Abstract

Three-dimensional density fields of the twin jets were numerically and experimentally investigated. The present study focused on the comparison of the density distribution for the twin jets. The results obtained by the computational fluid dynamics (CFD) and three-dimensional background-oriented schlieren (3D-BOS) indicate that the periodic density fluctuation appears in the potential core each nozzle, and the flow structure of the twin jets is quite similar. The distribution of the normalized density value at the nozzle centerline agrees well with CFD and 3D-BOS. The density value of the shear layer between the nozzles increases as the interaction of the twin jets occurs. The trend of increasing and decreasing the interference between the nozzles was almost the same as each other. On the other hand, the position where the interaction of the twin jets starts and the growth rate of interaction were different. This is probably due to the effect of the laminar-to-turbulent transition occurred in the results of CFD. This result indicates that the laminar-to-turbulent transition can be estimated from the velocity fields obtained by CFD and particle image velocimetry (PIV).

Graphic Abstract

中文翻译：

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双射流数值与实验分析的三维密度分布比较

摘要

对双射流的三维密度场进行了数值和实验研究。本研究的重点是比较双射流的密度分布。计算流体动力学（CFD）和三维背景定向纹影（3D-BOS）的结果表明，每个喷嘴的势核都出现了周期性的密度波动，双射流的流动结构非常相似。喷嘴中心线处归一化密度值的分布与 CFD 和 3D-BOS 非常吻合。喷嘴之间剪切层的密度值随着双射流的相互作用而增加。喷嘴之间的干扰增加和减少的趋势几乎相同。另一方面，双射流相互作用开始的位置和相互作用的增长速度不同。这可能是由于 CFD 结果中发生的层流到湍流转变的影响。该结果表明，可以从 CFD 和粒子图像测速 (PIV) 获得的速度场估计层流到湍流的转变。

图形摘要