Counter lung

Counter lung, incorporated in closed-loop rebreathing system, accommodates user's breathing tidal volume so that the loop pressure is relatively constant during breathing cycles

Aircrew oxygen system development Flight test report

Flight tests of breadboard version of aircrew oxygen syste

Aircrew oxygen system

Closed-loop rebreather system which includes pilot provides oxygen for use in aircraft by safe, reliable method of low weight and size and reduces expense of ground equipment. Water electrolysis generated oxygen is fed into rebreather loop which allows nitrogen elimination and water and carbon dioxide removal

Effect of vortex generators on corner flow separation caused by shock wave-boundary-layer interaction

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Wind tunnel experiments were conducted to investigate the effect of vortex generators on a corner flow separation caused by an interaction between a normal shock wave and the boundary layer in a Mach 1.4 flow. The shape of the vortex generators was rectangular. The vortex generators were mounted on a bottom wall of the test section. The parameters of the vortex generators were the rotation direction of the vortex, their size and their location. When the leading edge of the vortex generators turn towards the corner, the effect of the vortex generators on the corner flow separation decreased monotonically as the vortex generators size decreased. An independent separation appeared on the bottom wall in the case. When the leading edge of the vortex generators point in the opposite direction, the flow structure was changed by the size and the location of the vortex generators. We categorized the flow structures into three modes. The effect of the vortex generators and the three modes were successfully collapsed with the location parameter normalized by the second power of the scale parameter

Force production mechanisms for a flat plate wing at low reynolds numbers (Invited)

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Micro Air Vehicles (MAVs) operate in highly unsteady and often separated flow conditions which are well outside the usual design space of conventional lifting surfaces. This paper aims to coalesce theory and simply explain the physical mechanisms behind force production for such unsteady and separated flows with regards to added mass and circulatory (vortex dynamics) effects. Particle Image Velocimetry (PIV) and flow visualisation are additionally used to show that the ’non-circulatory’ added mass forces are responsible for production of vorticity bound to the wing surface, thus can be confused with free vortices in the flow field. Changes to the ’added mass vorticity’ and thus forces derived from this are shown to be independent of flow topology and perhaps viscous effects in general with exception to edge conditions. A technique to simply quantify the distribution of the bound vorticity from PIV measurements is additionally described and utilised

Nozzle geometry effects on corner boundary layers in supersonic wind tunnels

Experiments on supersonic flows are typically conducted in wind tunnels with rectangular cross-sections, which use two-dimensional nozzles of two different types. A “full” setup consists of two contoured nozzle surfaces symmetric about the tunnel centre-height. The “half” configuration is also common, with a curved ceiling nozzle surface and a straight horizontal floor.Air Force Research Laboratory UK National Wind Tunnel Facilit

On-board aircraft oxygen generating system

Onboard oxygen generation equipment with minimal ground support equipment and applicable to spacecraft and submarine us

Experiments to investigate lift production mechanisms on pitching flat plates

© 2016, The Author(s).Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study the unsteady flowfield development. Two pitch axis positions are investigated, namely a leading edge and a mid-chord pitch axis. A novel PIV approach using twin laser lightsheets is shown to be effective at acquiring full field of view velocity data when an opaque wing model is used. Leading-edge vortex (LEV) circulations are extracted from velocity field data, using a Lamb–Oseen vortex fitting algorithm. LEV and trailing-edge vortex positions are also extracted. It is shown that the circulation of the LEV, as determined from PIV data, approximately matches the general trend of an unmodified Wagner function for a leading edge pitch axis and a modified Wagner function for a mid-chord pitch axis. Comparison of experimentally measured lift correlates well with the prediction of a reduced-order model for a LE pitch axis

Fiber release from impacted graphite reinforced epoxy composites

Carbon fibers released from composites by aircraft fires and crashes can cause electrical shorts and consequent equipment damage. This report investigates less vigorous release mechanisms than that previously simulated by explosive burn/blast tests. When AS/3501-6 composites are impacted by various head and weight configurations of a pendulum impactor, less than 0.2 percent by weight of the original sample is released as single fibers. Other fiber release mechanisms studied were air blasts, constant airflow, torsion, flexural, and vibration of composite samples. The full significance of the low single fiber release rates found here is to be evaluated by NASA in their aircraft vulnerability studies