Prediction model for self-similar propagation and blast wave generation of premixed flames. (14th September 2015)

• Record Type: Journal Article
• Authors: Kim, Woo Kyung; Mogi, Toshio; Kuwana, Kazunori; Dobashi, Ritsu
• Is Part Of: International journal of hydrogen energy. Volume 40:Number 34(2015)
• Page Start: 11087
• Page End: 11092
• Publication Date: 2015-09-14
• Subjects: Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2015.06.123
• Languages: English
• ISSNs: 0360-3199

Abstract

<abstract xml:lang="en" abstract-type="author" id="abs0010"> <title id="sectitle0010">Abstract</title> <sec> <p id="abspara0010">This paper presents a simple model to predict the flame speed and the blast pressure during an unconfined gas explosion. The proposed model is a modification to the fractal-based model proposed by Gostintsev et al. In the original model, the flame radius, <italic>r</italic>, is expressed as a function of time, <italic>t</italic>, as <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgj2f1gvrg3" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si1.gif" overflow="scroll" id="d13e202" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mrow><mml:mi>r</mml:mi><mml:mo>/</mml:mo><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mi>κ</mml:mi><mml:mo>/</mml:mo><mml:mi>ε</mml:mi><mml:msub><mml:mi>S</mml:mi><mml:mtext>L</mml:mtext></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:mrow><mml:mo>=</mml:mo><mml:msub><mml:mi>c</mml:mi><mml:mtext>g</mml:mtext></mml:msub><mml:msup><mml:mrow><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mrow><mml:mi>t</mml:mi><mml:mo>/</mml:mo><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mi>κ</mml:mi><mml:mo>/</mml:mo><mml:msup><mml:mi>ε</mml:mi><mml:mn>2</mml:mn></mml:msup><mml:msubsup><mml:mi>S</mml:mi><mml:mtext>L</mml:mtext><mml:mn>2</mml:mn></mml:msubsup></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:mrow></mml:mrow><mml:mo>]</mml:mo></mml:mrow></mml:mrow><mml:mi>α</mml:mi></mml:msup></mml:mrow></mml:math></alternatives></inline-formula>, where <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgj2f1gwknr" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si2.gif" overflow="scroll" id="d13e273" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>κ</mml:mi></mml:math></alternatives></inline-formula> is the thermal diffusivity, <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgj2f1gv6f8" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si3.gif" overflow="scroll" id="d13e277" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ε</mml:mi></mml:math></alternatives></inline-formula> is the volumetric expansion ratio, <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgj2f1gvjcb" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si4.gif" overflow="scroll" id="d13e282" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>S</mml:mi><mml:mtext>L</mml:mtext></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> is the laminar burning velocity, <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgj2f1gvrj6" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si5.gif" overflow="scroll" id="d13e290" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>c</mml:mi><mml:mtext>g</mml:mtext></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> is the model constant, and <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgj2f1gvqbc" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si6.gif" overflow="scroll" id="d13e298" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math></alternatives></inline-formula> is the acceleration exponent. The present model expresses model constant <inline-formula><alternatives><inline-graphic xlink:href="ark:/27927/pgj2f1gvrj6" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="si5.gif" overflow="scroll" id="d13e302" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>c</mml:mi><mml:mtext>g</mml:mtext></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> using the properties of gas mixture. In this study, field experiments of gas explosion are conducted for hydrogen/air, methane/air, and propane/air mixtures confined in a 1- or 27-m<sup>3</sup> regular cubic plastic tent. The experimental results demonstrate the nature of self-similarity in the explosions and the experimental acceleration exponent associated with a fractal dimension is evaluated. The model is developed by using the concept of self-similarity and an acoustic theory. The predicted flame speed and the blast pressure are compared with experimental data of larger-scale hydrogen/air, methane/air and propane/air explosions under a wide range of conditions. The model predictions agree reasonably well with the experimental data, validating the proposed model.</p> </sec> </abstract>