Aerodynamic characteristics of wind turbine blade airfoils

This chapter focuses on airfoils for wind turbine blades and their characteristics. The use of panel codes such as XFOIL and RFOIL and CFD codes for the prediction of airfoil characteristics is briefly described. This chapter then discusses the requirements for wind turbine blade airfoils and the effect of leading edge roughness and Reynolds...

Supplementing Haptic Feedback in Flight Envelope Protection Through Visual Display Indications

Haptic cues on the side stick are a promising method to reduce loss of control in-flight incidents. They can be intuitively interpreted and provide immediate support, leading to a shared control system. However, haptic interfaces are limited in providing information, and the reason for cues may not always be clear to pilots. This study presents...

Computing breakwater stability using SWASH: The effects of model choices, shallow foreshore and oblique waves on the stability of a rubble mound breakwater

On the east coast of Romania, at Eforie, coastal erosion manifests. To strengthen the coastal area a large coastal protection project was setup involving beach nourishment combined with the construction of breakwaters. The breakwaters are designed with the well-known modified Van der Meer formulas. To ensure confidence in the breakwaters...

An experimental study on the effects of friction modifiers on wheel–rail dynamic interactions with various angles of attack

By modifying friction to the desired level, the application of friction modifiers (FMs) has been considered as a promising emerging tool in the railway engineering for increasing braking/traction force in poor adhesion conditions and mitigating wheel/rail interface deterioration, energy consumption, vibration and noise. Understanding the...

Noise radiation of a low Reynolds propeller at an angle of attack: an experimental and analytical study

This work presents an experimental and analytical investigation of unsteady loading of a low Reynolds number propeller and its relation to aeroacoustics. The propeller is positioned at an angle of attack with respect to the freestream which causes a variation in loading along the azimuth. The propeller is operated at 4000 RPM with an advance...

The influence of the angle of attack on passenger comfort

The angle of attack (AOA) of an airplane changes the direction of the gravitational force on passengers and this thereby might influence passengers’ flying experience. However, the contribution of the AOA regarding comfort/discomfort is not fully explored. In this paper, we aim to fill this knowledge gap by identifying the relationships between...

An experimental and numerical analysis of the dynamic variation of the angle of attack in a vertical-axis wind turbine

Simulation methods ensuring a level of fidelity higher than that of the ubiquitous Blade Element Momentum theory are increasingly applied to VAWTs, ranging from Lifting-Line methods, to Actuator Line or Computational Fluid Dynamics (CFD). The inherent complexity of these machines, characterised by a continuous variation of the angle of attack...

WhirlWind: Wind Energy Harvesting Wireless System for Sensing Angle of Attack and Wind Speed

Probabilistic Design of Airfoils for Horizontal Axis Wind Turbine

This work follows the wind energy airfoil probabilistic design approach that allows to derive a probability density function which gives an estimation of how much the angle of attack is likely to fluctuate, according to the considered non-uniform perturbations in the wind speed. Several combinations of the perturbation sources are possible in...

Fluctuations of angle of attack and lift coefficient and the resultant fatigue loads for a large Horizontal Axis Wind turbine

Unsteady loads are a major limiting factor for further upscaling of HAWTs considering the high costs associated to strict structural requirements. Alleviation of these unsteady loads on HAWT blades, e.g. using active flow control (AFC), is of high importance. In order to devise effective AFC methods, the unsteady loading sources need to be...

Aerodynamic characteristics of wind turbine blade airfoils at high angles-of-attack

Airfoil characteristics at deep stall angles were investigated. It appeared that the maximum drag coefficient as a function of the airfoil upwind y/c ordinate at x/c=0.0125 can be approximated by a straight line. The lift-drag ratios in deep stall of a number of airfoils with moderate lower surface thickness coincide. It was found that the lift...

Improving BEM-based Aerodynamic Models in Wind Turbine Design Codes

Numerical simulation of leading-edge vortex flow

An analysis is presented of results of a computational method to simulate the steady compressible vortical type of flow around a 65-deg sharp-edged cropped delta wing. The discussion emphasizes some more fundamental aspects of the numerical simulation such as the separation of the flow, the structure of the leading-edge vortex core and the flow...

A method for computing the three—dimensional flow about wings with leading—edge vortex separation Part II: Description of computer program VORSEP

In part I of this report a method is described for computing the incompressible flow about slender, thin wings with leading-edge vortex separation. It is assumed that both the wing and the flow field are symmetric with respect to the x—z plane. The method can handle delta—like wings of quite general planform and shape. However, in the...