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Pressure oscillations in closed vessel explosion.

Haniff, Mohamed Syed S. (1974) Pressure oscillations in closed vessel explosion. Doctoral thesis, University of Surrey (United Kingdom)..

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Pressure oscillations in closed vessel explosions have been studied in mixtures of hydrogen-air, propane-air, and methane-air. Propane-air explosions have been studied in more detail and the results compared with those of cylinders. The explosions were conducted in a spherical vessel with central ignition. This is by far the simplest form of closed vessel explosion. Origin of the oscillations in spherical vessels is due mainly to the acceleration of the flame. Cellular flames would tend to accelerate more easily than laminar flames. This is because the sizes of the cells are constantly changing with increasing pressure. The area of the flame, and the flame speed would therefore be changing with time. This acceleration generates a perturbation which can trigger the acoustic instability of the flame. The oscillations are amplified when the initial amplitude is greater than a threshold, Rayleigh's criterion is obeyed, and the energy is fed back to the oscillations mainly through changes in flame area. In acoustic reinforced explosions the flame structure is found to vary with twice the period of the oscillations. These observations are in agreement with the Markstein and Squires' theory. During acoustic reinforced explosion the rate of pressure rise increases to abnormally high values. This type of explosion will only set in when the amplitude of the oscillations has reached a second threshold. At this threshold changes in flame speeds, due to changes in temperature, can no longer be neglected. And so energy is now fed back to the oscillations by both changes in flame area and flame speeds. The overall picture is one of a completely unstable flame which causes the pressure rise to increase sharply.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Haniff, Mohamed Syed S.
Date : 1974
Contributors :
Depositing User : EPrints Services
Date Deposited : 09 Nov 2017 12:17
Last Modified : 20 Jun 2018 11:37

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