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Influence of Rectangular Impinge Jet's Aspect Ratio on Dynamic Pressure

Author(s): Li Futian; Guifen Li; Lianxiang Wang

Linked Author(s): Lianxiang Wang

Keywords: 3D jet; Rectangular jet's aspect ratio; Dynamic pressure; RNG k--εmodel

Abstract: The spillways with free overflow are commonly used in high arch dams. In order to dissipate the huge kinetic energy carried by the overflow jet, the falling jets should be dispersed as far as possible by using various flip buckets. In China, the main forms of structures for dispersing nappes are differential flip buckets, tilted bucket, tongue shape bucket, expanding bucket with short guide wall, slit-type flip bucket, flaring gate pier dissipator and so on. All these types of structure not only disperse the falling jet, also change their section shape. In order to investigate the influence of free falling jet’s aspect ratio on dynamic pressure on the plunge bed of pool, the RNG k-εdouble-equation turbulence model is applied to the problem of three-dimension impinge jets issuing from rectangular orifices with aspect ratios of 1, 1. 6, 5, 16, 25. The calculation results of various aspect ratio show that the flow velocity distributions in free jet region are in good agreement with the conclusion given by predecessors. It implies that the turbulence model adopted is reasonable. The results show that the axial velocity of jet flow attenuates rapidly and results in the reduction of impact pressure acting of the wall with the increase of aspect ratio, when the initial momentum of the jet maintains constant.

DOI:

Year: 2007

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