A diversion structure for ventilation and air supply facilities in open flow flood discharge tunnels

Abstract

The invention discloses a flow guide structure of a ventilating and air supplementing facility of an open flow flood discharge tunnel. An arc flow guide ridge (7) used for guiding air flow to enter the open flow flood discharge tunnel is arranged at the connecting part between a ventilating and air supplementing facility and the open flow flood discharge tunnel (6), the arc length of the arc flowguide ridge is one fourth arc, and the radius of the arc is determined according to the maximum wind speed in the ventilating and air supplementing facility under the maximum flood discharge flow. Theventilating and air supplementing facility and the open flow flood discharge tunnel (6) are connected through the arc flow guide ridge, the flow direction of the air flow at the connecting part between the ventilating and air supplementing facility and the open flow flood discharge tunnel under the condition of high ventilation and wind speed can be smoothed, local position airflow vortexes are eliminated, the ventilating and air supplementing effects of the ventilating and air supplementing facility are improved, and strong noise generated due to the fact that the local air flows in an adverse flow state is avoided, the operation safety of the flood discharge tunnel of the water conservancy project and the production and living environment of workers are guaranteed.

Description

technical field [0001] The invention belongs to the technical field of flood discharge tunnels in water conservancy and hydropower projects, and in particular relates to a ventilation and air supply facility for open flow flood discharge tunnels. Background technique [0002] In order to meet the needs of flood discharge and emptying projects, large-scale water conservancy projects often need to build discharge structures such as flood discharge tunnels and emptying tunnels. Different from the traditional spillway, the tunnel-type open flow flood discharge tunnel is not directly connected with the atmosphere, so it is often necessary to use ventilation and air supply facilities such as ventilation wells and ventilation air supply tunnels installed at the entrance of the open flow flood discharge tunnel to supplement air into the open flow flood discharge tunnel. If the amount of air supplemented by the ventilation and air supply facilities cannot reach the required air volum...

AI Technical Summary

Problems solved by technology

This kind of structural design form, when the discharge flow of the open flood discharge tunnel is small (less than 2000-3000m 3 / s), when the flow velocity is low (less than 20-30m / s), the water flow in the cave is aerated and the amount of air carried in the margin of the cave roof is small, and the ventilation volume and wind speed in the ventilation and air supply facilities are low. The existing air supply capacity and ventilation noise problems are not outstanding; when the open flow flood discharge tunnel discharge flow is relatively large (greater than 3000m 3 / s), and when the flow velocity is high (greater than 30m / s, even some projects have exceeded 50m / s), the development of high-speed water flow aeration and the significant increase in the amount of air carried in the margin of the cave roof, the operation process of the open flow flood discharge tunnel The amount of supplementary air required in the process increases significantly, which leads to a significant increase in the ventilation volume and wind speed in the ventilation supplementary facilities, which will lead to a huge ventilation noise during operation, which seriously affects the normal production and living order of the project operation staff, especially In large and ultra-large hydropower projects, the existing problems are particularly prominent

The inventor also found in the research that when the flood discharge flow is large and the flow velocity of the flood discharge is high, the required ventilation volume increases sharply, resulting in a significant increase in the air flow velocity in the ventilation and air supply facilities, which will have three adverse effects on hydraulic operation : (1) When the air flows through the right-angle turn area between the ventilation and air supply facilities and the open flow flood discharge tunnel, a streamline turn is generated, and strong vortices are locally generated in some places in the open flow flood discharge tunnel, resulting in strong noise and local low pressure , which seriously affects the safety of the flood discharge tunnel structure. (2) The increase of the air flow rate causes the turbulence in the ventilation and supplementary flow channel facilities to increase, which is accompanied by strong noise during the dissipation process, which leads to a serious deterioration of the production and living environment of the staff. (3) The air flow is very easy to break away from the wall during the right-angle turning process. When the air flow velocity is high, the turning angle of the air streamline is also larger, which will directly impact the free surface of the water flow in the flood discharge tunnel of the open flow, causing serious instability of the free surface and causing the local water flow to "shock". "Cave top" situation appeared, affecting the normal operation of flood discharge

The usual way to solve the above problems is to expand the cross-sectional area of ​​the ventilation and air supply facilities, reduce the wind speed in the air flow channel, thereby reducing the turbulent intensity of the airflow and the vortex intensity of the turning disturbance, but this will not only be affected by the geological conditions of the engineering terrain Restrictions, but also greatly increase the amount of engineering, increase investment

Images