Study of oscillating flow structure and characterization of merging process in self-excited twin jets: Numerical and analytical approach

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer Pub Date : 2024-06-04 DOI:10.1016/j.icheatmasstransfer.2024.107643

Seyed Mohammad Jaafarian , Seyed Alireza Zolfaghari , Amir Omidvar , Javad Khadem , Mahtab Aminzadeh

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Abstract

In this paper, the characteristics of oscillatory flow have been numerically investigated in the isothermal closed cavity of self-excited oscillating twin jets for several nozzle spacing-to-width ratios, $0 \leq S / e \leq 12,$ and volumetric flowrates of $Q = 0.04, 0.08, and 0.12 m^{3} / s$ . The results showed that in $0 \leq S / e \leq 6.5$ two jets merge at a short distance after the nozzles and oscillate with a frequency equal to that of the single oscillating jet. At $6.5 < S / e < 9$ , the oscillatory behavior of the twin jet enters a transient and unstable oscillatory mode. By increasing the nozzle spacing to $9 \leq S / e \leq 12$ , the oscillating behavior of the jet becomes stable, and jet flows oscillate with a much higher frequency than the self-excited oscillating single and twin jets with $0 \leq S / e \leq 6.5$ . In this research, the critical nozzle spacing (minimum nozzle spacing in which merging does not occur) was calculated for different flow rates. Also, an analytical method was presented based on the concept of half velocity edges to predict the critical nozzle spacing. The results showed that the analytical model is accurate compared to the numerical results. It was also revealed that the capability of self-excited twin jets to intensify the oscillating features in the flow field will be evident at nozzle spacings greater than the critical value.

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研究自激双射流中的振荡流结构和合流过程特征：数值和分析方法

本文对等温封闭腔体内自激振荡双射流的振荡流动特性进行了数值研究，研究了几种喷嘴间距与宽度比（0≤S/e≤12）和体积流量（Q=0.04、0.08 和 0.12m3/s）。结果表明，在 0≤S/e≤6.5 时，两股射流在喷嘴后不远处汇合，并以与单股振荡射流相同的频率振荡。在 6.5<S/e<9 时，双射流的振荡行为进入瞬态不稳定振荡模式。当喷嘴间距增加到 9≤S/e≤12 时，射流振荡行为变得稳定，射流振荡频率远高于 0≤S/e≤6.5 时的自激振荡单射流和双射流。在这项研究中，计算了不同流速下的临界喷嘴间距（不发生合并的最小喷嘴间距）。此外，还提出了一种基于半速度边缘概念的分析方法，用于预测临界喷嘴间距。结果表明，与数值结果相比，分析模型是准确的。研究还发现，当喷嘴间距大于临界值时，自激双射流加强流场振荡特征的能力将非常明显。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Communications in Heat and Mass Transfer 工程技术-力学

CiteScore

11.00

自引率

10.00%

发文量

648

审稿时长

32 days

期刊介绍： International Communications in Heat and Mass Transfer serves as a world forum for the rapid dissemination of new ideas, new measurement techniques, preliminary findings of ongoing investigations, discussions, and criticisms in the field of heat and mass transfer. Two types of manuscript will be considered for publication: communications (short reports of new work or discussions of work which has already been published) and summaries (abstracts of reports, theses or manuscripts which are too long for publication in full). Together with its companion publication, International Journal of Heat and Mass Transfer, with which it shares the same Board of Editors, this journal is read by research workers and engineers throughout the world.

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