首页> 外文期刊>Combustion and Flame >The effect of stretch on cellular formation in non-premixed opposed-flow tubular flames
【24h】

The effect of stretch on cellular formation in non-premixed opposed-flow tubular flames

机译:拉伸对非预混对流管状火焰中细胞形成的影响

获取原文
获取原文并翻译 | 示例
       

摘要

Cellular formation in non-premixed flames is experimentally studied in an opposed-flow tubular burner. This burner allows independent variation of the global stretch rate and overall flame curvature. In opposed-flow flames formed by 21.7% hydrogen diluted in carbon dioxide versus air, cells are formed near extinction with a low fuel Lewis number and a low initial mixture strength. Using an intensified CCD camera, the flame chemiluminescence is imaged to study cellular formation from the onset of cells to near extinction conditions. The experimental onset of cellular instability is found to be at or at a slightly lower Damkohler number than the numerically determined extinction limit based on a two-point boundary value solution of the tubular flame. For fuel Lewis numbers less than unity, concave curvature towards the fuel retards combustion and weakens the flame and convex curvature towards the fuel promotes combustion and strengthens the flame. In the cell formation process, the locally concave flame cell midsection is weakened and the locally convex flame cell ends are strengthened. With increasing stretch rate, the flame breaks into cells and the cell formation process continues until near-circular cells are formed with no concave midsection. Further increase in the stretch rate leads to cell extinction. With increasing stretch rate, the flame thickness at the cell midsection decreases similar to a planar opposed-flow flame while the flame thickness at the cell edges is unchanged and can even increase due to the strengthening effect of convex curvature at the flame edges toward the low Lewis number fuel. The results show the existence of cellular flames well beyond the two-point boundary value extinction limit and the importance of local flame curvature in the formation of flame cells.
机译:在对流管式燃烧器中对非预混火焰中的细胞形成进行了实验研究。该燃烧器可以独立改变整体拉伸速率和整体火焰曲率。在由相对于空气稀释的21.7%氢气中稀释的氢气形成的逆流火焰中,在接近熄灭的状态下会形成电池,燃料的路易斯数较低且初始混合强度较低。使用增强型CCD相机对火焰化学发光进行成像,以研究从细胞发作到接近灭绝的细胞形成情况。基于管状火焰的两点边界值解,发现细胞不稳定性的实验开始时间等于或稍低于数字确定的消光极限的Damkohler数。对于路易斯数小于1的燃料,朝向燃料的凹曲率会阻碍燃烧并削弱火焰,而朝向燃料的凸曲率会促进燃烧并增强火焰。在气泡形成过程中,局部凹入的火焰盒中部被削弱,局部凸出的火焰盒端部被增强。随着拉伸速率的增加,火焰破裂成泡孔,泡孔形成过程继续进行,直到形成没有凹形中间部分的近圆形泡孔。拉伸速率的进一步增加导致细胞灭绝。随着拉伸速率的增加,电池中部的火焰厚度类似于平面逆流火焰而减小,而电池边缘的火焰厚度不变,甚至由于火焰边缘处的凸曲率向低点的强化作用而可能增加。刘易斯数燃料。结果表明,蜂窝状火焰的存在远远超过了两点边界值的消光极限,并且局部火焰曲率在形成火焰室中也很重要。

著录项

  • 来源
    《Combustion and Flame》 |2011年第5期|p.876-884|共9页
  • 作者

    S.W. Shopoff; P. Wang; R.W. Pitz;

  • 作者单位

    Mechanical Engineering Department, Vanderbilt University, Nashville, TN 37235, USA;

    Aerospace Engineering Department, Xiamen University, Xiamen, Fujian 361005, China;

    Mechanical Engineering Department, Vanderbilt University, Nashville, TN 37235, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    stretch; curvature; cellular instability; tubular flame; diffusion flame; hydrogen;

    机译:伸展;曲率细胞不稳定管状火焰扩散火焰氢;
  • 入库时间 2022-08-18 00:12:14

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号