Patent ID: 8726651
Filing Date: 2014-05-20
Classification: F03B,F05B,Y02E

Abstract:
1. A method for operating a hydropower plant comprising the steps of: exposing a submerged water turbine to a wafer flow in a watercourse such that the water turbine rotates at a speed in a range of 0.5-50 rpm, the water turbine having a plurality of vanes extending in parallel to a rotational axis of the water turbine and connected to a shaft of the turbine via arms; and providing a grating adjacent to the water turbine to prevent objects from flowing in the water from reaching the turbine, wherein the grating is configured to guide the flow in the water current such that the velocity of the water between the grating and the water turbine becomes non-uniform, such that the mean velocity of the water reaching the first half is larger than the mean velocity of the water reaching the second half, and such that the velocity profile of the water reaching the water turbine has a maximum in the water tangentially reaching said first half and a minimum in the water tangentially reaching said second half, wherein the grating includes a plurality of bars forming gaps between each other, the cross section of a bar perpendicular to the longitudinal extension thereof having a length defined as the distance between a nose point where the water flow reaches the bar and a tail point where the water flow leaves the bar, having a bar width measured perpendicular to said length, and having a guiding direction defined as the direction of said length, wherein the gaps between the bars of the grating are substantially smaller than a tangential distance between adjacent vanes of the water turbine, and wherein the grating varies with respect to at least one of the parameters; said length, said width, said guiding direction, the area of said cross section, and the profile of said cross section such that said at least one parameter varies from one bar to another for at least some bars, and such that said at least one parameter varies along the longitudinal extension of one bar.