Unsteady Aerodynamics of Wing-Gust Encounters

Wind gusts can be highly detrimental to the performance of fixed wing aircraft. At low flight speeds, gusts transverse to the lifting surfaces can cause massive changes to the angle of incidence, fluctuations in lift and drag, and result in flight instability. This may be catastrophic for small drones, and hazardous for larger aircraft during take-off and landing. Onboard gust sensing and counter-control is a promising solution, but requires a model of the wing-gust interaction. The problem is that only simple linear models such as Küssner’s theory exist, and the physics of large amplitude wing-gust encounters is unknown. This work is a fundamental study into the physics of such interaction. The aims are to uncover the phenomenon which contribute toward the force response of the wing. In particular, the role of free vortices and added mass are investigated and compared with the conditions modelled within Küssner’s transverse gust theory. Two sets of experiments were conducted using flat plate wing models in a water towing tank. Data was acquired using a combination of Particle Image Velocimetry (PIV), dye flow visualisation, and force measurements. A novel methodology was also developed to isolate added mass effects from standard resolution PIV. The first experiment involved accelerating the plate in translation and angular directions to validate the added mass extraction methodology, and investigate viscous effects on added mass. The experiments successfully demonstrated both the technique, and that the potential flow added mass solution is valid even for viscous and separated flows. For the second experiment, equipment was constructed to facilitate the generation of a ‘sharp edged’ top-hat shaped gust velocity profile in the towing tank. The wing models were towed through this, thereby replicating a wing-gust encounter. Test cases with gust ratios of 0.2, 0.5 and 1.0, as well as Reynolds numbers from 5,000 to 40,000 were conducted. The results showed that Küssner’s model predicted the force response for each encounter surprisingly well, albeit discrepancies emerged at the higher gust ratios. This was attributed to significant leading edge separation as well as deflection and subsequent roll-up of the gust shear layers. For wing-gust encounters it was shown that the force component attributed to added mass in Küssner’s model is not equivalent to that of an accelerating body, rather it can be attributed to the relative advection of gust shear layer vortices. We call this a ‘non-circulatory vortex force’. A second non-circulatory vortex force was additionally proposed, attributed to the generation of free vortices. This was shown to be responsible for the buoyancy and added mass like force, for cases where a flow field is accelerated past a stationary body.This work was funded by the Cambridge Commonwealth European and International Trust and Schlumberger Limite

Deaths of individuals aged 16-24 years in the UK after using mephedrone

Objective: Mephedrone is a stimulant drug chemically related to amphetamine, with effects similar to those of amphetamine and cocaine. This study aims to analyse fatalities following ingestion of mephedrone in the UK amongst 16-24 year olds in 2009-13, providing an update on data presented at the 2nd International Conference on Novel Psychoactive Substances. Methods: A literature search was undertaken to identify published information on pharmacology, toxicity, and fatalities associated with mephedrone. Fatalities involving mephedrone were extracted from the National Programme on Substance Abuse Deaths database, which receives information on drug-related deaths from Coroners in the UK and Islands and other data suppliers. Selection criteria: deceased aged 16-24 at time of death; mephedrone directly implicated in the cause of death and/or mentioned in the Coroner’s verdict. Results: Thirty cases met the study criteria and, when known, all were of White ethnicity, most (85%) had a history of drug use and 73% were male. Two-thirds (63%) were accidental poisonings. Mephedrone was used with other substances in most cases (87%); other substances were implicated in 60% of deaths. Conclusions: Mephedrone use can have potentially fatal consequences, especially in combination with other substances. Deaths in the 16-24 years age-group continue to occur from its use in the UK, despite it being a controlled drug. Health professionals and potential consumers should be alert to this risk.Peer reviewe

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Identidad - Una mirada al nuevo decreto

El autor sitúa en la tensión de la vocación a la Compañía de Jesús: “La llamada a ser fiel de una manera creativa a las ‘polaridades ignacianas’, es el principal reto al que nos enfrenta este nuevo decreto. Es muy difícil ser contemplativo y activo al mismo tiempo, sin impulsar un aspecto más que el otro. Aquí, insiste el decreto, está el corazón de la identidad jesuita: estar siempre totalmente enraizado en Dios y simultáneamente inmerso en el mundo. Idealmente, los jesuitas viven de una gracia sobrecogedora que nos inclina a ver el mundo con los ojos de Cristo, amándolo con Su corazón y sirviéndole con Su compasión. No se trata de buscar las necesidades, o hacer el bien, o actuar de un modo justo, solos. Ni se trata de tener fe, orar, o vivir de un modo contemplativo, solos. Más bien se trata de hacerlo juntos. Tanto en los párrafos del decreto sobre las polaridades ignacianas, como en los párrafos que tratan explícitamente de seguir a Cristo, se muestra que, cuando estamos con ÉL, estamos activos en el mundo y que, cuando estamos activos en el mundo, estamos con ÉL. El reto es no dejar nunca que se disuelva esta unión creativa entre la oración y el servicio”