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Numerical Simulation of Low-Pressure Pipe Irrigation Forebay Self-Discharge Desilting Basin Flow Field

Author: ZuoZhiChao
Tutor: ZhangYaoZhe
School: Northwest University of Science and Technology
Course: Hydraulics and River Dynamics
Keywords: Low-pressure pipe Vertical velocity Free surface Starting velocity
CLC: TV135
Type: Master's thesis
Year: 2010
Downloads: 91
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Abstract

Irrigation sediment problems that hinders the development of irrigated agriculture is one of the main factors, since a large settling basin Irrigation District canal headworks near a lot of land has been brought siltation or accumulated sediment disasters become more evident, the sediment of the whole Irrigation will become zero dispersion treatment an effective way to solve the problem of sediment. Low self-discharge pipeline forebay sedimentation basin in concept with limited head difference as a means of settling basin dredging has some prospects. To make this design philosophy applied to practical, low-pressure water pipelines from the row forebay sedimentation basin as a practical technique to further promote the need for research on various design parameters demonstration. Papers sediment problems in previous research on irrigation, based on the traditional scheme for the use of large sediment settling basin for irrigation centralized processing the problems and shortcomings, demonstrated in the irrigation canal system under the premise of sediment transport over long distances will Irrigation of sediment entering the necessity of decentralized distributed processing, and using theoretical analysis and numerical simulation method, the low-pressure pipeline from the row forebay sedimentation basin water flow field of research, has achieved initial results . First, since the low-pressure water pipelines forebay sedimentation basin upstream from the row directly with the general field channels that branch or Maoqu phase, support, distribution of flow velocity within Maoqu directly affect the flow field settling basin, so based on the settling Cell inlet flow conditions to further knowledge and understanding, the paper within the channel flow velocity field distribution was studied in order to import settling basin flow boundary conditions provide the basis for determining, through theoretical derivation, calculation of field channels to obtain a vertical velocity the distribution of new methods for the development and improvement of the theory provides a new idea. Secondly, the paper under different hydraulic pressure pipe geometry from the row sedimentation basin sedimentation conditions of the water flow field numerical simulation analysis, the settling basin of the relevant design parameters such as flow adjustment plate number, adjust the flow plate position, settling bottom slope were studied, through settling tanks flow field characteristics, turbulent kinetic energy and its dissipation rate distribution, flow lines and other aspects of comparative selection trajectory analysis, has been given the scale and head overcurrent conditions settling basin flow adjustment plate arranged the best solution, that number is a flow adjustment plate, the position after the transition section located at 1m, settling bottom slope is m = 1:2, the optimum flow settling tanks. Third, the low-pressure pipe from row forebay settling basin biggest feature is its ability to take advantage of the pool water and head for automatic flushing, replacing manual or mechanical dredging silt dug. Automatic flushing rely on settling tanks steep bottom slope, the pool water gravity, optimum flow conditions and from the combined effect of spin devices silt discharge outside the pool. Numerical simulation analysis of the preliminary results indicate that sediment conditions when settling tanks silt flow velocity can reach critical starting average velocity, indicating that the low-pressure pipe forebay sedimentation basin since the row with automatic flushing feasibility.

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