• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Combustion Science and Technology >VELOCITY PROFILES MEASURED ACROSS WRINKLED FLAMES―TO ASSESS FLAMELET ASSUMPTIONS
【24h】

VELOCITY PROFILES MEASURED ACROSS WRINKLED FLAMES―TO ASSESS FLAMELET ASSUMPTIONS

机译：整个皱纹火焰的速度分布图-评估火焰纹假设

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Velocity profiles were measured across a freely propagating premixed flame, as the flame undergoes a wrinkling process, in order to assess certain flamelet assumptions. Several models have been developed that use flamelet theory, as proposed by N. Peters (1986), which hypothesizes that a segment of a turbulent flame will retain some of the properties of an analogous laminar counterflow flame. Counterflow flames have idealized properties, including (a) zero vorticity everywhere, (b) zero strain rate variations in the reactants, (c) larger velocity gradients in the products than in the reactants, and (d) tangential gradients that are negligible compared to normal gradients. Axisym-metric wrinkling of a premixed flame was achieved by interacting a flame with a vortex to achieve conditions typical of a segment of a turbulent flame: the wrinkle size is 4 times the flame thickness, and rotational velocities were 3―10 times the laminar flame speed. It was found that during the wrinkling process the flamelet assumptions were valid providing that conditions were far from extinction (Case A) or were approaching extinction (Case B). After the onset of local extinction (Case C) it is shown that the flamelet assumptions breakdown. Prior to extinction, the velocity profiles and strain rate profiles did maintain the general features of counterflow flames, and tangential gradients were negligible compared to normal gradients. Surprisingly, even the presence of intense large-scale vorticity did not invalidate the flamelet assumptions.
机译：当火焰经过起皱过程时，在自由传播的预混火焰上测量速度分布，以评估某些小火焰假设。 N. Peters（1986）提出了几种使用小火焰理论的模型，这些模型假设湍流火焰的一部分将保留类似层流逆流火焰的某些特性。逆流火焰具有理想的特性，包括（a）零涡度，（b）反应物零应变率变化，（c）产品中的速度梯度大于反应物，以及（d）与之相比可忽略的切向梯度正常渐变。预混火焰的轴对称起皱是通过使火焰与涡旋相互作用以达到湍流火焰段的典型条件来实现的：皱纹大小是火焰厚度的4倍，旋转速度是层流火焰的3至10倍速度。已经发现，在起皱过程中，只要条件不是绝种（案例A）或接近灭绝（案例B），火焰小假设都是有效的。在发生局部灭绝之后（案例C），可以证明小火焰假设破裂了。灭绝之前，速度分布和应变率分布确实保持了逆流火焰的一般特征，并且与正常梯度相比切向梯度可以忽略不计。令人惊讶的是，即使存在强烈的大规模涡旋也没有使小焰假设无效。

著录项

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