Mixed-flow type water turbine for increasing survival rate of fishes

Abstract

The invention relates to a novel mixed-flow type water turbine for improving the fish-passing capability of the water turbine, wherein a smaller quantity of vanes is adopted to increase the length of the vanes and increase the size of a flow passage so as to maintain the same capacity and electricity-generating quantity; the wing shape near an upper crown is the negative curvature, a runner-vane inlet is thicker, the cross section is of a fish-shaped structure, and the ratio of the smallest thickness to the largest thickness of the wing shapes for the vanes is 0.2 to 0.3 so as to reduce the phenomena of cavitation corrosion and water-flow separation generated on a high water-head lower inlet edge and improve the passing safety conditions of the fishes; and the distance between a movable guide vane and a runner vane is increased so as to decrease the probability of suffering frictional damage of the fishes between the tail edge of the guide vane and a runner. According to the invention, the same capacity can be maintained under the condition of decreasing the quantity of the vanes, the flowing state of the flow passage is improved to minimize the cavitation corrosion, and the survival rate of the fishes passing the water turbine is increased on the premise of ensuring the electricity-generating efficiency as 90 percent.

Description

technical field [0001] The invention relates to a Francis water turbine, in particular to a Francis water turbine which increases the survival rate of fish by improving the design of the flow channel. Background technique [0002] Fish passing through turbines are susceptible to various forms of stress that can cause high mortality. Such stresses include the possibility of impingement by moving or stationary parts of the turbine (guide vanes, blades and vanes), sudden acceleration or deceleration and sudden changes in pressure. For the research on the damage mechanism of fish passing through the turbine, foreign countries (such as the United States, Canada, Sweden, the Netherlands, Germany and France) mainly use young salmon as the research object, and test the survival rate of young salmon under different operating conditions of the turbine. Mortality of smolt in the case of Francis turbines varied from less than 5% to more than 95%, with smolt mortality mainly due to the ...

AI Technical Summary

Problems solved by technology

At present, domestic water conservancy projects have given little or no consideration to the measures to help fish descend. As a result, fish, especially some rare fish species, have been injured or even killed in the water turbine flow channel, causing damage to fish resources. , During the operation of the Three Gorges Hydropower Station, there was an incident in which the Chinese sturgeon strayed into the flow channel of the water turbine and died, which caused a great loss to the rare Chinese sturgeon resources.

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