The Impact of Wind Shear and Turbulence on the Loads and Performance of Wind Turbines

Operating in real-world conditions, modern large capacity wind turbines often experience off-design situations, enduring dynamic loads characterized by complex unsteady aerodynamics. Key among the challenges in predicting these dynamic loads is understanding the effects of wind shear and turbulence, both individually and in their complex...

The interplay between wind and clouds in the trades

Cumulus clouds ('fair-weather clouds') form as a result of atmospheric convection and have vertical extents between a few hundred metres (humilis species) and several kilometres (congestus species). They are a major source of uncertainty in the estimation of climate sensitivity by climate models. In order to reach more agreement in cloud changes...

Application of Matching to Arrive a Wind Shear Relation for the Entire Atmospheric Boundary Layer

A new wind shear relation is derived based on the atmospheric equations of motion, which are, in turn, based on the Navier-Stokes equations. In order to make the obtained system of equations solvable, it is assumed that the air density and pressure follow the International Standard Atmosphere relations and that the wind speed is constant over...

The Morphology of Simulated Trade-Wind Convection and Cold Pools Under Wind Shear

A growing body of literature investigates convective organization, but few studies to date have sought to investigate how wind shear plays a role in the spatial organization of shallow (trade-wind) convection. The present study hence investigates the morphology of precipitating marine cumulus convection using large-eddy-simulation experiments...

Surface-Layer Wind Shear and Momentum Transport From Clear-Sky to Cloudy Weather Regimes Over Land

This study investigates how wind shear and momentum fluxes in the surface- and boundary layer vary across wind and cloud regimes. We use a 9-year-long data set from the Cabauw observatory complemented by (8.2 × 8.2 (Formula presented.)) daily Large Eddy Simulation (LES) hindcasts. An automated algorithm classifies observed and simulated days...

The Influence of Convective Momentum Transport and Vertical Wind Shear on the Evolution of a Cold Air Outbreak

To study the influence of convective momentum transport (CMT) on wind, boundary layer and cloud evolution in a marine cold air outbreak (CAO) we use large-eddy simulations subject to different baroclinicity (wind shear) but similar surface forcing. The simulated domain is large enough, (Formula presented.) km²), to develop typical...

How Wind Shear Affects Trade-wind Cumulus Convection

Motivated by an observed relationship between marine low cloud cover and surface wind speed, this study investigates how vertical wind shear affects trade-wind cumulus convection, including shallow cumulus and congestus with tops below the freezing level. We ran large-eddy simulations for an idealized case of trade-wind convection using...

Lidar and MCP in Wind Resource Estimations above Measurement-Mast Height

Modern multi-megawatt wind turbines are tall and may reach heights of 200 meter. Tall wind turbines require measurements above typical measurement mast height. As tall measurement masts are expensive and cumbersome to install, wind measurements at hub height are scarce. Currently, the use of lidars in wind measurement campaigns is increasing....

Assessment of the Validity of the Warranted Power Curve in non-standard Wind Conditions: An Empirical Study of the effects of density, turbulence intensity, wind shear, wind veer, and inflow angle on the Power Curve

This research aims to investigate the validity of the standard power curve (i.e. measured power curve M-PC) in non-standard wind conditions and the integration of those results into recommended practices for future warranty negotiations. The Power Performance Testing (PPT) is carried out on a ABC1 with rotor diameter between 105-110m and rated...

The Illusion of Power Curves: Understanding TI, Shear, and Atmospheric Stability in Power Performance

Power curves are a fundamental element of any wind resource assessment. These are required to estimate how much energy a wind turbine will convert. The theoretical power curves are validated with measurements in test sites, however they may not be fully applicable in different wind climates as they are dependent on the site where, and the...

De turbulente stroming over de zeereep

Doel van het project "Fysische modellering zeereepontwikkeling" is de ontwikkeling van een model waarmee effecten van beheersmaatregelen op de morfologische ontwikkeling van de zeereep kunnen worden voorspeld, teneinde daarmee het zeereepbeheer te optimaliseren. Dit model bestaat uit een tweetal deelmodellen. Een stromingsmodel berekend de...

A model and experimental analysis of pilot decision making behaviour for various approach conditions

This report deals with an investigation of pilots' failure detection performance in a realistic moving-base flight simulator. The task considered was the monitoring of stabilized automatic approaches. Abnormal conditions (excessive windshears or system failures) were to be detected on the basis of unacceptable deviations of displayed variables...

Wind-driven entrainment in a stably stratified fluid

Experiments on mixed-layer deepening in a straight wind flume initially containing a two-layer fluid were carried out. In order to simulate an effectively unlimited water body, or a situation where the presence of end walls is not yet noticeable, the water from the upper layer was withdrawn at the downstream end, and supplied again at the...

Wind shear on the approach: An investigation on the infuence of a tower measured wind environment on the symmetric motions of a simulated aircraft in an automatic approach

Measured wind profiles from the Royal Netherlands Meteorological Institute 200 m meteorological tower at Cabauw have been used to estimate wind shear effects on the symmetric motions of an approaching aircraft. Wind profiles as well as an automatically approaching DC-9 aircraft have been simulated on an electronic analog computer. The study...

Exploratory investigation of decelerating approaches of a twin-engined jet transport: Vol. II: Moving-base simulation and comparison with related experiments

Aircraft noise perceived on the ground can be reduced by decelerating the aircraft during the landing approach. As an additional benefit the lower thrust settings existing during a part of the approach and the shorter approach time result in a reduced fuel consumption as compared to a conventional approach. This report deals with an experiment...

Wind drag within a simulated forest canopy field

This report presents an experimental and analysis study of wind drag within simulated forest canopy fields. The drag coefficients, aerodynamic roughness and wind velocity profiles are studied for various types of forest canopies. Furthermore, a brushy canopy field was studied which simulated the leafy portion of a forest without the tree trunks...

The influence of wind on open channel flow

The effect of wind shear stress on the flow in an open channel is investigated for the case where wind and water move in the same direction. The investigation is based on experimental data obtained with a unique wind water tunnel. A method is developed by which it is possible to separate water surface shear stress and bottom shear stress. . The...