The influence of initial temperature on flame acceleration and deflagration-to-detonation transition

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The influence of initial mixture temperature on deflagration-to-detonation transition (DDT) has been investigated experimentally. The experiments were carried out in a 27-cm-inner diameter, 21.3-meter-long heated detonation tube, which was equipped with periodic orifice plates to promote flame acceleration. Hydrogen-air-steam mixtures were tested at a range of temperatures up to 650K and at an initial pressure of 0.1 MPa. In most cases, the limiting hydrogen mole fraction which resulted in transition to detonation corresponded to the mixture whose detonation cell size, {lambda}, was approximately equal to the inner diameter of the orifice plate, d (e.g., d/{lambda}{approximately}1). The only exception was in ... continued below

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16 p.

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Ciccarelli, G.; Boccio, J. L. & Ginsberg, T. July 1996.

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Description

The influence of initial mixture temperature on deflagration-to-detonation transition (DDT) has been investigated experimentally. The experiments were carried out in a 27-cm-inner diameter, 21.3-meter-long heated detonation tube, which was equipped with periodic orifice plates to promote flame acceleration. Hydrogen-air-steam mixtures were tested at a range of temperatures up to 650K and at an initial pressure of 0.1 MPa. In most cases, the limiting hydrogen mole fraction which resulted in transition to detonation corresponded to the mixture whose detonation cell size, {lambda}, was approximately equal to the inner diameter of the orifice plate, d (e.g., d/{lambda}{approximately}1). The only exception was in dry hydrogen-air mixtures at 650K where the DDT limit was observed to be 11 percent hydrogen, corresponding to a value of d/{lambda} equal to 5.5. For a 10.5 percent hydrogen mixture at 650K, the flame accelerated to a maximum velocity of about 120 m/s and then decelerated to below 2 m/s. This observation indicates that the d/{lambda} = 1 DDT limit criterion provides a necessary condition but not a sufficient one for the onset of DDT in obstacle-laden ducts. In this particular case, the mixture initial condition (i.e., temperature) resulted in the inability of the mixture to sustain flame acceleration to the point where DDT could occur. It was also observed that the distance required for the flame to accelerate to the onset of detonation was a function of both the hydrogen mole fraction and the mixture initial temperature. For example, decreasing the hydrogen mole fraction or increasing the initial mixture temperature resulted in longer transition distances.

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16 p.

Notes

INIS; OSTI as TI96011456

Source

  • 26. international symposium on combustion, Naples (Italy), 28 Jul - 2 Aug 1996

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  • Other: TI96011456
  • Report No.: BNL-NUREG--63051
  • Report No.: CONF-960772--22
  • Grant Number: AC02-76CH00016
  • DOI: 10.2172/258253 | External Link
  • Office of Scientific & Technical Information Report Number: 258253
  • Archival Resource Key: ark:/67531/metadc668465

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  • July 1996

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  • June 29, 2015, 9:42 p.m.

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  • April 7, 2016, 9:11 p.m.

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Ciccarelli, G.; Boccio, J. L. & Ginsberg, T. The influence of initial temperature on flame acceleration and deflagration-to-detonation transition, report, July 1996; Upton, New York. (digital.library.unt.edu/ark:/67531/metadc668465/: accessed October 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.