Wind Shear, Gust, and Yaw-Induced Dynamic Stall on Wind-Turbine Blades

This study examined the effect of a spanwise angle of attack gradient on the growth and stability of a dynamic stall vortex in a rotating system. It was found that a spanwise angle of attack gradient induces a corresponding spanwise vorticity gradient, which, in combination with spanwise flow, results in a redistribution of circulation along the blade. Specifically, when modelling the angle of attack gradient experienced by a wind turbine at the 30% span position during a gust event, the spanwise vorticity gradient was aligned such that circulation was transported from areas of high circulation to areas of low circulation, increasing the local dynamic stall vortex growth rate, which corresponds to an increase in the lift coefficient, and a decrease in the local vortex stability at this point. Reversing the relative alignment of the spanwise vorticity gradient and spanwise flow results in circulation transport from areas of low circulation generation to areas of high circulation generation, acting to reduce local circulation and stabilise the vortex. This circulation redistribution behaviour describes a mechanism by which the fluctuating loads on a wind turbine are magnified, which is detrimental to turbine lifetime and performance. Therefore, an understanding of this phenomenon has the potential to facilitate optimised wind turbine design.

Description of the ITER Tokamak Cooling Water System

In questa tesi ho inizialmente esposto cenni teorici sulle reazioni di fusione nucleare e le motivazioni che hanno spinto la comunità scientifica verso la ricerca di questa nuova fonte energetica. Ho descritto il progetto ITER nei suoi obiettivi e nei principi di funzionamento di un reattore di tipo Tokamak e di tutti i componenti principali dell'intero impianto. In primo piano, mi sono focalizzato sul sistema di raffreddamento primario ad acqua del Tokamak (TCWS), con una prima panoramica sui suoi sottosistemi descrivendo i loro obiettivi, quali asportazione di calore e sicurezza dell'impianto. Successivamente ho analizzato nello specifico i particolari tecnici dei principali sottosistemi quali i vari circuiti di asportazione primaria del calore (PHTS Loops) dei diversi componenti del Tokamak, il Vacuum Vessel, il First Wall Blanket, il Divertor e il Neutral Beam Injector; ho esaminato i processi di controllo della qualità e del volume del fluido refrigerante nei circuiti (CVCS); ed infine le funzioni e le caratteristiche dei sistemi di drenaggio e di riempimento dei circuiti con i propri serbatoi ordinari e di sicurezza, e del sistema di asciugatura del fluido refrigerante con le sue diverse modalità operative.

Coral communities exposed to differential large amplitude internal waves cooling and a severe heat stress in 2010 in the Andaman Sea

Tropical scleractinian corals are particularly vulnerable to global warming as elevated sea surface temperatures (SST) disrupt the delicate balance between the coral host and their algal endosymbionts, leading to symbiont expulsion, mass bleaching and mortality. While satellite sensing of SST has proven a good predictor of coral bleaching at the regional scale, there are large deviations in bleaching severity and mortality on the local scale, which are only poorly understood. Here, we show that internal waves play a major role in explaining local coral bleaching and mortality patterns in the Andaman Sea. In spite of a severe region-wide SST anomaly in May 2010, frequent upslope intrusions of cold sub-pycnocline waters due to breaking large amplitude internal waves (LAIW) alleviated heating and mitigated coral bleaching and mortality in shallow LAIW-exposed waters. In LAIW-sheltered waters, by contrast, bleaching susceptible species suffered severe bleaching and total mortality. These findings suggest that LAIW, which are ubiquitous in tropical stratified waters, benefit coral reefs during thermal stress and provide local refugia for bleaching susceptible corals. The swash zones of LAIW may thus be important, so far overlooked, conservation areas for the maintainance of coral diversity in a warming climate. The consideration of LAIW can significantly improve coral bleaching predictions and can provide a valuable tool for coral reef conservation and management.

Power plant cooling water chlorination in northern California /

Issued March 1978.

Cooling efficiency of different air velocities in hot environments /

Mode of access: Internet.

Cooling and holding eggs on the ranch /

Mode of access: Internet.

Toxicity of chlorinated power plant condenser cooling waters to fish /

Grant no. R-800700.

Ceramic applications in turbine engines.

Energy Department, Office of Vehicle and Engine Research and Development, Washington, D.C.

Environmental readiness document : solar heating and cooling of buildings /

September 1979.

Hazardous properties and environmental effects of materials used in solar heating and cooling (SHAC) technologies : interim handbook /

Issued Dec. 1978.

Boiler and turbine room instruments; serial report of the Prime Movers Committee (1925-1926)

Mode of access: Internet.

Cooling towers,

Reprinted from the Engineers' list, March 1907.