Francis turbine or francis pump or francis pump turbine

Abstract

The invention relates to a Francis turbine or other machine built according to the Francis principle; with an impeller having rotor blades; with a volute housing that surrounds the impeller; with a traverse ring comprising a number of traverses; with an inner rotor blade ring having larger traverses, which is arranged downstream of the traverse ring. The invention is characterised by the following features: suggested is an outer rotor blade ring that is arranged upstream of the traverse ring; a part of the traverse ring extends with larger traverses over a part of the circumference of the impeller, beginning at the start of the volute, and a part of the traverse ring extends with smaller traverses over the broader circumference of the impeller as far as the end of the volute.

Description

Technical field [0001] The invention relates to a Francis water turbine or Francis pump or Francis water pump turbine, in particular to a guiding device of such a water turbine, which is used to transport water to an impeller. Background technique [0002] For hydraulic turbines such as Francis turbines, higher and higher requirements are put forward in terms of efficiency and the widest possible scope of work. It is expected that the water flow can be variably applied from extreme partial load operation to overload operation. In all load ranges, the highest possible efficiency should be achieved in the vibration-free operation of the turbine. [0003] Francis turbines can adapt to different operating conditions by adjusting the guide blades. However, particularly unstable flow conditions under partial load can cause strong machine vibration. Especially when the natural frequency of the component is consistent with this kind of vibration, material damage will occur. For large m...

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Problems solved by technology

However, the spiral shell is not ideally rotationally symmetric

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