US-20260126026-A1 - Self-Cleaning Stator for Water Turbine

US20260126026A1US 20260126026 A1US20260126026 A1US 20260126026A1US-20260126026-A1

Abstract

A turbine suitable for micro hydro turbine applications provides a stator with a self-cleaning front edge employing one or a combination of a rotating surface and guillotine cutter, the self-cleaning front edge allowing larger upstream gratings for improved net water flow.

Inventors

Vito R. Gervasi
Randal Mueller
Bruno Patrice-Bernard Lequesne

Assignees

Cadens, LLC

Dates

Publication Date: 20260507
Application Date: 20250813

Claims (14)

1 . A self-cleaning fluid flow structure comprising: a fluid flow channel along a fluid flow axis; a submerged component positioned within the fluid flow channel, said submerged component having at least one leading edge that obstructs the fluid flow; and wherein the leading edge of the submerged component provides a rotating surface about a rotational axis crosswise to the fluid flow axis.
2 . The self-cleaning fluid flow structure of claim 1 wherein the submerged component is a stator of a turbine, the stator providing a set of blades engaging fluid in the fluid flow channel to provide an axial swirl to the fluid, the turbine having a plurality of blades rotatable about the axis receiving the fluid after the stator.
3 . The self-cleaning fluid flow structure of claim 2 wherein the leading edge of the stator is a rod rotatable about the rotational axis.
4 . The self-cleaning fluid flow structure of claim 3 further including an actuator rotating the leading edge of the blade of the stator about the rotational axis during a first time interval and to hold the leading edge of the blade without rotation about the rotational axis during a second time interval.
5 . The self-cleaning fluid flow structure of claim 4 further including a controller controlling and switching between the first time interval and second time interval according to a measurement of the output of said turbine.
6 . The self-cleaning fluid flow structure of claim 4 further including a controller controlling and switching between the first time interval and second time interval according to flow conditions.
7 . The self-cleaning fluid flow structure of claim 4 further including a controller controlling and switching between the first time interval and second time interval according to a combination of a measurement of the output of said turbine and of flow conditions.
8 . The self-cleaning fluid flow structure of claim 3 wherein the rod includes a first circumferential portion having a surface roughness less than a second circumferential portion, wherein the first circumferential portion is adapted to allow debris to slide off of the first circumferential portion and the second circumferential portion is adapted to grip debris and wherein the actuator positions the first circumferential portion at the leading edge of the blade of the stator during the second interval.
9 . The self-cleaning fluid flow structure of claim 1 further including a cutter movable along the leading edge of the blade and providing a knife having a knife edge for engaging and cutting material draped over the leading edge of the blade.
10 . The self-cleaning fluid flow structure of claim 9 wherein the leading edge of the blade provides a notch extending along the rotational axis receiving a portion of the knife edge within the notch to pass under debris draped over the leading edge.
11 . The self-cleaning fluid flow structure of claim 10 further including a controller for periodically moving the cutter along the leading edge of the blade according to at least one of a measurement of the output of said turbine and flow conditions in the channel.
12 . The self-cleaning fluid flow structure of claim 2 further including a grating positioned upstream from the stator to prevent a passage of debris.
13 . The self-cleaning fluid flow structure of claim 2 further including an electrical generator rotatably communicating with the turbine.
14 . A self-cleaning fluid flow structure comprising: a fluid flow channel along a fluid flow axis; a stator providing a set of blades engaging fluid in the fluid flow channel to provide an axial swirl to the fluid; a turbine rotatable about the axis receiving the fluid after the stator and having blades to extract rotated energy therefrom; and wherein a leading edge of the blades further includes a cutter movable along the leading edge of the blade and providing a knife having a knife edge for engaging and cutting material draped over the leading edge of the blade.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. provisional application 63/775,403 filed Mar. 21, 2025, and U.S. provisional application 63/686,239 filed Aug. 23, 2024, both hereby incorporated by reference. BACKGROUND OF THE INVENTION The present invention relates to hydroelectric generators and pumps and in particular to a stator for turbines used in such applications and resistant to fouling from debris such as vegetation and trash. There is a considerable amount of available, but so far unused, energy at US non-power dams in rivers and streams and at canal drops in man-made water channels. Many of these sites are suitable for small capacity micro hydro systems, typically with 15 feet or less of head and generating 1000 kW or less. In such systems, the water is driven towards a turbine consisting of stationary and/or rotating blades, the turbine shaft being connected to typically an electrical generator. Debris from the waterways can thus float towards the turbine blades, occasionally becoming entangled with the turbine or other related, submerged components such as support structures for radial bearings or shaft sleeves. This is a significant issue for a turbine or propeller of any size operating in any water, be it rivers, seas, or man-made canals and conduits as it reduces the system efficiency, and, in more extreme cases, can stall the turbine. But this is a particular challenge for smaller systems. The modest pressures and water flow at these sites can present a problem from debris such as trash and vegetation such as milfoil, leaves, and twigs, as well as man-made material (plastic bags, for instance) that can collect on the turbine components. Aside from the turbine itself, the energy-producing unit may include ancillary stationary submerged elements, such as support structures for radial bearings or shaft sleeves. The system can also include a sediment passage intake, with submerged supports, which may also get clogged by debris. In sediment passage intakes, particularly those designed for ecological purposes, a significant challenge arises from the accumulation of natural debris such as leaves, twigs, and other vegetation. This debris can become hung up on the leading edges of intake structures, leading to reduced water flow, decreased efficiency of sediment or fish passage, and in severe cases, complete blockage of the intake. Such blockages can compromise the intended environmental benefits and necessitate costly and frequent manual clearing, especially in remote locations. Screens or gratings placed upstream from the turbine can be used to block or deflect such debris; however, the necessary small opening size in such gratings, needed to remove threadlike debris that can accumulate on the turbine, can significantly reduce water flow and creates an additional burden in cleaning the grating. SUMMARY OF THE INVENTION The present inventors have recognized that threadlike small debris can often pass cleanly through the turbine allowing the grating size of any upstream filtration to be relatively coarse. This type of debris, however, presents a problem primarily when it drapes over the turbine stator in such a way that it is retained by balanced water pressure on each side of the debris. Accordingly, in one embodiment, the invention destabilizes this balanced debris through the use of a rotating leading-edge which urges the debris into an unbalanced configuration where water pressure removes it from the stator. This rotating edge may be combined or replaced with a mechanism such as a guillotine serving to cut the debris to disrupt the balancing and stabilizing forces of water pressure on the debris. More specifically, in one embodiment, the invention provides a self-cleaning turbine having a water flow channel along a water flow axis and a stator providing a set of blades engaging water in the water flow channel to provide an axial swirl to the water. A turbine is positioned to rotate about the axis and to receive the water after the stator and has blades to extract rotated energy therefrom. A leading edge of the blades of the stator along the axis provides a rotating surface about a rotational axis crosswise to the water flow axis. It is thus an object of the invention to provide a mechanism for destabilizing debris trapped on the leading edge of the stator. The leading edge of the stator may be a rod rotatable about the rotation axis. It is thus a feature of at least one embodiment of the invention to provide a simple implementation of a moving edge that can be readily fit into a stator blade. The self-cleaning turbine may include an actuator rotating the leading edge of the blade of the stator about the rotational axis during a first time interval and holding the leading edge of the blade without rotation about the rotational axis during a second time interval. In some cases a controller may control a switching between the first time interval and second time in