Purpose

The purpose of this study is to understand experimentally the mixing characteristics of a two-stream exhaust system with a supersonic Mach 1.5 primary jet that exits the rectangular C-D nozzle surrounded by a sonic secondary jet from a convergent rectangular nozzle by varying the aspect ratio (AR = 2 and 3) similar to those that can be available for future high-speed commercial aircraft.

Design/methodology/approach

This paper focuses on the experimental results of effects of AR at various expansion levels of jets issued/delivered from a central rectangular convergent-divergent nozzle of AR 2 and 3 surrounded by a coflow from a convergent rectangular sonic nozzle. The lip thickness of the primary nozzle is 2.2 mm. various nozzle pressure ratios (NPRs) ranging from 2, 3, 3.69 and 4 were chosen for pressure measurements.

Findings

For all the NPRs, AR 3 had a shorter core than AR 2. Also, AR 3 was found to decay faster in the transition and fully developed zones. The lateral plots show that the AR has an influence on the jet spread.

Originality/value

The structure of waves existing in the potential core of the rectangular coflow jet along with the major and minor axis planes was visualized by the shadowgraph technique.

中文翻译：

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长径比2和3的顺流矩形喷嘴混合特性研究

目的

本研究的目的是通过改变纵横比（AR = 2 和 3) 类似于未来高速商用飞机可用的那些。

设计/方法/方法

本文重点研究了 AR 2 和 3 的中心矩形收敛-发散喷嘴发出/输送的射流在不同膨胀水平下的影响的实验结果，该喷嘴被来自收敛矩形声波喷嘴的共流包围。主喷嘴的唇缘厚度为 2.2 毫米。选择范围为 2、3、3.69 和 4 的各种喷嘴压力比 (NPR) 进行压力测量。

发现

对于所有 NPR，AR 3 的核心都比 AR 2 短。此外，发现 AR 3 在过渡区和完全发育区衰减得更快。横向图显示 AR 对射流扩散有影响。

原创性/价值

矩形共流射流的潜在核心中存在的波浪结构以及长轴和短轴平面通过阴影图技术可视化。