US2232611A - Guide apparatus for axial flow turbomachines - Google Patents

Description

Feb. 18, 1941. C KELLER 2,232,611.

GUIDE APPARATUS FOR AXIA.. FLOW TURBOMACHINES I Filed oct. 24. 193e lm! iig@ 4 A 10 15 Fig.2' I

P i'iterrter.d, Febr '18', 11941 tannini, assigner-4to ilk-' A Techniiche l Studien,

' curtlxeiier, "zuricnfswl tiengeseilschaft Fuer .1,Zurich,Switzer land, a corporation-or'switzerp n Applicatieoeu'nmrzi;193s,sentirne.'23am In SwitzerlandzNovember 3,1931 ,l sommaicigs-j-'zsi "This invention relates to a guide apparatus for` more expensive. Thus only'- a comparatively axial flow turbomachines; `more especially turbinesv and blowers intended f or operation at i high" temperatures and in-wh'ich the defiecting or guide bladesproper .arejlet- ,into aguidegdisc and an 'iouterring or rim surrounding the latter andfconnected' to it by supporting or strut blades located '1.1 irrjfront 'of I tion of this kind has theadvantage that the have totransmii'wthe forces'. acting on the g'uidedisathisfiunction being taken over bythe strutswhich present` a'hih moment A direction parallel `to the 1 *Inf most casesw'the outer `the saidguideblades n construcguide 'blades "do not.

of resistance mainly in faring, thestruts and the guide disc are cast in' one temperatures, Jhowever, it'- that, the 'maximum stressesv set'up in 'the 'struts f reeistantto heat have f predautions" btaken.

' andnssuresfzfare wh'e'ievjthd struts meetf'the cotnparatively thick ring 01' the' thiclcriisc and in-tliis Way the guide .whel is greatly weakened, even Yif it. isnot ren# I. dered quite unserviceable.

canberesisted witna 4'ltd heat and, still more,

'snare this .drawback-and, for this purposepossible expedient is to em The diillculties' larising inathelrnanuiacture of', auch"complicatedqcastingsaregreatly aggravated zflwhen'thosefkinds; ofcast steelwhichfare highly to,be used'. I Unless special in suchpcases.' pipe holes t The objecterthefpresenr intention is' to euml# liil'llllii. in a'- Aguide radialcavitiesy in the guide disc'and are secured ,regain t` radial displacement. vln thisv way a 'com- -v oithe' bipartite members l `and 2 bear against Lpositeguide apparatus -is' provided,v in whichthe t outer ringand the by .rn'illingforturning 'before assembly.

axial longitudinal sufiicientfr'narginof safety. 'turbine-ff f Atjte'mpera-tures' over about 500 C. the resistance f' ,thecree'p resistance fall ofvery rapidly in-allkinds'of steeLso that, when 1 relatively high diierences of pressure have'to be* provided for the only l ploy a large ,number ortniclrstruts.` guide .apparatus according 'to likely to form at theI -pointsV the apparatus-of the kind referred" A 'to, are' introduced according to, the'said inven tion through. radial bores in the outer' ring mw u the guideepperatilt l.,

` way `as to be prevented irom displacement both guide disc are connectedby 'strutsl constructed as separate.. elements. The i -.separate struts. the outerring andthe guide disc i .therefor-aI vbe made independently of' each .v athen- Accordingly;the'outer ring and "ftlie'q "giiiddisc' may be made of an ordinary` cast or' 'forged material; while the withstand the greatest 4rst erases, are manufactured "t5 iromla' high grade material'- which;y however, is

:disc forming `a running seal struts, which vhave to small amount oi the expensvetbut'highlyheat resistantlmaterial.. has' .to f be" used inf' constructing `parts ot the struts?" the inner wall of the outer'ring-and the outer wall oi the guide dise, can beiaccurately machine finished, as

The struts', -afterpbeing passdthr'ough the outer ri/ng' and-intoxthefguide disc maybe held againstfradial displacement by welding them to thse patti/S.`

'The inventionv isdescribed moreI particularly 15 hereinafter 'with .reference to thev accompanying drawing( which shows' constructional embodiments "of `the inventiongbyway oi example. In

Ythis drawing:

.fFig;,-f1ry1s partly'. affront. view and partly an 2o portionpf the exiailongitudmai section through the turbine oi Fig. ion4 an enif `largeri scale. v

Elg.f"3` is partly aside elevation' and 'partly a section on the line III-III oi Fig. 2 through a,

the inventiom i Fig; 4 'is a section taken on line IV--IV of Fig.

2, developedin the planeet-.the drawing, ,end ,o

drawn toj a larger'scale than Fig. 2, and

Fig. :5 'is partly a sideapparatus.

1""hereference vI- denotes-twoipartl guide discs, 35

strut blades conaref-let into the lsection through` an axial flow f l elevationand partly a l i section through av second-embodiment oi a guide necting the members I and 2 together.. I denotes 1- 'megane blades proper,V which guide ,discs i `and the outer rings 2. The rotor 40 wheels' snr-the turbine are. integral with'the turbine shaft l and 1 is a turbine casing, in which 2.,! are mounted -in such a axially and radially, andthe two vrespective lhalves bores s (Figsz yand ai or right' through each outer j exposed part of each of the struts 3 is preferably' of the streamlined cross section, as shown in Fig. 4, so that it shall offer as little resistance as possible to the now of the working medium.

Instead of welding the struts 3 to the members I and 2 these struts may be prevented from moving radially by threading them into the' outer ring 2, as shown in Fig. 5, where I2 denotes screw threads.

The struts 3 are preferably made of forged metal'while the outer rings 2 and the guide discs I are made of a weldable casting metal or alloy. In any case the material of the struts should be more resistant to heat and to fatigue than the material of the outer rims and the guide discs.

In some cases the struts may be subjected to initial stress when iltting them in place, for instance, they may be a force fit in the guide disc and in the outer ring or these elements may be shrunk on to them. I

Since, in this guide apparatus, a highly heat resistant material can be used for the construe` tion of the struts, these latter can be relatively fewer in number and relatively thinner than in the case of guide apparatus cast in one piece. Losses due to friction are reduced accordingly, as the current of working medium encounters fewer and smaller resistance bodies (struts) as it flows through the guides.

What is claimed is:

1. Guide apparatus for turbomachines including a casing and a rotor-wheel shaft mounted in said casing, said guide apparatus comprising an inner ring adapted to encircle the shaft and having radial cavities extending inward from its outer periphery, an outer ring concentric with and encircling said inner ring and adapted to be xedly mounted in said casing, said outer ring 2,232,6 1 1 ring 2. The struts l are introduced through these having an internal diameter larger than the external diameter of the inner ring and being provided with radially extending bores corrponding in number with and aligned with the radial cavities in the inner ring; guide blades proper sustained by said rings and extending across the interval therebetween; separately formed struts of high strength material characterized by high creeping strength and resistance t`o high temperature, said struts being located in advance of said guide blades and each extending through a corresponding bore of the outer ring into an aligned cavity of the inner ring, and means for ilxing said struts in position. A

2. The combination defined in claim 1 in which the struts are of forged material and the rings are of cast material and welded to said struts.

3. A multi-stage axial flow turbomachine cpmprising a generally cylindrical casing; a rotor shaft with 'a plurality oi' axially spaced rotor wheels fixed thereon in spacedrelation, said shaft being mounted to rotate coaxially in said casing; and a plurality of interstage guide structures, one interposed between each pair oi' adjacent wheels and each comprising an inner ring closely encircling said shaft and having on its outer periphery a circumferential series of radial cavities, an outer ring surrounding and spaced from said inner ring, and sustained by Said casing against motion in the direction of and transverse to the axis of said shaft, each outer ring being provided with radially extending bores corresponding in number with and aligned with the radial cavities in the correspending inner ring, guide blades proper sustained by and extending across the interval between said inner and outer rings and in coactive relation with said rotor wheels, separately formed' struts of high strength material characterized by high creeping strength and resistance to high.

temperature, said struts being located in i'ront of the guide blades proper and extending into the aligned bores of the two rings, and means ior fixing said struts in position in said bores.

CURT KELLER.

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