Showing papers by "Vaughn College of Aeronautics and Technology published in 2005"
TL;DR: In this article, the authors provide answers to a number of critical questions: What are the key drivers of each type of airline's business model? Is there a difference in passengers' perceptions between low-cost carriers and full-service incumbents in a mature European market and in a rapidly developing Asian economy?What are the principle reasons why a passenger chooses a particular airline model?
403 citations
TL;DR: The first digital particle image velocimetry (DPIV) analysis of the flow field around the wings of an insect (the tobacco hawkmoth Manduca sexta, tethered to a 6-component force-moment balance in a wind tunnel) suggests that if there is any spanwise flow in the LEV towards the end of the downstroke its velocity is less than 1 m s-1.
Abstract: Here we present the first digital particle image velocimetry (DPIV) analysis of the flow field around the wings of an insect (the tobacco hawkmoth Manduca sexta , tethered to a 6-component force-moment balance in a wind tunnel). A leading-edge vortex (LEV) is present above the wings towards the end of the downstroke, as the net upward force peaks. Our DPIV analyses and smoke visualisations match the results of previous flow visualisation experiments at midwing, and we extend the experiments to provide the first analysis of the flow field above the thorax. Detailed DPIV measurements show that towards the end of the downstroke, the LEV structure is consistent with that recently reported in free-flying butterflies and dragonflies: the LEV is continuous across the thorax and runs along each wing to the wingtip, where it inflects to form the wingtip trailing vortices. The LEV core is 2-3 mm in diameter (approximately 10% of local wing chord) both at the midwing position and over the centreline at 1.2 m s-1 and at 3.5 m s-1 flight speeds. At 1.2 m s-1 the measured LEV circulation is 0.012±0.001 m2 s-1 (mean ± s.d.) at the centreline and 0.011±0.001 m2 s-1 halfway along the wing. At 3.5 m s-1 LEV circulation is 0.011±0.001 m2 s-1 at the centreline and 0.020±0.004 m2 s-1 at midwing. The DPIV measurements suggest that if there is any spanwise flow in the LEV towards the end of the downstroke its velocity is less than 1 m s-1. Estimates of force production show that the LEV contributes significantly to supporting body weight during bouts of flight at both speeds (more than 10% of body weight at 1.2 m s-1 and 35-65% of body weight at 3.5 m s-1).
183 citations
TL;DR: In this article, a numerical simulation was performed using LS-DYNA3D transient dynamic finite element analysis code for calculating contact forces during impact along with a failure analysis for predicting the threshold of impact damage and initiation of delaminations.
138 citations
TL;DR: In this article, four different ways of modelling delamination growth of a double cantilever beam test (DCB) are proposed, based on a cohesive zone model: the interface being represented either by using delamination elements or non-linear springs.
87 citations
TL;DR: In this paper, the authors examined the seemingly inexorable decline in yield in the airline industry and found that the traffic mix of economy, business and first class passengers has changed over a 10-year period as proportionally more travellers choose to use economy class products.
86 citations
TL;DR: In this paper, the effect of volcano topography on ground deformation at Mt. Etna has been simulated by a finite element approach, where a large grid of isotropic sources of pressure, spaced at 0.5 km in the three dimensions, was simulated in a given volume.
28 citations
TL;DR: In this paper, the authors measured the flow field surrounding a sphere sedimenting at a distance of one, two and three ball diameters from the wall using 3D particle image velocimetry.
Abstract: Through the use of stereoscopic 3-D particle image velocimetry (3-D PIV), the flow field surrounding a sphere sedimenting at a distance of one, two and three ball diameters from the wall is measured. A Newtonian (constant shear viscosity, inelastic) fluid, a Boger (constant shear viscosity, elastic) fluid and a shear-thinning (variable shear viscosity, elastic) fluid are used to study the effects of shear-thinning and elasticity. There are significant differences in the flow fields that can be observed for the different types of fluids and the different distances from the wall from which the sphere is dropped. We find that the structure of the flow field and the motion perpendicular to the wall are dependent on the distance from the wall at which the sphere sediments.
15 citations
TL;DR: In this article, the effects of surface roughness on the Mach 8·2 hypersonic turbulent shockwave boundary layer interaction characteristics of a deflected control flap configuration were investigated. And the authors found that roughness significantly increased the extent of the interaction, while increasing the magnitude of the peak pressure and heat flux just aft of reattachment.
Abstract: An experimental investigation was performed to study the effects of surface roughness on the Mach 8·2 hypersonic turbulent shockwave–boundary-layer interaction characteristics of a deflected control flap configuration. In particular, the surface pressure and heat transfer distribution along a quasi-2D ramp compression corner model was measured for flap angles between 0° and 38°, along with a Schlieren flow visualisation study. It was found that surface roughness, of scale 10% of the hinge-line boundary layer thickness, significantly increased the extent of the interaction, while increasing the magnitude of the peak pressure and heat flux just aft of reattachment. The incipient separation angle for a fully turbulent, Mach 8·2 boundary layer with a hinge line Reynolds number of 1·44 × 106, was estimated at 28-29°, reducing to between 19-22° with the introduction of laminar sub-layer scale surface roughness.
12 citations