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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]
As explained above, a deflagration is a subsonic reaction, whereas a detonation is a supersonic (greater than the sound speed of the material) reaction. Distinguishing between a deflagration or a detonation can be difficult to impossible to the casual observer.
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.
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.
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 ...
For comparison the deflagration limit of gasoline in air is 1.4–7.6%, and of acetylene in air, [15] 2.5–82%. Therefore, when equipment is open to air before or after a transfer of hydrogen, there are unique conditions to take into consideration that might have otherwise been safe with transferring other kinds of gases.
The chemistry of ANFO detonation is the reaction of ammonium nitrate with a long-chain alkane (C n H 2n+2) to form nitrogen, carbon dioxide, and steam.In an ideal stoichiometrically balanced reaction, ANFO is composed of about 94.5% AN and 5.5% FO by weight.
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.