Draft tube
As the suction tube from the water downstream -carrying area of a hydropower plant is referred to in hydraulic engineering, extending from the turbine to the free underwater.
Description
Two kinds of tasks does the intake manifold ( action as a diffuser ), called for larger systems as a Suction hose:
- Ensure the utilization of the height difference from underwater transom height and height impeller outlet (static suction lift )
- Energy recovery from one part of the height of the exiting speed of the turbine water is realized by a continuous widening of the flow cross -section (dynamic suction)
In particular, the arrangement of a Saugrohrers in low-pressure systems and equipment is carried out with high-speed turbines to achieve an increase in efficiency. Also to be reduced by a gradual transfer free as possible expansion of the cross section of the intake manifold the risk of cavitation. Due to the high risk of cavitation in the connection to the turbine, the suction hose runs armored in this area. Furthermore, a reduction in costs by eliminating expensive formwork can be achieved by the use of a steel lining in the bend region. A critical area represents the transition from the armored part of the structure to the concrete-made represents the design of the suction pipe or suction hose is taken for the basis of model experiments, on the other hand, with the aid of computational models. An optimal matching of the components Sprialgehäuse, diffuser, turbine and vacuum hose ensures economical operation and minimizes the risk of the occurrence of cavitation considerably. The underwater conditions and their effect on the flow in the suction hose require special consideration when planning.