The principle of fixed overflow weir is mainly based on the weir flow phenomenon, that is, after setting a barrier (weir) in an open channel, the water flows over the top of the barrier and overflows. Fixed overflow weir is a common hydraulic structure, mainly used to control water flow, such as flood control, irrigation, shipping, power generation, etc. It sets a fixed overflow height so that when the water level exceeds this height, the water flow can smoothly overflow the weir top and continue to flow.
Overflow: When the upstream water level rises to exceed the weir top of the fixed overflow weir, the water flow begins to overflow the weir top and flow down along the weir surface. In this process, the water flow is resisted by the weir surface, the flow rate gradually decreases, and the direction of the water flow also changes.
Flow Control: Fixed overflow weir controls the flow by setting different weir top heights. When the upstream water level is low, the water flow will not overflow the weir top, but continue to flow through other channels or pipes. When the upstream water level rises to exceed the weir top, the water flow begins to overflow and flow down through the weir surface. Therefore, by adjusting the height of the weir top, the flow rate can be precisely controlled.
Energy conversion: During the overflow of water, part of the kinetic energy of the water flow is converted into potential energy, and the water flow is also subject to certain resistance. In this process, the energy of the water flow is converted and consumed to a certain extent, thereby realizing the control and regulation of the water flow.
Types: Fixed overflow weirs can be divided into many types according to their shapes and uses, such as thin-walled weirs, wide-top weirs, etc. Each type of fixed overflow weir has its specific application scenarios and advantages and disadvantages.
Features: Fixed overflow weirs have the characteristics of simple structure, easy maintenance, and precise flow control. At the same time, it can also adapt to different water flow conditions and water level changes to ensure that the water flow remains stable and orderly during the overflow process.
Fixed overflow weirs are widely used in water conservancy projects, urban drainage systems and other fields. For example, in water conservancy projects, fixed overflow weirs can be used to control the discharge of reservoirs and ensure that the reservoirs operate below safe water levels; in urban drainage systems, fixed overflow weirs can be used to regulate the peak flow of rainwater runoff and reduce the size and construction cost of downstream rainwater dry ditches.
