Research On The Stilling Basin With Additional Counter Momentum

A large number of medium and small size sluices and dams are playing important roles on the hydraulic structures for the modernization of our nation. However, the hydraulic jumps are often used in these structures to dissipate energy under low Froude number. If the problem is not well solved, it would influence the normal operation, even to endanger the safety of the hydraulic structures. In the view of the problems in energy dissipation with hydraulic jump of traditional sluices and dams, a kind of new form is introduced in this paper, which uses of the access placed under the floor of sluice gate to form opposed jet flow, on the one hand it bumped with the direct outflow to dissipate energy; on the other hand it heightens tailwater which makes the flow to form stability hydraulic jump to dissipate energy in the stilling basin. This article approaches a subject on this type of energy dissipator from different aspects, such as hydraulic method, hydraulic experiments and mathematic stimulation. Furthermore it analyses the flow patterns of fluid in the stilling basin and the effect on downstream. The main tasks of this paper are the follows:1. The recent research works about Energy dissipation of hydraulic structures have been summarized.2. The flow of convective stilling basin is theoretically analyzed in hydraulic method. Then basic formula for energy dissipation rate and some other equations are derived. Moreover the causes why the energy disspation of convective stilling basin is superior to that of normal ones are analyzed in theory.3. Many groups of experiments on convective stilling basin are carriedout, and the ratio of energy dissipation, velocity field, pressure field are measured and calculated. According to experimental data, the relation between the ratio of energy dissipation and Froude number is established. The theoretical values are well coincided with the experimental results.3. The governing equations are formulated in rectangular coordinate system, The flow fields of convective stilling basin are simulated by RNG k- ε and k- ε turbulent models. The computed results show that RNG k- ε turbulent model is more successfully used to predict flow field.The research work shows that convective stilling basin has high ratio of energy dissipation. For low Froude numbers the ratio of energy dissipation can averagely be risen by 15% or so; The flow is stable and is easily to be controlled as submerged jump so that it can decrease scouring on downstream and can shorten the length of the stilling basin ; it also can adjust and control the development of the bed river, So it can reduce investment of the project and save maintenance and repair cost of the strand. It has practical values on hydraulic project, as well as important significance in energy dissipation of the hydraulic jump. The examples in this paper provide valuable reference for the design of the facilities of energy dissipator. This type of energy dissipator is applicable not only for outlet structures of low water head but also for outlet structures of high water head or box stilling basin, and also important to arrangement plan of the project.