US1919376A - Reversible pump turbine - Google Patents

Description

July 25, 1933. l.. F. MOODY 1,919,376

REVERSIBLE PUMP TURBINE Filed an.`11, 1929 s Sheets-sheet 1 INYEToR Leww t July 25, 1933 L. F. MOODY REVERSIBLE PUMP TURBINE e 'sheets-sheet 2 Filed Jan.

NVENTOR. 'fj mvv-zb( AT ORNEY.

Filed Jan. l1, 1929 6 Sheets-Sheet 3 July 25, 1933.

L. F. MOODY` REVERSIBLE PUMP TURBINE 6 Sheets-Sheet 4 Filed Jan.

July 25, 1933. L. F. Moon# @$19,376

REVERSIBLE PUMP TURBINE Filed Jan. 11, 1929 s sheets-sheet 5 a Big-I3 Loss or HEAD we To ENLArzqEr/lem' 1N %of= EN mFFERENcE mvELocrrY mams xr EHTRANcEg mscumqe AND ASHS EQUNALEu-v ComcAx-Tube C ozzaspommq To GLM-na VME PSSAGES PSM-r 1-" PONT lNIKE- Va.. Cuzva Foz @Aang l 7 CE2-ER I GRAVWY L l {Ams oF l.

A-r BAFFLE July 25, 1933. L. F-.MooDY REVERSIBLE PUMP TURBINE Filed Jan, ll1, 1929 6 Sheets-Sheet 6 Patented July 25, 1933 PATENT Frio LEWIS FERRY MOODY, 0F PHILADELPHIA, PENNSYLVANIA REVERSIBLE PUMP TUBBINE Applicationy led January 1l, -19589. Serial No. 331,910,

This invention relates' generally to hydraulicmachines of the reversible pump-turbine type and one object of this invention is to produce a hydraulic machine which Will operateefliciently' and el'ectivelf j at times as a turbine or hydraulic motor r converting hydraulic powers into mechanical power, and at other times yas a pump, utilizing mechanical power to impart head to water or to raise water against a head.

Another object is to produce such/a ina-- chine adapted to Worlr asa turbine under a given head, or range oi heads, and at a given speed, which will be reversible so 'as to be V capable ot pumping. effectively against appproximately the same head or range of heads, or against a head only moderately in exc-ess of that head, While running at substantially the same speed orat a speed notl greatly in excess of the first value` Another object is to produce a machine which will be interchangeable in action from turbine to pump by reversing at the same time both the direction of low of the working iluid and the direction oli revolution oi the rotating element, and which, by adhering to the principles hereinafter described, may be applied to either low or high heads by suitably proportioning the parts.

Another object is to produce a machine which is capable oi operating either as pump or turbine., and which when used as a turbine will be regulatable to control its speed or load.

Still other objects and advantages will appear from the *following description oi the 4 accompanying drawings in which;

llig. l is a sectional view oi a high specilic speed propeller type unit embodying the principles of my invention,

llg. 2 is aplan vievv talren inst helovf vgenerator ci Fig. i,

Fig. 3 is a developed conical section through the blades talsen substantially on line 3-3 oi Fig., l,

Fig. l is a `sectional view oil a. mixed lovv Francis type unit embodying the principles of my invention, i

llig. 5 is a section similar to Fig. 3 and taken on line 5-5 of lig. 4,

' Fig. 6 is a diagrammatic plan view of Fig. 4, Fig. 7 is a vertical section of a ciic speed Francis type turbine the principles of my invention, through the collector passage being taken tor simplicity along the line 7 7 of Fig. 8,

8 is a diagrammatic plan view of Fig.

Fig. 9 is an enlarginl substantially horizontal section ol tvvo adjacent runnervanes and ssociated guide varies taken on line 9' of Figs. l0 and ll are equivalent conical tube curves el the runner and guide vane passages,corresponding to Figs.` TF9,

Fi l2 is the velocity curve' tor determining t e cross-sectional areas ci the casing or inlet, for the turbine oi Figs. 7 to 9,

lower speembodying lig. i3 is a curve showing the relation he tween loss ol head and rate el enlargement of `the passage,

Figs. ll and l5 are a rdia ;rammatie plan and section lol a volute casing or passage,

Fig. i6 is an equivalent rectangular passage,

Fie. i7 is a diagram of a moderate specic speed runner having vanes with considerahle overlap and showing a method ol obtaining the proper passage lietvveen the tvvo successive vanes,

Fig. 18 is a vertical sectional vievv o' anl adjustable hlade runner and hlade adjusting mechanism.

Frequently in hydrzniliel power developments, and` sometimes in connection with lsteam power stations, opportunities arise, for storing or accumulating power -dnr` g periods ott lovv power demand on the sysiem, so that this stored power may he utilised during periods of loads.. This may he feasible when a natural reservoir is availahle or when one may he created lay d ms, and when a supply oi v ater or secon rvoir is availahle, together vvitli a. dinerence ci? level hete/een surfaces to give a suitable head. Such power storage may he feasible hoth in hydraulic developments on v'rivers and in tidal power developments, and

may sometimes be valuable in `connection the section itk pumps to store' power for peak load utilization in the steam power system. i

The pumping and utilization of the stored l Water may be accomplished by using separate pumps and turbines, the pumps being operated when excess plant capacity or river flotv is available and the turbines being operated at times of high load demand. According to the present invention it is proposed to use the same by hydraulic unit coupled to an electric generator or motor, both for pumping and turbine operation. When pumping the electric motor operates as a motor and when utilizing the stored Water the same electric motor runs as a generator, the direction of rotation of the rotating element of the hydraulic and electric unit being reversed.

The hydraulic machine may be described as hydrodynamically reversible. Centrifugal pumps as customarily built are not adapted to run efficiently as turbines, and tur bines of customary forni are not adapted to operate effectively as pumps, or Without prohibitive hydraulic losses. The usual forms of the rotating element or runner'are not adapted to operate reversibly with the desired degree of efficiency. Pumps of usual type if run as turbines are not only unsuited in form of runner but do not have the means for regaining the kinetic energy of the water dischargin from the runner with reversed flow and t erefore would develop but little power and efficiency; and moreover lack regulating means for governing speed and load. Turbines of customary forms, such as the Francis turbine, are incapable of effective use as pumps, because with reversed flow the runner vanes are so formed that the passages between them enlarge so rapidly in crosssection that prohibitive enlargement losses7 would occur; and in addition to this the turbine casings are not adapted to handle reversed flow without causing large losses in -eddies and turbulence, and are not capable,

without radical changes in form and proportions, ofacting as efficient diffusers or re gainers of the kinetic energy of the high velocity discharge from the runners if il should be'attempted to run them as pumps. Moreover, the incorrect hydraulic conditions would promote rapid deterioration through hydraulic corrosion or pitting,

n the hydraulic machine of this invention, the water passages to and from the runner are so formed and proportioned that the velocity gradually accelerates in the entrance passage as the runner is approached, and

graduall decreases'in velocity or decelerates as the uid flows away from the runner; so that when the flow is reversed the gradual deceleration in what was before the discharge passage becomes a gradual acceleration, and the gradual acceleration in What was before the entrance passage becomes a gradual deceleration; and in each -passage sudden enlargements and rapid curvatures of walls which Would permit the flow to separate from the Walls are avoided for both directions of flow. By these means the machine incorporates a discharge passage which will act as an eficient diffuser or regainer of kinetic energy Whichever direction of flow is considered. The runner is so formed that the cross-sectional area of the vane passages, measured normally to the relative velocity of flow, either remains approximately constant, or increases at so gradual a rate when the runner is operating as a pump iinpeller that the relative velocity of entrance to the impeller will be efficiently decelerated.

For convenience of identification the usual turbine inlet and draft tube pasages are referred to respectively as the inlet or entrance passage and the discharge passage even though the reverse functions are performed by these passages whenl operating as a pump.

In one specific aspect of the invention the above principles are embodied in a high specific speed propeller type unit as shown in Figs. 1-3 wherein the unshrouded propeller runner 15 has a usual form of conical hub carrying a relativelv small number of diagonal blades 16 which preferably overlap in the manner shown `in Fig. 3, that is. with respect to a line normal to the nath of flow 66. This overlapping of the blades effects efficient diifusion and gives stability of operation. A spiral inlet passage 17 commencing at the intake 17 and an annular spreading discharge passage 18 conduct water relative to the lrunner which is disposed at the juncture of the passages, this juncture being defined by the indicated turbine parts such as the curb ring 19 and the head cover 20 and the stay ring 21. This ring has fixed guide or stay vanes 21 suitably arranged and shaped to cooperate with'the flow in accordance with the principles of this invention, these principles also applying to bafile 21 which is the terminal of thespiral inlet. The runner is spaced from the guide vanes to form a transition space 22, while lower stay vanes 23 are also provided a substantial distance from the runner. The spreading annular passage 18 terminates at 24 in a collector passage 25 which extends downstream, the Wall of the collector approaching the discharge edge 24 as at 26. The conical core 27 preferably extends up to the runner hub to form a r'elatively smooth continuation of the outer surface thereof while the outer Wall of passage 18 comprises ther plate metal 28. or may, as

los

shown in Fig. 4, be made wholly of concrete. The runners in all forms herein disclosed are connected, as shown, directly to the shaft of the motor or generator M, the function thereof being dependent on whether pump or turbine operation is had.

In Figs. 7 to 9 there is shown a low specific speed turbine to which the pr.inciples of my invention have als'o been applied. The runner 40 when operating as a turbine receives water from a casing 41 and discharges into an annular spreading draft tube 43'and collector passage 44 While relatively thin Wicket gates 45 are adapted to vary the an le of whirl imparted to the flow, these gatesgbeing adjusted by usual mechanism'v including 4a shifting ring 46. 'As is usual in low speciiicL speed turbines the blades 47 are relatively large in number in comparison -to the propeller runner Where usually not more than about six blades vare used, but-'are fewer in number than in a usual non-reversing turbine of corresponding specific sneed. this being illustrated by the disclosure of Fig. 9 wherein the spacing of the blades is such as to require only eight blades. It will also be noted that in the low specific turbine of Fig. 9 the blades llave a greater degree of curvature in the direction of flow than does the propeller runner and that the'blades are longr Iin direction ot' flow to permit `gradual deceleration. In the orms'of the invention shown in Figs. 1 and .7 the outern wall of the runner passage 1n meridian section has a large radius of curvature which is conducive to ellicient and stableV operation, it .being noted that in general the radius of curvature of the outer surface is notA less than approximately two-thirds oil the throat diameter, noting in particular Fig. *1g -Whereas in Fig. 7 the radius of curvature is approximately equal to the full radius ofthe throat diameter. The throat is considered as being that portion of the passage having the smallest diameter adjacent the runner. It will be further observed in all three forms that the flow passage and/or runnerpassages from the lower side of: the runner up to the guide vanes do not increase in width when measured in meridian planes, or as expressed in another aspect,'the transverse Width of the ,iiow passage :adjacentb the guide va'nes when measured in a meridian plane either l'alls Within or is not greater than the transverse Width. oif'fthe ,paage adi acent the lower portion oi-the runner. For instance, the guide vanes 54, Fig. or ap precialoly less length than would normally loe the case with a usualnon-reversible Francis type turbine While in connection with 1 the dow passa-ge leading upwardly 'rorn the runner to the point adjacent the guide venes 2l is oi= substantially uniform* Width.

ln Fig. 4 a moderately high specific speed` or mixed flow type of Francis unit is shown having a runner 50 provided with rnoderately large number of spoon-shaped blades 51, a spiral entrance passage 52 and spreading annular discharge passage 53. The runner blade passages and entrance and discharge passages are designed in accordance with the principles herein outlined as is also the case With the adjustable guide Vancs 54 rlhe collector passages may bevaried in their design, for instance, in Fig. 6 collector 56 has its spiral portion start at a lateral point 57 While in Fig. v8 it starts at a central point 58. 'lhe upper and lower Walls 59 at entrance have gradual relative divergence.

As a guide in proportioning both the entrance and discharge passages and the runner and guide vane passages, equivalent conical tubes may be laid out in diagrams, an example of which is as follows: Along an axis 60, Fig. l1, distances are measured representing to scale distances measured along the middle How line of the passage, which is here the runner passage of Fig. 9. At each point so located on the axis 60 a diameter (or radius ld as in lig. 11) is drawn perpendicular to the axis representing to the same scale the diameter or radius of a circle having an area equal to the transverse area oi' the passage at the corresponding point, taken perpendicularly to the new. These diameters or radii R determine the walls 61 cfa conical tube; and it ecient diri'usion or deceleration is to be accomplished, the angle of llare, or angle or the conical Wall to -the axis o the cone, should be' between about 4 and 7 for the discharge assages, and should no tmaterially exceed and in the equivalent cone corresponding tothe runner vane passage, the angle of dare should not exceed about 5 on account ot the high relative velocity of flow through the runner. angle of flare igor ellicient deceleration at about 7 it should be understood that an exact limit can not be prescribed for the reasonthat the loss or head accompanying deceleration varies with respect to the" angle in accordance Witha curve, reaching its extremek minimum value in the neighborhood oi about creasing rate as the angle 1s increased. i The character or the relation is shown by the 'curve ld. llrom this it will be seen troni the rounded forni oli the. curve that angles somewhat greater than the best cause a moderate increase in the loss, but as the is lurther increased the loss increases rnore and more rapidly, so lthat il" one departs troni restricted Zone.l excessive losses will be incurred. lain practice, in large machines, the most economical angle will not l be that 'for the extreme minimum" shown on the curve, but considering the final discharge loss and the increased dimensions and cost Vaccoinpanying the useio very long gradually tapering passages, the best angle in most ln placing the limiting v llt) and increasing at a progressively inlid vcases can be advantageously made\ greatery than 3 or 4, and may be from 5 to 10 in practice, a value of about 6 or 7 being found from experience to be consistent with economy and high eiiiciency. Preferably the angle of Hare of the equivalent cone corresponding to the runner passage may be made about 3 or 4, so that when operative as a turbine the runner will have a slightly and gradually contracting passage between successive vanes; and, when operating' as a pump there Will be a gradual deceleration ot the relative Velocity during the passing of the water through the impeller and while it is increasing in static pressure due to the transformation of mechanical energy into head; but as pointed out above slightly reater angles, namely 6 or 7, can be atvantageously used 1n many cases as consistcnt'with both economy and high eiliciency.

`Applying to the Fig. 7, 9 form of runner passages, as an illustration, the above outlined method for determining the equivalent conical tube` distances L1, L2 etc., are measured along the middle iiow line 62 and the transverse areas at the lines 63, 64 etc. are determined.- The radii of circles having areas equal to these transverse areas are then laid oi from the axis 60, Fig. l1 as radii R and thus the outline 61 of one half of the conical tube is obtained.

To plot the equivalent cone ior the difuser channel between two blades 16 of the propeller runner, transverse areas are taken equal to 'B b sin (Figs. 1 and 3) at selected points along the center line of flow 66 at distances L1 etc. from the end of thel passage. (The center line of flow is the mean How line at the center of the annular/area at about seven-tenths of the tip radius.) Then from #52:3 b sin fin/d BXJ R v 7T sin and plot. R vs. L as in Fig. 11. rl`hen a is the angle of fiare of the equivalent cone, and a should not exceed about 5. 4

To plot the equivalent conical tube for the discharge passage, one specific method which may be followed for an annular spreading passage is disclosed in my Patent No. 1,315,232 while the equivalent conical tube for the guide vanes as shown in Fig. l() is determined by the same methods used for the runner vane passages. The equivalent conical tube for draft tubes of elbow or other formation could be determined in accordance with the principles outlined herein.

In designing the volute casing for eflicient deceleration, instead of laying out an equivalent conical tube having cross-sectional areas equal to those of the casing, as in the case of the runner vane and guide vane passages and the draft tube, a modified procedure must be followed Aon account of the fact that the volute casing or entrance passage (i8, diagrammatically shown in Figs. 14 and 15, is continuously receiving additional quantities of luid-around the turbine periphery due to the lateral entrance of fluid from the periphery of the runner and guide vanes. This varying quantity of the fluid flowing in the casing is taken care of by plotting a curve Fig. 12 of velocities at successive points in the casing with respect to distances L, measured along the mean line of flow 69 (drawn to pass through the centers of gravity of the successive casing sections) see Figs. 14 and 15. Now taking the radius of a circle having an area equal to that of any section of the casing and calling this R, a curve is plotted between V and L, (Fig. l2) to scale, V being the velocity at the section considered in feet per second. Calling the scales to which diagram is plotted Sv and SL where Sv=scale for ifel ufitics=iliclics on diagram representing 1 :tt/sec.

SLL-scale for lengths==inches on diagram representing 1 ft.

then the corresponding angle of flare a of an equivalent conical tube having the same rate of deceleration is calculated from the formula in which 8 is the angle of slope of the velocity curve at the point considered, measured from the diagram as indicated in Fig. l2. The values of a so determined, should be small and preferably not materially greater than about 7 at any point in the casing to give suiliciently gradual deceleration Jfor eflicient regain of velocity head.

In a turbine the velocity of flow in the casing is cutomarily made low relatively to the head on the turbine, the corresponding velocity head being in usual practice between 2% and 5% of the head on the turbine. In such a machine used solely for turbine operation, no loss is incurred in rapidly accelerating the velocity from the casing to the runner, since fluid may be rapidly accelerated in a contracting passage without causing turbulence or loss. In a machine designed for interchangeable pump operation however the Velocity leaving the runner is high compared to the head, and gradual de celeration of this velocity is essential if turbulence and material loss of head is to be avoided; this requires that this gradual deceleration must be effected throughout the transition from the ruimer to the easing, and throughout the casing itself, and consequently the casing velocity must in many cases be much higher than` that provided in the usual turbine and lmust 4gradually decrease throughout the casing. In a pump of moderate or high specific speed the velocity head required in the volute casing will in general be of the order of 10% to 25% of the head, or several times that used in turbines. and to make. the machine efficiently operable as a pump, the sections of the volute casing will have to be mad-e much smaller than in normally designed turbine. with casing velocities two orr more times the values used for normal turbines.

As another criterion for thel form of the runner vane passage, it a diagram is constructed, Fig. 16, by rectifyiug the centerline oi'- flow between two successive vanes so as to obtain a straight axis such as 6() in drawing the equivalent cone, and the width of passage from vane to vane and the breadth perpendicular to the shroud ring and hub are laid oli to iorm a rectangular tube, the walls of the tube in either direction should not diverge from each other by more than about 10 if there is divergence in both directions. In general, however, u2 (Fig. 16) will be negative;vthat is, the transverse breadths of the runner vane passage measured in a plane containing the runner axis (meridian plane) as shown at (S3, Gli in Fig. 7, will gradually decrease in the direction of the flow when pumping; so that the walls formed by the hub and shroud ring will gradually converge. At the saine time the transverse Widths from vane to vane in a section normal to the meridian section (the conical section of Fig. 9) will gradually increase in the direction of pump low, giving a positive angle of divergence, a5, which should not exceed about 10; so that the entire divergence of the walls formed by the back of one vane and face of the next will not exceed about 20.

To construct the equivalent rectangular passage for the propeller runner, the values of B and (Z) sin ,8) respectively are plotted against L as shown in Fig. 16. In this rectangular equivalent tube neither al nor al, should exceed 10.

ln an ordinary Jform of runner in which the vanes have a substantial amount of overlap, the channel area may be calculated as above tl'iroughout, or the middle portions as shown in Fig. 17 may be taken as Xn, so that R= li;

and the rect-angular equivalent tube drawn by plotting B and 'n against L.

'ln order to provide regulating means for the turbine and also to permit the discharge during pump operation to be adjusted to compensate or the change in condition due to this reversed operation at substantially the same speed and head, as frequently desired, the movable guide vanos or wicket gates 45 or 54 may be provided at entrance to the runner (running as a turbine). 'Fliese are shaped to conform to the gradually deceler- `ating flow oi" the runner dlscharge during pump operation, so that the areas between these guide vanes, when in approximately their normal position for pumping, must increase at a rate consistent with an equivalent cone or tube as shown in Fig. 1() and aocording to the same rule as for the other passages; and the guide vane surfaces must be relatively fiat and free from sharp curva tures, and must be relatively thin and have gradually tapering discharge edges for both directions of `flow, to enable the streams passing between the guide vanos to merge and reunite in a single continuous stream after discharging from them. To permit the use of relatively thin guide vanes, relatively large collars 45 may be provided to obtain su cient strength between the guide vanes and shafts therefor.

rtheoretically considered, a machine following the principles above described can be reversed in direction of revolution and flow, all the velocities remaining the same in amount but reversed in direction, and the vector diagrams of velocities will then remain the same with only the directions .reversed, and the flow will continue to agree with the runner vane angles at entrance and discharge and no impact losses due to disagreement between the flow direction and the vane direction will occur. This reversal at constant speed of revolution would however require the head acting to be different for pump operation Jfrom that for turbine operation, to give identical velocity diagrams. rThe head acting upon the machine, Jfrom entrance to discharge or Jfrom discharge to entrance, minus the head loss in the machine due to friction, eddies and discharge fvelocity head losses, may be termed the etective head on the runner and denoted HQ. When operating as a pump the total head on the machine is Hp and calling the head lost in the machine HLP, then in which Ep is the pump eii'iciency; but when operating as a turbine the total head on the machine is BT and calling thehead then lost in the machine Hm, the relation is: H=HTHLT=HE, in which E, is the turn bine efficiency. Hence to obtain the same eieeetive head on the runner and the same velocity diagrams when the machine is reversed the head en the machine would have te be changed `from for pump operatien to H, for turbine operation, according to the relation: H

that is the head would have to be changed in the ratio:

Under usual requirements, however, the head will remain approximately the same, or be. slightly lower for turbine action than forpump action due, to conduit losses, outside of thel machine` lo obtain exactly similar velocity diagrams in this case. it would therefore be necessary to correct the speed of' revolution to keep u w/He the same (where u is the linear velocity of a point of the runner). In the ease of H,=H, we should have Ham the effective head on the runner for pump action. greater than Het, that for turbine action, according to the relation:

1 Ua H=IIZL =H,=Y so that H figg-EPE y The speeds would then have to be adjusted to give: v

.llif- A '\/I]cp 'JHM or would bear the ratio:

Ui UT Hw fElf in which Ut and Un are the linear velocities of a point on thc runner for turbine and pump action respectively, these being proportional to the revolutions of the runner. '.lhat is, for equal total heads, the speed for tui'- bine operation should be w/ E-,-E, times the pump speed, that is the pump speed multiplied by the geometric mean offtheefficiencies. Taking for example. a turbine hav which would operan vcfiiciency of 80% the should theoretically 'be' reate as a pump with turbine speed duced to times the pump speed, or to about 85% of the pump speed. The loss in supply and discharge conduits can be taken into account by using for En and EL theloverall efficiencies including these coudiiit losses, instead of the efficiencies of the machine proper.

Now for large machines where high values of efficiencies may be counted upon, this speed correct-ion may probably be kept somewhat within the 15% reduction required by the above example; and by operating the pump vslightly below its exact speed for best effilciency and ruiming the turbine somewhat overspeeded, such a speed variation may be divided between the pump and turbine opera tion so that each operation will be only slightly off-speed; and since the efficiency curves of both turbines and pumps are usually relatively flat in the maximum efficiency region they may be operated slightly offspeed without serious reduction in efficiency. Moreover, if the turbine is equipped with guide vanes these may be opened somewhat above their position for normal pump operation, thus increasing the discharge as a tiirbine and improving the efficiency as Well as increasing the power developed to a value more nearly approaching the motor capacity required for pumping. It Will, therefore, be practicable under mostr conditions to maintain the same speed for both turbine and pump operation. Of course the above relations involve the efficiencies actually to be attained, and these can be reliably determined only by tests on a definite design. -When large machines are built, the efficiencies both as pump and turbine will increase with the size (according to a rule verified by tests, the percentage of loss in geometrically similar machines varies inversely as the fourth root of the linear dimensions), so that for large installations the variation from best speed will be relatively less. In .some cases, for example if the total head for pumping must be considerably'greater thanfor turbine operation, as when long supply conduits or pipe lines are used, it may be desirable to use a variable speed motor or generator such as one having pole-changing provisions, to maintain speeds close to the maximum efficiency conditions.

The guiding rules set out above for proportioning the riiiiiiei vane channels and discharge and intake passages to give the most efficient deceleration are directed more particularly to machines of moderate or 10W specific speeds, applicable in usual practice to heads greater than about 60 to'75 feet. For lower heads, below these valuesthe machine will be more economical if of the propeller type, with axial or diagonal flow uiishrouded runners, and of high specific speed. The diagonal propeller type machine will probably he applicable to heads even higher than 75 feet, as soon as there is opportunity tf gain experience in actual installations under such heads. The angles of flare of the equivalent conical tubes used for a basis of design of the runner vane channels and discharge passages will be subject to modification in propeller machines, a larger range of choice of these angles then being called for on acnim Leraars justing the machine to the best clliciency conditions 'when chanwin from turbi ne to um i operation, as well as to increase the range and flexibility oit operation for variations in head or quantity oi dow for either turbine or pump use. ln reversible high specific speed propeller turbines tor low or moderate heads, adjustable blade runners Will have advantages in some eases, both for pump and turbine operationyvvith the blades adjustable either While running or by shutting down the unit 'tor a short period. lhe blade adjustment will permit the most favorable conditions to be secured to suit the head, either for increasing the eiiiciency or the capacity, and by this means the change in conditions When reversing from turbine to pump operation or vice-versa can be provided tor and the best blade angle secured for each mode oi operation under the particular value of the head then existing. The reduction in power as a turbine compared to pump operation can be more completely compensated by turning the blades toward the vertical position and 'farther from the horizontal position When operating as a turbine, in order better to utilize the capacity of the electrical machine (generator-motor) or conversely the blades can be turned to a more horizontal position to avoid overloading the motor during pumping. The use of adjustable runner blades may be advantageously applied to propeller type pumps of high specitic speed, Whetherreversible or not, Whenever a variable discharge is desired. Adjustable run- 'ners and operating mechanism suitable for the above purposes and a's shown here in Fig. 18 are disclosed more specifically in my Patent Nos. 1,837,568 and 1,853,139, it suihcing to state herein that adjustable blades l0 are mountedl on shafts 71 journalled in the runner hub, Which shafts have arms 72 connected by links 73 to a common axially movable rod 74 centrally disposed in a hollen7 runner shaft 7 5, thus effecting angular adjustment of the runner blades upon axial movement of the rod 74 Under many conditions however, and probably under the more usual requirements, the machine may be made to give satisfactory performance for reversible operation Without going to the expense of providing runner blade adjustment, With its mechanical complication.

Revcrting to the conditions in a loW or moderate speed pump or turbine, it will be clear fromv the previous explanations that turbines ot ordinary form involve too rapid acceleration ot the relative velocity of iow While passing through the runner, so that it pump operation is attempted the rapid acceleration then becomes a rapid deceleration which cannot be etiiciently secured.- When the dow passes through rapidly enlarging passages it does not actually decelerate at a rate sutlicient to take up a velocity equal to the quantity divided by the passage area. but continues to flow at nearly its original velocity and the flowing stream only partly fills the passage, leaving regions oi eddies and backward flow; and instead of efficient deceleration there is merely a reduction oi velocity by dissipation oi' velocity head and loss ot energy. rlhc requirements 'for a reversible machine are therefore the formation of the runner with vane shapes consistent `with a very gradual change ot relative velocity and with discharge velocity not greatly different in amount rom entrance velocity, thus avoiding unstable operation, corrosion and loss oi eificiency.

'lhe conditions ot gradual change in relative velocity and tlatly curved blades With little chan e ot direction, and discharge velocity near y equal to entrance velocity, are all consistent vvithobtaining the most edicient design o't high speciiic speed turbine and pump runners of the propeller type. To avoid cavitation, or separation oi the streams from the blade surfaces vvith resulting unstable operation, vibration and pitting ot the surfaces exposed to the tlovv, a blade area substantially equa-l to, or not materially less than, the dish area should be provide and Wide openings between successive blade edges should be avoided. 'lhis will insure proper guidance ofthe dow and avoidance ot regions of high local vacua during both pump and turbine operation; and is particularly im'- portant in the pump operation, since there will then be a certain degree of deceleration between the blades and this necessitates even a greater degree of guidance or cell effectthat is, constraint ot the 'dow Within enclosed passages-than does the turbine operation, particularly it the runner must be set a 'con- Sider-'able distance above the tailvvater or sump Water surface.

Tl/Vhen the machine is equipped with guide vanes, these are preferably placed at entrance to therunner tor turbine action, that is at the runner discharge for pumping. 'lhese Will be fully effective for turbine regulation or gdverning by a usual governor control as set forth in my copending applicationpreviously referred to herein, and may also be used Jfor adjusting the pump load or discharge; but the latter adjustment will be effective only Within a relatively small range ot guide vane anglesince the pump is dependent -or good eiliciency on the deceleration in the diffuser or casing, the guide. vanes not being long enough to provide anything approaching complete deceleration between them within practicable limits of size, while the casing maybe designed to provide a long path of flow for the entire stream with correspondingly gradual deceleration.

To find the relation between the specific speed of the machine running as a turbine and its speciiic speed as a pump, the following is the theoretic basis for this transformation, considering the case where the total head is changed to give equivalent hydraulic action, that is similar vector diagrams of velocity, or Where the speed is corrected to give this equivalent action. The pump specific speed is defined by the formula in which Np is the number of revolutions per minute and QD the cubic feet of wat-er per second discharged when pumping. The turbine speciic speed is defined by the formula iin which Nt is the revolutions per minute back, we have and HPt the horsepower delivered on the shaftwhen operating as a turbine. Expressing the last formula in terms -of the water quantity Qt discharged by the turbine instead of in terms of Hts in which W is the specific weight of the water in pounds per cubic foot. Now referring H c==HzEz and H r. .EpEli and this was based on the same velocities of water and points on the runner for both turv With Vif-:62.4 this becomes a N EpfE sz: Ns, 2.97

This relation will be useful as a guide in approximate calculations, but is subject to variations from the exact final conditions which should be determined by tests on models geometrically similar to any proposed installations, since exactly similar` How conditions, as here assumed, will not be secured in reversed operation, due to differences in the distribution of velocities across the chanynel sections in the runner and elsewhere; and such tests are also necessary to determine the exact values of Ep and Et; but if the machine is proportioned in accordance with the principles here set out this relation should Iurnish a useful guide in preliminary calculations and provide a basis for thc design The relation between speciic speeds for turbine and pump action also be expressed in terms of the speciic s )eed based on quantity for the turbine, a simi ar expression to that used for pumps, (as described in. paper by me in ASME. Trans. 1921: The present trend oit hydraulic turbine development), namely:

QL H ,M

instead of the usual specific speed, based on Nsqt=Nt hence the relation expressed in these terms becomes NIU! N.,

This way may be used for the same purpose as the one previously derived.

In the design of the machine for pump operation it is sometimes desirable, particu-- larly in the case of high speeic speed, to direct the iow into the runner with an initial whirl, that is with rotational velocity-components around the runner axis, which for high specific speed should be in the same d irection as the runner rotation. If entrance guide vanes are placed in the entrance passage for this purpose, they should be located at some distance from the impeller, and preferaly at a large radial distance from the axis and at a point of lower velocity than at the impeller, to provide a large intermediate transition space between the guide vanes and impeller, since when the machine runs as a turbine the rotational components in the discharge flow from the runner will differ somewhat in amount from those required for Leraars pump action and will vary with guide vane opening, and this dilerence would re= sult in loss ot head it the guide vanes were placed close to the runner..

'llhe setting of this machine required for reversible operation will diiler in each case wfrom that required for turbine operation alone,or required for a non-reversible turbine ot equal capacity and speed., @wing to the loss ol head inherent in the decelerating action inv the draft tube during turbine operation the absolute pressure at the entrance to the draft tube, that is at the discharge from the runner, is reduced to Aan extent equal to that portion or the velocity head which can be reconverted into pressure head by the decelerating -action of the tube, and this can never amount to of the velocity head, but in most cases will be in the neighbourhood ot 80% or somewhat more. rlire turbine can be raised with respect to tails-vater, when determining its setting, by an amount correspending to this loss of head or in the neighbourhood of 20% of the velocity head or somewhat less, compared to the setting which would be necessary with perfect regain ot velocity head. On the other hand, when the machine is pumping, the absolute pressure at the upper end of the draft tube, that is at entrance to the runner, is reduced by the full extent of the velocity head below the static pressure corresponding to the elevation, and by an additional amount corresponding to the loss of head in the tube, which in this case is mainly that due to pipe friction. Therefore the elevation ot the runner for pump operation must be lower than that permissible for turbine operation by an amount equal to the sum of the losses of head in the tube during both pump and turbine operation, to avoid the occurrence of an absolute pressure less than the vapor pressure of water, with resulting cavitation.,

The commercial feasibility of utilizing a reversible hydraulic machine as here proposed will depend to an important extent on the eliciency attainable during both pump and turbine operation, since all of the power stored by pumping is subject to the loss occurring during pumping and again to loss during utilization, that is during turbine operation and with a given capacity of reservoir the power which can be developed trom the stored Water is proportional to the product of the elliciencies of pump and turbine actions; so that in most cases these efficiencies will be a controlling factor in determining whether an installation is economically justified.

The few types of runners herein disclosed have been chosen as examples to which the principles of my invention may be applied but it is to be understood that'other specific forms of runners may be used when the blades and 4vpassages are properly proportioned in accordance with the theory and principles herein `lorth. "Examples oli a few other :terms oi runners adapted to be modiiied in accordance with. this invention are shown in my Patent No. llfli and application, Serial No.. eresia, aan api-u is, 1920.

Flhe propeller type turbine oiiilligs. l and 2 may also be equipped with movable guide vanes such as shown in Il between the stay vanes 2l transition space 22, the vanes being placed farther from the turbine axis and the contour of the upper end of curb ring i9 being suitably altered to accommodate these movable guide vanes, which would be arranged similar to vanes 5ft in lzlig. il..

lnstead oi annular spreading types ci draft tube shown in the figures, other eicient forms oli draft tube may be employed such as those 01"' improved elbow type, but it is essential in all cases to preserve gradual deceleration in the draiit tube and to employ forms having high efiiciency of regaining kinetic energy.

lt should be noted that the above principles tor obtaining gradual deceleration of the water leaving the runner when pumping'result in modified intake passage up to the runner when considered as a turbine, ditlering from usual turbines which are not reversible. 'lhus in Fig. l the transverse distance B across the passage, which has the value B at the runner, changes gradually and continuously in passing through the transi tion space E22, stay ring 2l until reaching the casing l?, in order that the passage area transverse to llow in the plane of the ligure shall increase gradually and consistenly with a limited rate or deceleration of the meridian components oi velocity, that is the components in the plane of the figure. This consideration results in a transverse width across the passage at 21 and 22, and a height of guide vanes or stay vanes 2l, which is materially smaller for a given size of runner than is employed in irreversible or usual turbines ot the same specific speed. ln general, in high specific speed reversible propeller turbines, the transverse width of the passage at B', Fig. l., at the guide vanes or stay vanes, will be less than, or not greater than, the minimum width lB at the runner.

In hydraulic power plants having suicient pondage or reservoir capacity to permit the useful storage of power by pumping during off-peak load demands, while at the same time having considerable river flow or direct power generation, it will in general be the economical'solution to install a limited number ot the reversible units described above, in combination with a number of non-reversible turbines which would be shut down durin the pumping operation, and would be utllized during a limited portion of the load cycle including pealr load periods. That is, in such developments only a portion of the .installed units would be of this reversible type, depending on the economical amount of pumped water. untilization in comparison with the total plant capacity required for direct powergeneration and peak loadcapacity.

It will of course be understood by those skilled inthe art that various changes may be made without departing from the spirit of the invention as set forth in the appended claims.

I claim 1 1. A hydraulic reversible pump-turbine comprising entrance and discharge passages and a runner having blades forming passages therebetween, the walls o' all of said passages being arranged whereby the iiow areas thereof are so proportioned that if laid out as equivalent conical tubes the angle of the conical wall to the cone axis will be relatively small as by being within a range of values with a maximum limit of approximately 10 whereby in either direction of runner rotation the fluid flow throughout will be accelerated or decelerated at a relativly small rate.

2. A hydraulic reversible pump-turbine comprising entrance and discharge passages and a runner disposed therein provided with vane passages in which any rate of enlargement in one direction ot flow is below a predetermined relatively small value, and the rate of enlargement of said passages in directions away from said runner is also of small value, said small value being between limits ranging from approximately 3 to 10 determined by layin out the passages as equivalent conical tribes and measuring the angle between the conical wall and the cone axis. v

3. A hydraulic .reversible pump-turbine comprising a runner having vane passages adapted to effect a relatively small rate of change in velocity ofthe fluid flow therethrough, and means providing entrance and discharge passages for said runner in either direction of runner rotation, said vane pas-- sages and entrance and discharge passages being so proportioned that if laid out as equivalent conical tubes the angle of the conical wall to the cone axis will be relatively small as between limits ranging from ap.- proximately 3 to 10 whereby said passages are adapted to effect relatively low rates of acceleration and deceleration, the discharge passage during pump operation which comprises the entrance passage during turbine operation being of volute formation.

4. A hydraulic reversible pump-turbine comprising a runner having vane passages with an angle of equivalent, conical flare falling below approximately 5, and passages leading therefrom in opposite directions and adapted to rovide gradual deceleration of iiuid disc arged 'in either direction of runner rotation.

5. A hydraulic reversible pump-turbine comprising a runner having vane passages in which the angle of equivalent Iconical iiare falls below approximately 5, and passages leading therefrom in opposite directions with an angle of equivalent conical fiare fallingbelow approximately 7 6. A hydraulic reversible pump-turbine comprising a runner having vane passages, entrance and discharge passages and guide vanes spaced to provide passages, all of said passages being proportioned so that if laid out as equivalent conical tubes the angle oi the conical wall to the cone axis will be relatively small as between limits with a maximum value'of approximately 10 to ciiect at the most only relatively snall rates of change in the velocity of the tlow therethrough during either direction of runner rotation.

'.7. A hydraulic reversible pump-turbine comprising a ruimer having vane passages in which the angle of equivalent conical flare falls below approximately 5, means providing a gradual flow decelerating discharge passage for said runner in either direction of runner rotation, and guide vanes spaced to provide passages through which pump discharged flow passes with a relatively small rate of change of velocity, said discharge passage having an equivalent conical flare of preferably about 7.

8. The combination as set forth in claim 7 further characterized by having said guide vanes adjustable. y

9. A hydraulic reversible pump-turbine comprising a runner, flow passages therefor and guide vanes, the flow areas through said elements being proportioned so that if laid out as equivalent conical tubes the angle of the conical wall to the cone axis will be relatively small as between limits ranging from approximately 3 to 10 thereby to effect relatively small changes in the rate of any acceleration or deceleration of flow therethrough, and means whereby said runner may normally operate as a pump at a higher rate of speed than during turbine operation.

10. A hydraulic reversible pump-turbine comprising a runner having vane passages in which the equivalent angle of conical flare falls below approximately 5, and How passages therefor being adapted to eflect a gradual rate of deceleration of Huid discharged during either turbine or pump operation, whereby said runner is adapted to normally operate in either direction of runner iotation at substantially the same normal s ee P11. A hydraulic reversible pump-turbine comprising a runner having vane passages in which the angleof equivalent conical flare falls below approximately 5, entrance and discharge passages each adapted to eliect relatively gradual deceleration of flow discharged from the runner, and angularly disposed guide venes in said entrance passage. L.'

so y

liti

misero 12. The combination set forth in claim "lll further characterized by having guide venes also in the dow passage which forms an entrance passage during turbine operation,

13, er hydraulic reversible pump-turbine comprising a runner, and entrance and discharge passages one ci which is o' materially@ greater axial extent than the other, each or saro passages being proportioned so iii laid out as an equivalent conical the angle olii conical vvall to the cone airis will be relatively small as between limits rangin ieroin approximately 3 to lilo thereby to eitect a gradual rate oi deceleration of? dism charge dow during pump or turbine operation.

ld. Ilhe combination in a' hydraulic reversible pump-turbine comprising a high specilic speed propeller type runner in which the vane passages have an angle ol equivalent conical dare falling preferably below approximately 5, and entrance and di charge passages each having an angle equivalent conical ilare falling below approximately thereby to ehect a gradual rate oi change in the velocity oi idovv therethrougho l5. it hydraulic 'reversible pump-turbine comprising a mixed flow Francis type runner having vane passages vproportioned so that it laid out as equivalent conical tubes the angle of the conical Wall to the cone axis Will be relatively small as between limits ranging from approximately 3 to 109 thereby to give at the most a gradual rate of c ange in the velocity of flow therethrough, and passages adapted to eiect gradual deceleration of and eiiicient regain of energy from Huid discharged .from said runner in either direction o runner rotation.

16. The combination set forth in claim ld further characterized by having said discharge passage comprising a spreading annular passage.

17. The combination set forth in claim 1t further characterized by having said entrance passage in the form of a volute.

18. A hydraulic reversible pump-turbine comprising a low specific speed Francis runner having vane passages of such cross-sectional area that a relatively small rate ot change in the velocity of flow therethrough is obtained, and means forming a discharge passage for said runner in either direction oit runner rotation and adapted to eliect a relatively'low rate of deceleration of the discharged fluid in each case, all ol said passages being so proportioned that if laid out as equivalentconical tubes the angle oi the conical wall to the cone axis will be relatively small as between limits ranging from approximately 3 to 10'.

19. A hydraulic reversible pump-turbine comprising a runner and flow passages leading to and away from the runner each adapted to elect relatively gradual deceleration oi iiovv received 'from the runner, said runnerdiaving vane passages in which the opposing walls at any section normal to the diverge troni each other at angle not substantially greater thanlllo with respect the airis ci the passage, thereby said runner adapted to operate efficiently with ilovv in either direction relatively thereto.

A. hydraulic .reversible pump-turbine comprising a runn r and tlovv passages leadto and array the runner each adaptcd to elieect relati ely gradual deceleration lion received 'from the runner, said runner hexvinfv a passage between successive van-es such in an equivalent rectangular tube having a rectified centerline or length equal 'to the center den line oi said passage and having the same transverse areas at corresponding points the centerline, the opposing walls at any section diverge from each other at an angle not substantially greater than 10 with respect to the airis of the passage, whereby said runner is adapted to operate eiliciency with iiovv in either direction relatively thereto. l

21. A hydraulic reversible pump-turbine adapted to operate as either a turbine or pump, having a runner the passages between Athe vanes oi which gradually enlarge in 'the direction or dow when pumping, and a discharge passage `troni said runner `when operating as a turbine, said discharge passage being iormed with gradually enlarging crosssections receding from the runner and adapted for ellicient deceleration ot dow received -troni the runner, all or'D said passages being so proportioned that iii-laid out as equivalent conical tubes the angle orP the conical wall to 4'the cone axis will be relatively small as between limi-ts ranging from approximately 3 to -10 22. A reversible pump-turbine installation comprising a headrace and a tailrace, and a reversible hydraulic machine, an electrical generator-motor directly connected thereto, operable at times as a turbine-generator unit and at other times as a pumprnotor unit, said hydraulic machine having a runner and a draft tube receiving the tow therefrom when operating as a turbine, and said draft tube being formed to provide gradual deceleration ot the tlow therethrough and eciently to regain velocity head of the runner discharge, said runner being placed at an elevation above the level in the tailrace which is less than that perrnissible in a non-reversible turbine of the same specihc spe-ed by an amount at least equal to the loss ci head in the draait tube dur ing turbine operation.

23. A high specific speed reversible pumpturbine comprising, in combination, means forming entrance and discharge passages having a gradual rate of tlare falling Within fi' i Eli CII

a limit of approximately 7 based on an equivalent conical passage, and a runner having a hub carrying a small number of adjustable blades forming passages therebetween with an equivalent conical flare falling within approximately 5.

9.4. A high specific speed reversible pumpturbine comprising, in combination, means forming entrance and discharge passages having a gradual rate of flare falling within a limit of approximately 7 based on an equivalent conical passage, a propeller type runner having a hub and blades carried thereby for 'adjustment about axes intersecting the hub axis, said blades forming passages therebetween with an equivaient conical flare falling within approximately and means for simultaneously adjusting said blades While the runner is rotating.

'25. A hydraulic reversibie pump-turbine comprising entrance and discharge passages, and a propeller type runner having adjustable blades with flow passages therebetween, all of said passages having their flow areas so proportioned that if laid out as equivalent conical tubes the angle of the conical wall to the cone axis will be relatively small as by being within a range of values with the maximum limit of approximately 10 whereby during normal operation of the apparatus either as a pump or turbine the flow throughout is accelerated or decelerated at a relatively small rate.

26. The combination in a reversible pumpturbine, of a runner provided with vanes which are everywhere forwardly inclined to the radial when operating as a turbine and rearwardly inclined when operating as a pump, and entrance and discharge passages for said runner, each of said latter passages and the passages formed between the runner vanes so proportioned that if laid out as equivalent conical tubes the angle of the wall to the cone axis will be relatively small as between limits ranging from 3 to 10.

27. The combination set forth in claim' 26 further characterized in that the working face of said runner vanes is nowhere concave in sections taken in the direction' of flow.

28. The combination set forth in claim G further characterized in that the guide vanes are relatively thin and gradually tapered in both directions of discharge therefrom as during either pump or turbine operation.

29. The combination set forth in claim 1 further characterized by the provision of an electrical machine connected to the runner shaft and adapted to operate as a. motor during pump operation at a speed in excess of that at which it operates as a generator during turbine operation.

30. The combination set4 forth in claim 1' further characterized by the provision of an electrical machine connected to the runner shaft and adapted to operate as a motor during pump operation at a speed in excess of that at which it operates as a generator during turbine operation, said electrical machine being adapted to obtain its change in speed by pole-changing provisions.

31. The combination set forth in claim l further` characterized by the provision of an electrical machine connected to the runner shaft and adapted to operate as a motor during pump operation at a speed in excess of that at which it operates as a generator' during turbine operation` said electrical machine being adapted to obtain its change in speed by pole-changing provisions, said speed for turbine operation bearing a ratio to that for pump operation approximately euuai to the square root of the product oi the overali eiliciencies oi turbine and pump operation.

3% lThe combination set forth in claim 1 further characterized by the provision of an electrical, machine connected to the runner shaft and adapted to operate as a motor during pump operation at a speed in excess ot that at which it operates as a generator during turbine operation, said electrical machine being adapted to obtain its change in speed by pole-changing provisions. said speed for turbine operation bearing a ratio to that for pump operation of not less than approximately 85 per cent. as nearly as obtainable by said pole-changing provisions.

33. A hydraulic reversible pump-turbine comprising entranceand discharge passages provided with a throat portion, and a runner disposed adjacent said throat and provided with blade passages, all of said passages being so proportioned that if laid out as equivalent conical tubes the angle of the wall to the cone axis will be relatively small 'as between limits ranging from 3 to 10o while the outer surface of the entrance and discharge passages adi acent the runner has a relatively large radius of curvature 4 when viewed in meridian section, said surface curving from an axial direction toward radial and having a radius of curvature not less than substantially two-thirds of the throat radius.

84:. The combination in a reversible pumpturbine, of a low specific speed reaction type runner provided with a relatively small number of blades in comparison to a number eniployed in a runner used only for turbine operation and of the same specific speed, said blades being everywhere forwardly inclined to the radial when voperating as a turbine and rearwardly inclined when operating as a pump, and entrance and discharge passages for said runner, each of said latter passages and passages formed between the runner blades so. proportioned that if laid out as equivalent conical tubes the angle of the wall to the cone aXi-s will be relatively small as between limits ranging from 3 to 100'.

35, rlhe combination' in a reversible pump- 'turbine comprising a runner provided with v vv- .s

blades which are nowhere concave on their faces in sections taken substantially normal to the runner axis, and entrance and discharge passages for said runner. both of said latter passages and the passages formed between the runner blades so proportioned that if laid out as equivalent conical tubes the angle of the wall to the cone axis will be relatively small as between limits ranging from 3 to 10.

36. A hydraulic reversible pump-turbine comprising entrance and discharge passages and a runner having blades forming passages therebetween, the walls of all of said passages being arranged whereby the iiow areas there-4 of are so proportioned that if laid out as equivalent conical tubes the angle of the conical wall to the cone axis will be relatively small as by being within a rangel of values with a maximum limit of approximately l0 whereby in either direction of runner rotation the fiuid flow throughout will be accelerated or deCeler-ated at a relatively small rate, and governor controlled guide vaines for variably controlling the fiow of fluid to said runner during turbine operation.

37. The combination in a. reversible pumpturbine comprising entrance and discharge passages, and a runner having blade passages, all of said passages being so proportioned as to efect a relatively gradual rate of acceleration or deceleration during pump or turbine operation and said runner passages expanding in one plane and contracting in perpendicular section with divergencev in either drection of fiow not exceeding substantially 10 based on an equivalent conical tube.

38. The combination in a hydraulic reversible pump-turbine of the high specific speed propeller type comprising fiow passages and a propeller runner having a relatively small number of overlapping blades, said fiow passages and runner passages being so proportioned that if laid out as'equivalent conical tubes the angle of the wall to the cone axis will be relatively small as between limits ranging from 3 to 10.

39. A reversible hydraulic pump-turbine comprising a runner provided with a hub and blades carried thereby, and ilow passages leading to and away from the runner each adapted to eiect relatively gradual deceleration of fiow received from. the runner, said runner having blade passages in which the opposing blade surfaces diverge from each other at an angle not greater than substantially 20" during pump operation, while the opposing walls formed by the runner hub and outer wall oi the flow passage gradually converge in the direction of How.

40. reversible hydraulic pump-turbine comprising a runner and iow passages leading to and away from the runner each adapted to effect relatively gradual deceleration of tion of pump flow, said divergence not beingsubstantally greater than 20.

41. A'reversible hydraulic pump-turbine comprising a runner and fiow passages leading to and away from the runner each adapted to effect relatively gradual deceleration of fiow received from the runner, said runner having a passage between successive vanes such that in an equivalent rectangular tube having a rectified centerline of length equal tothe center fiow `line of said passage and having the same transverse sections at corresponding points of the centerline, the walls corresponding to the runner hub and opposing Wall gradually converge in the direction of pump flow, while the walls corresponding to the vane surfaces diverge from each other in the same direction of flow at an angle not substantially greater than 20.

42. A reversible hydraulic pump-turbine comprising, in combination, entrance and discharge passages, and a propeller type runner having adjustable blades, said entrance and discharge passages and the runner blade passages all being so proportioned that if laid out as equivalent conical tubes the angle of the wall to the cone axis will be relatively small as between limits ranging from 3 to 10 whereby the fiow throughout will be accelerated or decelerated at a relatively gradual rate for either pump or turbine operation.

43. A reversible hydraulic pump-turbine comprising, in combination, entrance and discharge passages, a propeller type runner having adjustable blades, said entrance and discharge passages and the runner blade passages all being so proportioned that iflaid outas equivalent conical tubes the angle of the wall to the cone axis will be relatively small as between limits ranging from 3 to 10 whereby the dow throughout will be accelerated or 'decelerated at a relatively gradual rate for either pump or turbine operation, and fixed guide vanes disposed in the passage which constitutes the entrance passage during turbine operation, said guide vanes being inclined so as to impart whirl to the fluid owing to said runner.

LEWIS FERRY MOODY.

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