US1544253A - Turbine blading - Google Patents

Description

June 30, 1925.

R. MARSLAND TURBINE BLADING Filed May 31, 1922 1i: u A? 1/ l H fln B-Maraland INVENTOR ATTORNEY Patented June 30, 1925.

UNITED STATES} 1,544,253- PATENT OFFICE.

ROLAND MARSLAND, OF ESSING'ION, PENNSYLVANIA, ASSI CGNOE T O VESTINGHOUSE ELECTRIC AND MANUFACTURING COIIIPANX, -A CORPORATION OF PENNSYLVANIA.

TURBINE BLADING.

Application filed May 31, 1922. Serial No.'564,749.

T 0 all whom it may concern:

Be it known that I, lROLAND MAnsLANn, a citizen of the United States, and a resident of Essington, in the county of Delaware and State of Pennsylvania, have invented a new and useful Improvement in Turbine Blading, of which the following is a specification.

My invention relates to turbine blading, more particularly to blading of the wide type adapted to receive steam axially and to discharge it peripherally, and it has for its object to provide apparatus of the character designated which may be more easily manufactured and which, for the same strength, employs less material then heretofore required for blading of this type.

Apparatus embodying features of my invention is illustrated in the accompanying drawings, forming a part of this application, in which: Fig. 1 is a longitudinal sectional view of a turbine showing my improved blading applied thereto; Fig. 2 is an enlarged sectional. view taken along the line IIII of Fig. 1; Fig. 3 is an enlarged detail view showing, one of the blade sections and Fi gs. 41 and Bare detail views of a modified form of blade. Y

In the application of Alexander T. Kasley, Serial No. 486,517, filed July 21,1921, continued as Serial No. 521,872, filed December 12, 1921, and assigned to the Vestinghouse Electric and Manufacturing Com pany, there is disclosed and claimed a type of wide exhaust turbine blade which is adapted to receive steam axially and to discharge it peripherally. It is characteristic of the type of blading disclosed in this application that each blade comprises an inner approximately radial or plane portion'and an outer curved or spoon-outline portion. In order to avoid bending moments being imposed upon the inner plane portions of the blades, it is necessary to design the outer curved spoon-outline portions so that the sum of the centrifugal moments of portions thereof with respect to a median thickness line of the plane portion shall be equal to zero; and, in order to resist stresses applied at the middle portion of the curved or spoon-outline blade portion, it has been heretofore necessary to thicken that portion particularly at the middle.

In accordance with my invention, I provide a blade with an outer curved or spoonoutline portion, which is made of approximately uniform thickness and which is strengthened by being radially corrugated; and, byextending these corrugations well toward the root of the blade, it may be stiffened against lateral vibration.

' Referring now to the drawings for a more detailed description of my invention, I show a turbine comprising a rotor '10, having journal portions 11, fitting in bearings 12, carried by the casing orcylinder 13, the casing or cylinder and the rotor being provided Wlfh energy-abstracting elements. for abstracting energy from steam supplied from the conduit lh'and after the available energy 1s abstracted, the steam enters the exhaust blades 18, carried by the rotor 10 and av row of re-directing blades 19 interposed therebetween. After being discharged from the last row of moving blades 1.8, the steam is then fractionally expandedby the stages comprised by the stationary and moving rows of blades 20 and 21 carried by the cylinder or casing 13 and the rotor 10, respectively; and, after being discharged from the last row of moving blades 21, the steam then'passes between the guide blades '22 for entry bet-ween the'wide exhaust blades 23 from which it is discharged peripherally to the exhaust chamber 15. The particular construction of'the blading 18, 19, 20 and 21, constitutes nopart of my invention and it is referred to'for illustrative purposes only. r r i The wide exhaust blades 23 comprise inner substantially radial or plane portions 24 and outer curved or spoon-outline portions 25, the=latter portions being adapted to ex pand and discharge the steam at small angles peripherally. The blades 23' are preferably made up of a plurality of sections 27 in order tofacilitate manufacture. The outer curved or spoon-outline portions 25 are made of metal of substantially uni form thickness; and, in order to provide adequate strength to resist centrifugal bend ing moments, the outer blade portions are corrugated in substantially radial directions, as may be seen from Figs. 2 and 3.

Referring to Fig. 3, itwill be seen that,

in order to avoid bending stresses at the section aa, the centrifugal moments to the left ofthe center line 00 should be balanced by those to the right of that line.

This requirement has heretofore been satis fied by thickening the bottom portion of the curved or spoon-outline portion in order to provide sufiieient area in stress approximately at the position indicated by the line 6-?) to resist the centrifugal bendng moments due to the portion of the blade above the latter line. In accordance with my invention, the portion above the line a-a and constituting the curved or spoon-outline portion may be made of substantially uniform thickness, adequate strength being provided in order to resist bending moments by radially corrugating'theblade portions in the manner shown in Figs. 2 and 3.

In order to stiifenithe entire blade structure against lateral vibration, the corrugations above described may be extended nearly to the root of the blade as indicated at 3030 in Figs. 4 and 5. Obviously, these corrugations in the main body of the blade would not be of a depth permissible in corrugations confined to the spoon tip, inasmuch as they lie more or less transverse to the steam path and would render the same too tortuous if of excessive depth.

From the foregoing, the operation of apparatus made in accordance with my invention will be well understood: Steam is expanded in the usual way in the blading, andmy novel construction of the outer portions of the wide exhaust blades, permits of the latter being made of substantially uniform thickness, and, at the same time, with the preservation of sufiicient strength to resist centrifugal bending moments.

VVhile I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

' What I claim is: V a

1. In a turbine, a row of blades having portions normally subject to centrifugal bending moments, said portions being corrugated radially in order to resist said moments. 7

2. In a turbine, a row of blades having outer curved discharging portions provided with radially extending corrugations in order to strengthen the curved portions.

3. In a turbine, a row of blades having curved portions subject to centrifugal bending moments and which are corrugated radially in such a direction as to strengthen the peripherally at small angles, each of the I blades being composed of a plurality of sections and having the outerv curved or spoonoutline portions --of substantiallyl uniform thickness and the latter portions being corrugated in order to strengthen vthem.

5. In a turbine, a row of blades adapted to recei vest-eam at one sideand to discharge it at the tips, comprising inner substantially plane portions and outer curved portions for discharging the stea'm'at, small angles,

said outer portions being corrugated sub stantially normally to the tips in order to strengthen the outer curved blade portions. 6. In a turbine, a rotor blade having a substantially flat body portionv parallel to and substantially radial corrugations in said.

body portion and in said tip adapted to stiffen the entire blade structure against lateral vibration and to stiffen said tip against the action of centrifugal force. I

8. In a turbine, a row of blades adapted to receive fluid axially and to discharge it peripherally comprising inner plane POI? tions and outer curved or spoon-outline portions for expanding and discharging steam peripherally at small angles, each of the blades being CO'IIIIPOSGCI of a plurality of sections and each of the sections being corrugated substantially throughout its length in order to stiffen the same against forces acting transverse thereto' In testimony whereof, I have hereunto subscribed my name this 26th day of May,

' ROLAND MARSLAND.

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