US2475316A - Fluid pumping system - Google Patents

Description

G. H. GARRAWAY FLUID PUMPING SYSTEM Filed Dec. 27, 1946 I5 Sheets-Sheet 1 1 G. H. GARRAWAY FLUID PUMPING SYSTEM 3 Sheets-Sheet 2 Filed Dec. 2'7, 1946 y. a 2 T. ,3 m m Gttorncg' G. H. GARRAWAY 2,475 316 3 Sheets-Sheet 3 Zhwentoi 'rawa:

Gttomeg 6601 gel 501' FLUID PUMPING SYSTEM FiledDec. 27, 1946 Patented July 5, 1949 I UNITED STATES PATENT OFFICE" 2,475,316 FLUID PUMPING SYSTEM George H. Gan-away, Verona, N. 1., aslignor to Curtiss-Wr'lght Corporation, a corporation Application December 27, 1946, Serial No. 718,827

11 Claims. 1

This invention concerns fluid pumping systems and is concerned particularly with the provision of means to increase the efllciency of centrifugal pumps and augmentation of the pressure in the fluid which feeds such pumps.

The system of this invention, while having general utility in pumps used for other purposes, is particularly adapted for the pumping of highly volatile fluids from tankage where the absolute pressure on the fluid in the tank may be substantially less than, ground atmospheric pressure. Under such conditions, pump intake suction may cause the fluid to flash into vapor, thereby producing cavitation at the pump inlet and severe reduction in the quantity of fluid delivered by the pump and in the pressure rise in the fluid created by the pump. One expedient to overcome such 7 to drive a plurality of pumps, one serving to pump fuel, another serving to pump a coolant and a third serving to pump liquid oxygen. The pumping of the latter fluid is the most'critical. The provisions of this invention include a booster pump unit associated with the liquid oxygen primary pump, such booster pump operating at relatively low speed and imposing a relatively low increase in head on the liquid oxygen. The booster pump draws liquid oxygen from tankage at substantially ambient pressure and delivers it to the intake of the primary pump at sufliciently increased pressure so that cavitation at the primary pump inlet will be prevented. The primary pump then imparts a high pressure rise to the liquid oxygen, the outflow passing through a low speed impulse turbine and thence to the point of utilization of the fluid, the low speed turbine directly driving the booster pump. By this arrangement, the booster pump and turbine may become a unit assembly and a complicated mechanical drive for the booster pump "is wholly avoided. A very considerable weight saving may be attained in the entire system at the expense bly construction between elements of the system;

of only a very small diminution in the efliciency and the provision of positive means in rotating seals to establish definite pressure gradients across seal assemblies.

Further objects of the invention will become apparent in reading the annexed detailed description in connection with the drawings. Such description and drawings, however, are to be construed only as exemplary of the invention and are not to be read as defining the scope or limits of the invention, reference being had to the annexed claims for this purpose.

In the drawings in which similar reference characters indicate similar parts, Fig. l is a plan of a turbine driven pump assembly including a turbo-booster according to the invention,

Fig. 2 is a side elevation of the entire pump assembly;

Fig. .3 is an enlarged end elevation, partly insection, on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged section on the line 4-4 of Fig. 2;

Fig. 5 is an enlarged end elevation of a seal ring, on the line 5-5 of Fig. 6;

Fig. 6 is an enlarged longitudinal section of a ring seal arrangement, comprising a portion of Fig. 4; and

Fig. 7 is a schematic view, similar to Fig. 6, showing fluid pressure distribution upon the sealing ring.

Referring first to Figs. 1' and 2, I show a unitary assembly wherein the portion I 0 comprises a twostage turbine fed by motive fluid such as steam through a pipe I2,- the fluid passing into the turbine and driving the runner thereof (not shown) at high speed and exhausting from the turbine through a pipe H. To the left of the, turbine l0, centrifugal pumps I 6 and I8 are secured, both of these pumps being direct driven from the turbine shaft. The pump it may be used for pumping fuel in a rocket system while the pump it may be used for pumping coolant. The inlets for these pumps are shown respectively at 20 and 22 while one of their outlets is shown at 24. a spacing adapter 28 is secured to which a high speed. high pressure centrifugal pump 28 is attached. Some of the details of the pump 28 will be shown in the other flgures. This pump has an inlet duct 30, in the form of a volute, and an outlet duct 82. The pump 28 may be of any desired capacity and may have any desired pressure rise characteristics; a particular embodiment of this pump includes a runner operating at 12,000 R. P. M. imparting to the fluid a pressure rise of about 500 p. s. 1. (pounds per square inch).

Now referring particularly to Fig. 3, a booster unit 34 is associated with the pump 28, the booster unit comprising at one end a low head, low speed. centrifugal pump 35 having an inlet 88 which is connected to supply tankage, a runner 88 mounted upon a shaft 40, and an outlet volute 42 communicating with .an. outlet pipe 44 connected directly by a suitable joint 46 to the inlet pipe 80- of the pump28. The outlet pipe 82 from the pump 28 connects through a joint 48 to a volute 50 of a hydraulic impulse turbine the volute communicating with a plurality of impulse nozzles 52 through which a pressure drop is effected concurrently with an increase in velocity, the fluid from the nozzles 52 being directed against the runner 54 of the impulse turbine, said runner being secured directly to the shaft 40 which drives the booster pump runner 88. Eilluent from the turbine passes through a turbine eye 58 to a discharge pipe 58 leading to a rocket combustion chamber or' other appropriate apparatus requiring the pumped fluid. The turbine may be of reaction, rather than impulse type.

In Fig. 3 it will be noted that the joints 46 and 48 between the booster unit and the main pump each comprise planar flange'assemblies disposed in V relation at substantially 90 degrees. Since the pipes 80 and 32 of the main'pump and the pipes 44 and 50 of the booster unit are rigid and integral with their respective structures, this easily machined 90 degree joint arrangement enables simple fabrication of the components with the assurance that they will align and match perfectly, theflange of the pipe 44 lying co-planar with the flange of the pipe 30, and the flange of the pipe 50 lying co-planar with the flange of the Pipe 32. Upon being fitted to one another, without stress of either part in virtue of their inherent matching relationship, the flange joints 48 and 48 may be secured by bolts or other appropriate means. This arrangement is superior to one wherein the joints 46 and 48 might be coplanar since the co-planar relationship on separate parts would be diflicult to attain by conventional machining practices and would usually result in joints which would have to be sprung into engagement to overcome the inevitable inaccuracies in machining.

In Fig. 3 I have indicated by the symbols Pl, P2, P3 and P4 the four pressure states 01' the fluid being pumped. For a typical example of these pressure relationships in flight operation of a rocket using this pumping system, P-l might equal 5 p. s. i. absolute; P2 might equal approximately 20 p. s. i. absolute; the p. s. i. increase resulting from the pressure rise imparted by the booster pump 35. Thus, the pressure at the main pump suction would be p. s. i. absolute, sufllcient to enable operation of the main pump at high efllciency without. cavitation. The main pump raises the fluid pressure to P8 at a value of about 530 p. s. i. absolute which leads to the hy- To the right hand end of the turbine I0,

draulic turbine nozzles u through which'it an .fers a drop of about 30 p. s. i. so that P4 becomes about 500 p. s. i. absolute. No significant pressure drop occurs in the turbine runner 84; although a velocity drop is taken at this point. The final outflow from the turbine runner 54 in the pipe 58 thereby becomes P4 or about 500 p. s. i.

absolute. It will be appreciated that the booster turbine removes some of the energy from the high pressure fluid and imparts substantially the same amount of energy to the fluid at the intake of the main pump through the booster pump 88 less losses from booster turbine and pump inemciencies. Some power must. of course, be used to drive the booster pump-in the present invention, this energy is derived from the energy in the primarily pumped fluid rather than from a separate prime mover or from a shaft drive from the turbine I0. Were the booster pump to be mechanically driven, considerable weight and complication would be involved since the booster pump is designed to operate at a much lower R. P. M. than the primary pump, this low R. P. M.. of the order of 1200, or main pump speed, being necessary to enable boosting of the fluid to the main pump at a moderate pressure rise without cavitation or boiling of the fluid at the booster pump inlet. The actual loss in efflciency, in utilizing the turbine driven booster pump, is so small as to be wholly offset by the considerable gain in weight afiorded thereby. Substantial increases in weight would be entailed over the booster pump arrangement if the tanks were pressurized or alternatively, ii' the booster pump were driven by a power take-oil, through a reduction gear from the turbine ill or other prime mover. In

a typical rocket engine unit, over 700 pounds weight is saved by the use of the booster unit shown.

Referring to Fig. 4, some details of the main pump 28 are shown. This pump comprises the smoothly formed inlet volute 80 which includes the projection 64 which directs inlet fluid to a pump runner 66 secured to a, shaft 08 directly driven by the turbine ill, with initial swirl. While in ordinary pump practice, inlet volutes are considered inefficient, the present system is benefltl ted by use of the volute, to minimize drastic change in direction and velocity of the working fluid at the suction of the high speed pump. The runner 66 imparts high velocity to the pumped fluid discharging it to adifluser 10 where velocity head is converted in part to pressure head,

and thence to the outlet volute 28 communicating with the discharge pipe 32.

As has been pointed out, the runner 86 operates at high speed and imparts velocity and pressure heads to the fluid. It thereby becomes highly desirable to seal the pump discharge from the pump intake to avoid loss in efllciency. Such sealing arrangements are shown in Figs. 4 through 7 and 7 they comprise seal rings 12 non-rotatably and slidably engaged on cylindrical projections 14 formed on the pump housing. Sealing faces 14 are provided on both sides of the runner 68, the diameter of the seal faces being substantially similar. Chambers 18 and are formed in the housing which communicate, at the outer periphery of the runner, with the pump discharge so that these spaces are filled with fluid substantially at pump discharge pressure. Furthermore, spaces 82 and 84 are disposed inwardly of the seal rings 12 and contain the fluid at pump intake pressure, the space 82 having free communication with the pump intake through the intake pressure P2.

medium of holes 86 drilled through the pump runner from its active face to its inactive face. Thus, the pressure difference across the seal rings I2 is substantially the same as the pressure'difi ference between the pump intake and the pump outlet.

. As noted in Fig. 6. the cylindrical surface on the housing portion 14. identified as 86, has a diameter substantially midway between the inside diameter and the outside diameter of the sealing face I8 and of the coacting face of the ring I2. The ring 12 is substantially L-shaped in cross section as is clear in the drawings, a long limb of the L comprising that cylindrically formed portion which engages the cylindrical-portion 86. The clearance between these portions is sufliclently close to minimize leakage but is sufficiently large to permit free axial movement of the ring I2 relative to the housing. The ring I2 is constrained from rotation on the housing portion I4 by one or more pins 88 secure in the housing and loosely engaging bores 98 in the ring, said pins being parallel to the elements of the cylindrical face 86. If desired, preloading springs 92 may be utilized between the ring and the housing to cause engagement of the sealing face of the ring I2 with the runner sealing face I6. The outer portion'of the ring I2, opposite the outer part of the sealing face I8, is subject to pump outlet pressure P3 as indicated in Fig. 7,

andthe inner portion of theseal ring I2, inwardly of the cylindrical surface 86 and opposite part of the sealing face I8 is subject to pump Pressures P2 and P3 act on the seal ring over substantiallyequal areas and tend to force the ring I2 into engagement with the runner seal face I6. At the seal face, a straight line gradient is desired between. P3

' and P2 in order that the ring I2 will have balanced pressures operating at its opposite ends. In this connection, the pressures P3 and P2 act on the seal face with a uniform pressure drop from one to the other, and define a triangle which resolve into a resultant force acting rightwardly -(Fig. 7) on the seal ring I2 in equal opposition to the summation of the forces acting leftwardly on the stepped portions of the seal ring I2 remote from the face I8. The'actual fluid pressures on the seal ring then are substantially balanced under all conditions of operation and the only positive force to enforce seal engagement at the face I6 is that afforded bythe springs 92. Thus, a predeterminate sealing face pressure may be attained under all conditions of operation, this sealing face pressure being selected to secure not only adequate sealing but to minimize wear and frictional heating effect upon the seal. In attaining this balanced pressure condition, theseal gardless of the length of use of the pumping sysface I6 and the coacting ring seal face may be made quite wide as shown, as compared with face seals of the prior art, to providelarge balancing forces as compared with static friction forces. To assure a uniform pressure gradient across the wide seal face, one or more shallow spiral grooves 94 are formed in the seal face. The spiral groove may run either with or counter to pump runner rotation as it progresses from the inner to the outer edge of the seal face,'the direction of the spiral preferably being selected so that leakage through the seal is minimized consistent with adequate seal face lubrication. While the spiral groove 94 permits leakage in slight degree, it makes the seal assembly'determinate in character so that definite leakage may be initially attained and may be maintained retem. This distinguishes from prior arrangements wherein a seal might be tight and leak-free at the outset, but as the operating time on the pump accumulates, leakage increases and the pump efficiency correspondingly decreases. Prior art wide-f ace seals yielded an indeterminate gradient across them with consequent unbalance of forces. while prior balanced narrow-face seals are subject to such small fluid forces that friction effects upset the balance relationship. The cylindrical sliding joint 86 for the ring I2 maybe modified to other forms, such as a diaphragm or bellows. which will permit pressure P3 to act on the outer part of the ring and pressure P2 to act on the inner part of thering.

The above described type of seal has general utility in pumps and turbines of any sort and may be used, if desired, in low head pumps such as the booster pump shown in detail in Fig. 3. However, since the booster. pump of Fig. 3 is a low speed, low head unit, I prefer to use therein seals of different type such as the bellows type shown at 96.

Referring to Fig. 3, details of the booster assembly 34 are shown, including both the pump and the turbine components thereof. The pump runner 38 is provided with annular seal surfaces 98,

of substantially equal diameter on both ends thereof, with which the bellowsseals 96 engage. said seals being non-rotatably secured as shown to the pump housing. The pressure within the seal diameter is at pump intake pressure, this pressure'being transmittedto the rear face of the runner through holes I88 through the back plate thereof. The spaces outside of the seals 96 are under pump discharge pressure and this pump discharge pressure is transmitted through a conduit I82 to the interior of a tubular casing I 84 integrally joining the pump and turbine components. At the left end of the tubular casing I84, a bearing I86 is provided for the shaft 48 which carries the pump runner 38. Slight leakage of pumped fluid may occur through the hearing but this leakage is small as the pressure difference between opposite sides of the bearing is small. The right hand end of the tubular casing I84 is integrally secured to the turbine housing 5| and is provided with a labyrinth seal I88 through which the shaft 48 passes to carry toward its rightward end the turbine runner 54. The shaft 48 continues rightwardly as shown to a closed-end outboard bearing II8 mounted in struts I I2 in the turbine outlet. It will be appreciated from what-has been described that the pressure in the turbine outlet is vastly greater than that existing in the booster pump inlet or outlet; if this pressure were permitted to act upon the rightward end of the shaft 48, it would impose an axial force upon the booster shaft of considerable magnitude. To avoid this efiect and to substantially balance the rotating system axially, the shaft 48 is drilled axially as at 4, the left end of the ho e II4 communicating with the P2 zone within the tubular casing I84 by cross holes H6 and communicating with a clearance space I I8 at the right hand end of the shaft 48 within the closed bearing II8, through crossholes I28. Thus, pressure on the right hand end of the shaft 48 is at P2 rather than at P4, and since P2 is only slightly greater than PI, axial forces on the shaft 48 are substantially balanced. By this arrangement, there will be a pressure drop from P4 to P2 across the bearing II8 so that a small leakage due to this pressure drop pumped fluid and the same fluid operates the turbine Bl as is operated on by the pump 35. Accordingly, an interchange of fluid from the turbine to the pump in small amount is not important. No positive seals, which are usually booster pump, seals in said booster pump to mini characterized by rapid wear, are necessary or.

desirable.

Where the pump system herein described is used for liquid oxygen, the temperature of the mize leakage of booster pump eiliuent to the pump inlet, seals in said main pump to minimize leakage of main pump eflluent to the ,main pump inlet, and meansin at least one of said seals to establish a determinate pressure gradient there- 1 across.

- 5. A pump assembly comprising a booster pump, a main pump fed thereby, a turbine driven by the main pump outflow, said turbine having means drivably interconnecting it with said booster pump, seals in said booster pump-to 'minimize leakage of booster pump effluent to the system varies from atmospheric when the pump is not operating to temperatures well below zero when the pump is in operation. Thus, particular care must be utilized in bearing and seal design to avoid any possibility of binding. Such possi-' bility is overcome by the arrangements herein shown.

' It will be clear from acting thereon, making unnecessary any utilization of thrust bearings other than locating buttons such as I22 and I24 as shown in Fig.3.

Though but a single embodiment of the invention has been illustrated and described, it is to the arrangements described, that the runners of the main pumps, the 'booster'pump and the turbine are substantially balanced within themselves as to axial forces raise the pressure of the fluid, the same fluid delivered by said pumpserving to drive said turbine, and means to impose a substantially equal fluid, pressure on the opposite ends of the direct drive connection between said runners.

2. A fluid pump booster unit comprising a centrifugal pump runner and a coaxial turbine runner directly connected to said pump runner for driving same, pressure increasing means between the pump outlet and the turbine inlet to raise the pressure of the fluid," the same fluid delivered by said pump serving to drive said turblue, and means to impose on both ends of the direct drive connections between said runners the pressure existing at the pump.

3. A turbine-pump unit comprising an impulse turbine runner operating at high pressure having velocity drop thereacross and substantially no pressure drop, a shaft on which said runner is secured, a housing including bearings mounting said shaft, a centrifugal low-head pump runner mounted on said shaft, the end of said shaft at the pump runner intake being subject topump intake pressure, one of said shaft bearings being disposed at the downstream side of said turbine and one side of said-bearing being subject to tu'r-' bine pressure, and'means-to'impose pump pres sure on-the other side ofsaid bearing and on the turbine end of said shaft.

4. A pump assembly comprising a booster pump, a main-pump fed thereby,-a turbine driven by ;the mainpump outflow, said turbine having means drivably interconnecting it with said pump inlet, seals in said main pump to minimize leakage'of main pump eilluent to the main pump inlet, means in at least one of said seals to establish a determinate pressure gradient thereacross and means incorporated in said one seal to substantially balance the pressures acting thereon.

6. A pump assembly comprising incombination a housing having an inlet eye an outflow chamber, a centrifugal impeller borne in said housing so driven as. to force fluid from said eye to said chamber with substantial pressure rise, a rotating seal means between said outflow chamber and said eye comprising a substantially annular flat seal face on the impeller, an annular portion on the housing having an end spaced from said seal face, a non-rotating seal ring axially movable with respect to and sealably coasting with said housing annular portion, and having an annular .face seal surface engaged with the impeller flat sea] surface, the diameter of said housing annular portion being midway between the inside and outside diameters of said annular face seal surface.

7. A pump assembly comprising in combination a housing having an inlet eye an outflow chamber, a centrifugal impeller, borne in said housing so driven as .to force fluid from said eye to said chamber with substantial pressure rise, and rotating seal means between said outflow chamber and said eye comprising a substantially annular flat seal face on'the impeller, an annular portion on the housing having an end spacedfrom said seal. face, a non-rotating seal ring axially movable with respect to and sealably coacting with said housing annular portion, and having an annular face seal surface engaged with the impeller flat seal surface, the diameter of said housing annular portionbeing intermediate the inside and outside diamet'ers'of said annular face seal surface, and a shallow groove in one and extending about the axis of said flat annular seal faces to establish a determinate pressure gradient thereacross from the impeller'eye'pressure to the chamben-pressure.

8. A pumpassembly comprising in combination a housing having an inlet eye an outflow chamber, a centrifugal impeller borne in said housing so drivenas to force fluid from said eye to said chamber with substantial pressure rise, and rotating seal. meansbetween said outflow chamber and said eye comprising. s. substantially flat seal face on the impeller, a cylindrical portion' on the housing-having an end spaced from said seal face, a non-rotatingseal ring having a cylindrical portion slidably -fl tt ed to and ooacting with said hous c lin rical o tionisn a in an nula'r face seal surface engaged with. t he impeller flat seal surface, the diameter 'of said cylindrical portion. being intermediate the inside and outside diameters of said annular face seal surfaceand a shallow spiral groove in one of said ac-mere tating seal means between said outflow chamber and said eye comprising a substantially flat seal face on the impeller, a. cylindrical portion on the housing having an end spaced from said seal face, a non-rotating seal ring having a cylindrical portion slidably fitted to and coacting with said housing cylindrical portion, and having an annular face seal surface engaged with the impeller fiat seal surface, the portion of the end of said ring remote from its face seal surface and disposed on one side or said cylindrical portion being in unrestricted communication with said outflow chamber and the portion of said ring end on the other side of said cylindrical portion being in unrestricted communication with said eye the diameter of said cylindrical portion being intermedlate the inside and outside diameters of said annular race seal surface, said cylinder diameter being so chosen that the axial components of fluid pressure drop across said seal faces is substantially equal. to the sum or the axial components of chamber pressure acting on the seal ring outwardly of the cylindrical portion plus the axial components of eye pressure acting on the seal ring inwardly oi the cylindrical por-- tion.

10. A seal arrangement between relatively rotating members defining high and low pressure zones, comprising a hat annular seal face on one member, a coaxial circular support portion on the other member spaced from said one member, a ring seal having circular means engaged with said circular support for non-rotatably holding said ring for atrial movement so that on one side or said circular support one end oi said ring is in urestricted communication with said high pressure zone and on the other side of said support said ring end is in unrestricted communicatlon with said low pressure zone, said ring having a flat annular seal face engageable with the seal face of said one member, and the outer and inner diameters of said annular seal face being respectively greater and smaller than the effective diameter of the circular support between said ring and said other member.

11. In a pumping system for fluids; a main pump unit including a housing having inlet-and outlet ports for said pump; a booster pump unit comprising an auxiliary pump, a turbine drivably connected to said auxiliary pump, and a housing having inlet and outlet ports for its auxiliary pump and for its turbine, said booster unit housing being secured to said main unit housing with its auxiliary pump outlet port registering with the main pump inlet port and with its turbine inlet port registering with the main pump outlet port.

GEORGE E. GARRAWAY.

REFERENCES CITED The following referenhes are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 921,118 Kasley May 11, 1909 1,089,248 Michell Mar. 3, 1914 1,197,755 Moller Sept. 12, 1916 1,607,306 Peterson Dec. "1, 1926 1,869,955 Daugherty Aug. 2, 1932 2,003,168 Allen May 28, 1935 2,021,346 Allen Nov. 19, 1935 2,109,679 Nevellng Mar. 1, 1938 ,2 250,311 Meyer July 22, 1941 FOREIGN PATENTS Number Country Date 325,930 Great Britain Mar, 6, 1930

Images