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Flow Mixing and Screech Characteristics of Elliptical Supersonic Jet
International Journal of Turbo & Jet-Engines ( IF 0.9 ) Pub Date : 2021-05-01 , DOI: 10.1515/tjj-2018-0006
S. Manigandan 1 , K. Vijayaraja 2
Affiliation  

The acoustic and flow characteristics of a jet with elliptical throat is studied at different levels of nozzle expansion ratio. In this study, we have taken two types of CD nozzle configuration (circular and elliptical throat) and it is studied for various NPR ratios of 2, 3, 4 and 6. In addition, the acoustic characteristic of the jet flow is also measured for respective NPRs. Measurements of acoustic data are done using microphones placed at 30, 60 and 90 degrees to imprison the effects of screech tone. At NPR 2, 3 and 4, the jet with elliptical throat witnesses superior mixing and shorter core length compared to the circular throat. Its surprising to see both the configurations provides the identical oscillation at NPR 2, 3 and 4, however the efficiency of jet mixing is larger in elliptical throat jet. As the nozzle pressure ratio increased from 2 to 3 and 3 to 4, the potential core length of the jet reduces marginally about 5 to 10 % for every NPR until nozzle pressure ratio of 5. At NPR 2 and 3, the centerline pitot pressure profile shows, the decay of jet from the elliptical throat is healthier than a circular jet. At various levels of nozzle expansion, shock cell shows an appreciable change with an increase in NPR. Introduction of the elliptical throat on circular modifies the structure of shock cell which significantly changes the magnitude of screech tone due to the weakening of shock waves.

中文翻译:

椭圆形超音速射流的流动混合与蠕变特性

研究了在不同喷嘴膨胀率水平下具有椭圆喉的射流的声学和流动特性。在这项研究中,我们采用了两种CD喷嘴配置(圆形和椭圆形喉管),并针对2、3、4和6的各种NPR比率进行了研究。各自的NPR。声学数据的测量是使用放置在30、60和90度的麦克风进行的,以监禁尖叫声的影响。在NPR 2、3和4处,与圆形喉头相比,具有椭圆形喉头的射流具有出众的混合效果,并且芯长更短。令人惊讶的是,这两种配置在NPR 2、3和4处提供了相同的振荡,但是在椭圆喉头喷射中喷射混合的效率更高。随着喷嘴压力比从2增至3和3增至4,对于每个NPR,射流的潜在芯长度会略微减少5%至10%,直到喷嘴压力比为5为止。在NPR 2和3时,中心线皮托管压力曲线如图所示,从椭圆形喉咙喷出的气流比圆形气流更健康。在不同的喷嘴膨胀水平下,随着NPR的增加,冲击池显示出可观的变化。在圆形处引入椭圆形的喉部会改变震动盒的结构,由于震动波的减弱,震动盒的音调会显着改变。椭圆喉的射流衰减比圆形射流更健康。在不同的喷嘴膨胀水平下,随着NPR的增加,冲击池显示出可观的变化。在圆形处引入椭圆形的喉部会改变震动盒的结构,由于震动波的减弱,震动盒的音调会显着改变。椭圆喉的射流衰减比圆形射流更健康。在不同的喷嘴膨胀水平下,随着NPR的增加,冲击池显示出可观的变化。在圆形处引入椭圆形的喉部会改变震动盒的结构,由于震动波的减弱,震动盒的音调会显着改变。
更新日期:2021-04-29
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