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Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2017 Vol.18 No.10 P.807-818
Characterization of the mean velocity of a circular jet in a bounded basin
Abstract: A circular jet has broad and important applications in practical engineering. Most research in this area has focused on a free jet, a wall jet or a vertical jet in a bounded domain. In this study, the mean velocities of circular offset jets were studied for four jet exit Froude numbers (Fr), three offset heights (S) (S/d=1, 2, 3) and three submergence ratios (ht/S) (surface jet, mixed jet, and submerged jet) in a bounded basin. Based on the results, we propose a velocity decay formula for a circular jet. The lateral velocity spread was more consistent with Gaussian and Cauchy–Lorentz distributions than the vertical velocity. Moreover, Fr had little effect on the decay of the mean velocity for a circular jet when Re>1×104. The lateral and vertical spreads showed a quadratic relationship with the streamwise distance for different values of Fr at X/d<10. The positions of maximum mean velocity decay were independent of Fr and S/d when X/d<10. The spread rate was more uniform in the lateral direction than that in the vertical direction in a certain region for different S/d and ht/S. Therefore, the decay, spread, and maximum velocity position of the mean velocity for a circular offset jet can remain stable under different values of Fr, offset height, and submergence ratio.
Key words: Circular jet; Velocity decay; Froude number (Fr); Offset height; Submergence ratio
Chinese Summary <42> 有限空间内圆形射流时均流速特性研究
创新点:1. 推导出圆形跌坎射流主流方向上流速与射流距离之间的关系;2. 综合考虑了不同Fr、跌坎高度和淹没度对有限空间内的圆形射流流速分布的影响.
方法:1. 通过理论推导,验证流速测量方法的可行性和合理性;2. 通过试验的方法,分析Fr、跌坎高度和淹没度的变化对圆形射流时均流速衰减和扩散的影响规律.
结论:1. 得出圆形射流主流方向流速衰减的公式;圆形射流的横向流速分布与高斯、柯西-洛伦兹分布吻合较好.2. 当 Re>1×104时,Fr变化对流速衰减影响较小.3. 当X/d<10时,横向和垂向流速扩散与主流方向的距离呈二次方关系.4. 时均流速最大值的位置与Fr和S/d无关.
关键词组：
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DOI:
10.1631/jzus.A1600761
CLC number:
TV131.3
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On-line Access:
2024-08-27
Received:
2023-10-17
Revision Accepted:
2024-05-08
Crosschecked:
2017-09-07
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