1403 An Experimental Study on Local Burning Velocity Characteristics of H2-O2-Ar Premixed Turbulent Flames

A typical stationary premixed turbulent flame is the developing flame, as indicated by the growth of mean flame thickness with distance from flame-stabilization point. The goal of this work is to assess the importance of modeling flame development for RANS simulations of confined stationary premixed turbulent flames. For this purpose, submodels for developing turbulent diffusivity and developing turbulent burning velocity, which were early suggested by our group (FSC model) and validated for expanding spherical flames [4], have been incorporated into the so-called Zimont model of premixed turbulent combustion and have been implemented into the CFD package Fluent 6.2. The code has been run to simulate a stationary premixed turbulent flame stabilized behind a triangular bluff body in a rectangular channel using both the original and extended models. Results of these simulations show that the mean temperature and velocity fields in the flame are markedly affected by the development of turbulent diffusivity and burning velocity.

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An Experimental Study on Properties of Local Burning Velocity for Hydrogen Added Hydrocarbon Premixed Turbulent Flames

ASME/JSME 2011 8th Thermal Engineering Joint Conference ◽

10.1115/ajtec2011-44039 ◽

2011 ◽

Author(s):

Masaya Nakahara ◽

Koichi Murakami ◽

Jun Hashimoto ◽

Atsushi Ishihara

Keyword(s):

Burning Velocity ◽

Quantitative Relationship ◽

Lewis Number ◽

Turbulent Flames ◽

Laminar Flames ◽

Mean Values ◽

Laser Tomography ◽

Turbulence Condition ◽

Turbulent Burning Velocity ◽

Local Burning

This study is performed to investigate directly the local flame properties of turbulent propagating flames at the same weak turbulence condition (u′/SL0 = 1.4), in order to clarify basically the influence of the addition of hydrogen to methane or propane mixtures on its local burning velocity. The mixtures having nearly the same laminar burning velocity with different rates of addition of hydrogen δH are prepared. A two-dimensional sequential laser tomography technique is used to obtain the relationship between the flame shape and the flame displacement. The local flame displacement velocity SF is quantitatively obtained as the key parameters of the turbulent combustion. Additionally, the Markstein number Ma was obtained from outwardly propagating spherical laminar flames, in order to examine the effects of positive stretch and curvature on burning velocity. It was found that the trends of the mean values of measured SF with respect to δH, the total equivalence ratio Φ and fuel types corresponded well its turbulent burning velocity. The trend of the obtained Ma could explain the local burning velocity of turbulent flames only qualitatively. Based on the Ma, the local burning velocity at the part of turbulent flames with positive stretch and curvature, SLt, is estimated quantitatively. As a result, a quantitative relationship between the estimated SLt and the SF at positive stretch and curvature of turbulent flames could be observed for mixtures with increasing the Lewis number.

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