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Deflagration To Detonation Transition
Deflagration to detonation transition (DDT) refers to a phenomenon in ignitable mixtures of a flammable gas and air (or oxygen) when a sudden transition takes place from a deflagration type of combustion to a detonation type of explosion. Description A deflagration is characterized by a subsonic flame propagation velocity, typically far below , and relatively modest overpressures, typically below . The main mechanism of combustion propagation is of a flame front that moves forward through the gas mixture - in technical terms the reaction zone (chemical combustion) progresses through the medium by processes of diffusion of heat and mass. In its most benign form, a deflagration may simply be a flash fire. In contrast, a detonation is characterized by supersonic flame propagation velocities, perhaps up to , and substantial overpressures, up to . The main mechanism of detonation propagation is of a powerful pressure wave that compresses the unburnt gas ahead of the wave to a temp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substances undergoing combustion vaporize, but when it does, a flame is a characteristic indicator of the reaction. While the activation energy must be overcome to initiate combustion (e.g., using a lit match to light a fire), the heat from a flame may provide enough energy to make the reaction self-sustaining. Combustion is often a complicated sequence of elementary radical reactions. Solid fuels, such as wood and coal, first undergo endothermic pyrolysis to produce gaseous fuels whose combustion then supplies the heat required to produce more of them. Combustion is often hot enough that incandescent light in the form of either glowing or a flame is produced. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compression Heating Ignition
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-called compression-ignition engine (CI engine). This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine (gasoline engine) or a gas engine (using a gaseous fuel like natural gas or liquefied petroleum gas). Diesel engines work by compressing only air, or air plus residual combustion gases from the exhaust (known as exhaust gas recirculation (EGR)). Air is inducted into the chamber during the intake stroke, and compressed during the compression stroke. This increases the air temperature inside the cylinder to such a high degree that atomised diesel fuel injected into the combustion chamber ignites. With the fuel being injected into the air just before combustion, the dispersion of the fuel is uneven; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Detonation
Carbon detonation or carbon deflagration is the violent reignition of thermonuclear fusion in a white dwarf star that was previously slowly cooling. It involves a runaway thermonuclear process which spreads through the white dwarf in a matter of seconds, producing a Type Ia supernova which releases an immense amount of energy as the star is blown apart. The carbon detonation/deflagration process leads to a supernova by a different route than the better known Type II (core-collapse) supernova (the type II is caused by the cataclysmic explosion of the outer layers of a massive star as its core implodes). White dwarf density and mass increase A white dwarf is the remnant of a small to medium size star (the Sun is an example of these). At the end of its life, the star has burned its hydrogen and helium fuel, and thermonuclear fusion processes cease. The star does not have enough mass to either burn much heavier elements, or to implode into a neutron star or type II supernova as a large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supernovae
A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the ''progenitor'', either collapses to a neutron star or black hole, or is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months. Supernovae are more energetic than novae. In Latin, ''nova'' means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word ''supernova'' was coined by Walter Baade and Fritz Zwicky in 1929. The last supernova to be directly observed in the Milky Way was Kepler's Supernova in 1604, appearing not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermobaric Weapon
A thermobaric weapon, also called an aerosol bomb, a vacuum bomb or a fuel air explosive (FAE), is a type of explosive that uses oxygen from the surrounding air to generate a high-temperature explosion. The fuel–air explosive is one of the best-known types of thermobaric weapons. Thermobaric weapons are almost 100% fuel and as a result are significantly more energetic than conventional explosives of equal weight. Many types of thermobaric weapons can be fitted to hand-held launchers, and can also be launched from airplanes. The largest Russian bomb contains a charge of approximately 7 tons of a liquid fuel that when detonated creates an explosion of 39.9 tons TNT equivalent. Terminology The term ''thermobaric'' is derived from the Greek words for 'heat' and 'pressure': ''thermobarikos'' (θερμοβαρικός), from ''thermos'' (θερμός) 'hot' + ''baros'' (βάρος) 'weight, pressure' + suffix ''-ikos'' (-ικός) '-ic'. Other terms used for the family of weapons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combustion Chamber
A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Internal combustion engines In an internal combustion engine, the pressure caused by the burning air/fuel mixture applies direct force to part of the engine (e.g. for a piston engine, the force is applied to the top of the piston), which converts the gas pressure into mechanical energy (often in the form of a rotating output shaft). This contrasts an external combustion engine, where the combustion takes place in a separate part of the engine to where the gas pressure is converted into mechanical energy. Spark-ignition engines In spark ignition engines, such as petrol (gasoline) engines, the combustion chamber is usually located in the cylinder head. The engines are often designed such that the bottom of combustion chamber is roughly in li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shchelkin Spiral
The Shchelkin spiral is a device that assists the transition from deflagration (subsonic combustion) to detonation in a pulse detonation engine. The spiral is named after Kirill Ivanovich Shchelkin, a Russian physicist who described it in his 1965 book ''Gas Dynamics of Combustion''. In pulse detonation engines, direct detonation of the combustible mixture can be relatively straightforward, but require more energy than when detonation is preceded by deflagration. The deflagration to detonation transition Deflagration to detonation transition (DDT) refers to a phenomenon in ignitable mixtures of a flammable gas and air (or oxygen) when a sudden transition takes place from a deflagration type of combustion to a detonation type of explosion. Descri ... (DDT) must however occur within the length of the detonation tube, which can be solved by providing the Shchelkin spiral. The Shchelkin spiral acts as an obstacle by creating a partial blockage of the detonation tube, effectively sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2020 Beirut Explosions
On 4 August 2020, a large amount of ammonium nitrate stored at the Port of Beirut in the capital city of Lebanon exploded, causing at least 218 deaths, 7,000 injuries, and US$15 billion in property damage, as well as leaving an estimated 300,000 people homeless. A cargo of 2,750 tonnes of the substance (equivalent to around 1.1 kilotons of TNT) had been stored in a warehouse without proper safety measures for the previous six years after having been confiscated by the Lebanese authorities from the abandoned ship . The explosion was preceded by a fire in the same warehouse. As of , an investigation by the Lebanese government is ongoing. The blast was so powerful that it physically shook the whole country of Lebanon. It was felt in Turkey, Syria, Palestine, Jordan, and Israel, as well as parts of Europe, and was heard in Cyprus, more than away. It was detected by the United States Geological Survey as a seismic event of magnitude 3.3 and is considered one of the most powerfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buncefield Fire
The Buncefield fire was a major fire at an oil storage facility that started on 11 December 2005 at the Hertfordshire Oil Storage Terminal, located near the M1 motorway, Hemel Hempstead, in Hertfordshire, England. The terminal was the fifth largest oil-products storage depot in the United Kingdom, with a capacity of about 60 million Imperial gallons (273 million litres) of fuel. The terminal is owned by TOTAL UK Limited (60%) and Texaco (40%). The first and largest explosion occurred at 06:01 UTC near tank 912, which led to further explosions which eventually overwhelmed 20 large storage tanks. The emergency services announced a major emergency at 06:08 and a firefighting effort began. The cause of the explosion was a fuel-air explosion in a vapour cloud of evaporated leaking fuel. The British Geological Survey monitored the event, which measured 2.4 on the Richter scale. News reports described the incident as the biggest of its kind in peacetime Europe and certainly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phillips Disaster Of 1989
On 23 October, 1989 at approximately 1:05 PM Central Daylight Time, a series of explosions occurred at Phillips Petroleum Company's Houston Chemical Complex in Pasadena, Texas, near the Houston Ship Channel. The initial blast registered 3.5 on the Richter scale, and the resulting fires took 10 hours to bring under control, as efforts to battle the fire were hindered due to damaged water pipes for the fire hydrants from the blast. The initial explosion was found to have resulted from a release of extremely flammable process gasses used to produce high-density polyethylene, a plastic used for various consumer food container products. The US Occupational Safety and Health Administration fined Phillips Petroleum Company $5,666,200 and fined Fish Engineering and Construction, inc, the maintenance contractor, $729,600. The event killed 23 employees and injured 314. Prior to the disaster The HCC produced approximately per year of high-density polyethylene (HDPE), a plastic material us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_sunk_as_target_with_FAE_1972.jpg "Click for more on -> Thermobaric Weapon")
