Suction pipe (hydraulic engineering)
As a suction pipe or suction hose in is Hydraulic the downstream-carrying water from the area of a hydroelectric power plant referred to, which extends from the turbine to the free underwater extends.
description
In its effect as a diffuser, the suction pipe fulfills two tasks:
- Utilization of the height difference from the underwater level and the height of the impeller outlet (static suction height)
- Energy recovery from part of the speed of the water exiting the turbine, realized by a continuous expansion of the cross-section through which the flow passes (dynamic suction lift)
In particular, a suction pipe is arranged in low-pressure systems and systems with high-speed turbines in order to achieve an increase in efficiency. Likewise, the risk of cavitation is to be reduced by a gradual expansion of the cross section of the suction pipe that is as detachable as possible. Due to the high risk of cavitation following the turbine, the suction hose is armored in this area. Furthermore, by using steel armor in the elbow area, a cost reduction can be achieved by eliminating complex formwork. A critical area is the transition from the armored structural part to the one made of concrete. The dimensioning of the suction pipe or suction hose is based on the one hand on model tests and on the other hand with the aid of computational models. Optimal coordination of the volute casing, diffuser, turbine and suction hose components ensures economical operation and considerably reduces the risk of cavitation. The underwater conditions and their effect on the flow in the suction hose also require special consideration when planning.
Types of suction pipes
- Straight suction pipe
- Preferred use for turbines with a horizontal shaft such as B. Bulb turbines, circular conical or bell-shaped cross-section, slight curvature in the inlet, high diffuser efficiency, increased risk of cavitation
- Elbow or knee suction tube
- Use in machine sets with a standing wave, curvature of approx. 90 °, oval or rectangular cross-section merging into a rectangular cross-section, lower diffuser efficiency, lower sensitivity to cavitation
- Extension or spreading suction pipe
- to recover the outlet swirl on the impeller
Individual evidence
- ^ A b Strobl T., Zunic F .: Hydraulic engineering, current basics-new developments. Springer-Verlag, Berlin Heidelberg New York, 2006, ISBN 3-540-22300-2 .
- ^ A b Giesecke J.; Mosonyi E .: Hydropower plants, planning, construction and operation. Springer-Verlag, Berlin Heidelberg New York, 2005, ISBN 3-540-25505-2 .