| Research measuring water of irrigation channels is the core of the work of irrigation management, From the economy and stability point of view, the kind of water-measuring facilities are the focus of the existing water-measuring facilities, and has widely promoted value. At present, flow measurement flumes are mainly for rectangular, trapezoidal, U-shaped channel section. To adapt to the way of lining section of majority irrigation channels and management, the paper design a new cut-throat water-measuring flume in view of arc-based trapezodoil canal. Using RNG k-ε turbulence model and VOF approach to the free surface, numerical simulation research on different sizes flume and different bottom slope has been carried out, the paper draws the following conclusions:(1). Combined with parallel computing and efficient computing workstations, you can speed up the efficiency of research and development. Taking parabolic flow measurement flume for example, it proofs that RNG k-ε turbulence model and VOF approach are reliable. The results show that the model can be applied to the flow field simulation of the flume, makes a comprehensive, accurate simulation be possible.(2). Using RNG k-ε turbulence model and VOF approach to the free surface, the paper carries out a comprehensive experimental study the water-measuring flume, and then get out of the water line, regular pattern of the velocity distribution, comparing the calculated flume flow and channel flow, it proves the numerical model can be used to predict the three dimensional flow of flume.(3). By studying the impact of different combinations of structural parameters on the relationship between water level and discharge, the results indicate that contraction ratio and slope of channel have more effect on water flow, With contraction ratio ε decreases and channel size increases, the water measuring flume gradually form a unified flow relationship in the larger scope of the bottom slope.(4). To study the variation of the flow coefficient and flow index under different sizes, the results showed that flow coefficient has increased with channel and flume size increases, flow index is opposite. Flow coefficient, contraction ratio and width of flow measurement flumes have a good relationship. By regression analysis, the error value of the measured flow formula is within 5 percent, which meets the flow measurement requirements.(5). By studying the impact of different combinations of structural parameters on the head loss and Froude number and so on. The results indicate that Froude number is less than 5%, and increases with an increase in contraction ratio, yet has a little change in the bottom slope, the critical flow is happened on the flume outlet section. Head loss accounts for an average of about 7.5 percent of the total head upstream, less than 13% of long-throated flume. The head loss decreases with bottom slope slowing down and increases with contraction ratio decreasing. The critical submergence degree ranges from 0.78 to 0.89, and there is a wide range of free outflow. The backwater height increases with contraction ratio decreasing and decreases with bottom slope slowing down, the different slope and size of the channel which is suitable for the amount of flume to choose has to be analyzed... |
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