US3734649A

US3734649A - Turbopump having cooled shaft

Info

Publication number: US3734649A
Application number: US00146333A
Authority: US
Inventors: J Sandy
Original assignee: AIRCRAFT CORP U
Current assignee: AIRCRAFT CORP U
Priority date: 1971-05-24
Filing date: 1971-05-24
Publication date: 1973-05-22
Anticipated expiration: 1990-05-22

Abstract

A turbopump having an inducer and a two stage centrifugal pump has hydrogen entering an inducer and passing through a first stage impeller and a second stage stage impeller to the exit thereof. A turbine is located on the opposite side of said impellers from the inducer and has an integral shaft extending through the impellers and inducer on which they are mounted. A front radial bearing means is positioned between the inducer and first impeller and a thrust balancer means and rear radial bearing means are positioned between the second impeller and the turbine. An interstage seal extends between the two impellers. Hydrogen is taken from the hydrogen path to operate the axial thrust bearing and to cool the two radial bearings. Further, the hydrogen flow is taken from the inlet to the second stage impeller and directed through the shaft having a tortuous path therethrough to provide a desired cooling action. Dead air spaces are provided adjacent the turbine mounting to aid in the formation of a heat transfer barrier.

Description

Stats tnt [191 Unite Sandy, J r.

[ 51 May 22, 1973 [75] Inventor: James J. Sandy, .112, Lake Park, Fla.

[73] Assignee: United Aircraft Corporation, East Hartford, Conn.

[22] Filed: May 24, 1971 [21] Appl. No.: 146,333

Primary Examiner-C. J. Husar Attorney-Jack N. McCarthy 5/1964 Shiley et al. ..417/901 X [57] ABSTRACT A turbopump having an inducer and a two stage centrifugal pump has hydrogen entering an inducer and passing through a first stage impeller and a second stage stage impeller to the exit thereof. A turbine is located on the opposite side of said impellers from the inducer and has an integral shaft extending through the impellers and inducer on which they are mounted. A front radial bearing means is positioned between the inducer and first impeller and a thrust balancer means and rear radial bearing means are positioned between the second impeller and the turbine. An interstage seal extends between the two impellers. Hydrogen is taken from the hydrogen path to operate the axial thrust bearing and to cool the two radial bearings.

Further, the hydrogen flow is taken from the inlet to the second stage impeller and directed through the shaft having a tortuous path therethrough to provide a desired cooling action. Dead air spaces are provided adjacent the turbine mounting to aid in the formation of a heat transfer barrier.

10 Claims, 3 Drawing Figures T Wm PAIENIE HLYZZIHYS SHEET 2 OF 3 TURBOPUMP HAVING COOLED SHAFT BACKGROUND OF THE INVENTION This invention relates to a turbopump and its cooling means, and more particularly to those turbopumps having a very hot turbine and a very cold pump.

SUMMARY OF INVENTION A primary object of the present invention is to provide a tiebolt shaft concept that is also integral with the turbine disk and which will operate under adverse environmental conditions.

In accordance with the present invention, a rotor assembly is formed wherein all of the rotating parts are assembled on a shaft integral with a turbine disk.

In accordance with a further aspect of the invention a turbopump is provided having a shaft cooling system which can use the fluid being pumped to properly cool and permit proper rotation of the shaft.

This invention includes a tortuous path of pumped fluid through the shaft of the turbopump and also including a dead gas chamber means between the passageway extending through the shaft and the turbine disk.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing the front portion of the turbopump; and

FIG. 1A is a view showing the rear portion of the turbopump.

FIG. 2 is a sectional view showing the transition section between the rear bearing and turbine disk with isotherms.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 1A, the turbopump is made up of two main parts, the stationary housing 4 and rotor assembly 6.

The rotor assembly 6, which comprises the rotating portion of the turbopump, is formed of eight main parts. These are (l) the inducer 8, (2) the mounting means for the inner race of the front bearing 1 1 and accompanying inner seal members 7 and 9, (3) the first stage impeller 12, (4) the inner seal member 14 of the interstage seal 15, (5 the second stage impeller 16, (6) the thrust piston 18 of the thrust balancer, (7) the mounting means for the inner race 20 of the rear bearing 21 and accompanying inner seal members 17 and 19, and (8) the turbine assembly 22 and its integral shaft 24. Said shaft 24 extends through all eight main parts and has a cap 26 affixed to its forward free end.

The cap 26 contacts the inducer 8 and is held on by a bolt 28.

The stationary housing 4, which comprises the stationary portion of the turbopump, is formed of eight main parts. These are (l) the casing 40 forming the housing for the inducer 8, (2) the mounting means for the outer race 42 of the front bearing 11 and accompanying

outer seal members

44 and 46, (3) the housing for the blades 89 of the first stage impeller 12, 4) the outer seal member 48 of the interstage seal 15, 5) the housing for the blades 90 of the second stage impeller 16, (6) a housing 50 for the thrust piston 18 of the thrust balancer, (7) the mounting means for the outer race 52 of the rear bearing 21 and accompanying outer seal members 54 and 56 and 8) the housing 58 which includes a passageway 61 into which blades 23 of the turbine assembly 22 project. For ease of assembly of the rotor assembly 6 within the stationary housing 4, some main parts are constructed of a plurality of cooperating smaller parts.

The rotor assembly 6 and stationary housing 4 cooperate in the following manner to produce a thermal transition section in the turbopump that will withstand large thermal gradients. The turbine disk 60 of the turbine assembly 22 is formed having the integral shaft 24 extending forwardly thereof. Seal member 19 is mounted on integral shaft 24 and has one side contacting the turbine disk 60. The inner seal member 19 is spaced from the forward face of the turbine disk 60 by an axially extending flange 62 and forms an annular chamber 64 with the turbine disk, shaft 24 and flange 62. The inner seal member 19 includes annular sealing edges projecting outwardly from the rear of the seal member. The inner race 20 of the rear bearing 21 is located on the shaft 24 adjacent the seal member 19 and is positioned over a section having cooling slots for the passage of a cooling fluid.

The thrust piston 18 of the thrust balancer is made integral with and extends outwardly from a hollow shaft section 66 which has its rear end adjacent the forward end of the inner race 20. These two adjacent ends have cooling slots therebetween for the passage of a cooling fluid. For details of the thrust balancer, see US. Pat. No. 3,485,541. The hollow shaft section 66 has internal splines 68 on an inwardly extending circular flange 70 at its rear end which engage splines 72 on shaft 24 to insure like rotation of both parts. The forward part of the hollow shaft section 66 includes annular sealing edges projecting outwardly. The part of the hollow shaft section 66 forward of the flange 70 extends to a point spaced radially inwardly from the inlet to the second stage impeller 16 and forms an annular space with the shaft 24.

The second stage impeller 16 is mounted on the shaft 24 with a rearwardly extending annular flange 74 extending into the annular space just referred to. An annular flange 76 located around flange 74 engages the forward end of the hollow shaft section 66. These mating ends have stepped sections which meet to position the two members axially and radially. The annular flange 74 forms a U-shaped passage with the hollow shaft section 66 and the shaft 24. The annular flange 74 has long splines which engage mating long splines on the shaft 24. A space is provided between the radial end of each spline and its cooperating member to permit a fluid to flow thereby for a purpose to be hereinafter described. An annular flange 78 extends inwardly from the forward end of annular flange 74 for abutment with the shaft 24. A plurality of passageways 80 extend through said flange 78. A plurality of passageways 82 in flange 76 are arranged to cooperate with a plurality of passageways 84 in the mating free end of hollow shaft section 66.

The back of the second stage impeller 16 is spaced from the back of the first stage impeller 12. This is done by annular flanges 94 and 96 on the impellers l6 and 12, respectively, which face each other and have spline means 98, therebetween. The inner seal member 14 of the inner stage seal is positioned above said projections 94 and 96 and is held between the backs of the impellers l6 and 12.

The first stage impeller 12 is mounted on the shaft 24 by a mounting sleeve 102 on which is located the inner race and the inner seal members 7 and 9. A flange 104 extends forwardly from the first stage impeller 12 and has an outer facing radial surface and a forwardly facing axial surface which engage an inner facing radial surface and a rearwardly facing axial surface, respectively. Downwardly extending projections from the end of the flange 104 engage rearwardly extending projections from the bottom of the mounting sleeve 102. The inner seal member 9 includes annular sealing edges projecting outwardly from a flange located at the rear end of mounting sleeve 102. The inner race 10 of the front bearing 11 is located on the mounting sleeve 102 adjacent an abutment on the sleeve. The abutment mating with the inner race 10 and the portion of the sleeve under the inner race is formed having cooling slots. The seal member 7 is positioned with one side against the forward end of the inner race 10. A forwardly extending flange extends from the outer edge thereof.

A nut member 106 is threaded onto the forward part of shaft 24 on threads108 and tightened against the forward end of the mounted sleeve 102 until it is properly torqued to hold the parts just enumerated in their proper position.

The inducer 8 is then placed over the forward end of the shaft 24 having an inner cylindrical member 110 which fits over the forward end of the mounting sleeve 102 and engages the inner seal member 7. Splines on the interior of member 110 engage mating splines on nut 106 and the forwardly projecting part of mounting sleeve 102. Another nut 112 is pivotally mounted on the forward end of shaft 24 to engage an inwardly ex-' tending flange 114 on the inducer 8 to fix it in place. Any locking means may be used to fix the nut 112 in place. A cap 26 is then placed over an opening in the front of the inducer 8 to provide a smooth forward surface thereto. An annular chamber 116 is formed between the forward part of the shaft, the inducer 8 and the cap 26. A plurality of openings 118 extend from said chamber to the outer surface of said cap for a purpose to be hereinafter described.

The shaft 24 is formed as a hollow member. The forward part of the shaft includes a long passageway 130 which extends to a point just below the inlet to the second stage impeller. From this point to the forward edge of the rear bearing 21 a bore 132 is formed approximately twice the diameter of passageway 130. At this point, two enlarged cut-out annular sections 134 and 136 are formed which extend to the forward face of the turbine disk 60. These sections are separated by flange 138 extending inwardly to a short cylindrical member 140.

A center tube member 150 is positioned within said opening 132 and said portions 134 and 136. The forward part of the center tube is formed as a pipe member 154 having an inner diameter equal to the diameter of passageway 130 while the rear part, extending across the cut-out annular sections 134 and 136, is formed having a cylindrical section 155 at its forward end and a cylindrical section 156 at its rearward end. Said sections are separated by a solid partition aligned with the short cylindrical member 140. The forward end of the rear part of the center tube has a flange 160 thereon which engages a surface 161 at the end of opening 132, the forward end of the rear part of the center tube has a flange 158 thereon which engages an opening through the center of the turbine disk 60, and the center section of the rear part of the center tube has a flange 164 thereon which engages the inner surface of the cylindrical member 140. Closure member 157 is fixed in the end of the rear part of cylindrical section 156. The rearward end of the pipe member 154 is fixed within the forward part of the cylindrical section and the forward end of the pipe member 154 is fixed in the rearward end of the passageway 130. It can be seen that the cylindrical section 155, pipe member 154, and passageway 130 combine to form an elongated passageway.

A plurality of passageways extend radially through the shaft 24 from a point just rearwardly of the flange 78 into the opening 132 and a plurality of passageways 174 extend radially through the shaft 24 connecting chamber 116 to the forward part of passageway 130. The flange 160 has a pluralityof openings 162 therein. A plurality of openings connect the rear end of cylindrical section 155 with the rear end of the cut-out annular section 134 and the forward end of cylindrical section 156 has a plurality of passageways connecting it to the cut-out annular section 136. It is noted that the cut-out section 136 forms a dead gas chamber with center tube member 150 and cylindrical section 156 forms a dead gas chamber in view of the fixed end 157. A plurality of openings 182 connect these dead gas chambers.

The stationary housing 4 as stated hereinbefore, is positioned around the rotor assembly and with each part performing its function as intended with the mating portion from the rotor assembly. The casing 40 includes a cylindrical inner surface 200 which engages the outer tips of the blade of the inducer 8 and a flange 202 is located at its forward end for engagement with a flange 204 of a mating conduit 206 passing hydrogen to the turbopump.

The mounting means for the outer race 42 of the front bearing 11 and accompanying

outer seal members

44 and 46 comprise a plurality of support members 210 which extend inwardly from the stationary housing to a point between the rear of the inducer and the forward part of the impeller 12 to support an annular member 212. The outer surface of the annular member 212 forms the inner side of the passageway connecting the inducer to the first stage pump while the interior thereof has downwardly extending annular flange 214 which provides a surface for the seal member 46 and provides an abutment for one end of the outer race 42 of the front bearing 11. Areas for permitting coolant flow engage the outer race 42. A washer member 216 is placed against the forward edge of the outer race 42 and an externally threaded nut 218 threadably engages an internally threaded portion at the forward part of annular member 212. A tab on the washer 216 extends into a groove on the washer to aid in locating it in place. The inner surface of the nut 218 provides the mating seal surface for seal member 44.

A passageway 250 extends from a point adjacent the outlet of the impeller 12 through the housing 4 and support members 210 to the outer race 42 of the front bearing 11. A restrictor 252 is located in the passageway 250 in the sections through the support members 210. The fluid then flows around the outer race 42 and inner race 10 and axially through its seal members and back into the inlet of the impeller 12. The restrictor 252 is a supply orifice and sets the total flow around the front bearing 11.

The portion of the housing cooperating with the first stage pump is composed of several parts and one is the annular flange 220 which extends downwardly between the rear faces of the first stage pump and second stage pump. The inner surface of this flange 220 carries the outer seal member 48 of the inner stage seal for cooperating with the inner seal member 14.

The portion of the housing cooperating with the second stage pump is also composed of a composite of parts and this is also true of the portion of the housing cooperating with the thrust piston 18 of the thrust balancer. The rear of the stationary housing 4 forms a housing which supports the outer seal member 54, an annular member 226 and an annular member 230.

Outer race 52 of the rear bearing 21 is fixedly mounted I on annular member 226 between a nut, and an inwardly extending flange extending from the member 226. An annular'member 230 is positioned at the end of the stationary housing 4 and holds the member 226 in place by a forwardly extending flange 232. An inner surface 234 on this member 230 serves as one cooperating outer seal member for part of the inner seal member 19 and the other part of seal member 56 carries a cooperating surface for cooperation with remaining sealing portion of inner seal member 19.

A passageway (not shown) connects the outlet of the second stage impeller 16 to an annulus 260. This annulus 260 is in turn connected to an annular space formed between the housing and the front portion of member 226. Said annulus is in turn connected to a forwardly facing part of the bearing 21. The flow into this area is also carried beneath the inner race 20 by the formation of the cooling passages around the inner race. Another annulus is formed rearwardly of the inner race of the bearing 21 and is connected by passageways in the inner seal member 19 to an annulus placed just back of the bearing. This annulus is connected between the inner and

outer seal members

19 and 56 to the first stage of the turbine. A restrictor 270 located in passageway 262 sets the total flow through and around rear bearing 21.

The housing 58 is conventionally formed and provides the duct 61 for the hot gases flowing over the blades 23 of the turbine.

Hydrogen enters the turbopump from the conduit 206 at the inlet of the inducer 8, and then travels through the inducer into the first stage impeller 12. The hydrogen is then increased in pressure through the first stage impeller and collected in the first stage manifold 300. The hydrogen leaves the first stage manifold 300 through a diffuser and a cross-over tube (not shown) to the inlet of the second stage impeller 16. At this point hydrogen as a coolant is bled off through

passageways

82 and 84 to cool the shaft.

This coolant flow travels radially inwardly through the passageways and then rearwardly along the passageways formed by the shaft section 66 and annular flange 74 where it turns and goes forwardly through the splined section of annular flange 74 and shaft 24. At the annulus formed at the forward end of the splined section the flow is divided into two paths, one path continues to flow along the shaft forwardly under the first and second stage impellers to where it is discharged radially outwardly through passageways 310 which extend through the rearward part of the mounting sleeve 102 and the spacing provided between the annular flange 214 and the first stage impeller into the inlet of the first stage impeller.

The other path flows radially through passageways into the opening 132 around the pipe member 154 and then through openings 162 in flange 160 into the annular chamber formed by the cut-out annular section 134 and the rear part of the center tube member 150. The flow then passes radially inwardly through openings into the cylindrical section 155 of the rear part of the center tube member 150 where it flows through the pipe member 154 into passageway 130. The passageway 130 extends to the forward end of the shaft 24 and at this point the coolant flows radially outwardly through the passageways 174 into the chamber 116. Passageways l 18 directs the coolant from chamber 1 16 into the inlet of inducer 8.

In a construction of a turbopump as set forth herein the flow of coolant passing through the passageways 82 was made to be 0.2 pounds per second and the flow through each of the paths starting at the annulus in front of the splined sections of the flange 74 and shaft 24 was made to be 0.1 pounds per second. The flow through and around the rear bearing was made to be 0.65 pounds per second. These flows gave substantially the isotherms shown in FIG. 2 for normal operation. It is noted that the shaft 24 and turbine disk 60 in FIG. 2 are not cross-sectioned so that the isotherms may be readily seen. The isotherms shown connect like temperatures on the shaft.

1 claim 1. A turbopump including in combination a pump section and a turbine section, said turbine section having a turbine disk for supporting turbine blades, said disk having an integral shaft, said pump section having impeller means mounted on said shaft, bearing means supporting said shaft, a dead gas chamber being formed in said shaft adjacent said turbine disk, a passageway extending from said pump section for conveying a pumped fluid through and around the shaft to a point near the dead gas chamber to maintain a proper thermal environment, said bearing means supporting said shaft comprising a front bearing means located adjacent said pump section and a rear bearing means located near said turbine disk, means for directing a pumped fluid through and around said bearing means.

2. A turbopump as set forth in claim 1 wherein a first annular chamber is formed in said shaft at a location radially inwardly from said rear bearing means, said annular chamber forming a part of said passageway, said dead gas chamber being positioned between said first annular chamber and said disk.

3. A turbopump as set forth in claim 2 wherein said passageway has its inlet connected to said pump section, said passageway extending from said inlet to a second point adjacent said rear bearing means, said passageway extending from said second point in the opposite direction to a third point in the mid portion of the shaft, said passageway extending radially inwardly from said third point to an annular passageway within said shaft, said annular passageway directing its cooling fluid to said first annular chamber.

4. A turbopump as set forth in claim 3 wherein said passageway having an opening for directing its flow of cooling fluid into said pump section.

5. A turbopump as set forth in claim 3 wherein an inducer means is mounted forwardly of said pump section, said inducer means being connected to said shaft, said passageway extending forwardly through said shaft from said annular chamber, said passageway having an opening for directing its flow of cooling fluid into said inducer means.

6. A turbopump as set forth in claim 2 wherein said shaft has a first passage therein, the end of said shaft fixed to said disk having an enlarged bore intersecting said passage, the end of said bore adjacent said disk having an enlarged cut-out section forming an annular space, a center tube member fixed in said bore, said center tube member having a second passage therein, the outer surface of said center tube adjacent said disk forming a closed annular chamber with said cut-out section, said outer surface of said center tube member also forming an annular passage with said bore, said second passage cooperating with said first passage, openings in said center tube connecting said annular passage with second passage, said annular passage, second passage, openings, and first passage forming part of said passageway.

7. A turbopump as set forth in claim 6 wherein the end of said center tube member under said closed annular chamber has a chamber therein.

8. A turbopump apparatus including in combination, a supply of cold fluid, a pump section for pumping cold fluid, a supply of hot fluid, a turbine section for receiving a hot fluid; said turbine section having a turbine disk for supporting turbine blades; said disk having an integral shaft; said pump section having impeller means mounted on said shaft; shaft bearing means supporting said shaft; means between said impeller means and turbine disk for maintaining a proper thermal environment, said last named means including: a dead gas chamber formed in said shaft adjacent said turbine disk, a second chamber formed in said shaft adjacent said first dead gas chamber, a first passageway extending from said pump section for conveying the pump cold fluid around the shaft at a point near the first dead gas chamber, a second passageway extending from said pump section for conveying the cold pump fluid through the shaft and through said second chamber adjacent the dead gas chamber, said shaft bearing means including bearing means located near said turbine disk, means for directing the cold pumped fluid through said bearing means.

9. A turbopump as set forth in claim 8 wherein a third passageway extends from said second chamber to said pump section to return the cold pumped fluid back to the pump.

10. A turbopump as set forth in claim 8 wherein said hot fluid reaches temperatures over 1,000R and the cold fluid in said second chamber encounters temperatures in the order of R.

Claims

1. A turbopump including in combination a pump section and a turbine section, said turbine section having a turbine disk for supporting turbine blades, said dIsk having an integral shaft, said pump section having impeller means mounted on said shaft, bearing means supporting said shaft, a dead gas chamber being formed in said shaft adjacent said turbine disk, a passageway extending from said pump section for conveying a pumped fluid through and around the shaft to a point near the dead gas chamber to maintain a proper thermal environment, said bearing means supporting said shaft comprising a front bearing means located adjacent said pump section and a rear bearing means located near said turbine disk, means for directing a pumped fluid through and around said bearing means.

4. A turbopump as set forth in claim 3 wherein said passageway also extends axially from said third point to a fourth point adjacent said front bearing means, said passageway having an opening for directing its flow of cooling fluid into said pump section.

10. A turbopump as set forth in claim 8 wherein said hot fluid reaches temperatures over 1,000*R and the cold fluid in said second chamber encounters temperatures in the order of 100*R.