Experimental Study On Flow Characteristics Of Apron Extension Expanded Stilling Basin

Stilling basin is a common underflow energy-dissipation project in hydraulic engineering,which is usually built in the river following the brake, bridges and steep slopes,so as to cut the energy difference generated upstream and downstream water level, reducing the flow rate of the river, to avoid channel erosion damage. The composition of stilling basin usually includes steep slope in font of stilling basin,stilling basin,apron extension and anti notching. The common shape of stilling basin is mono-spaced rectangle. There is a diffusion shape of stilling basin in engineering practice which is began in front of stilling basin. Stilling basin is one of the major river engineering energy dissipation structures,which is widely used in the production practice.In this paper,the experiment is to study the stilling basin whose apron extension is diffused. Apron extension expanded stilling basin means that the river section from apron is lager than the stilling basin section. At present,study about the theory of Apron extension expanded stilling basin is less, this paper combined closely with the engineering practice and the length and depth of Apron extension expanded stilling basin research,though the hydraulics experiments of Apron extension expanded stilling basin, explore water’s feature in the stilling basin,providing applied basic theory and technical support for engineering practice. There were seven schemes of hydraulic model experiments in this paper including non-proliferation apron stilling basin,sudden enlargement ratio 1.2,1.4,1.5 and divergent angle of 18.43°,26.57°,45°. Through the analysis of experimental data, the conclusion is as follows:(1)The change rule of the flow regime and the turbulent structure of the downstream is as follows: with the bigger of the sudden enlargement ration and the divergent angle, the more unstable of the flow regime and the turbulent structure of the downstream in the stilling basin, the more obvious of the rhombus wave and the bigger of the vortex next to the side after the bank when the flow is the same. The rule is the same when variable exchange.(2)The flow Characteristics of Apron Extension Expanded Stilling Basin, including the water’s depth changing both in the stilling basin and in the downstream channel, the Froude number and effect of energy dissipation in the stilling basin, are all related to the style of the Apron extension stilling basin.(3)Comprehensive analysis of the flow regime and the dissipation size, the Apron extension stilling basin in the 26.57°divergent angle has the best hydraulic characteristics.(4)By the method of contrast, summary and induction, put forward the formula of the Water depth after hydraulic jump and the formula of the length of the stilling basin.