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力学与实践 ›› 2002, Vol. 24 ›› Issue (1): 0-0.doi: 10.6052/1000-0992-2000-230

• 应用研究 •    

冲击高度对自由冲击射流影响的实验研究

徐惊雷 徐忠 张堃元 黄淑娟   

  1. 南京航空航天大学能源与动力学院动力工程系 西安交通大学流体工程系 710049 南京航空航天大学二系204教研室 210016 西安交通大学流体工程系
  • 收稿日期:2000-07-24 修回日期:2001-06-14 出版日期:2002-02-10 发布日期:2002-02-10

EXPERIMENTAL STUDY OF THE EFFECT OF THE NOZZLE-TO-PLATE SPACE ON THE FREE TURBULENT IMPINGING JET FLOW

  • Received:2000-07-24 Revised:2001-06-14 Online:2002-02-10 Published:2002-02-10

摘要: 采用热线风速仪测量了雷诺数为23000时四种冲击高度下紊流自由冲击射流流场, 并给出详细的结果. 表明壁面的``阻尼''影响主要集中在近壁面0.5D以内. 小冲击高度时径向速度下降得比大冲击高度时明显要快,量值也较小;在r/D≤1.5$处,小冲击高度时紊动能的数值大小和分布趋势与大冲击高度时不同,特别是在喷管出口距冲击板高度Z与喷管直径$D$之比$Z/D$为8时分布特殊, 在其它测点处, 紊 动能的分布趋势基本一致,只是大冲击高度下的值较大;流动结构在Z/D为6~8时发生了较大的变化,这种变化与势流核心区有关,在势流核心区的顶端以及下游的一段距离内紊流度都很高.

关键词: 冲击射流, 半封闭冲击射流,热线风速仪, 紊流, 势流核心区

Abstract: Using the IFA-300 Hot Wire/Film Anemometer, the detailed measurement results are obtained on the effect of the nozzle-to-plate space on the free turbulent impinging jet flow field. The Reynolds number considered is 23000, and the space of nozzle-to-plate is set as 2D (D is the diameter of the pipe), 4D,6D,8D above the impingement plate, respectively. It is shown that the "damping"effect mainly exists in the zone of 0.5D from the impingement wall. Under a small nozzle-to-plate space, the radial velocity decreases more rapidly than that under a large one. And the velocity under the small space is somewhat smaller. In the area r/D ≤1.5, the trend and the quantity of the turbulent kinetic energy of the small and large spaces are quite different. For the other radial positions, the trend is the same though the quantity under a larger space is greater. It also shows that the flow structure is greatly changed when the nozzle-to-plate space is around Z/D=6, which is attributed to the effect of the potential core of the jet. Consequently, the turbulent kinetic energy keeps large at the end of the potential core and in the area of several diameters downstream of it.

Key words: free impinging jet, Hot Wire/Film Anemometer, turbulence, potential core