旋回流中の予混合火炎伝播挙動に与える密度比および層流燃焼速度の効果に関する数値解析(熱工学,内燃機関,動力など)

概要

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In order to clarify the effects of density ratio and laminar burning velocity on the vortex bursting phenomenon, the premixed flame propagation in swirling flow has been examined by the numerical calculation for various preheating temperatures and equivalence ratios. In this calculation, the flame is fixed in the computational domain by adding an axial flow to the unburnt premixed gas so as to obtain the steady state propagation characteristics. The obtained results are as follows: The present flame propagation velocities relatively agree on "the back-pressure drive flame propagation theory (radial expansion)" proposed by Ishizuka et al. The variation of the pressure along the vortex axis occurs between the inflow part and the flame front, and the pressure in the burnt region is almost uniform. Therefore, the propagation speed must be estimated by the Bernoulli's equation by using the density of unburnt mixture. We have proposed a new formula on the basis of the present calculation results, and have confirmed that flame propagation speed accords qualitatively and quantitatively with this formula. Moreover, we have suggested that, considering the application to the combustor with swirling flow, the preheating of premixed gas enhances its performance due to the large burning velocity.
2005-09-25