• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>International Journal of Heat and Mass Transfer >Numerical investigation of passive scalar transport and mixing in a turbulent unconfined coaxial swirling jet
【24h】

Numerical investigation of passive scalar transport and mixing in a turbulent unconfined coaxial swirling jet

机译：湍流无边同轴涡旋射流中被动标量传输和混合的数值研究

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

This paper presents the numerical results of a study on passive scalar mixing in coaxial jets under the influence of swirl. Two cases with different swirling strengths are considered and compared to a non-swirling case. Each jet is injected with an individual scalar to better understand the mixing between jets. The case with intermediate swirling strength exhibits faster centerline decay and radial spread in the mean streamwise velocity in the downstream region when compared to the non-swirling case. The case with strong swirling exhibits the formation of an internal recirculation zone. The mean scalar distributions indicate a better spreading rate of scalars in the intermediate swirling case in the far downstream region, whereas the strong swirling case exhibits maximum spread far upstream. These results are confirmed based on entropy, which is a measure of the diffusion of scalars. Furthermore, the ambient fluid reaches the centerline earlier with the introduction of swirl as a result of an increase in the entrainment rate caused by swirl. The enhanced presence of ambient fluid is observed to influence scalar fluctuations. Otherwise negligible turbulent azimuthal fluxes of both scalars exhibit higher values in the swirling cases. The positive correlation between scalar fluctuations is more evident farther upstream in the intermediate swirling case compared to the non-swirling case. This phenomenon is a result of the enhanced presence of ambient fluid. However, in the strong swirling case, this process takes place far upstream based on additional effects of the internal recirculation zone. The joint probability density function of scalar fluctuations at the leading centerline stagnation point of the internal recirculation zone contains two distinct peaks, indicating the presence of flapping between inner and outer jet scalars caused by the oscillating stagnation point. (C) 2019 Elsevier Ltd. All rights reserved.
机译：本文介绍了在旋流影响下同轴射流中被动标量混合研究的数值结果。考虑了两种旋流强度不同的情况，并将其与非旋流情况进行了比较。每个射流都注入一个单独的标量，以更好地了解射流之间的混合。与非旋流情况相比，具有中等旋流强度的情况在下游区域的平均流向速度中表现出更快的中心线衰减和径向扩展。具有强烈旋流的情况显示出内部再循环区的形成。平均标量分布表明，在远下游区域的中间旋流情况下标量的散布率更高，而强旋流情况在远上游区域表现出最大散布。这些结果基于熵进行了证实，熵是衡量标量扩散的指标。此外，由于涡旋引起的夹带率增加，环境流体随着涡旋的引入更早到达中心线。观察到环境流体存在的增加会影响标量波动。否则，在涡旋情况下，两个标量的可忽略的湍流方位角通量将显示较高的值。与非旋转情况相比，在中间旋转情况下，标量波动之间的正相关性在上游更明显。这种现象是环境流体存在增加的结果。但是，在强烈涡旋的情况下，由于内部再循环区的附加影响，该过程发生在上游。内部再循环区的领先中心线停滞点处标量波动的联合概率密度函数包含两个不同的峰，表明存在由振荡停滞点引起的内部和外部射流标量之间的拍动。 （C）2019 Elsevier Ltd.保留所有权利。

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