Vortex velocimetry of air flows using Helium Filled Soap Bubbles (HFSB)

This thesis work illustrates the first of its kind solution to this problem of lack of seeding at vortex core in air flows, by the use of Helium Filled Soap Bubble (HFSB) which is a neutrally buoyant tracer particle in air flows. To analyse the lack of seeding in the vortex core, a 2D numerical simulation of particle motion in vortex flow is...

Estimation and reduction of peak-locking errors in PIV measurements

In PIV, the systematic tendency of the measured sub-pixel displacement to be biased towards the integral pixel values is called peak-locking. This occurs when the particle image diameter is less than a pixel. The bias error causes inaccuracy in the measured PIV data which does not reduces with increase in the sample size. Recently developed...

On the tracing fidelity of helium-filled soap bubbles for PIV experiments

This thesis follows a previous study on the aerodynamic characterization of helium-filled soap bubbles (HFSBs) for large-scale PIV measurements and aims at characterizing statistically the tracing fidelity of HFSBs in PIV experiments, considering the statistical distribution of the bubbles diameter, slip velocity, relaxation time and density....

Going against the flow: An experimental investigation into the flow mechanics of dimpled surfaces in turbulent boundary layers

Any reduction in vehicle drag or fluid resistance provides a potential of substantial energy savings, with obvious benefits to the economy, environment and overall industrial competitiveness. Although various experimental studies have confirmed the potential drag reduction of dimpled surfaces in a turbulent boundary layer (BL), the working...

Experimental study on the energy deposition of an ns-DBD plasma actuator and its effect on a laminar boundary layer

An experimental study aimed at the influence of different barrier materials on the energy deposition of nanosecond pulsed dielectric barrier discharge (ns-DBD) plasma actuator was carried out. Additionally, the direct effect of the discharge of an ns-DBD plasma actuator on a low velocity laminar boundary layer was investigated. Three barrier...

Stereoscopic PIV on a delta wing in supersonic flow

Ever since the 1950s delta wings are being used as an efficient planform for supersonic flight. Over time extensive research on the aerodynamics of this type of wings has been performed using many different measurement techniques. Due to technical difficulties, measurements on delta wings in a supersonic flow are still scarce and often limited...

Experimental analysis of the flow around a cylinder with a square cross-section

The present work investigates the flow around a two-dimensional square section object at varying angles of incidence. The experimental approach employs Particle Image Velocimetry for the determination of the time-averaged velocity field and the unsteady large scale coherent variations (e.g. vortex shedding) as well as turbulent fluctuations. The...