Aerodynamics and wind energy

Active flow control for boundary layers
Aerodynamics and wind energy, Aviation

Active flow control for boundary layers

Author: Henry Tol, PhD Candidate Aerospace Engineering, TU Delft Article published in Leonardo Times Magazine, Edition of January 2017. Turbulence and the transition to turbulence are recognized as unsolved problems in physics. Likewise, control theorists have hardly ever come across a problem this challenging. The goal of active flow control is to cross these interdisciplinary boundaries by considering the relevant flow physics when designing the control algorithms. Motivation The ability to control fluid flows to any desired state has great consequences for many applications. Imagine future aircraft where the traditional control surfaces (elevator, rudder, etc.) are replaced with flow control devices, which can accelerate the flow over the wings to generate lift and control m...
Airfoil Design for a Vertical Axis Wind Turbine
Aerodynamics and wind energy, Aviation

Airfoil Design for a Vertical Axis Wind Turbine

With the depletion of fossil fuels, increasing emissions, and the inevitability of global warming, the interest in renewable energy grows. Conventional solutions, like horizontal axis wind turbines, are reaching the limits of their capabilities. Therefore, there is renewed interest in other models, such as the Vertical Axis Wind Turbine (VAWT). While there are multiple variations on the VAWT, the most viable one is the Darrieus turbine, patented in 1932 (Darrieus, 1931). This turbine operates on the principle of aerodynamic forces acting on vertically placed blades, spinning around an offset center. When enough torque is generated, power is produced. The advantages of this configuration are that it is easily scalable, will not suffer from gravitational loads and ha...
A Floating Wind Farm
Aerodynamics and wind energy, Aviation, News

A Floating Wind Farm

With a focus shifting towards global sustainability, more effort is being put into improving the efficiency of renewable energy technologies. Wind energy is a predominant area of interest and now it takes on a new twist.   In July 2015, we published an article on the different ways to make a wind turbine float. Many pilot projects have been conducted to test which ones were the most effective. Statoil was the first company to makes significant strides in the area, and now that they have refined their design, a new project is about to set sail.   The Hywind Park has recently been approved to develop the world’s first, and largest, floating wind farm. The ocean off the coast of Scotland will soon be welcoming five floating six-megawatt turbines, anchored 24-35km from la...
CFD in the Nuclear Industry
Aerodynamics and wind energy, Aviation

CFD in the Nuclear Industry

Bechtel is a large construction company working on one of the largest environmental cleanup projects in history. As an intern, the task at hand was to help ascertain the reliability of a pulsejet mixing system that is used to mix various compositions of nuclear and chemical waste byproducts from Cold War era plutonium enrichment processes. Bechtel as a company works on some of the largest engineering projects in the world, having worked on the Hoover Dam, the Euro tunnel, and the Bay Area Rapid Transit system in San Francisco, it currently employs approximately 50,000 people worldwide. Within the company, a small band of engineers known as the Advanced Simulation and Analysis (ASA) group, operates. One of the projects on which Bechtel and the ASA group are currently working is known as...
Formation Flight: The effect of trimmed flight
Aerodynamics and wind energy, Aviation, Operations

Formation Flight: The effect of trimmed flight

A flock of birds flies in formation when travelling long distances, due to an energy saving advantage. Research on this phenomenon has been conducted throughout the beginning of the twentieth century, and it focused on how much can be gained using formation flight, where unfavorable effects have only been a topic of research for the last few decades.   Background The phenomenon of birds in formation has been researched since 1914 by Wieselberger (Wieselberger, 1914), who initially identified a benefit. This benefit was defined in aerodynamic theory by Lissaman et al. in 1970 (Lissaman, 1970). Behind a finite lifting surface, a region of upwash and downwash is created. Both regions are separated by the tip vortex, present due to the finiteness of the lifting surface. A grap...
Plasma Enhanced Aerodynamics
Aerodynamics and wind energy, Aviation, Dynamics and control

Plasma Enhanced Aerodynamics

An experimental study on plasma characteristics Active flow control by the use of dielectric barrier discharge (DBD) plasma actuators has been proven to be a promising concept for the delay and even elimination of boundary layer separation. Both the simplicity of the system as well as the potential for flow and even flight control make plasma actuators increasingly interesting for research in aerodynamics worldwide.   Plasma actuators for flow control In the past few years, the term plasma actuator has made its entry into the aerodynamics’ flow control jargon. In this field, two different types of dielectric barrier discharge actuators are currently investigated. Alternating current (AC-DBD) and nanosecond pulsed direct current (ns-DBD) plasmas differ in terms of input vol...
Large Eddy Simulation of Wind Farms
Aerodynamics and wind energy, Aviation

Large Eddy Simulation of Wind Farms

Numerical Experiments with Energy-Conserving schemes To predict the power produced by a wind farm, one must at least know the velocity of the air flowing through the farm. The wind velocity can be measured using meteorological masts with devices that can assess wind speed and direction a given point or even over a limited area. However, this data is not enough to study complex flow phenomena like gusts, kinetic energy transport, and the effect of the wind farm on local weather. This article explains the challenges involved in complementing experimental data with that from simulations. A wind farm consists of a cluster of wind turbines placed over a piece of land or at sea, that work together to produce electricity from the wind. The wind turbines are generally placed in a manner that...