Science, Year 4, Level M Consider buying goggles and rubber gloves disposable gloves they use in hospitals. The most dangerous thing they will be using household cleaners, but they are chemicals and it would be good to be protected against splashes and spills as well as to build a good habit.
Detonation A detonation wave is essentially a shock supported by a trailing exothermic reaction.
It involves a wave travelling through a highly combustible or chemically unstable medium, such as an oxygen-methane mixture or a high explosive. The chemical reaction of the medium occurs following the shock wave, and the chemical energy of the reaction drives the wave forward.
A detonation wave follows slightly different rules from an ordinary shock since it is driven by the chemical reaction occurring behind the shock wavefront. In the simplest theory for detonations, an unsupported, self-propagating detonation wave proceeds at the Chapman-Jouguet flow velocity.
A detonation will also cause a shock of type 1, above to propagate into the surrounding air due to the overpressure induced by the explosion. Schlieren photograph of the detached shock on a bullet in supersonic flight, published by Ernst Mach and Peter Salcher in Shadowgram of shock waves from a supersonic bullet fired from a rifle.
The shadowgraph optical technique reveals that the bullet is moving at about a Mach number of 1. Left- and right-running bow waves and tail waves stream back from the bullet and its turbulent wake is also visible.
Patterns at the far right are from unburned gunpowder particles ejected by the rifle. Bow shock detached shock [ edit ] Main article: Bow shock aerodynamics These shocks are curved and form a small distance in front of the body.
Directly in front of the body, they stand at 90 degrees to the oncoming flow and then curve around the body. Detached shocks allow the same type of analytic calculations as for the attached shock, for the flow near the shock.
They are a topic of continuing interest, because the rules governing the shock's distance ahead of the blunt body are complicated and are a function of the body's shape.
Additionally, the shock standoff distance varies drastically with the temperature for a non-ideal gas, causing large differences in the heat transfer to the thermal protection system of the vehicle. See the extended discussion on this topic at Atmospheric reentry.
These follow the "strong-shock" solutions of the analytic equations, meaning that for some oblique shocks very close to the deflection angle limit, the downstream Mach number is subsonic. See also bow shock or oblique shock Such a shock occurs when the maximum deflection angle is exceeded.
A detached shock is commonly seen on blunt bodies, but may also be seen on sharp bodies at low Mach numbers. Space return vehicles Apollo, Space shuttlebullets, the boundary Bow shock of a magnetosphere.
The name "bow shock" comes from the example of a bow wavethe detached shock formed at the bow front of a ship or boat moving through water, whose slow surface wave speed is easily exceeded see ocean surface wave.
These shocks appear as attached to the tip of sharp bodies moving at supersonic speeds. Supersonic wedges and cones with small apex angles. The attached shock wave is a classic structure in aerodynamics because, for a perfect gas and inviscid flow field, an analytic solution is available, such that the pressure ratio, temperature ratio, angle of the wedge and the downstream Mach number can all be calculated knowing the upstream Mach number and the shock angle.
These follow the "weak-shock" solutions of the analytic equations.
In rapid granular flows[ edit ] Shock waves can also occur in rapid flows of dense granular materials down inclined channels or slopes. Strong shocks in rapid dense granular flows can be studied theoretically and analyzed to compare with experimental data. Consider a configuration in which the rapidly moving material down the chute impinges on an obstruction wall erected perpendicular at the end of a long and steep channel.
Impact leads to a sudden change in the flow regime from a fast moving supercritical thin layer to a stagnant thick heap. This flow configuration is particularly interesting because it is analogous to some hydraulic and aerodynamic situations associated with flow regime changes from supercritical to subcritical flows.
Shock waves in astrophysics Astrophysical environments feature many different types of shock waves.
Some common examples are supernovae shock waves or blast waves travelling through the interstellar medium, the bow shock caused by the Earth's magnetic field colliding with the solar wind and shock waves caused by galaxies colliding with each other.
Another interesting type of shock in astrophysics is the quasi-steady reverse shock or termination shock that terminates the ultra relativistic wind from young pulsars. Meteor entering events[ edit ] The Tunguska event and the Russian meteor event are the best documented evidence of the shock wave produced by a massive meteoroid.
Technological applications[ edit ] In the examples below, the shock wave is controlled, produced by ex. Recompression shock on a transonic flow airfoil, at and above critical Mach number.Dear Twitpic Community - thank you for all the wonderful photos you have taken over the years.
We have now placed Twitpic in an archived state. Reuters explores the strategy behind China's military ambitions, and reveals how U.S. allies and profit-driven individuals are helping Beijing bypass arms sanctions. An iridis-photo-restoration.com Inta made this example.
He took a spherical Helmholtz resonator with a volume of m 3 and a cylindrical neck with length m and cross-sectional area m iridis-photo-restoration.com excite it, he struck it with the palm of his hand and then released it. Pulsed microwave voice-to-skull (or other-sound-to-skull) transmission was discovered during World War II by radar technicians who found they could hear the buzz of the train of pulses being transmitted by radar equipment they were working on.
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