The dynamic coupling between the pulse wake mixing strategy and floating wind turbines

In recent years, control techniques such as dynamic induction control (often referred to as “the pulse”) have shown great potential in increasing wake mixing, with the goal of minimising turbine-to-turbine interaction within a wind farm. Dynamic induction control disturbs the wake by varying the thrust of the turbine over time, which results in...

Using the Helix Mixing Approach on Floating Offshore Wind Turbines

In recent years dynamic induction control has shown great potential in reducing wake-to-turbine interaction by increasing the mixing in the wake. With these wake mixing methods the thrust force will vary in time. If applied to a floating offshore wind turbine, it will cause the platform to move. In this paper the effect of the Helix mixing...

The emergence of supersonic flow on wind turbines

The future generation of wind turbines will be characterised by longer and more flexible blades. These large wind turbines are facing higher Reynolds numbers, as a consequence of longer chord lengths and increased relative wind speeds. Higher tip speeds, however, also result in an increased Mach number. Although the maximum tip speed in...

Performance analysis of wind turbines with leading-edge erosion and erosion-safe mode operation

For offshore wind turbines, Leading-Edge Erosion (LEE) due to rain is posing a serious risk to structural integrity and can lead to a performance loss of the order of a few percent of the Annual Energy Production (AEP). A proposed mitigation strategy is the so-called Erosion-Safe Mode (ESM). In this work, the AEP losses caused by LEE or by...

Adjoint optimisation for wind farm flow control with a free-vortex wake model

Wind farm flow control aims to improve wind turbine performance by reducing aerodynamic wake interaction between turbines. Dynamic, physics-based models of wind farm flows have been essential for exploring control strategies such as wake redirection and dynamic induction control. Free-vortex methods can provide a computationally efficient way...

Vertical-axis wind turbine aerodynamics

This chapter highlights the main aerodynamic phenomena and challenges of vertical-axis wind turbines. First, an introduction is provided on the VAWT history and (dis-)advantages. The basics of VAWT aerodynamics and the various rotor simplifications/representations are presented. Further, the state-of-the art aerodynamic modeling techniques,...

Assessment through high-fidelity simulations of a low-fidelity noise prediction tool for a vertical-axis wind turbine

Vertical-axis wind turbines have the potential to be installed nearby urban areas, where noise regulations are a constraint. Accurate modelling of the far-field noise with low-order fidelity methods is essential to account for noise early in the design phase. The challenge for the vertical-axis wind turbine is the unsteady azimuthal variation...

Controlling dynamic stall using vortex generators on a wind turbine airfoil

Vortex generators (VGs) have proven their capabilities in wind turbine applications to delay stall in steady flow conditions. However, their behaviour in unsteady conditions is insufficiently understood. This paper presents an experimental study that demonstrates the effect of VGs in unsteady flow, including controlling and suppressing the...

The 3D effects of a vertical-axis wind turbine: Rotor and wake induction

This paper deals with the 3D effects of a vertical-axis wind turbine caused by the tip vortices. In this study, the VAWT rotor is simplified by the infinitely bladed actuator cylinder concept. The loads are prescribed to be uniform and normal to the surface and are distributed between the upwind and downwind half. Depending on the load...

Experimental test of variable loads on a vertical-axis wind turbine

The paper presents an experimental study of applying variable loads on a vertical-axis wind turbine (VAWT). The experiment is conducted in an open-jet wind tunnel on a two-bladed Darrieus VAWT equipped with active individual blade pitch control. Variable loads are achieved by dynamically changing the pitch angle of the individual blades and...

Comparison of 3D aerodynamic models for vertical-axis wind turbines: H-rotor and Phi-rotor

Since the first commercial projects, the development of vertical-axis wind turbines (VAWTs) has been impeded by the limited understanding and inability to accurately model VAWTs. This paper investigates and compares different aerodynamic modelling techniques for VAWTs in 3D. All considered models are using the same blade-element...

New dynamic-inflow engineering models based on linear and nonlinear actuator disc vortex models

Two new engineering models are presented for the aerodynamic induction of a wind turbine under dynamic thrust. The models are developed using the differential form of Duhamel integrals of indicial responses of actuator disc type vortex models. The time constants of the indicial functions are obtained by the indicial responses of a linear and...

An extended actuator cylinder model: Actuator-in-actuator cylinder (AC-squared) model

In this paper, the actuator-in-actuator cylinder (AC-squared) model is presented. This model is an extension of the original actuator cylinder model of Madsen and is capable of modelling the effect of a two concentric actuation surfaces in 2D. The induced velocity at every point in the 2D field is affected by the force field acting on the two...

Airfoil optimisation for vertical-axis wind turbines with variable pitch

To advance the design of a multimegawatt vertical-axis wind turbine (VAWT), application-specific airfoils need to be developed. In this research, airfoils are tailored for a VAWT with variable pitch. A genetic algorithm is used to optimise the airfoil shape considering a balance between the aerodynamic and structural performance of airfoils. At...

Towards the understanding of vertical-axis wind turbines in double-rotor configuration

Vertical-axis wind turbines (VAWTs) in double-rotor configuration, meaning two rotors in close proximity, have the ability to enhance the power performance. In this study, we work towards the understanding of vertical-axis wind turbines in double-rotor configuration. Numerical simulations are performed to gain insight in the physics behind...