WO2010024686A1

WO2010024686A1 - Water turbine and turbine blades

Info

Publication number: WO2010024686A1
Application number: PCT/NO2009/000296
Authority: WO
Inventors: Terje Dyrstad; Hilmar Tollefsen
Original assignee: Rovas As
Priority date: 2008-08-22
Filing date: 2009-08-24
Publication date: 2010-03-04
Also published as: NO20083626L; NO329157B1

Abstract

The invention relates partly to an arrangement for a turbine wheel, where, at the circumference of a carrier flange (13) carried by a turbine hub (11), are arranged turbine blades (15), in particular Pelton blades, each having an protruding pair of legs (27, 28) which cooperates with the edge of the carrier flange (13), where the turbine blades are connected to the carrier flange by axially protruding bolts (16); and partly to a blade for a turbine wheel comprising of a single or a double cup portion (23, 24) being integrated with a pair of fastening legs (27, 28) being equipped to be mounted on the rim of a carrying flange (13) in a turbine wheel; where the stay (38) between the fastening legs (27,28) are equipped to make up a contacting plane against a protrusion (17) outranging at the edge of the carrying flange (13) and that it is manufactured from a plastics or a composite material comprising a plastics.

Description

WATER TURBINE AND TURBINE BLADES

This invention relates to a water turbine according to the ingress of claim 1, and blades or cups for such a water turbine.

More specific, this invention relates to an arrangement of turbine wheels, to where there along the circumference of a carrier flange on the turbine centre, are arranged turbine blades, in particular Pelton blades or cups, each with a protruding pair of legs cooperating with the rim of the carrying flange, where the blades of the turbine are fastened onto the carrying flange by axially passing bolts.

Further this invention comprises a turbine blade having a single or double cup-shaped section integrated with a pair of fastening legs adapted to be mounted to the rim of the carrier flange of a turbine wheel.

BACKGROUND

It is prior known to produce turbine wheels of the category Pelton turbines, having a carrying flange on a turbine wheel hub, where there along the circumference are mounted a series of turbine blades made of metal or plastics, or possibly of plastic composites. The turbine blades used to have a pair of protruding legs arranged alongside the edge or rim of the carrying flange and fastened onto the same by axially stretching bolts.

Increased use of small power stations has lead to an increasing interest in optimising water turbines for such small power stations, both related to the efficiency, the erection costs, the wear resistance, and other parameters important for the working capacity and accordingly the over all stability and economy.

Among measures taken, are methods for producing blades for such water turbines from plastics. Use of plastics as material in such blades provides great flexibility concerning the design of the details, to be inside acceptable economic limits. Additionally, the selection of such materials result in possibilities of reduced production time, and the possibilities of maintaining a good storage capacity of extra blades, will also reduce the total costs during a stop in the manufacturing process, repair work and maintenance of the turbine wheels, is accordingly reduced. Accordingly, it is prior known to produce turbine wheels for Pelton turbines having blades of metal or plastic with a protruding pair of legs fastened at the edge or rim of a carrying plate.

When the blades are made of metal, this structure is usually acceptable. However, when the blades are made out of plastics, this structure will not result in an acceptable strength.

From Norwegian Patent No. 322857 there is prior known a turbine wheel having blades of metal. In this solution, the integration of the turbine blades and the hub portion of the turbine wheel have not been adapted for use with blades of plastics or of a composite plastic material.

OBJECTS OF THE INVENTION:

The main object of this invention is to obtain a turbine blade, in particular for a Pelton turbine, having an increased strength in the integrated connections compared to prior art turbine wheels.

A still more specific object is to enhance the power transmission between the blades and the carrier flange, so the blades can be shaped from plastics in larger dimensions, or probably by using a reduced amount of material to prior art blades of plastics.

Further, it is an object to arrange the integration of the blades and their carrying flange in such a manner that the mounting and replacement may take place for one blade at the time, as previously described.

In addition it is an object of the invention to obtain a turbine wheel or a blade (or cup) which may be less time consuming when it comes to finishing treatment or polishing of the final shape. It should preferably be possible to treat the carrier flange by data-controlled cutting e.g. by shaping or welding the blades in a blade manufacturing process, preferably directly from plastics in such a manner that the product may be ready for use with a minimum of finish to complete the treatment processes.

The invention relates to a turbine wheel as described in the claim 1, and a turbine blade as stated in the claim 5. The invention is distinctive as the bearing flanges are provided by protruding carrier dogs, preferably one for each of the turbine blades, as the blades are arranged to make contact with each of the element's contacting surfaces.

It should be especially beneficial if the contacting surfaces of the carrier dogs have a generally radial stretching contacting face.

The carrier dogs are preferably pointed towards their free ends, and these ends may be covered by a carrying rib behind the front side of the turbine blades. This design may give advantageous streaming conditions in the turbine wheel.

Each of the turbine blades are fixed by a fixing bolt as the pair of legs represents a connecting plane facing towards next adjacent pair of legs.

The turbine blade is arranged in such a manner that the traversing stay between two fastening legs make up a contacting plane turning towards a protruding end portion arranged close to the edge of the carrying flange.

It is particularly advantageous if there, at the trailing end facing towards the next adjacent blade, are arranged two pairs of strengthening ribs. These strengthening ribs may preferably be shaped as prolonged portions of the fastening legs.

The fastening legs may be pointed at app.18 degrees and may be designed to completely seal towards the row of blades.

AN EXAMPLE:

Below the invention is a more detailed description with reference to the figures, in which

Fig. 1 shows a partly split perspective view of a turbine wheel designed in accordance with the invention; Fig. 2 and 3 represent perspective views from two sides, of a turbine blade designed in accordance with the invention.

The turbine wheel in the Fig. 1 comprises a tube shaped hub 11 intended to connect the hub to the generator axes, equipped with an end flange 12 carrying a circular ring shaped plate 13, below named as a "carrying flange". The working connection between the end flange 12 and the carrying flange 13 in this example is obtained by a number of axially arranged bolts 14.

The carrying flange 13 is arranged for mounting of a number of turbine blades 15, in this example in the number of 20, each covering a sector of 18 degrees of the turbine wheel's circumference. The turbine blades 15, which will be more closely described with reference to alternative embodiments shown in the figs 2 and 3, are fastened to the carrying flange 13 by a screwing bolt 16 for each of the turbine blades 15.

At the circumference of the carrying flanges close to each blade 15 there is arranged a protruding follower 17 having a generally radial adjacent flange 18 facing towards the next adjacent turbine blade 15 with a back 19 at a small angel to the supporting flange 18. The function of the supporting flange 18 and the follower 17 will be better understood from the following description of the turbine blade 15.

The space 20 between a supporting flange 18 and the back plane of the subsequent follower 17, gives the possibility to mounting of a turbine blade. The bottom 21 of the space 20 defines an angel to the circumference that corresponds to the next backside of the turbine blade 15, as described below. At the back end (related to the rotation direction), a step 22 is arranged.

The turbine blades 15 are preferably produced from plastics, possible from a combination of plastic and fiber reinforcement, or a similar composite material comprising a plastic content.

The Figs 2 and 3 each represent an example of a turbine blade according to the invention. The turbine blade 15 can have a basic shape including a main portion comprising a double-cup 23, 24 (a split bucket) in which each portion 23 24 of the bucket, where the two portions are integrated along a linear egg shaped barrier (partition) 25. The internal portion 26 of this barrier (25) is designed to seal against the step 22 of the carrier flange 13.

The two blade parts 23 24 both have at the internal end two legs 27 28 protruding parallel to the plane of the cup openings at an angle of 18 degrees in the plane of the carrier flange towards the free end, straight side walls and with an opening 30 between the legs 27 28 corresponding to the thickness of the carrier flange 13. Through the legs 27, 28 there is a hole 32 that corresponds to a hole 33 in the carrying flange 13 (Fig. 1) made for inserting a screwing bolt 16. At the outer end of the legs 27 28 they pass into a supporting rib 34 which curves similar to the curving of the bottom and the blades, and leads the water jet line to the next adjacent blade.

The outwardly turning blade profile between the legs 27 28 has an end wall portion 38 designed to contact the followers' 17 contact plane 18. Accordingly, this contacting plane will transfer power from the turbine blades 15 to the carrier flange and accordingly cause the generator or a different rotational machine to be activated.

Accordingly the outwardly facing cup brim or sidewall 39 between the legs 27 28 will make contact with the space or the bottom 21 between the two followers 17.

On the trailing edge of turbine blade a rib 40 is arranged, that at the mounted blade 15 will be situated in the prolonged portion of the corresponding follower 17. The rib 40 stretches towards the inflow edge 41 of the blades.

On the backside of the blade there is in connection to the prolonged ribs 34 arranged a pair of reinforcement ribs 42 43 having their outer ribs facing towards the adjacent blade. The reinforcement ribs 42 43 make up a prolongation of the fastening legs 27 28.

Claims

1. Arrangement for a turbine wheel, where there at the circumference of a carrier flange (13) carried by a turbine hub (11) are arranged turbine blades (15), in particular Pelton blades, each having an protruding pair of legs (27, 28) which cooperates with the edge of the carrier flange (13), where the turbine blades are connected to the carrier flange (13) by axially protruding bolts (16), characterized as/by/What characterizes this is that

The carrier flange (13) is provided with protruding followers (17) preferably one for each turbine blade (15), as the turbine blades (15) are adapted to contact the contacting face (18) of the followers (18) and that the turbine blades (15) are manufactured from plastics or a composite material including plastics.

2. Arrangement in accordance with claim 1, characterized by that the followers (17) are provided by a generally radial extending contacting plane (18).

3. Arrangement in accordance with claim 1, or 2, characterized by that the followers (17) are pointed towards the free end (37), and that this end is covered by a controlling rib (40) behind the turbine blades' input edge (41).

4. Arrangement in accordance with claim 1, 2, or 3 characterized by that each of the turbine blades is fastened by a fastening bolt (16) as the pair of legs (27,28) provides a contacting face towards the adjacent leg.

5. A blade for a turbine wheel comprising a single or a double cup portion (23, 24) being integrated with a pair of fastening legs (27, 28) being equipped to be mounted on a rim of a carrying flange (13) in a turbine wheel, in accordance with one of the claims 1 - 4, characterized in this that the stay (38) between the fastening legs (27,28) is equipped to make up a contacting plane against a protruding follower (17) at the edge of the carrying flange (13) and that it is manufactured from a plastics or a composite material comprising a plastics.

6. A blade according to claim 5, characterized in this that it is manufactured from polyethylene or from a composite material with polyethylene and a reinforcement.

7. A blade according to claim 5 or 6, characterized in this that there at the backside of the blade are arranged a pair of strengthening ribs (42, 43) having an egg shaped outer edge turned towards the adjacent blade.

8. A blade according to claim 7, characterized in this that the strengthening ribs (42, 43) represent an elongation of the fastening legs (27, 28) over the ribs (34) there between.

9. A blade according to one of the claims 5 to 8, characterized in this that the fastening legs (27,28) are pointing at an angle of appr. 18 degrees to a centre line, and that they are shaped to seal tightly along the series of blades.