Tire dependence for the aerodynamics of yawed bicycle wheels

The aerodynamic characteristics of a modern road cycling wheel in cross wind are studied through force- and planar PIV measurements in the TU Delft Open Jet Facility. The performance of the 62 mm deep rim is evaluated for three tire profiles, and yaw angles up to 24°. All measurements are executed at 12.5 m/s (45 km/h) freestream- and wheel...

Development of robotic volumetric PIV: with applications in sports aerodynamics

Particle image velocimetry (PIV) is the state of the art for quantitative, full-field, 3D flow diagnostics. Despite the maturity of the technique, two bottlenecks are identified which are addressed in this thesis: the achievable measurement volume size, and the optical access to geometrically complex objects. Both aspects are well illustrated...

Aerodynamics of a cycling wheel in crosswind by coaxial volumetric velocimetry

The aerodynamic characteristics of a modern road cycling wheel in crosswind are studied through force measurements and 3D velocimetry in TU Delft’s Open Jet Facility. The performance of the 62 mm deep rim is evaluated for two tire profiles, and yaw angles up to 20◦ . All measurements are executed at 12.5 m/s (45 km/h) freestream- and wheel...

Recent advancements towards large-scale flow diagnostics by robotic PIV

The present work reviews the recent developments in the domain of particle image velocimetry (PIV) with attention to its use for large-scale problems of interest for industrial aerodynamics. The article introduces the fundamental principles of flow seeding for large-scale experiments based on the helium-filled soap bubble (HFSB) technique....

Object surface reconstruction from flow tracers

Abstract: A method to identify the surface of solid models immersed in fluid flows is devised that examines the spatial distribution of flow tracers. The fluid–solid interface is associated with the distance from the center of a circle to the centroid of the tracers ensemble captured within it. The theoretical foundation of the method is...

Flow pressure evaluation on generic surfaces by robotic volumetric PTV

An experimental approach for the measurement of the time-average fluid flow pressure over the surface of generic three-dimensional objects is presented. The method is based on robotic volumetric PTV measurements followed by the integration of the pressure gradient. The domain for pressure evaluation is subdivided in two parts: in the...

Aerodynamic pressure reconstruction on generic surfaces from robotic PIV measurements

A multi-model method for static pressure evaluations based on 3D PTV data is presented. The volumetric measurement domain is partitioned into an irrotational part where pressure is evaluated in a point-wise manner through Bernoulli’s equation, and a rotational domain where the pressure gradient is spatially integrated. In a third step, the field...

Robotic Volumetric PIV measurements of a full-scale swimmer’s hand

The flow field around a full-scale swimmer’s hand model with varying thumb positions is investigated by robotic volumetric PIV. The experiment is conducted in the Open Jet Facility wind tunnel at TU Delft at 15m/s. Quantitative flow field information is constructed with 3D-PTV in a 120 liter volume, encompassing the full hand and arm. The effect...

Coaxial volumetric velocimetry

This study describes the working principles of the coaxial volumetric velocimeter (CVV) for wind tunnel measurements. The measurement system is derived from the concept of tomographic PIV in combination with recent developments of Lagrangian particle tracking. The main characteristic of the CVV is its small tomographic aperture and the...

Robotic volumetric PIV of a full-scale cyclist

A novel approach to the measurement of large-scale complex aerodynamic flows is presented, based on the combination of coaxial volumetric velocimetry and robotics. Volumetric flow field measurements are obtained to determine the time-averaged properties of the velocity field developing around a three-dimensional full-scale reproduction of a...

Surface pressure visualization by 3D PTV

Some recent trends in the development of PIV techniques are leading to the realization of velocity measurement at large scale. Moreover, methods for evaluating the fluid flow pressure from PIV data have been successfully demonstrated at small scale and for simple geometries. Methods for quantitative visualization of surface flow properties such...