摘要
利用概率密度函数模型（PDF）,针对不同空气旋流强度下气泡雾化喷嘴出口下游庚烷雾群的燃烧过程进行了数值模拟研究.研究结果表明：随着空气旋流强度的增加,中心回流区逐渐向上游移动,且回流区长度减小、径向扩张,而角回流区则逐渐消失.适度提高空气旋流强度有利于强化离散相与连续相之间的混合过程,但过大的空气旋流强度将造成未蒸发的雾颗粒穿透剪切边界层,进入回流区内,造成不完全燃烧,甚至发生脱火.随着空气旋流强度的增加,火焰高温区域将逐渐前移,火焰张角有所增大;燃烧产物中CO的浓度随燃烧温度的提高有所降低,而NO的浓度则大幅提高.本文研究的气泡雾化喷嘴,匹配旋流数S=0.8-1.41的配风装置可以取得较好的燃烧效果.
The swirl combustion of effervescent atomized heptane spray in a cylindrical combustion chamber was numerical simulated at different air swirl intensities using PDF. Enhancing of air swirl intensity will cause the central recirculation zone move upward, shorten in axial and expand in radial direction. And the corner recirculation zone will reduce and disappear little by little. Augmenting air swirl intensity moderately is propitious to strengthen the mixing of gases and droplets. Whereas, as the swirl number is too lager, the droplets will penetrate the boundary layer and enter into the central recirculation zone. That will cause incomplete combustion and flame liftoff. As the swirl intensity increases, the high temperature zone moves upriver, the flame expands in radial direction, and the average temperature of combustion chamber heightens. At the same time, the mass fraction of CO of exhaust gases decreases and the volume fraction of NO enhances remarkably. For effervescent atomizers, the swirl number S = 0.8 - 1.41 is recommended.
出处
《河北工业大学学报》
CAS
北大核心
2010年第3期77-81,97,共6页
Journal of Hebei University of Technology
基金
国家自然科学基金(50876026)
河北省自然科学基金(E2009000079)
天津市应用基础及前沿技术研究计划(08JCZDJC22800)
关键词
旋流强度
气泡雾化
液雾
湍流燃烧
数值模拟
swirl intensity
effervescent atomization
spray
turbulent combustion
numerical simulation
作者简介
刘联胜（1970-），男（汉族），教授．
