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Numerical Simulation of Turbulent stepped spillway and energy dissipation Factors

Author: BuShuQi
Tutor: TangXinJun
School: Xinjiang Agricultural University
Course: Water Resources and Hydropower Engineering
Keywords: Stepped spillway Numerical Simulation Flexible ladder VOF method Turbulence model Energy dissipation rate formula Aerated impact factor
CLC: TV651.1
Type: Master's thesis
Year: 2010
Downloads: 78
Quote: 1
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Abstract


Stepped spillway is a use of spillway setting step for energy dissipation of new energy dissipator with smooth spillway compared, because of their energy dissipation effect is obvious, simplifying downstream stilling facilities, saving investment, etc., so that has been widely research and application. In order to further discuss the ladder spillway turbulent numerical simulation and analysis of energy dissipation factors, this paper numerical simulation as a means mainly discussed the step height, chute slope, stepped shape of the hydraulic characteristics and relative energy dissipation rate effects and the initial right Flexible Lining stepped spillway water flows in a numerical simulation, while the absolute energy dissipation rate formula, the flow rate formula aeration influence coefficients are discussed and evaluated. In this paper, VOF method, using standard k-ε, RNG k-ε and Realizable k-ε three models on the ladder spillway numerical simulation, and with the measured results were compared and found RNG k-ε model simulation results and computational efficiency is relatively better, and feasible and reasonable. In order to analyze, investigate the impact of stepped spillway effect factors, we designed several different step heights, chute slope, stepped shape of the simulation program, through numerical simulations found that: When the bottom slope, height of the same, to a lesser flow conditions, step height change on the relative energy dissipation rate of more significant, in the larger flow conditions, step height change on the relative energy dissipation rate of less; in the test range, when the slope angle of 5.71 ° ~ 33.69 °, there is a step height allows the relative energy dissipation rate reaches the maximum; when the step height, flow, height of the same, with the bottom slope slows, the relative energy dissipation rate has increased, but the increase was smaller, reflecting the end of slope relative energy dissipation rate of less; when the bottom slope, flow, dam are the same, different step shape (or step arrangement form) relative energy dissipation rate are quite different, indicating stepped shape of the relative energy dissipation rate certain influence, where, V-shaped stairs, transitional style with convex style steps and rectangular-shaped stairs relative energy dissipation rate is large, each step shape case relative energy dissipation rate (η) size of the order of: ηV shaped gt; η transition formula ≈ η convex type gt; η rectangular gt; η wedge gt; η chamfered gt; η repair fillet. For the use of geomembrane bags constitute ladder for energy dissipation Flexible Lining Stepped Spillway, this paper attempts using VOF method and RNG k-ε model as the way to simulate this spillway water flows in and compared the simulation results with the experimental results, found that the two basically similar, and the overall trend is consistent description using the above method to approximate simulation of flexible stepped Lining spillway flow characteristics is feasible. In the same flow with gradient case, contrast geomembrane bags tilt-up position, the formation of steps and horizontal step formed two programs under the numerical simulation results and found that tilt upward placement programs chute end of the average velocity is small, the relative energy dissipation rate higher. In the test data, based on the paper discusses evaluation of the absolute energy dissipation rate formula applicability, and soup up before sliding energy dissipation rate formula was amended proposed correction formula, corrected results are more close to the actual energy dissipation rate; discussion Luo Kai north velocity formula Aeration influence coefficient K, with test data curve fitting, at 30 ° lt; θ lt; 60 °, 0.72 lt; dc / T lt; 7.2 under the conditions given K value estimation formula.

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CLC: > Industrial Technology > Hydraulic Engineering > Water control,hydraulic structures > Discharge structure > Riparian discharge structure > Spillway
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