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The phenomenon is exploited in pulse detonation engines, because a detonation produces a more efficient combustion of the reactants than a deflagration does, i.e. giving a higher yields. Such engines typically employ a Shchelkin spiral in the combustion chamber to facilitate the deflagration to detonation transition. [2] [3]
Compared with deflagration, detonation doesn't need to have an external oxidizer. Oxidizers and fuel mix when deflagration occurs. Detonation is more destructive than deflagrations. In detonation, the flame front travels through the air-fuel faster than sound; while in deflagration, the flame front travels through the air-fuel slower than sound.
Pyrotechnic deflagrations. Deflagration (Lat: de + flagrare, 'to burn down') is subsonic combustion in which a pre-mixed flame propagates through an explosive or a mixture of fuel and oxidizer. [1] [2] Deflagrations in high and low explosives or fuel–oxidizer mixtures may transition to a detonation depending upon confinement and other factors.
In spark-ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
A schematic diagram of a shock wave situation with the density , velocity , and temperature indicated for each region.. The Rankine–Hugoniot conditions, also referred to as Rankine–Hugoniot jump conditions or Rankine–Hugoniot relations, describe the relationship between the states on both sides of a shock wave or a combustion wave (deflagration or detonation) in a one-dimensional flow in ...
The detonation velocity values presented here are typically for the highest practical density which maximizes achievable detonation velocity. [ 1 ] The velocity of detonation is an important indicator for overall energy and power of detonation, and in particular for the brisance or shattering effect of an explosive which is due to the ...
It states that the detonation propagates at a velocity at which the reacting gases just reach sonic velocity (in the frame of the leading shock wave) as the reaction ceases. [ 1 ] [ 2 ] David Chapman [ 3 ] and Émile Jouguet [ 4 ] originally (c. 1900) stated the condition for an infinitesimally thin detonation.
Detonation velocities are of limited value in assessing the reaction rates of nitrocellulose propellants formulated to avoid detonation. Although the slower reaction is often described as burning because of similar gaseous end products at elevated temperatures, the decomposition differs from combustion in an oxygen atmosphere.