{"title":"长宽比对十字形孔板射流平均流动特性的影响","authors":"Rajesh Kumar S., Nishchay Sadrani, Kannan B.T.","doi":"10.1108/aeat-08-2022-0205","DOIUrl":null,"url":null,"abstract":"<h3>Purpose</h3>\n<p>The purpose of this study reports the effects of aspect ratio (AR) on mean flow characteristics of the cruciform orifice jet.</p><!--/ Abstract__block -->\n<h3>Design/methodology/approach</h3>\n<p>The aspect ratio is the height-to-width ratio of the lobe of the cruciform shape. The aspect ratios considered are 0.25, 0.5, 0.75, 1, 2, 3 and 4. The turbulent jet flow is issued through an orifice being fitted to the jet tunnel facility. The velocity measurements are recorded with the help of pitot-static tube connected to a digital manometer setup. The Reynolds number calculated using the equivalent diameter 50.46 × 10<sup>–3</sup> m and exit velocity 51.23 m/s was 1.75 × 10<sup>5</sup>. Based on the experimental data, the streamline velocity decay plots, the potential core length (PCL), mean velocity profiles and velocity half widths were plotted, and discussions were made based on the measured data. A smoke-based flow visualization was carried out at moderate Reynolds number 5396.</p><!--/ Abstract__block -->\n<h3>Findings</h3>\n<p>The PCL remains almost constant for the aspect ratio 0.25:1 and then starts decreasing for the aspect ratio 1:4. The decrease in PCL indicates improved mixing. The off-center peaks are found along the major axis in mean velocity profiles for almost all cruciform jets. More than one axis switching occurs and can be identified by the crossover points. The location of the first crossover point shifts forward, and the second crossover point shows an oscillating trend. The flow visualization exhibits the jet evolution, and the distance up to which the jet maintains the cruciform shape is increased with the aspect ratio.</p><!--/ Abstract__block -->\n<h3>Research limitations/implications</h3>\n<p>The experiments are limited to air in air jet under isothermal conditions.</p><!--/ Abstract__block -->\n<h3>Social implications</h3>\n<p>The cruciform orifices can be used as fuel injectors and in air-conditioning systems, thereby improving efficiency and energy usage.</p><!--/ Abstract__block -->\n<h3>Originality/value</h3>\n<p>The aspect ratio effects on PCL and axis switching are used to explain the mixing characteristics. Flow visualization was also used to support the discussion.</p><!--/ Abstract__block -->","PeriodicalId":55540,"journal":{"name":"Aircraft Engineering and Aerospace Technology","volume":"12 1","pages":""},"PeriodicalIF":1.2000,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Effect of aspect ratio on mean flow characteristics of cruciform orifice jet\",\"authors\":\"Rajesh Kumar S., Nishchay Sadrani, Kannan B.T.\",\"doi\":\"10.1108/aeat-08-2022-0205\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<h3>Purpose</h3>\\n<p>The purpose of this study reports the effects of aspect ratio (AR) on mean flow characteristics of the cruciform orifice jet.</p><!--/ Abstract__block -->\\n<h3>Design/methodology/approach</h3>\\n<p>The aspect ratio is the height-to-width ratio of the lobe of the cruciform shape. The aspect ratios considered are 0.25, 0.5, 0.75, 1, 2, 3 and 4. The turbulent jet flow is issued through an orifice being fitted to the jet tunnel facility. The velocity measurements are recorded with the help of pitot-static tube connected to a digital manometer setup. The Reynolds number calculated using the equivalent diameter 50.46 × 10<sup>–3</sup> m and exit velocity 51.23 m/s was 1.75 × 10<sup>5</sup>. Based on the experimental data, the streamline velocity decay plots, the potential core length (PCL), mean velocity profiles and velocity half widths were plotted, and discussions were made based on the measured data. A smoke-based flow visualization was carried out at moderate Reynolds number 5396.</p><!--/ Abstract__block -->\\n<h3>Findings</h3>\\n<p>The PCL remains almost constant for the aspect ratio 0.25:1 and then starts decreasing for the aspect ratio 1:4. The decrease in PCL indicates improved mixing. The off-center peaks are found along the major axis in mean velocity profiles for almost all cruciform jets. More than one axis switching occurs and can be identified by the crossover points. The location of the first crossover point shifts forward, and the second crossover point shows an oscillating trend. The flow visualization exhibits the jet evolution, and the distance up to which the jet maintains the cruciform shape is increased with the aspect ratio.</p><!--/ Abstract__block -->\\n<h3>Research limitations/implications</h3>\\n<p>The experiments are limited to air in air jet under isothermal conditions.</p><!--/ Abstract__block -->\\n<h3>Social implications</h3>\\n<p>The cruciform orifices can be used as fuel injectors and in air-conditioning systems, thereby improving efficiency and energy usage.</p><!--/ Abstract__block -->\\n<h3>Originality/value</h3>\\n<p>The aspect ratio effects on PCL and axis switching are used to explain the mixing characteristics. Flow visualization was also used to support the discussion.</p><!--/ Abstract__block -->\",\"PeriodicalId\":55540,\"journal\":{\"name\":\"Aircraft Engineering and Aerospace Technology\",\"volume\":\"12 1\",\"pages\":\"\"},\"PeriodicalIF\":1.2000,\"publicationDate\":\"2023-12-08\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Aircraft Engineering and Aerospace Technology\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://doi.org/10.1108/aeat-08-2022-0205\",\"RegionNum\":4,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ENGINEERING, AEROSPACE\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Aircraft Engineering and Aerospace Technology","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.1108/aeat-08-2022-0205","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENGINEERING, AEROSPACE","Score":null,"Total":0}
引用次数: 0
摘要
设计/方法/途径纵横比是指十字形叶片的高宽比。考虑的长宽比分别为 0.25、0.5、0.75、1、2、3 和 4。湍流喷射流通过安装在喷射隧道设备上的孔口喷出。借助连接到数字压力计装置上的皮托管记录速度测量值。根据等效直径 50.46 × 10-3 m 和出口速度 51.23 m/s 计算得出的雷诺数为 1.75 × 105。根据实验数据，绘制了流线速度衰减图、潜在核心长度（PCL）、平均速度剖面图和速度半宽，并根据测量数据进行了讨论。在中等雷诺数（5396.FindingsThe PCL remains almost constant for the aspect ratio 0.25:1 and then began decreasing for the aspect ratio 1:4.PCL 的降低表明混合效果得到改善。几乎所有十字形喷流的平均速度剖面图都沿主轴出现了偏离中心的峰值。轴切换不止一次，可通过交叉点识别。第一个交叉点的位置向前移动，第二个交叉点则呈现振荡趋势。社会影响十字形喷口可用作燃料喷射器和空调系统，从而提高效率和能源利用率。原创性/价值利用纵横比对 PCL 和轴切换的影响来解释混合特性。此外，还使用了流动可视化来支持讨论。
Effect of aspect ratio on mean flow characteristics of cruciform orifice jet
Purpose
The purpose of this study reports the effects of aspect ratio (AR) on mean flow characteristics of the cruciform orifice jet.
Design/methodology/approach
The aspect ratio is the height-to-width ratio of the lobe of the cruciform shape. The aspect ratios considered are 0.25, 0.5, 0.75, 1, 2, 3 and 4. The turbulent jet flow is issued through an orifice being fitted to the jet tunnel facility. The velocity measurements are recorded with the help of pitot-static tube connected to a digital manometer setup. The Reynolds number calculated using the equivalent diameter 50.46 × 10–3 m and exit velocity 51.23 m/s was 1.75 × 105. Based on the experimental data, the streamline velocity decay plots, the potential core length (PCL), mean velocity profiles and velocity half widths were plotted, and discussions were made based on the measured data. A smoke-based flow visualization was carried out at moderate Reynolds number 5396.
Findings
The PCL remains almost constant for the aspect ratio 0.25:1 and then starts decreasing for the aspect ratio 1:4. The decrease in PCL indicates improved mixing. The off-center peaks are found along the major axis in mean velocity profiles for almost all cruciform jets. More than one axis switching occurs and can be identified by the crossover points. The location of the first crossover point shifts forward, and the second crossover point shows an oscillating trend. The flow visualization exhibits the jet evolution, and the distance up to which the jet maintains the cruciform shape is increased with the aspect ratio.
Research limitations/implications
The experiments are limited to air in air jet under isothermal conditions.
Social implications
The cruciform orifices can be used as fuel injectors and in air-conditioning systems, thereby improving efficiency and energy usage.
Originality/value
The aspect ratio effects on PCL and axis switching are used to explain the mixing characteristics. Flow visualization was also used to support the discussion.
期刊介绍：
Aircraft Engineering and Aerospace Technology provides a broad coverage of the materials and techniques employed in the aircraft and aerospace industry. Its international perspectives allow readers to keep up to date with current thinking and developments in critical areas such as coping with increasingly overcrowded airways, the development of new materials, recent breakthroughs in navigation technology - and more.
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
