Wave generated ‘white hole’ boosts Hawking radiation theory
Hawking radiation is a concept that sees photons escaping the event horizon of a black hole, where the gravitational effects start to draw all particles and light into its centre. A team from the University of British Columbia have designed an experiment with a trough of flowing water that contains an airplane wing shaped obstacle, to model the Hawking radiation effect.
The obstacle creates a region of high velocity flow which blocks surface waves generated downstream from flowing back upstream. Shallow surface waves split to form pairs of deep water waves similar to photons in Hawking’s theory, seeing one flow upstream and the other down and like a black holes they show a thermal spectrum.
Answers to black hole evolution on the horizon?
Analysing the region outside of the event horizon of a black hole may provide ways of determining its evolutionary state. Researchers at Queen Mary’s college, University of London have developed a method based on the Kerr solution of black holes, that which is time independent in general relativity and rotating. This new analysis looking outside the event horizon shows how much a dynamical black hole differs from the Kerr solution and at what final evolutionary state the black hole is in.
Better turbine spacing for wind turbines
Wind farms are cropping up on larger and larger scales across the orld, however operators are still looking for the most efficient way to space them.
Charles Meneveau a fluid dynamics and turbulence expert has found the optimal spacings for wind turbines, which require greater spacing between individual turbines. Currently the average spacing required between turbines is 7 turbine diameters, however the optimal spacing predicted to improve the efficiencies by up to 10% require spacings of 15 turbine diameters. This new model accounts for why current arrays appear to produce less energy than predicted. Taking into account local atmosphere wind flow and turbulence drawing stronger air from the upper atmosphere, the power drawn from the wind can be increased.
Insect eyes inspiring solar cells
Japanese researchers have been inspired by the eyes of moths to create anti reflective coatings for solar cells that will reduce the amount of light that is reflected thus ensuring the maximum amount of light is absorbed by the cell. Moth eyes were the best anti reflective coatings found by the team studying the eyes of numerous insects. The difficulty ahead for the team is to produce a seamless high throughput that will roll out into a film for the coating.
How to tame hammer droplets
In old buildings people tend to hear pounding noises in the plumbing systems, this is a well known effect called a water hammer. A water hammer occurs when a valve suddenly opens or closes in a pipe carrying water or steam causing a pressure wave to travel down a pipe with enough force to cause a burst pipe. New research has shown a similar effect happening when a droplet hits a surface. The effect can be applied to steam based power stations to explain turbine degredation and can be used to increase durability in the future. This should increase the longevity of turbines and overall efficiences, reducing downtime and increasing output thus curbing emissions.
Smaller effects are used in the research of hydrophobic (water repelling) surfacess. When a droplet hits the surface it undergoes rapid deceleration and high pressures exerted account for pitting and erosion occurring on turbines. Studies will look at small scale texturing to reduce pressure exersion and wetting on the surface of turbine blades.