On the extension of k−ω−SST corrections to predict flow separation on thick airfoils with leading-edge roughness

Modern wind turbines employ thick airfoils in the outer region of the blade with strong adverse pressure gradients and high sensitivity to flow separation, which can be anticipated by leading-edge roughness. However, Reynolds average Navier-Stokes simulations currently overpredict the Reynolds shear stresses near the surface, and the flow...

The aerodynamic effects of the location of baseball seams: An experimental study by PIV

The aerodynamic behaviour of a pitched baseball depends on the combination of the translational velocity, the rotational velocity in combination with the rotation axis and the seam positions. For small spin parameters the effect of seam positions dominates the Magnus effect. This study focusses on a visual understanding of the seam position by...

Soap bubbles for large-scale PIV: Generation, control and tracing accuracy

Particle Image Velocimetry (PIV) relies upon the introduction of particle tracers that scatter sufficient light and follow the flow accurately. The use of submillimetre helium-filled soap bubbles (HFSB) as flow tracers for PIV is investigated for the purpose of enabling velocity measurements in large-scale industrial wind tunnels. That soap...

On the unsteady development of the flow under transonic Buffet conditions: Experimental study of the interaction of shock and pressure waves using PIV and Schlieren visualization

This thesis presents an experimental study of the unsteady phenomenon known as transonic buffet. Completely developed in the High Speed Lab of the Aerospace Faculty at TU Delft (The Netherlands), the experiments were conducted in the transonic/supersonic wind tunnel TST-27. In order to achieve time and spatial resolution of the phenomenon, high...

Drag Analysis from PIV Data in Speed Sports

Aerodynamic drag is computed from velocity measurements obtained with particle image velocimetry (PIV). This allows determining the drag force in combination with the visualization of the flow structures responsible for drag generation. Two experiments are conducted to illustrate the working principle of the approach, which is meant for...

Design and Construction of an Open-circuit Wind Tunnel with Specific Measurement Equipment for Cycling

In order to overcome resistance a cyclist has to deliver a total power output of which 90% is necessary to overcome the aerodynamic drag [1,2]. In order to perform research in this aerodynamic drag a wind tunnel has been built by the Belgium company Flanders' Bike Valley. This wind tunnel is designed using classical design rules and with...

Tomographic particle image velocimetry and its application to turbulent boundary layers

Tomographic Particle Image Velocimetry is a new experimental method developed to study three-dimensional motion in turbulent flows. The technique is an extension of standard PIV and makes use of several simultaneous views of illuminated tracer particles and their three-dimensional reconstruction as a light intensity distribution by means of...