US-12624676-B2 - Bucket of a Pelton turbine

US12624676B2US 12624676 B2US12624676 B2US 12624676B2US-12624676-B2

Abstract

A bucket of a Pelton turbine with an outlet edge curved at least in segments. To achieve a particularly high efficiency the outlet edge forms a rear hump in a side view, wherein a center of curvature of the hump is positioned below the outlet edge in the side view and a peak of the hump is located closer to the cup base than to the bucket face.

Inventors

Gervais NICOLAS
Loic ANDOLFATTO

Assignees

ANDRITZ HYDRO GMBH

Dates

Publication Date: 20260512
Application Date: 20230320
Priority Date: 20220607

Claims (9)

1 . A bucket of a Pelton turbine with an outlet edge curved at least in segments, wherein the outlet edge forms a rear hump in a side view, wherein a center of curvature of the rear hump is positioned below the outlet edge in the side view and a peak of the rear hump is located closer to a cup base than to a bucket face, wherein the rear hump protrudes past a center splitter to a height above the center splitter.
2 . The bucket according to claim 1 , wherein the rear hump extends from the cup base roughly to a center between the cup base and bucket face.
3 . The bucket according to claim 1 , wherein the rear hump comprises a first concave region having a center of curvature that is positioned above the outlet edge in the side view, a second convex region having a center of curvature that is positioned below the outlet edge in the side view, and a third concave region having a center of curvature that is positioned above the outlet edge in the side view.
4 . The bucket according to claim 1 , wherein the bucket further comprises a front hump that is curved at least in segments, wherein a center of curvature of the front hump is positioned below the outlet edge in the side view, and wherein a peak of the front hump is arranged closer to the bucket face than to the cup base.
5 . The bucket according to claim 4 , wherein the front hump has a smaller height than the rear hump.
6 . The bucket according to claim 4 , wherein the outlet edge comprises a concave region between the rear hump and front hump.
7 . The bucket according to claim 4 , wherein the rear and front humps are symmetrically arranged on both sides of a center plane of the bucket.
8 . The bucket according to claim 1 , wherein a center of mass of the rear hump is positioned between the cup base and a center between the cup base and the bucket face.
9 . A bucket of a Pelton turbine with an outlet edge curved at least in segments, wherein the outlet edge forms a rear hump in a side view, wherein a center of curvature of the rear hump is positioned below the outlet edge in the side view and a peak of the rear hump is located closer to a cup base than to a bucket face, wherein the rear hump protrudes past a center splitter, and wherein the rear hump extends from the cup base roughly to a center point between the cup base and the bucket face.

Description

The invention relates to a bucket of a Pelton turbine with an outlet edge curved at least in segments. Pelton turbines have long been part of the prior art and are known in particular from the document CA 32918 A. Whereas initially only buckets with flat outlet edges were used, as described in the document DE 39 38 356 C2 for example, Pelton turbine buckets with curved outlet edges have also been known for some time, in particular from the documents EP 1 386 076 B1 and EP 2 868 912 A1. The objective thereby has always been an improvement in efficiency through a beneficial influence on flow produced by the bucket shape. Accordingly, it is also the object of this invention to specify a Pelton bucket of the type named at the outset with which a particular high efficiency can be achieved. According to the invention, this object is attained by a bucket of the type named at the outset in which the outlet edge forms a rear hump in a side view, wherein a center of curvature of the hump is positioned below the outlet edge in a side view and a peak of the hump is located closer to the cup base than to the bucket face. In the course of the invention, it was found that, in this manner, an outlet height of the water jet can be increased, whereby a better control of the exiting flow is achieved, which in turn results in an increase in the efficiency. The embodiment according to the invention enables the design of innovative bucket profiles with more geometry possibilities in terms of positions, curvatures, and angles in order to: optimize the energy transfer to the runner for a better hydraulic efficiency;optimize the reverse flow of water from the cup, in order to reduce the reverse flow to the nozzles and the runner, and to alter the points of impingement of the water on the nozzles or casing;optimize the thickness distribution in the runner to improve the tension level in the runner;optimize the mass distribution in the runner to improve the dynamic characteristics of the shaft line. A radial inner end of the bucket or of the cup when the bucket is arranged on a Pelton wheel is understood as a cup base, and a radial outer end of the cup in an arrangement of the bucket on the Pelton turbine as intended is understood as a bucket face. The rear hump is thus typically arranged in a radial inner half of the bucket and mostly does not protrude past a pitch circle diameter. In particular, a peak of the hump, that is, a point of the hump at which the hump has a maximum distance from a theoretical flat outlet edge, typically lies radially within the pitch circle diameter. It is beneficial if the hump protrudes past a center splitter. A flat portion of the outlet edge, that is, a region in which the outlet edge in a side view forms an essentially straight connecting line between the bucket face and cup base, can be arranged below the center splitter so that, in a preferred embodiment, the flat edge lies below the center splitter and only the hump protrudes past the center splitter. It has proven effective that a center of mass of the rear hump is positioned between the cup base and a center between the cup base and bucket face. In this manner, a beneficial flow is achieved both in a radial outer region and in a rear region, or a region of the cup that lies radially further inward. Here, the part of the cup which protrudes past a direct, straight connecting line of the cup base and bucket face is understood as the hump. Consequently, the center of mass of this part, which protrudes past the flat edge, is understood as the center of mass. In this case, the statements radial inner and radial outer refer, of course, to a cylindrical coordinate system starting from a rotational axis of the Pelton wheel on which the bucket is arranged, or can be arranged, as intended. It is preferably provided that the rear hump extends from the cup base roughly to a center between the cup base and bucket face. In principle, the hump, which is part of the outlet edge, can be embodied in the most diverse ways. To achieve beneficial flow conditions, it is preferably provided that the hump comprises a first, concave region having a center of curvature that is positioned above the outlet edge in a side view, a second, convex region having a center of curvature that is positioned below the outlet edge in a side view, and a third, concave region having a center of curvature that is positioned above the outlet edge in a side view. Preferably, the rear hump thus comprises two inflection points and, therebetween, a roughly crest-shaped formation, and the first, concave region and the third, concave region tangentially transition into the adjacent edge of the bucket, which consequently typically corresponds in a side view to a straight connecting line of the cup base and bucket face, or a flat edge. Normally, it is provided that the rear bump extends approximately to the cup base, but the cup comprises in the region of the cup base an outlet edge having a heig