This thesis investigates a novel load alleviation technique known as mini-tabs, small devices placed on the upper surface of wings to reduce lift. Reynolds-Averaged Navier-Stokes (RANS) simulations were conducted to analyze the impact of geometrical properties on mini-tab performance in reducing the load on a wing.

The initial simulations focused on a single mini-tab, varying parameters such as height, aspect ratio, chordwise, and spanwise positions. Results indicate that increasing height or aspect ratio leads to decreased lift due to flow deceleration at the leading edge and expansion of the separated flow region downstream of the mini-tab. This will also increase the pressure drag. Increasing the height or aspect ratio also accelerates the flow at the lower surface, further reducing the lift generated by the wing.

Placing mini-tabs closer to the wingtip exhibits similar effects on lift reduction as increasing the height of the mini-tabs. This is because the relative height of the mini-tab with the local chord length increases when the mini-tab is positioned closer to the wingtip. A maximum lift reduction is also achieved when the mini-tab is placed at a 60% chordwise position.

Subsequent simulations explored the performance of multiple mini-tabs, revealing that orienting them orthogonal to the wind direction may not be optimal due to gap formation between the mini-tabs that energizes the wake downstream of the mini-tabs and reduces the reduction in lift. Conversely, aligning the mini-tabs with the leading edge has a higher efficiency in the reduction of the lift.

Overall, the findings suggest that mini-tabs offer a viable method for reducing wing forces and for load alleviation

This thesis presents the development of an entropy-corrected full potential flow solver (EC-Flow) within a finite element framework to enhance the representation of shock waves in transonic flow regimes. By addressing limitations in traditional isentropic full potential flow solvers, EC-Flow improves aerodynamic predictions whilst maintaining low computational cost, making it suitable for early design phases in aeroelastic analysis.

The methodology integrates an entropy correction based on the Rankine-Hugoniot relations, with shock detection achieved through gradient-based and normal Mach number methods. An iterative downstream approach ensures consistent application of the correction across the shock-affected domain.

Results for the NACA0012 and RAE2822 airfoils demonstrate improved shock representation, and faster convergence compared to the uncorrected solver. Validation against Euler solutions confirms the effectiveness of the entropy correction in enhancing accuracy without significant computational overhead.

This thesis investigates the flow and heat transport phenomena in a pipe and Pressurized Water Reactor (PWR) rod bundle geometries using high-fidelity Direct Numerical Simulation (DNS). These geometries are essential for nuclear reactor systems, where efficient heat transfer and stable flow patterns are vital to ensure operational safety, reliability, and performance. The study focuses on evaluating the limitations of traditional thermal-hydraulic modeling approaches and advancing the understanding of flow physics in complex geometries.
Since Computational Fluid Dynamics (CFD) simulations are computationally expensive, system codes such as RELAP5, TRACER, and SPECTRA (developed by NRG) are widely used in reactor safety and design analysis. These codes rely on conventional pipe flow correlations to approximate thermal-hydraulic behavior, which are not representative of the intricate flow patterns observed in rod bundle arrangements. Such geometries are characterized by secondary vortices, gap street vortices, and the coupling of these vortices across multiple planes, forming a complex rod bundle vortex network. This study addresses these challenges by comparing the flow and thermal characteristics of pipe and subchannel geometries to evaluate the validity and limitations of pipe-based correlations.
To identify the subchannel geometry that best represents a rod bundle arrangement, square and 2×2 subchannel configurations were selected for detailed investigation. These geometries were modeled with a pitch-to-diameter (P/D) ratio of 1.3263, typical of PWR fuel assemblies, and simulated at a Bulk Reynolds number (Reb) of 5300. The square subchannel geometry represents a simplified cross-sectional domain, while the 2×2 subchannel configuration captures inter-subchannel interactions and the enhanced coupling effects seen in rod bundles. Using the Nek5000 spectral element solver, the simulations employed advanced numerical techniques, including spatial-temporal averaging through flow-through time (FTTs) metrics and further spatial averaging over unit cells, to achieve statistically converged results. Rigorous validation of pipe configuration with reference data ensured the accuracy of the computational framework.
The results highlight significant differences in turbulence structures and heat transfer performance between the pipe, square subchannel, and 2×2 subchannel configurations. While pipe correlations provide a baseline for comparison, they fail to capture the complex flow interactions observed in rod bundles. The 2×2 subchannel geometry emerges as a more accurate representation of rod bundle dynamics due to its ability to simulate enhanced inter-subchannel mixing and vortex coupling. These findings emphasize the importance of geometry-specific modeling in accurately predicting thermal-hydraulic behavior in nuclear reactors.
This work bridges the gap between simplified system codes and detailed physics-based modeling of rod bundle flows. The insights gained from this study provide a foundation for improving thermal-hydraulic predictions and advancing the design and safety of nuclear reactor systems. Future research will extend these findings to explore higher Reynolds numbers, diverse Prandtl numbers, wall effects, and alternative rod bundle configurations, further contributing to the development of advanced engineering tools for nuclear applications.

As the automotive industry increasingly shifts toward electrification, reducing vehicle drag becomes crucial for enhancing battery range and meeting consumer expectations. Additionally, recent European regulations require tire and car manufacturers to provide reliable drag data. A significant factor influencing vehicle drag is the highly turbulent wake generated by rotating tires. Accurate correlation between wind tunnel experiments and numerical simulations is essential, yet discrepancies often arise due to the dynamic behavior and technical challenges in measuring tire deformation, leading to inconsistencies between tire deformations observed in wind tunnels and those modelled in simulations.

This Master’s Thesis investigates the aerodynamic impact of realistic tire deformation parameters—specifically, bulge and contact patch deformations—using Computational Fluid Dynamics (CFD) simulations conducted with PowerFLOW. The deformation parameter tests are carried out in a standalone tire setup, which is validated from previous work by Dassault Systèmes and experimental results. To further assess the impact of these deformations on vehicle drag, the tests were repeated using the DrivAer model, an IP free model provided by the Technical University of Munich. Given the complexity of the flow features in a tire wake, the analysis of the results consisted of two different approaches: a statistical approach based on Principal Component Analysis (PCA), and a vortex behaviour and wake development analysis, including a vortex tracking algorithm based on the Gamma 2-Criterion and single-link hierarchical clustering.

The results identify the most influential deformation parameters based on their impact on the drag coefficient and the wake behaviour changes. Two primary wake development behaviours were identified: wake contraction and wake expansion. An analysis of the transient flow showed how these two trends resulted from changes in the unsteady behaviour introduced by certain deformation parameters. The relevance of these wake development changes was portrayed by the impact of certain deformations on the full vehicle drag as a result of
complex wake interactions.

This thesis presents a comprehensive study on Floating Offshore Wind Turbine’s (FOWT’s) modeling and simulation, focusing on the IEA 15MW wind turbine coupled to the VolturnUS-S semi-submersible platform. The primary goal was to develop the building blocks of a high-fidelity Computational Fluid Dynamics (CFD) coupled model using OpenFOAM to simulate large-scale FOWT behavior, verify, and compare each component individually against the mid-fidelity tool OpenFAST. The project builds on the frameworks of previous studies by Pere Frontera Pericàs [81] and Scarlatti [98], expanding them to accommodate the complexities of a larger turbine and more intricate environmental conditions.

The model was implemented using OpenFOAM’s waves2Foam and Moody libraries for wave and mooring modeling, respectively, while aerodynamic simulations employed the turbinesFoam package with an actuator line approach. A spatial convergence study optimized mesh parameters for computational efficiency and accuracy, ensuring reliable and stable simulation results for motions up to 24 meters in surge. Comparisons between OpenFOAM and OpenFAST using a P-Q analysis highlighted significant differences, particularly in modeling damping. OpenFAST was shown to underestimate both linear and quadratic hydrodynamic damping due to its simplified representation of fluid dynamics. Discrepancies in the equilibrium positions were found between the decay tests using CFD; their origin still needs more investigation.

In aerodynamic simulations, steady-state and prescribed motion tests revealed critical differences in thrust and power predictions between OpenFOAM and OpenFAST. OpenFAST overpredicted the reduction in axial wind speed, leading to a reduced power output for steady turbine simulations. The CFD model provided a more accurate representation of rotor wake effects and dynamic responses, particularly in high-frequency surge conditions, where OpenFAST overestimated power fluctuations. These findings underscore the importance of using high-fidelity models like OpenFOAM to improve the accuracy of performance predictions in floating wind turbines.

The study concludes by offering recommendations for future research, including model validation using experimental data and the implementation of overset mesh techniques to improve simulation stability for large motions. The work establishes a reliable CFD framework for simulating this large FOWT, offering insights into enhancing mid-fidelity models and guiding future developments in floating wind turbine design and analysis. It also builds a fully coupled CFD model in OpenFOAM to investigate its behavior.

Computational Fluid Dynamics (CFD) simulations of objects like the Kitepower V3A Leading Edge Inflatable (LEI) kite require accurate experimental data for validation. However, for these kites, particularly in steady-state simulations, such data is scarce. LEI kites are soft and deform continuously during flight, making validation complex. To address this, a unique experiment in the Open Jet Facility (OJF) at TU Delft, testing a rigidized subscale model of the V3A kite, marking the first wind tunnel test on a rigid kite.

The rigid model was made of carbon fiber reinforced polymer and mounted on a custom support structure that allowed adjustments to the kite’s angle of attack and sideslip. Aerodynamic forces and moments were measured at different wind speeds and orientations, with and without zigzag tape to study its effects on low Reynolds number flow.

The results were compared to existing CFD simulations, including Reynolds-Averaged Navier-Stokes (RANS) and vortex step methods. The experimental data aligned well with these simulations at low Reynolds numbers, validating the setup. However, some discrepancies highlighted areas for improvement, such as reducing interference from the support structure and better matching Reynolds numbers between simulations and experiments.

One of the novel methodologies in computational physics research is to use mimetic discretisation techniques. Among these, the mimetic spectral element method holds special promise as it not only has the benefits of mimetic methods but also the additional benefit of higher-order discretisations using higher polynomial degrees. These methods are aided by the development of algebraic dual polynomials, resulting in a sparser system for better computational efficiency. This combination was used to develop a formulation that would result in topological relations for equilibrium of forces as well as the symmetry of the stress tensor for linear elasticity as well as the first steps for Stokes flows in an orthogonal domain. As a result, this study was extended to look at how a modified formulation would behave for an unsteady linear elastic solid, with the intention to extend this method to Fluid-Structure Interaction cases. However, the choice of both primal and nodal basis functions makes it impossible to undertake this challenge, demanding a rethink in strategy towards looking at linear elastic solids when the physical domain is not orthogonal. With the use of bundle-valued forms to represent physical quantities, a new hybrid formulation is developed where the equivalent of the physical problem is computed on a reference domain, which is orthogonal and thus can utilise the spectral bases defined before. The physical problem is defined on a skewed domain, where partial transformation of components results in a formulation that can conserve linear momentum point-wise, but not conservation of angular momentum, although angular momentum does converge on refinement of polynomial degree and mesh parameters. A change in bases with partial transformation aiming to make angular momentum conservation topological is not fruitful, although the value of the error decreases in the process. The final attempt is through full transformation, which results in a formulation with an inherent error in the formulation, owing to erroneous assumptions.

Hydrofoils can under certain circumstances cause a phase change from liquid water to water vapor. This phenomenon is called cavitation and is caused by the low pressure over the hydrofoil when the vessel exceeds a certain velocity though the water. Cavitation can take different forms depending the angle of attack α and the flow conditions which are characterized with the cavitation number σ . The different types of cavitation can have different effects on flow and loads.
Computational Fluid Dynamics (CFD) is widely used in aero and hydrodynamic design, with (U)RANS most commonly used for CFD in the industry due to its relatively low computational cost while providing sufficiently accurate results. Cavitation models in URANS simulations need a multiphase framework in order to model the liquid/vapor interface of the cavitation bubbles. The Schnerr-Sauer cavitation model uses simplified bubble dynamics equations for relatively fast calculation while providing accurate results. In current project, a Volume of Fluid method is used the Schnerr-Sauer cavitation model is used with URANS CFD simulations to improve and enhance the behaviour and performance prediction of hydrofoils sections under cavitating conditions. Given the industrial context of this project, the simulations are conducted using constrained computational resources.
Validation is performed for a non-cavitating test case using a NACA-0012 section, followed by validation for a cavitating test case using a modified NACA-66 section. Mesh convergence studies have been performed, turbulence models have been compared and the turbulent viscosity has been modified. The final set-up uses the SST turbulence model with a modified turbulent viscosity exponent n = 2.3.
To assess the flow behavior and hydrofoil section performance under cavitating conditions, a comparison is made in CFD using cavitation models, relative to the current practice. This study shows that the lift and drag results for a simulation without cavitation model are underestimated compared to the simulation with cavitation model in conditions of stable cavitation. For conditions with unstable cavitation, strong unsteady disturbed flow and loads are found that are not captured by the simulation without cavitation model. The transition from stable to unstable cavitation is studied by investigating cavitation bubble length and its
corresponding fluctuation as a function of the stability parameter
ps = σ/2(α−α0) . The conditions found for the transition from stable to unstable cavitation are consistent with reference value at about ps = 4. The inception of stable cavitation is found at about ps = 7 which is considered to be more optimized to delay the formation of cavitation compared to the NACA-0012 at ps = 8.5.
The lift, drag and performance polars are studied for several values of σ . The lift and drag polars for lowerσ , i.e. higher cavitation rate, show a stronger increase in both lift and drag for stable cavitation cases. The performance (or Lift over Drag) is slightly increased at α = 4◦ for σ = 1.2 and 1. For higher angles of attack, the increase in drag surpasses the increase in lift and the performance decreases. These finding only hold the stable cavitation cases (α < 8◦ for all tested σ , and α = 6◦ for σ = 1) since the unstable cavitation results are
inconclusive.
The main limitation of the set-up developed in the current project is that the predictions show significant discrepancies in capturing the unstable bubble shedding characteristics, with respect to the reference data. As a result, the cloud cavitation shedding frequency is not accurately captured, resulting in an inadequate representation of vibrations and loading due to cloud cavitation.

The purpose of this study has been to develop an aerodynamic load model for the energy harvesting (traction) phase of leading-edge inflatable (LEI) kites operating in an airborne wind energy (AWE) context. The load model stems from multivariate polynomial regression analyses expressing the airfoil lift, drag and moment coefficients as polynomial functions of the angle-of-attack and 2D non-dimensional (relative to the chord length) shape parameters: non-dimensional tube diameter, maximum camber magnitude and chordwise position of maximum camber. The regression analyses relied on numerical data attained from computational fluid dynamics (CFD) simulations of the 2D flow fields around parameterised LEI wing profiles. The RANS equations, closed by the k-ω SST turbulence model, have been used for this purpose. The parameterisation and subsequent geometric construction of LEI wing profiles has been a key aspect of this study. As such, the effects of the shape parameters on the flow field have been assessed.

The hunt for new methods to harness wind energy is at an all-time high as wind energy quickly overtakes other renewable energy sources. Deep waters are promising alternatives with higher average wind speed (thus, higher yields) and also due to lesser availability of land on shore. Even though the design of the blades and rotor of a FOWT is largely similar to that of onshore counterparts, they are mounted on floating platforms, unlike the fixed platforms on onshore wind turbines. Due to the excitation from wind and waves, these foundations are made to oscillate in all six degrees of freedom. Pitch and surge motions have the most significant effects out of all the possible types of motions. Since surging motion comes closest to the pitching motion, this study attempts to compare the aerodynamics of these two motions by simulating a pitching wind turbine using an actuator disk CFD model. This study can also be considered a continuation of the actuator disk study of the surging motion.

The primary objective of this thesis is to understand the differences between the aerodynamics of a surging and a pitching wind turbine using an actuator disk model. The actuator disk is made to pitch sinusoidally with the prescribed pitching frequency and amplitude. In order to identify the effects of motion and thrust prescription separately, three different types of actuator disk models were created. Using the first model, which simulates a pitching actuator disk with constant thrust, the effects of pitch motion are captured. The second model which simulates a still actuator disk with dynamic loading gives the effects of change in thrust on the rotor. The last model, which is a combination of the first two with a pitching actuator disk under dynamic loading, attempts to simulate a more realistic pitching actuator.

On comparing the surge and pitch motions of the actuator disk, the stark difference observed is the meandering in wake due to flow shear and asymmetric tip vortex shedding. At high thrust and low-frequency cases, turbulent wake
states are also visible in the wake. At higher frequencies, they are nearly as strong as the tip vortices and introduce non-linear effects on the induction field. They also tend to introduce varied dynamic responses based on the radial location. It was also observed that the motion introduces a phase delay that varies with the radial position on the rotor.

Thus, this project provides a comprehensive view of the effects of platform pitching motion on a FOWT and it differences with respect to the surging dynamics. This project also confirms that an actuator disc model is capable of reproducing the effects of pitching in a FOWT. Using the insights provided in this thesis, a better dynamic inflow can be developed for use in industries

A 3D panel method code, named AWSM3D, is developed as an extension to the AeroModule aerodynamic software suite of TNO which includes a Blade Element Momentum theory (BEM) and a Lifting Line (LL) code. The underlying panel code method is presented along with a gradual process of simulation validation culminating in validating the code against the New MEXICO experimental dataset and an established panel code. In view of exploring the avenue of sweeping wind turbine blades as a way of increasing wind turbine efficiency, the capabilities of the three proposed aerodynamic models in solving flows about swept geometries are studied. The unmodified BEM model is incapable of adequately modeling flows over swept geometries. The limits of the cross-flow theory which the LL simulation hinges on for the simulation of swept flows are put to the test. Both a fixed wing and a conventional Horizontal Axis Wind Turbine case show that the LL solution in proximity to body extremities where the cross-flow component is prominent fails to capture smaller-scale local effects caused by said cross-flow. Despite this, the larger-scale effect is reproduced well. Although AWSM3D requires no airfoil polars and produces an accurate inviscid flow solution for more complex body geometries, it currently excludes viscosity and has a much higher computation time in comparison to an LL. A number of further AWSM3D development and research into the effects of sweep suggestions are formulated.

In response to the leading narrative of increasing sustainability in the yachting sector, a research collaboration is started between the Delft University of Technology and Dykstra Naval Architects to examine the potential use of hydro generation on board sailing superyachts. By harvesting energy from the water flow when under sail, diesel generator use can be limited, reducing overall emissions. Currently, it is not yet possible to quantify the impact of a chosen hydro generation system on the overall design during the early stages of yacht design. To assess the correct balance between the inevitable increase in system weight and size relative to, for example, emission reduction. To allow for this, a novel method is developed, presenting the designer with the opportunity to explore various hydro generation systems quickly. With the ability to complete this in an early design stage, more opportunities for hydro generation remain, and the need for a feasibility study for hydro generation is removed. In this thesis, the developed method is described, and results are presented that provide insight into its applicability. The design method considers the impact of six variables that influence hydro generation. The first three variations concern size and include the propeller diameter, battery capacity, and sail area. The remaining considerations relate to operational and design choices and include decisions on energy consumption, fixed or controllable pitch propellers, and generation in the first or third quadrant. A scenario for an ocean crossing with a sailing yacht aiming to limit fuel consumption demonstrates the influence of these considerations. The results presented in the thesis show that the method provides the basis for a later detailed design stage when an actual hydro generation system is implemented.

With an ever increasing demand for sustainable energy, limitations of current sustainable technologies are studied widely. In wind farms, the so-called wake effect provides the biggest limitation on wind farm total power output. Using wind from the unaffected boundary layer to re-energize the wind flow in the wake provides a method of limiting this wake effect. In this study, kites are introduced to steer the wind flow of the unaffected boundary layer into the wake through a downwash velocity. RANS (Reynolds-averaged Navier-Stokes) simulations are performed in Computational Fluid Dynamics (CFD) software OpenFOAM of the atmospheric boundary layer (1), a small four-turbine wind farm (2) and a wind farm with static kites between the turbines (3). The turbines are modelled through the actuator disc approach, and kites are introduced through the more complex actuator line method. Results of the athmospheric boundary layer (ABL) and wind farm simulations correspond well with literature. Through extensive kite parameter studies, an optimal layout of kites in the wind farm is presented yielding a wind farm efficiency increase of 2.3 %, which increases over 5% for even larger kites. Kite size and the kite’s downstream location show to impact the re-energising levels of the wake flow the most. The kites generate a downwash wake instead of a single downwash velocity, a finding that should further be studied in future research.

It is the need of the hour to focus research and development towards curbing emissions due to the growing aviation industry. Employing boundary layer Ingesting(BLI) propellers for development of propulsive fuselage concept(PFC) aircraft while utilizing hydrogen as an alternative energy source, is the idea behind project APPU(Advanced Propulsion and Power Unit). However, the empennage wake is detrimental to the propeller. This study uses chord-wise wake blowing technique to fill the empennage wake in order to mitigate the detrimental effects of the wake on the inflow of the aft mounted BLI propeller. A near complete wake filling was observed for the blown configuration, with a 99.7% uniformity in the velocity profiles for the filled empennage wake. The addition to the overall aircraft drag due to the wake blowing system was less than 2 drag counts and a mass flow rate of 0.91-1.23Kg/s was found to be required in the blown cases.

Aerodynamics has played a significant role in the industry of motorsports in improving the performance and handling of the race car. Rob Smedley, the former head of vehicle performance at Williams Racing stated that - "Where teams have problems is when their development or simulation environment – so CFD [Computational Fluid Dynamics] or wind tunnel – doesn’t describe well what happens in reality (although in truth, no-one’s wind tunnel correlates absolutely 100%)". One of the reasons for this poor correlation could be arising from the fact that, in real life on track scenarios, the race cars undergo accelerating, decelerating, or cornering motion which can have a different influence on the aerodynamics of a race car which is not accounted for in the wind tunnel and simulation environment where a steady constant flow is employed. This research aims to numerically investigate the flow past the front wing of a Formula One car in ground effect subjected to accelerating and decelerating flows to understand the trends in the aerodynamic performance.

A scaling analysis is performed to determine the relevant non-dimensional numbers that influence the flow for translationally accelerating airfoils and two dimensionless numbers are arrived at, namely, the Reynolds number and the Froude number. Numerical investigations are carried out for translationally accelerating wings in ground effect to determine the influence of these dimensionless numbers on the aerodynamic forces.

Transient simulations were performed on a two-dimensional airfoil and a three-dimensional wing in ground effect subjected to translational acceleration and deceleration. The Shear Stress Transport (SST) based on k-ω was employed to model the turbulent flow. The results from the numerical investigations revealed a temporary change in the downforce and the drag force coefficients, as the airfoil (or wing) in ground effect is subjected to translational acceleration (or deceleration). In this study, the mechanisms that contribute to this temporary change in the aerodynamic force coefficients are discussed.