US2633327A - Gas turbine wheel with liquid cooling means - Google Patents

Description

March 31, 1953 c. M. MCDOWELL GAS TURBINE WHEEL WITH LIQUID COOLING MEANS 2 SHEETSSHEET 1 Filed March 1, 1946 I IN V EN TOR. CZamnce/Y/Ycfla March 31, 1953 c. M. MCDOWELL 2,633,327

GAS TURBINE WHEEL WITH LIQUID COOLING MEANS Filed March 1, 1946 2 SHEETSSHEET 2 I C(drencflf By I Patented Mar. 31, 1953 UNITED GAS TURBINE .WHE EIi WITH LIQUID: GO OLIN G MEAN S Clarence'M. McDowell, Toledo, Ohio, assignor'to Packard'MotorCar Company; Detroit, Mich., a

corporation' ofMichi'gan Application Marchl, 1946,.ScrialNo. 651,208;

3 Claims.

The.inventioncrelatesgenerally to gas turbines:

and'more particularly to a turbine wheel orrotor. construction therefor.

The generalobjecti f the invention i's'to pro;- videiaunovel" construction for the wheelor rotor of a; gas, turbine, which. provides, for cooling the wheel so that it. can safely; Withst'and" relatively high unit stresses.

Another: object" is to provide a" novel turbine wheel construction provided with cooling means to avoid the necessity of making therwheel' of highlyheateresistant material;

A1furtherobject is to" provide a novel turbine wheel construction in which coolant'is circulated; with the coolant makingdirectcontactwith those portions'of' wheel-which are subjectto thelargest centrifugalforces.

More specifically; it isan object to' provide a" novel turbine wheel construction" having" means for circulating a coolant therein; particularly in direct contact with the-portions" subjected to" the greatest heat; suchas the bladesupporting"por= tions of the wheelproper-and" the supporting" or retaining portions of the blades.

Still another object is'to provide a novel tur bine wheel construction'supplied witha coolant and utilizing the rotation of the wheel 1 to: efiect circulation of the coolant in contact with? the portions of the wheel subjected: to? the" greatest heat.

A still' further object is to provide a novel tur= bine wheel construction havingmeans-for -circu+ lating coolant in contact with the peripheralrpor tion of the-wheelproper, as well as withthesupporting portions of'the blades; thecoolantbeing of such character asto establish a seal in any spaces--that occur between the blades and the wheel.

It is' also. an object toprovidea novel'turbine wheel construction provided; with coolant circulating. means utilizing the turbine-fuel as the coolant and therebyeliminating the-necessity-of maintaining a supply of liquid other'than the fuel f orithe 1 op er ation of theiturbine.

A further: object. is to provide a. novel method of cooling; a: turbine. wheel, utilizing the turbine fuel as the coolant and. causing carbonization thereof at points whereany slight leakage .of cool-jantmay occurto effect deposition of carbon to seal such points.

Still another. object. is. to. provide; a novclturnine wheel. construction provided with novelcool' ant circulating means. so constructed that; it may be readily assembled in the wheel;

A still .further obiectis to provide? a;novelt'ur,-- binewheel construction provided with coolant circulating means adapted to" supply coolant; to a* cavity within the wheel, the; lattenhavingj a two-part construction with the two partsprovid ing the cavity; between them andipermittingf the assembly of the: co'olantcirculating means as an incident to the assemblyof'the two: parts;

Other objects and advantages will become ap parent from the following descriptionta'ken' in connection with the accompanying drawings; in which:

Figure 1 is a" perspective View; on a reduced scale, of a turbine wheel embodying thefeat'ures of f the invention;

Fig.12 is a fragmentary axial 'sectional' view of the turbine wheel shownin'Figr 1'.

Fig. 3'-i's a'sectional view takenz-on'theline"3 3 of'Fig. 2.

Figs;- 4 -and 5' are enlarged sectionalviewstaken respectivelyon thelines 4-4 and 5 5 ofFig: 3i

Fig.- 6 isa View" of a portion ofthe periphery of the wheel shown inthe. precedingfigures'.

Fig; 7 is a view similar't'o Fig. 2',- but showing a. modified formof construction.

The advantages" of gas'turbines have long-been known? but-difilcuIty has beenexperiencedjn' the practical use thereof because of problems arising from the heat of the; gas. In turbines-of this type, the radially extending blades on the-periphery oi; the Wheel as well as the peripheral portion of thezzwheel are subjected tothe high'temperatures of the gas. In theearl'y-daysbf develop.- ment; of turbines ofithis'. kind, practical use of such: turbines was:- prevented to agreat extent by.the,lack'oftmateria1s which could'operate at the; high; temperatures resulting from the temperature. of: the gas and at the sametime main.- tain. sufficientz. strength. Highlyheat-resistant materialsv have; been. developed but cost consid erations havesbeen aLIimiting: factorin the use of .such materials.

The present invention provides aconstruction which. utilizes a cooling .action on the peripheral portion of the wheel so. thattsuch' portion is maintained at: a lower temperatureith'an: would otherwise be the case and th'erefore; permits the-wheel to resisthighstresses to. a. greater: degree; In

fact, the cooling of the peripheral portion of the wheel may be sufficient to permit use of a material less resistant to heat as well as to permit a somewhat lighter construction so that the centrifugal forces involved will thereby be decreased. The cooling effect preferably not only is applied to the peripheral portion of the wheel, but also to the bas or supporting portions of the blades so that such base portions will correspondingly be better able to resist the stresses to which they are subjected.

To accomplish such cooling, a turbine wheel embodying the features of the invention has a construction which provides a cavity within the wheel, circular in form and extending radially to a point adjacent the periphery of the wheel. Mounted within the cavity is a means for supplying a coolant thereto and for withdrawing the coolant therefrom after it has absorbed heat from the peripheral portion of the wheel. Preferably, the wheel is rotated relative to such means and the latter may be either held stationary or rotated at a controlled speed differing from the speed of the wheel. Said means may comprise generally a plurality of radial supply pipes within the cavity for supplying coolant in liquid form to the peripheral portion of the cavity. Such means also includes a plurality of return pipes provided with means at their outer ends, preferably in the form of scoops, for picking up the heated coolant and withdrawing it from the cavity. Thus, the rotation of the wheel is utilized to effect circulation of the fluid in the peripheral portion of the cavity thus may be withdrawn by projecting the return pipes 2| into such stream with an opening in the outer end of each return pipe facing in a direction opposite to the flow of coolant. Thus, I provide each of the return pipes 2| with a scoop 22 at its outer end, facing circumferentially and in a direction opposite to the flow.

In effecting a rapid transfer of heat from the wheel to the coolant, several factors enter into consideration. The coolant as it is supplied through the supply pipes 29 has a greater density than after it becomes heated from contactv with the wheel. Such difference in density will tend to cause the cooler fluid to move to the extreme peripheral portion of the cavity and to force the hotter fluid toward the inner portion of the stream. Thus, with the scoops 22 located as shown in the drawings, the hotter fluid will thereby he picked up by such scoops for withdrawal from the wheel and a natural flow is thereby effected. However, the scoops 22 also have the effect of creating turbulence within the stream of and permits withdrawal of the fluid by the stationary scoops positioned in the stream of coolant tending to rotate with the wheel. The centrifugal action on the coolant also maintains the coolant in contact with the extreme peripheral portion of the'wheel and thus effects a scrubbing action, resulting in a rapid transfer of heat from the metal of the wheel to. the liquid coolant. As shown in the drawings, I provide a hollow wheel body, indicated generally at 9, comprising a pair of side walls H and |2 spaced from each other to provide an internal circular cavity l3. The side walls H and 2 are integrally formed with a rim portion [4. The latter is provided with a plurality of slots l5, here shown in the shape of a T, to receive blades |6 extending radially from the wheel and of proper form to cause rotation of the wheel when gas under pressure impinges upon them in an axial direction. Each blade |6, accordingly, is provided with a T-shaped base portion fitting snugly within the T-shaped slot l5. Preferably, the cavity |3 within the wheel extends radially to open into the blade slots |5 so that the cavity I3 is bounded partially by the rim portion M of the wheel and partially by the various base portions ll of the blades I6.

To supply liquid coolant to the cavity I3, I provide a plurality of radially extending supply pipes 20 mounted within the cavity l3 and preferably held stationary. I also provide a plurality of return pipes 2|, with the supply and return pipes mounted alternately and preferably of equal number. The return pipes 2| serve to withdraw the coolant from the cavity l3 after it has absorbed heat from the wheel. Coolant is supplied to the supply pipes 2|! under pressure and as it emerges from the outer ends of the supply pipes, the rotation of the wheel tends to cause the fluid to rotate with it. Thus, the coolant will circulate in an annular path limited by the peripheral margin of the cavity.

The coolant as it rotates in an annular stream coolant, which is beneficial in effecting heat transfer. The stream of coolant itself will not rotate at quite as high a speed as the wheel so that there is also a flow of coolant relative to the wheel resultin in a scrubbing action from the high centrifugal forces acting on the liquid.

Such action enhances the heat transfer.

The supply pipes 20 and the return pipes 2| may be mounted within the cavity |3 in any suitable manner. In the present instance, I have shown all of such pipes threaded radially into a hub 23 centrally positioned within the cavity. The hub 23 is provided with a plurality of axially extending eccentrically positioned passages 24 communicating with the respective supply pipes 2|! and opening at one side of the hub. The

- hub is also provided with a plurality of radially extending passages 25 connecting the return pipes 2| with a central passage 26 in the hub. To supply and withdraw fluid from the respective passages, a pair of concentric pipes 30 and 3| are threaded to the hub 23, the inner pipe 3| being of such diameter as to be located radially inside of the passages 24. Thus, coolant may be supplied to the passages 24 through the annular space between the pipes 30 and 3| while heated coolant may be withdrawn from the central passage 26 through the interior of the inner pipe 3|. The pipes 30 and 3|, in the present instance, extend through a central opening 32 in a hub portion of the side wall l2 of the wheel. The hub 23 is preferably journaled as at 33 on a central boss 36 provided on the inner face of the side wall H, the boss 34, in the present instance, closing one end of the central passage 26.

With the wheel having a one-piece construction and being cast with a core to provide the cavity l3, provision is made for insertion of the coolant supply and return means and particularly for the supply and return pipes 2|? and 2|. The hub 23 as well as the pipes 39 and 3|,- of course, may be readily inserted through the opening 32 in the side wall i2. To permit insertion of the supply and return pipes, each of these is dimensioned so that it may be inserted through a blade slot 5. To facilitate handling of these pipes for such insertion, each is provided at its outer end with internal splines 35. Thus, with the splines 35, a tool having a correspondingly splined portion may be inserted into the end of the pipe and the pipe passed through the blade slot l5 and turned to thread it into the hub 23. The scoops 22 for the return pipes 2| are preferably provided withshank portions 36 which are splinedrand? adapted to be forced-into the-splined ends. 3.5 of the-return pipes.v Thescoop" 22-L'may beheld, during such assembly-,- by a: magnetized tool, or a small: boss: (notshowmmaybe provided on the-outer end ofthe-scoop, by'which it maybe Any-.suitable sort of liquidcoolant, of course, maybeutilizedin the present: construction. However, fuel utilized for producingtlie. gas for driving'theturbine may be. used, if? desired. B'y utiliZing-such-fuel, the necessity of providing a supply of an: additionalliquidfor operation of the turbine is avoided. Furthermore, the fueLmay' have a further advantage in that it will provide a ready'means forcl'osing anyslight leakage between the base portions ll" of the blades and the rim M of the wheel. Thus; utilizing fuel as the coolant, carbonization of the fuel at the points of leakage would result from the presence of heat, pressure and lack of oxygen which are the prime conditions necessary for destructive distillation. The fuel utilized in gas turbines of the type herein contemplated is usually in the nature of kerosene and should readily carbonize under the conditions present to completely prevent any leakage. If it were desired to utilize some other liquid as a coolant or to seal any leakage before operating the turbine, a sealing film could be created in the peripheral portion of the cavity l3 by galvanizing, metalizing or enameling, introducing the material for such film in the form of a liquid or powder spray through the coolant inlet tubes. Some form of ceramic material might also be utilized.

In Fig. '7 I have shown a modified form of construction to facilitate assembly of the coolant supply means within the wheel. To this end, I make the wheel of a two-part construction comprising a pair of dished members 40 and 4!, preferably shaped in substantially the same manner as the side wall portions II and 12 in the previously described construction. By such construction, the two dished members may be made as forgings rather than castings, if desired. The dished members or side walls 48 and 4| are provided with rim portions 152 adapted to be held in abutment with each other and preferably formed on their abutting faces in such a manner that a tight fit therebetween will be effected. In the present instance, I have shown the abutting faces as provided with coacting 'V-shaped grooves 43. With a construction of this character, the hub 23. together with the supply and return pipes, may be completely assembled and inserted in proper relation to the side wall Gil. The side Wall 4| is then placed in assembled relation with the side wall 40 and the two may be held together by means which may include or comprise peening over the outer ends of the base portions of the blades, as indicated at 44, which serves also to secure the blades in position. With this construction, the difficulty of inserting the supply and return pipes through the blade slots is eliminated.

With either of the foregoing constructions, a highly effective cooling action may be obtained. Thus, with the coolant supply held stationary, the liquid coolant is forced under pressure from the ends of the supply pipes and immediately is picked up and tends to rotate with the wheel. The high speed of the wheel produces a strong centrifugal force on the fluid and, although the fluid will not rotate at the speed of the wheel, it will be caused to move to the peripheral portion of the cavity 13 under a high centrifugal force 6 and 1 produce: 8;; scrubbing: actionj. resulting; in a; rapid transferzof heat: from'athe peripheral iportion. of the: wheel, .as well: as: from 1the..base por-= tions of the blades, toz-thezliquid;v Theheat'ed.

. liquid,.by virtue of its; lesser density-than: thecooler 1iquid=,. will. tend i to: be. forced; toward; the inner portion. of the-irotating' streamiiand'"; willabe. pickedeup by the :scoops .222 toibezwithdrawnifromi the wheel. The: turbulence: within; the; rotating; stream: created by the. scoops 22: a'lsoltendszto; cause-additional transfer r of" heatzfrom; the-wheel! to the liquid.

By cooling-the'wheel-in: this manner, heat is removed from that portion of the wheel subjected to the highesttemperatures and consequently material; less. resistanhtc;heatgmay; be employed than would be the case where.- novcoolingiwerejs effected. By.the.reductionoftemperature in the periphery of the body portion ofthe wheel, such body-portion may be mademf" somewhat lighter construction, which in turn reduces the centrifugal forces involved and the consequent stresses on the material of the body portion. In addition to cooling the periphery of the body portion, the construction herein shown also provides for the cooling of the base portions of the blades and thus is of benefit in that respect since such base portions are subjected to material stresses during operation. The present construction thus provides for cooling of all portions of the assembled wheel, which are subjected to high temperatures and relatively high centrifugal stresses.

Iclaim:

1. A tur'ibine wheel construction for a gas turbine, comprising a hollow rotatable body having a central opening at one face, the other face being closed, blades mounted on the periphery of said body, and means for circulating liquid coolant within said body comprising a stationaryhub centrally mounted within said body and hav. ing independent supply and return passages therein, a plurality of radially extending supply and return pipes carried by said hub and connected to said passages, said return passages having scoop means supported at their outer ends, and means extending through said central opening for supplying coolant to said supply passages and for withdrawing coolant from said return passages.

2. A turbine wheel construction for a gas turbine, comprising a hollow rotatable body having a central opening at one face, the other face being closed, blades mounted on the periphery of said body, and means for circulating coolant within said body comprising a stationary hub centrally mounted within said body and having a plurality of concentrically positioned axially extending passages and a central bore connected to a plurality of radially extending passages, a plurality of radially extending supply pipes carried by said hub and connected to said axially extending passages, a plurality of radially extending return pipes carried by said hub and connected to said radially extending passages, and means for supplying coolant to and for withdrawing coolant from said passages comprising a pair of concentric pipes secured to said hub and extending through said central opening of the body, the interior of the inner pipe communicating with said central bore and the annular space between said pair of pipes communicating with said axially extending passages.

3. A turbine wheel construction for a gas turbine, comprising a hollow rotatable body having a central opening at one face and a centrally positioned boss extending inwardly from the other face, blades mounted on the periphery of said body. and means for circulating coolant within said body comprising a hub mounted within said body on said boss and provided with supply and return passages, a plurality of supply and. return pipes carried by said'hub and connected to said passages, and means extending through said central opening and connected to said passages for supplying coolant thereto and withdrawing coolant therefrom.

-' CLARENCE M. MCDOWELL.

REFERENCES CITED UNITED STATES PATENTS Name Date Bostedo Feb. 7, 1922 Number Number 5 Number Name Date Belluzzo Jan. 24, 1928 Back July 2, 1929 Morton Oct. 27, 1931 Koch June 28, 1932 Brooke Dec. 12, 1933 Belluzzo Mar. 16, 1937 Holzwarth Jan. 25, 1944 Berger Feb. 5, 1946 Halford June 11, 1946 Ray May 25, 1948 Moore Mar. 8, 1949 FOREIGN PATENTS Country Date Great Britain May 21, 1908 Great Britain Jan. 29, 1935 France Feb. 18, 1935

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