Atoll research bulletin.

no.494 (2001

Atoll research bulletin.

no.531-542 (2005

Conceptual and Numerical Analysis of Active Wingtip Vortex Cancellation in Propeller-Driven Electric Aircraft

As battery and electric motor technology continues to advance rapidly, propeller-driven electric aircraft are likely to become a significant part of the aviation market in the near future. One proposed design configuration for electric aircraft involves using large, wingtip- mounted propellers to actively cancel wingtip vortices, a method called active wingtip vortex cancellation (AWVC). By reclaiming part of the kinetic energy that would otherwise be lost to tip vortex formation, drag is decreased. In addition, the induced spanwise flow and upwash from the propeller causes the spanwise lift distribution to remain more uniform at the wingtips, increasing lift. Previous wind tunnel testing of this configuration characterized a significant increase in lift and decrease in drag, particularly in low-aspect-ratio configurations. This paper builds on that research by examining several test cases with a 3D, transient, viscous, sliding mesh CFD analysis in an effort to validate numerical methods for future conceptual design studies. In addition, many practical considerations regarding the implementation of this design are analyzed. Geometry from the aforementioned wind tunnel literature was reconstructed and analyzed. CFD indicated an 18.1% increase in lift and 5.1% increase in net thrust was possible solely through the phenomenon of AWVC. Furthermore, this CFD analysis matched wind tunnel data to within approximately 1%, validating the CFD approach for the analysis of more exotic configurations involving active wingtip vortex cancellation

Improving Intellectual Access in Temporary Exhibitions for Sight Loss Visitors Through Co-creation and Co-assessment

The research project conveyed in this article explores how to inclusively design and curate a non-permanent design exhibition in a large regional gallery (the National Centre for Craft and Design, UK), focusing on enhanced intellectual access for blind and partially sighted visitors. Intellectual access is defined in this research as making it easy for visitors to grasp the content of an exhibition, even if the recipient has no previous knowledge of the subject. The context and rationale for the research, and how the author has attempted to collaborate with various stakeholders and tailor the co-creation research to the specific needs of the blind and partially sighted participants are imparted. The resulting multi-sensory non-permanent exhibition is also described and how it was tested

Neutron star accretion and the neutrino fireball

The mixing necessary to explain the Fe'' line widths and possibly the observed red shifts of 1987A is explained in terms of large scale, entropy conserving, up and down flows (calculated with a smooth particle 2-D code) taking place between the neutron star and the explosion shock wave due to the gravity and neutrino deposition. Depending upon conditions of entropy and mass flux further accretion takes place in single events, similar to relaxation oscillator, fed by the downward flows of low entropy matter. The shock, in turn, is driven by the upflow of the buoyant high entropy bubbles. Some accretion events will reach a temperature high enough to create a neutrino fireball,'' a region hot enough, 11 Mev, so as to be partially opaque to its own (neutrino) radiation. The continuing neutrino deposition drives the explosion shock until the entropy of matter flowing downwards onto the neutron star is high enough to prevent further accretion. This process should result in a robust supernova explosion

Binary and Millisecond Pulsars at the New Millennium

We review the properties and applications of binary and millisecond pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1300. There are now 56 binary and millisecond pulsars in the Galactic disk and a further 47 in globular clusters. This review is concerned primarily with the results and spin-offs from these surveys which are of particular interest to the relativity community.Comment: 59 pages, 26 figures, 5 tables. Accepted for publication in Living Reviews in Relativity (http://www.livingreviews.org

Measurement of molybdenum mirror reflectivities

The reflectivity versus angle for a variety of molybdenum mirrors has been measured for both hard and soft x-rays in an attempt to deduce any variation in performance between single crystal, polycrystalline, and evaporated mirrors. A filling technique has been used to arrive at the roughness of the mirrors. An approach to utilize such measurements to characterize mirrors and derive low energy optical constants or many elements is outlined. 19 refs., 7 figs