Turbulent flow over liquid-infused superhydrophobic surfaces: An experimental investigation into the drag performance and flow mechanics

Surfaces that induce slip at the wall have been shown to reduce skin friction drag in the turbulent regime. While superhydrophobic and liquid-infused surfaces are capable of drag reduction in turbulent hydrodynamic flows, neither would be feasible in aerodynamic applications due to the added roughness and the minuscule slip lengths created by...

Turbulent boundary layers over surfaces with streamwise-preferential permeability: Experimental investigation into the drag and flow mechanics

Turbulent drag is the largest source of fuel consumption in aviation and forms a significant contribution to climate warming. Recent numerical studies have suggested the ability of surfaces with streamwise-preferential permeability to reduce turbulent friction, and a theoretical framework behind the working mechanism has been proposed. This work...

Turbulent Viscous Drag Reduction in Air by Compliant Surfaces

This research studies the fluid-structure interaction (FSI) of compliant surfaces in air flows, with an objective of finding possible turbulent viscous drag reduction. A compliant surface is a thin layer of viscoelastic material drawing inspiration from dolphin epidermis, which was thought to have drag-reducing capabilities by Gray (1936)....

Numerical investigation of the turbulent boundary layer over dimpled surfaces

Dimples are shallow, indented surfaces that attempt to reduce drag in turbulent boundary layer flows. However, the underlying effect of the dimples on the drag is not entirely understood. This thesis sets out to expand our understanding; a numerical investigation of turbulent boundary layer flow over dimpled surfaces is conducted. This research...

Experimental parameter study for passive vortex generators on a 30% thick airfoil

Passive vane-type vortex generators (VGs) are commonly used on wind turbine blades to mitigate the effects of flow separation. However, significant uncertainty surrounds VG design guidelines. Understanding the influence of VG parameters on airfoil performance requires a systematic approach targeting wind energy-specific airfoils. Thus, the 30...

Structural modelling and numerical analysis of dynamic passive flow control mechanisms in flight feathers

Within 100 years of the Wright Brother's first flight, we are already approaching the top of aviation’s technological S-curve. Breakthrough technical improvements have resulted in an undeniable increase in efficiency and range, but today’s aircrafts are still relatively inefficient resulting in a large amount of air and noise pollution. In order...

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...

Flow visualization over drag reducing dimpled surfaces in turbulent boundary layers using Particle Image Velocimetry

Although various experimental studies have confirmed a potential drag reduction of dimpled surfaces in turbulent boundary layers, the working mechanism behind the effect remains largely unresolved. The goal of this experimental study is to reveal the flow structures that could explain this drag reduction. To this end, flow visualizations over...

Passive Flow Separation Control for High Lift: An Experimental Investigation on a Novel Vortex Generator

A current focus in the quest for improvement in fuel efficiency in aircraft design is the simplification of complex high lift systems. A simpler high lift system in combination with flow separation control is potentially able to meet the current high lift performance requirements, while still reducing overall complexity. Passive flow separation...

An integral boundary layer method for modelling the effects of vortex generators

In this work, the measured modulated integral boundary layer (IBL) characteristics of low-profile vortex generators (VGs) are used to validate new developments in a viscousinviscid interaction code which is modified to incorporate the effect of the passive mixing devices. The motivations are laid out and sample validation data is presented...