US1910845A

US1910845A - Radial flow turbine

Info

Publication number: US1910845A
Application number: US495624A
Authority: US
Inventors: Lysholm Alf
Original assignee: Ljungstroms Angturbin AB
Current assignee: Ljungstroms Angturbin AB
Priority date: 1929-12-10
Filing date: 1930-11-14
Publication date: 1933-05-23
Anticipated expiration: 1950-05-23

Description

y 1933- A. LYSHOLM 1,910,845

RADIAL FLOW TURBIfiE Filed Nov. 14. 1930 2 Sheets-Sheet 1 7INV; TO 2 BY May 23, 1933- A. LYSHOLM Q 1,910,845

RADIAL FLOW TURBINE Filed Nov. 14. 19:50 2 Sheets-Sh et 2 BY "25mm Patented May 23, 1933 UNITED STATES PATENT OFFICE ALF LYSHOLM, OF STOCKHOLM, SWEDEN, ASSIGNOR 'I O AKTIEBOLAGEI LJ'UNGSTROMS ANGTUBBIN, OF .STOCKHOLM, SWEDEN, A JOINT-STOCK COMPANY RADIAL rLow TURBINE Application filed- November 14, 1930, Serial No. 495,624, and In Sweden December 10, 1.929.

The present invention relates to radial flowvelastic fluid turbines adapted to oper- .ate against back pressure and provided with a turbine casing immediately surrounding the radial flow blade system, said casing providing one or more spiral or volute shaped exhaust chambers extending around the full periphery of the outer blade ring of the turbine.

In prior forms of radial .flow turbines, steam is exhausted from the radially outermost blade ring in a radial direction, and

this direction of discharge causes losses due to turbulence and the formation of eddies, because of the necessity of sharply altering the direction of flow ofthe fluid after it has ence between the point where steam is exhausted from the turbine blades and where it is available for use at a lower pressure stage represents an energy loss which is produced largelyat the moment when the m0- tive fluid leaves the last blade row of the turbine. A principal object of the resent invention is to reduce exhaust losses of the above character in radial flow back pressure turbines, and this and other objects, as will hereinafter be more fully pointed out, are attained by the provision of novel blading in the last row of turbine blades, which blading is designed to give to the leaving steam a velocity component in the direction of the outlet or outlets of the turbine casing. This construction, when combined with a casing of spiral or volute form providing increasing flow area toward the outlet or outlets of the casing, provides an arrangement such that the losses due to turbulent flow and like factors are substantially eliminated and a pressure at the outlet of the turbine is maintained which is substantially equal to the pressure at the outlet of the last or outermost blade row of the turbine.

For a better understanding of the invention, reference may be had to the accompanying drawings illustrating the invention embodied in a turbine having a casing providing a single outlet for motive fluid.

In the drawings:

Fig. 1 is a lon itudinal central section of a radial flow turiine embodying the invention;

Fig. 2' is a transverse section taken through the center of the turbine, parts being omitted for the sake of clearness; and,

Fig. 3 is a diagram illustrating the charactor of the fluid discharged from the outer blade ring of the turbine.

Referring now more particularly to Fig. 1, reference characters 1 and 2 designate the oppositely rotating shafts of a double rotary form of turbine of the known Ljungstrom type. Steam is supplied to the turbines through conduit 3 and flows through themlet chambers 4 and channels 5 in the turbine rotors to the radial flow blade system 7 of the turbine from which it is discharged to the outlet chamber 8. The outlet chamber 8 is preferably disposed within an outer turbine'casing 9 and is formed by the volute shaped casing member 10, which in -the illustrated embodiment extends around the entire circumference of the blade system of the turbine.

As shown in Fig. 2, the casing 10 preferably consists of two parts, 100: and 10b, secured to each other in any suitable manner, as by means of flanges 11 and 12 adapted to be bolted together.

The casing 10 is held in position by means of suitable bolts 15 which secure the casing to the flanges 14 on the stationary members 13. These bolts-may advantageously be in the form of through bolts, as indicated in Fig. 1, the central portions of the bolts passing transversely though the chamber 8. These central portions, shown in section in Fig. 2, are preferably of stream lined cross section and arranged so as to assist 1n directing the steam discharged from the blade system toward the outlet.

As will be apparent from Fig. 2, the outer periphery of the volute casing 10 is arranged, with respect to the outer blade ring of the turbine, so that steam leaving said blade ring is directed so as to have a smooth flow from its point of dischargefrom the blade ring to the outlet 16 of the volute casing. The outlet 16 is preferably arranged tangentially of the casing as shown, and it will be apparent that, if desired, steam can be taken off from the casing at more than one pointby providing additional outlets.

The exhaust conduit 17, with which the outlet 16 communicates, is preferably supported by means, such as is indicated at 18 and 19, in a manner permitting movement of the exhaust conduit to compensate for expansion due to temperature differences and the like.

In accordance with the present invention, the shape and arrangement of the blades 7 in the last or outermost blade ring is such that the motive fluid is discharged from these blades in a direction having a component in the direction of discharge flow through the chamber 8.

The manner in which the desired direction of discharge flow from the blade system is accomplished is more clearly illustrated in the diagram of Fig. 3. In this figure, the character of the discharge flow from the last blade ring of a turbine of the prior art is shown in broken lines, and the direction of the discharge flow in accordance with the present invention is shown in full lines. Reference character a designates a blade arrangement for the outer blade ring which is in accordance with the prior art. lVith this arrangement, the outlet angle a is such that, with a peripheral velocity represented by the vector u and a relative discharge velocity represented by the vector 'v,

the resultant or a solute discharge velocity will be represented by the vector 0, which is directed radially of the blade system.

In order to avoid the losses through undesirable factors inherent in a turbine in which the motive fluid is exhausted in this manner, the blade m is arranged, in accordance with the present invention, so that the outlet angle (1 provides a relative discharge velocity represented by the vector 0 having a value greater than the value of the vector '0, so that the resultant vector 0 representing the absolute discharge, is disposed at an angle with respect to a radius vector.

If the vector c is resolved into its radial and peripheral components, it will be seen that, in accordance. with the present invention, there is provided a radial discharge velocity represented by a and a peripheral 1 dischar e velocity represented by the vector h, t e latter being parallel, but opposite in direction, to the velocity vector u I This velocityvector h represents the'dimotion and value of the discharge energy of the motive fluid in the direction-of the outlet of the turbine casing, and represents a force acting to discharge steam from the turbine. Obviously, the value of the peripheral or tangential velocityrepresented by the vector it varies with variations in size sired flow.

From the foregoing, it will be evident that the motive fluid will, in accordance with the present invention, have a pressure in the discharge conduit 17 substantially the same as that in the chamber 8, which is, in turn, substantially the same as the pressure at the point of discharge from the last blade row.

By arranging the. blades in the last blade row in the above described manner, some loss may be incurred, as compared with a like turbine in which the discharge from the last blade row is in radial direction, due to the greater discharge velocity of the motive fluid when it is discharged with an appreciable peripheral or tangential component, but this loss is considerably less than the pressure drop loss in the discharge casing when the motive fluid is discharged fromt-he last blade row in the usual radial direction.

It is obvious that, the present invention may be embodied, not only in the form of apparatus herein shown by way of illustration, but mayalso be embodied in other specific forms of turbines in which the single volute shaped exhaust chamber and outlet, illustrated herein, are replaced b a plurality of equivalents, each of whic receive and dischar e a portion of the total amount of motive uid discharged from the blade system.

What I claim is:

1. In a radial flow elastic fluid turbine, a blade system for expanding motive fluid comprising-a rotor carrying a plurality of blade rings including a blade ring constituting the outermost radial flow blade ring of the turbine, and a casing providing a volute shaped chamber having an outlet, said outermost blade ring discharging motive fluid to said chamber and comprising a pluralit of blades each arranged to simultaneous y discharge motive fluid therefrom with an absolute velocity havin a peripheral or tangential'component o flow, said flow being in the direction of the flow of motive fluid-in said chamber toward the outlet thereof. I

blade system for expanding motive fluid comprising a rotor carrying a plurality of blade rings including a blade rin constituting the outermost radial flow b ade ring of the turbine, and a casing providing a single volute shaped chamber encircling said outermostblade ring and receiving motive fluid discharged therefrom, said chamber having an outlet and said outermost blade ring comprising a plurality of blades each arranged to simultaneously discharge motive fluid therefrom with an absolute velocity having a peripheral or tangential component of flow, said flow being in the direction of the flow of motive fluid in said chamber toward the outlet thereof.

3. In a radial flow elastic fluid turbine, a blade system for expanding motive fluid comprising a rotor carrying a plurality of blade ringsincluding a blade ring constituting the outermost radial flow blade ring of the turbine, and a casing providing a volute shaped chamber having an outlet, said chamber increasing in cross-sectional area toward said outlet in a direction opposite the direction of rotation of said outermost blade ringand said outermost blade ring comprising a plurality of blades each arranged to simultaneously discharge motive fluid therefrom with an absolute velocity having a peripheral or tangential component of flow,"said flow being in the direction of increasing cross-sectional area of said chamher.

4. In a radial flow elastic fluid turbine, a blade system for expanding motive fluid .comprising a rotor carrying a plurality of blade rings including a blade ring constituting the outermost radial flow blade ring of the turbine, and a casing providing a single volute shaped chamber encircling said outermost blade ring and receiving motive fluid dischar ed therefrom, said chamber having an out et and increasing in cross-sectional area toward said outlet in a direction opposite the direction of rotation of said outermost blade ring and said outermost blade ring comprising a plurality of blades each arranged to simultaneously discharge motive fluid therefrom with an absolute velocity having a peripheral or tangential component of flow, said flow being in the direction of increasing cross-sectional area of said chamber.

5. In a radial flow elastic fluid turbine, a blade system for expanding motive fluid comprising a rotor carrying a plurality of blade rings including a blade ring constituting the outermost radial flow blade ring of the turbine, and a casing providing a volute shaped chamber having an outlet, said chamber increasing in cross-sectional area toward said outlet in a direction oppositethe direction of rotation of said outermost blade ring and said outermost blade ring comprising a plurality of blades each arranged to simultaneously discharge motive fluid therefrom with an absolute velocity having a peripheral or tangential component of flow, said flow being in the direction of increasing cross-sectional area of said chamber and the direction of absolute dischar of the motive fluid from said blades making an angle of at least 25 with respect to a radial line.

6. In a radial flow elastic fluid turbine, a blade system for expanding motive fluid comprising a rotor carrying a plurality of blade rings including a blade ring constituting the outermost radial flow blade ring of the turbine, and a casing providing a single volute shaped chamber encircling said outermost blade ring and receiving motive fluid discharged therefrom, said chamber having an outlet and increasing in cross-sectional area toward said outlet in a direction opposite the direction of rotation of said outermost blade ring and said outermost blade ring comprising a plurality of blades each arranged to simultaneously discharge motive fluid therefrom with an absolute velocity having a peripheral or tangential component of flow, said flow being in the direction of increasing cross-sectional area of said chamber and the direction of absolute discharge of the motive fluid from said blades making an angle of atleast 25 with respect to a radial line.

7. In a radial flow elastic fluid turbine, a blade system for expanding motive fluid comprising a rotor carrying a plurality of blade rings including a blade ring constituting the outermost radial flow blade ring of the turbine, an inner turbine casing pro viding a volute shaped chamber having an outlet, said outermost blade ring discharging motive fluid to said chamber and comprising a plurality of blades each arranged to simultaneously discharge the motive fluid therefrom with an absolute velocity having a peripheral or tangential component of flow, said flow being in the direction of flow of motive fluid in said chamber toward the outlet thereof, and means for securing said casing to a stationary portion of the turbine comprising parts extending transversely of said chamber, said parts being shaped and arranged to rovide ide vanes for aiding flow in the a oresaid irection of the motive fluid discharged from said blades.

8. In a radial flow elastic fluid turbine, a blade system for expanding motive fluid comprising a rotor carrying a plurality of blade rings including a blade ring constituting the outermost radial flow blade ring of the turbine, an inner turbine casing providing a volute shaped chamber having an outlet, said outermost blade ring discharging motive fluid to said chamber and comprising a plurality of blades each arranged to simultaneously discharge motive fluid lot therefrom with an absolute velocity havin a peripheral or tangential component flow, said flow being in the direction of flow of motive fluid in said chamber toward the 5 outlet thereof, an outer turbine casing and means for securing said inner turbine casing to a stationa part of the turbine supported by sai outer casin comprising a series of through bolts exten ing transversely of said chamber, the portions of said bolts within said chamber being shaped and arranged to provide guide vanes for aiding flow in the aforesaid direction of the motive fluid dischar ed from said blades.

In testimony w ereof, I have hereunto affixed my signature.

ALF LYSHOLM.