US1541657A - Turbine blading - Google Patents

Description

June'9, 1925. 4 1,541,657

0. A. PARSONS. ET AL TURBINE BLADING Filed May 24, 1924 3 Sheets-Sheet l e Fmmms W. GAZQN Q C. A. PARSQNS ET AL TURBINE BLADING Filed May 24, 1924 3 Sheets-Sheet 2 1 M 22 W W2 June 9, 1925. 1,541,657

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9 I f I 9 I Nv Y T0125.- QnARLEs A .PAzsMs Patented June 9, 1925.

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CHARLE$ ALGERNON PARSONS ANDFEANCIS VIII-LIAM. GARDNER, 0F NEWCASTLE; Old-TYNE, ENGLAND; SAID Gl-LRDllEl-lt. .EISSIGNO1ti'lOv SAID PARSONS.

TURBINE Application filed May 24,

T0 aZZ whom it may concern.

Be it known that we, CHARLES A'Lonnnou PARSONS and FRANCIS lVILLIAM GARDNER, both subjects of the King of Great Britain and Ireland, and both residing at Heaton llorlzs, lIewcastle-on-Tyne, in the county of florthumberland, England, have invented certain new and useful Improvements in and Relating to Turbine Blading, of which the "following is a specification.

This invention relates to the blading of turbines.

it is customary in turbines of the reaction type for the blades in the fixed and moving rows to be of the same dimensions and to be spaced. apart by means of suitable distance pieces so that the fluid passage through the rotor blades corresponds at all radial distances with the fluid passage througlrthe stator blades.

Further, the fixed and moving blades are somtimes twisted about their longitudinal axes so that cross-sections of the blade taken at di'ii eront radial distances make ditterent angles with the longitudinal axis of the rotor for the purpose of obtaininga more uni-form. opening along the blade or tor the purpose of varying the angle of the fluid discharge along the lengtl'i of the blade to suit the varying circumferential speed. In such cases also the steam pa, sage can be made to correspond in adjacent fixed and moving rows at all corresponding radial positions.

In some cases, however, it is found expedient to make the rotor blades taper in thickness from the root to the tip in order to l ease the stress at the root caused by centrifugal force. In such a case the corideuce between the adjacent fixed and moving blades no longer exists, so that in nontwistral blades the fluid passage through the tired blades cannot be made the same as that through the moving blades at all can-responding radial distances, the result being a diflerence in the velocity of the steam relatively to the blades in the case of the blades of the rotor and stator respectively. and also a lateral displacement of the fluid in passing between the adjacent fixed and moving rows with a consequent loss of e'flicien'cy.

In the case of the twisted blades, tapering of the rotor blades causes a similar READING.

1924. SeriaL No. 715,838.

lack of correspondence in the fluid passages. iii in such a case the amountof twist of either st'ator or rotor blades is increased or decreased so as to make the discharge opening of the fluid passages-equal at corresponding points, a further ditiiculty" is encountered, namely, the angle of discharge of the fluid no longer corresponds at all radial points to the circumferential velocity of the blades.

The object of the present invention is to overcome these diiiicultics.

lVil'h such an object the invention consists in the improvementsin turbine blading hereinafter described and particularlypointed out in the claims.

deter"ring to. the accompanying drawings which are to a certain extent of a diagramn'iatic nature Figure 1 shows a sectional elevation through part of an. axial-flow reaction turbine;

Figures 2, 3 and 4*" being cross-sections through adjacent blades taken respectively on the lines 22, and, 4 l of Figure 1 to show the taper of the blades, and

Figure 5 a corresponding sectional perspective view of one of the stator blades;

ligures 2P, 3" and 4" are cross-sections also taken respectively on the lines 2+2, 3+3 and of Figure 1 of i1,.1110dlfi02'.' tion in which the tapered blades are also twisted;

Figure 6' being a corresponding sectional perspective view of one of the stator blades, finally v Figure 7 shows a sectional elevation through. part of an axial-flow. reaction. turbine, in which the stator and rotor blades are of diilerentwidths', while Figures 8, 9 and 10 are cross-sections respectively on the lines 8S, 9'-9'and 10- 10 of Figure 7.

In each of the Figures 2 3? and t, 2*, 3 and t" and 8, 9 and 10, the stator blades are shown above and the rotor blades below, while the same reference letters are used throughout to denote corresponding parts in the diii'erentv figures;

In carrying theinventio'n into effect according to one form as shown in Figures 1, 2, 3,- 1 ando applied to an axial-flow reaction turbinm the spaced rotor blades, a, are secured in any suitable manner tothe rotor, b, and as shown by the cross-section in Figures 2, 8 and l decrease in thickness from root, a, to tip, (0 in order to lessen the stress due to centrifugal force. Similarly, the stator blades, 0, spaced to correspond are suitably secured to the stator body, d, but as shown in Figures 2 3 and at, decrease in thickness from tip 0, to root, 0, their thickness being equal to that of the rotor blades at equal radial distances. In Figure 5, a perspective view of such a stator blade is shown decreasing in thickness from the tip, 0 to the root end, 0, where it joins the root, (2, itself. By so proportioning and arranging the stator and rotor blades, it will be seen that the thick tips, 0 of the stator blades coact with the thick roots, a, of the rotor blades and the thin roots, 0, of the stator blades with the thin tips, a", of the rotor blades, so that the fluid passage through the stator blades corresponds at all radial distances with the tluid passage through the rotor-blades.

According to a modified form of the invention, the stator and rotor blades as re gards thickness and relative arrangement are as above described but in addition, as

shown in Fi ures 2? 3 and d are twisted about their longitudinal axes so as to make the angle of discharge of the fluid correspond at all radial distances to the circumferential velocity of the blades. As the section of the stator blades at any radial distance is the same as the section of the rotor blades at the same distance, the twisting of the blades will not alter the corre sponding steam passages between the rotor and the stator blades, and thus no loss in efiiciency will be incurred.

In Figure 6, a perspective view of such a twisted stator blade is shown, the thick tip being indicated at 0 and the thin root end at 0.

Further, in some cases, either to meet special stress conditions or for some other reason, it is convenient to adopt a stator blade of different width from the rotor blade. Thus, as shown in Figures 7 to 10, the stator blade, f, is of less width than the rotor blade, a, but decreases as before from the maximum thickness at the tip, F, to a minimum thickness at the root, 7'. The rotor blades, as before, decrease in thickness from the root, a, to the tip, (L2. In this case, as seen in Figures 8 to 10, the stator blades, 7', are more closely spaced than the rotor blades, a, so that the passages, it, for steam flow between the stator blades may be geometrically similar, or approximately geometrically similar, to the passages, 2", between the rotor blades.

The rotor and stator blades may be provided in the first place with the required taper or they may be tapered by any suitable means from blades of parallel section produced by any known method.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is 1. In combination in a turbine, relatively rotatable co-axial blade-carrying elements, outwardly-projecting blades decreasing in thickness from root to tip carried by one of said elements, and co-acting therewith inwardly-projecting blades decreasing in thickness from tip to root carried by the other of said elements, as set forth.

2. In combination in a turbine, co-axial stator and rotor elements and co-acting blades carried by said elements, said blades carried by said rotor element decreasing in thickness from root to tip and said blades carried by said stator element decreasing in thickness from tip to root, as set forth.

In combination in a turbine, relatively rotatable co-axial blade-carrying elements; o1itwardly-projecting blades twisted about their longitudinal axes carried by one of said elements, and co-acting therewith inwardly-projecting blades twisted about their longitudinal axes carried by the other of said elements, said outwardly-projecting blades decreasing in thickness from root to tip and said inwardly-projecting blades decreasing in thickness from tip to root, as set forth.

4. In combination in a turbine, relatively rotatable co-axial blade-carrying elements; outwardly-projecting blades decreasing in thickness from root to tip carried by one of said. elements, and co-acting therewith in wardly-projeeting blades decreasing in thickness from tip to root carried by the other of said elements, said outwardly-projecting and said inwardly-projecting blades having the same thickness at equal distances from the axis, as set forth.

5. In combination in a turbine, relatively rotatable (Jo-axial blade-carrying elements; outwardly-projecting blades decreasing in thickness from root to tip carried by one of said elements, and co-acting therewith in wardly projecting blades decreasing in thickness from tip to root carried by the other of said elements, said outwardly-projecting and said inwardly-projecting blades decreasing in thickness at the same 'rate, as set forth.

(5. A turbine stator blade thicker at the tip than at the root, as set forth.

7. A turbine stator blade thicker at the tip than at the root and twisted about its longiudinal axis, as set forth.

In testimony whereof we have signed our names to this specification. 7

CHARLES ALGERNON PARSONS.

FKANCIS XVILLIAM GARDNER.

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