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The Experimental Study on the Hydraulic Characteristics and Measurement about U-Shaped Channel

Author: GaoYang
Tutor: LvHongXing
School: Northwest University of Science and Technology
Course: Agricultural Soil and Water Engineering
Keywords: U-shaped channels Velocity distribution Turbulent characteristics of Buoy stream
CLC: TV133
Type: Master's thesis
Year: 2011
Downloads: 35
Quote: 1
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Abstract

Natural river, the flow of water in the irrigation canal system are turbulent, it is a fairly complex flow phenomena. Many scholars sink and field trials, the turbulent motion law of exploration and research. Cross section due to the complexity of the turbulence structure and over the water, the variability of the rough form of simple open channel flow, its description of the flow is still not perfect. In the actual project, U-shaped channels in our major irrigation district wide range of applications, but the velocity distribution and turbulence characteristics of the U-shaped channel cross section is still in the development stage, the cross-sectional flow measurement technology there are many basic research issues to be resolved. The U-shaped channels as the main object of study designed by the U-shaped channel cross section flow rate and buoys sidestream technology research, the U-shaped channel cross section of the velocity distribution formula and different degree of filling buoy flow formula. Were selected Nuotai Ke Vectrino small Veyron ultrasonic flow meter can accurately observed the three-dimensional flow rate of the water in the measuring point, so you can better analyze the three-dimensional turbulent characteristics of the U-shaped channel. Through the work of this study, the following main conclusions: 1.U shaped channels in the velocity distribution of the vertical line on both sides of roughly symmetrical equal to the maximum flow rate below the free surface in the vertical; close to the side wall at a flow rate of contour maps approximate contour in the side wall; decreased with the increase of water depth, the maximum flow rate points relative position; sectional maximum flow rate occurs below the surface of the water, the flow rate contours bend to the channel center in close proximity to water, with water depth greater the change more obvious. Dimensionless relative velocity u / v, and the relative depth y / H between good quadratic function, and determine the coefficients a, b, c in the different regions by the main factors affecting its corresponding determination function. 3 transverse velocity distribution in accord with the exponential function distribution, to obtain the correlation and the relative velocity v / VM, and the relative position 2z / B between the coefficients m, N of the variation range. By lateral velocity distribution generalizability analysis to determine the function of the U-shaped channel between the average vertical velocity and the average velocity in the horizontal correction factor kh. The three-dimensional fluctuating velocity probability distributions are in line with the normal distribution in the form. Regardless of the position of the measuring point, the horizontal velocity probability distribution is most concentrated. The frequency curve of the three-dimensional velocity at the probability distribution of the free turbulent area relatively close to the shear zone in the near-wall strong relative deviation is relatively large. From the surface to the bottom, a concentrated area of ??the longitudinal fluctuating velocity was first increases and then decreases variation, no significant changes in the horizontal and vertical fluctuating velocity concentrated area. The turbulence intensity along the vertical basic triangular species distribution, longitudinal and vertical maximum turbulence intensity down near the free surface area. Relative turbulence intensity and turbulence intensity distribution approximation only longitudinal relative turbulence intensity values ??near 0. 6. Longitudinal vertical Lei Nuoqie stress the y / h lt; 0.5, the sudden increase in the phenomenon of sudden reduction occurs. The the horizontal Reynolds shear stress basic linear distribution, through horizontal Reynolds shear stress friction velocity and uniform flow formula friction velocity is quite different. 7. Obtained through the analysis of the degree of filling of different buoys, buoys submerged depth increases, the virtual traffic will also increase accordingly. Different filling degrees next buoy measured stream flow formula.

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