Experimental study of dynamic inflow conditions of an actuator disc

The main objective of this master’s thesis is to experimentally investigate the effects of dynamic inflow conditions on the wake of an actuator disc. Dynamic inflow is the unsteady wake in momentum theory. Dynamic inflow can experimentally be generated by a gust generator. During the experiments, in which Particle Image Velocimetry (PIV) was...

The Fluid Dynamic Basis for Actuator Disc and Rotor Theories: Revised Second Edition

The first rotor performance predictions were published by Joukowsky exactly 100 years ago. Although a century of research has expanded the knowledge of rotor aerodynamics enormously, and modern computer power and measurement techniques now enable detailed analyses that were previously out of reach, the concepts proposed by Froude, Betz,...

Applicability of Dynamic Inflow Models of HAWT in Yawed Flow Conditions

Horizontal axis wind turbines (HAWTs) experience yaw misalignments due to the physical limitations of yaw controllers and various novel active yaw controls. Moreover, the motion of floating offshore wind turbines (FOWTs) accelerates yaw misalignment. The blade element momentum (BEM) method is widely used due to its computational efficiency for...

CFD study of induction and finite blade effect on a floating horizontal-axis wind turbine

As the need for abundant and reliable renewable energy increases, there is a growing interest in floating wind turbines, which would allow to harness the wind resource in areas where bottom-founded wind turbines cannot be used. However, the movements of the platform are expected to cause unsteady aerodynamics effects, including different wake...

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...

Dynamic Wind Speed in Dynamic Inflow Models

In the case of unsteady loading conditions at a rotor, the induced velocity response lags the thrust coefficient at the rotor. The two parameters that are responsible for unsteady loading conditions are rotor thrust (due to blade pitch, or rotational speed) and incoming wind speed. The induced velocity response to these two sources of...

The wake of an unsteady actuator disc

Blade Element Momentum (BEM) is the most important aerodynamic analysis method for wind turbines. BEM is derived assuming stationary conditions, which limits its ability to model the unsteady aerodynamic effects. This becomes increasingly relevant for the flexible blades of current large-scale turbines, and the employment of passive and active...

Analysis of an over the wing based distributed propulsion system

This project aims to investigate propeller wing interaction of an over the wing (OTW) based distributed propulsion (DP) system with the addition of a secondary wing. This research explored the opportunities that OTW configuration provides to DP concept, such as improving the lifting performance of system by inducing the flow over the upper...

Experimental Analysis of an Actuator Disk under cyclic unsteady loading

Experimental Analysis of an Actuator Disk under cyclic unsteady loading.<br/>Wind Energy is one of the cleanest forms of energy. It does not contribute to the greenhouse gases and is also one of the least expensive forms of renewable energy. Due to this, number of wind turbines are increasing annually. Therefore, it is crucial to understand the...

Experimental Study Of Flow Field Of An Aerofoil Shaped Diffuser With A Porous Screen Simulating The Rotor

This study presents an experimental investigation on a diffuser augmented wind turbine (DAWT). A screen mesh is used to simulate the energy extraction mechanisms of a wind turbine in experiment. Different screen porosities corresponding to different turbine loading coefficients are tested. Measurements of the axial force and of the velocity...

Verifying the Blade Element Momentum Method in unsteady, radially varied, axisymmetric loading using a vortex ring model.

Although the Blade Element Momentum method has been derived for the steady conditions, it is used for unsteady conditions by using corrections of engineering dynamic inflow models. Its applicability in these cases is not yet fully verified. In this paper, the validity of the assumptions of quasi-steady state and annuli independence of the blade...

On actuator disc force fields generating wake vorticity

Actuator disc calculations can be divided in two categories: force models where, for a prescribed force field, the flow is calculated using a CFD method, and kinematic models, where the wake is calculated based on wake boundary conditions and the force field is known when the velocities are known. In both categories, but specifically for the...