{"title":"An analysis of flow structures of underwater supersonic gas jets: a numerical study","authors":"A. Jana, L. Hoskoti, M. M. Sucheendran","doi":"10.1007/s00193-023-01141-6","DOIUrl":null,"url":null,"abstract":"<div><p>The present work is focused on the numerical analysis of the flow structures of high-speed underwater air jets. In an earlier work (Jana et al., J. Fluids Eng. 144(11):111208, 2022), the authors presented an analysis of the unsteady behavior of different flow variables of the jets. The present work is further extended to analyze the temporal evolution of the flow structures of different jet regions. The numerical simulations are conducted with the unsteady Reynolds-averaged Navier–Stokes equations with a homogeneous mixture model. The previous work rendered the effect of pressure ratio (the ratio of nozzle exit pressure to back pressure) on the behavior of the jet flow. In the present analysis, jet exit Mach number is also considered as another operating parameter. The results for three pressure ratios, 0.8, 1, and 1.2, and two exit Mach numbers, 2 and 3, are presented. Temporal behavior of the three major regions, namely, the core, shear layer, and mixing layer of the jet due to its interaction with surrounding water, is discussed. The flow physics of shock and expansion waves in the core region is analyzed, and the effects of the underwater ambience on the structures of shock waves are also explained. Various phenomena, such as necking, back-attack, and expansion, are also visualized and explained from the simulated flow variables. Given the limitations of experimental flow visualizations, these analyses aid to understand the major flow behavior of supersonic underwater jets.\n</p></div>","PeriodicalId":775,"journal":{"name":"Shock Waves","volume":null,"pages":null},"PeriodicalIF":1.7000,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00193-023-01141-6.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Shock Waves","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s00193-023-01141-6","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MECHANICS","Score":null,"Total":0}
引用次数: 0
Abstract
The present work is focused on the numerical analysis of the flow structures of high-speed underwater air jets. In an earlier work (Jana et al., J. Fluids Eng. 144(11):111208, 2022), the authors presented an analysis of the unsteady behavior of different flow variables of the jets. The present work is further extended to analyze the temporal evolution of the flow structures of different jet regions. The numerical simulations are conducted with the unsteady Reynolds-averaged Navier–Stokes equations with a homogeneous mixture model. The previous work rendered the effect of pressure ratio (the ratio of nozzle exit pressure to back pressure) on the behavior of the jet flow. In the present analysis, jet exit Mach number is also considered as another operating parameter. The results for three pressure ratios, 0.8, 1, and 1.2, and two exit Mach numbers, 2 and 3, are presented. Temporal behavior of the three major regions, namely, the core, shear layer, and mixing layer of the jet due to its interaction with surrounding water, is discussed. The flow physics of shock and expansion waves in the core region is analyzed, and the effects of the underwater ambience on the structures of shock waves are also explained. Various phenomena, such as necking, back-attack, and expansion, are also visualized and explained from the simulated flow variables. Given the limitations of experimental flow visualizations, these analyses aid to understand the major flow behavior of supersonic underwater jets.
本文对高速水下空气射流的流动结构进行了数值分析。在较早的研究中(Jana et al.， J. Fluids Eng. 144(11): 111208,2022)，作者对不同流动变量下射流的非定常行为进行了分析。本工作进一步扩展到分析不同射流区域流动结构的时间演化。采用非定常reynolds -average Navier-Stokes方程进行了均匀混合模型的数值模拟。先前的工作描述了压力比(喷嘴出口压力与背压的比值)对射流行为的影响。在本分析中，射流出口马赫数也被认为是另一个操作参数。给出了三种压力比0.8、1和1.2以及两种出口马赫数2和3的结果。讨论了射流的核心、剪切层和混合层这三个主要区域在与周围水相互作用下的时间行为。分析了核心区激波和膨胀波的流动物理特性，并解释了水下环境对激波结构的影响。各种现象，如颈缩，反攻，膨胀，也可视化和解释从模拟的流动变量。考虑到实验流动可视化的局限性，这些分析有助于理解超音速水下射流的主要流动行为。
期刊介绍：
Shock Waves provides a forum for presenting and discussing new results in all fields where shock and detonation phenomena play a role. The journal addresses physicists, engineers and applied mathematicians working on theoretical, experimental or numerical issues, including diagnostics and flow visualization.
The research fields considered include, but are not limited to, aero- and gas dynamics, acoustics, physical chemistry, condensed matter and plasmas, with applications encompassing materials sciences, space sciences, geosciences, life sciences and medicine.
Of particular interest are contributions which provide insights into fundamental aspects of the techniques that are relevant to more than one specific research community.
The journal publishes scholarly research papers, invited review articles and short notes, as well as comments on papers already published in this journal. Occasionally concise meeting reports of interest to the Shock Waves community are published.
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