US1999711A

US1999711A - Turbine apparatus

Info

Publication number: US1999711A
Application number: US710411A
Authority: US
Inventors: Zetterquist Eric
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1934-02-09
Filing date: 1934-02-09
Publication date: 1935-04-30
Anticipated expiration: 1952-04-30

Description

E. ZETTERQUIST TURBINE APPARATUS Filed Feb. 9, 1954 WITNESSES:

INVENTOR ERIC ZETTERQUIST.

BY @.%.M

ATTORNEY Patented Apr. 30, 1935 UNITED STATES PATENT OFFICE Westinghouse Electric & Manufacturing Coinpany, East Pittsburgh, Pa., a corporation of Pennsylvania.

' Application February 9, 1934, Serial No. 710,411

' 4 Claims. (01. 253-77) My invention relates to blading for axial flow elastic-fluid turbines and more particularly to blading of the end-tightened type; that is, blading wherein the axial clearance may be varied by 5 moving one of the relatively-rotating bladecarrying members axially with respect to the other blade-carrying member. V End-tightened blading in elastic-fluid turbines has the advantage of providing close working clearances during the normal operation of the turbine. However, in prior apparatus of this type, the advantage just mentioned has been ofiset to some extent'by the detrimental effect of eddy currents in the main stream of axiallyflowing motive fluid. The eddy currents are caused by the motive fluid escaping through the close working clearances and around a' row of blades'from the high pressure sidefthereof and entering again the mainstream at the low-pressure side of such row of blades at high velocities and in a direction transverse to the path of flow of the main stream. I It is anobj'ect of this invention to provide apparatus of this character wherein the aforementioned detrimental eddy currents are avoided.

A further and more specific object is to provide an improved form of axial clearance packing which is so constructed andarranged that the velocity of the motive fluid escaping therethrough is, dissipated before such fluid reaches the low pressure side of the blade; and hence, such escaping motive fluid enters the mainstream at the lowpressure side of the blades without causing the aforementioned detrimental eddy currents.

According to my invention, I provide first and second relatively-rotating blade-carrying members, and at least two cooperating rows of blades through which the motive fluid flows successively with the pressure of the motive fluid being decreased as it flows through each row, a first of such rows being carried by the first blade-carrying member and a second of such rows being carried by the second blade-carrying member. A blade shroud is secured to each row of blades and each shroud and the opposing blade-carrying member are arranged with an annular space therebetween. A first means provides an axial packing clearance between the shroud of the first row of blades and the second member, and a second means provides an axial packing clearance between the second row of blades and the first blade-carrying member, and both of the axial packing clearance means are constructed and arranged to permit axial movement of the first blade-carrying member relative to the second member to vary the packing clearance. The first and second axial packing clearance means are further constructed and arranged so that the velocity of motive fluid escaping therethrough from the high pressure side is dissipated in the relatively large adjacent annular space, thus lowering the velocity of the escaping motive fluid and. permitting such fluid to enter the main stream without eddying.

According to the specific embodiment of my invention shown on the accompanying drawing, one of the packing clearance means is in the form of an annular packing strip extending in an axial direction from the high pressure side of a row of blades and toward a blade-carrying member; and the other packing clearance means is in the form of an annular packing strip having at least the outer portions thereof extending in a direction opposite to the strip of the first-mentioned packing clearance means and cooperating with an annular shoulder carried by the opposing blade-carrying member to direct the escaping motive fluid radially against the blade shroud, thus aiding in reducing the velocity of the escaping motive fluid.

These and other objects are effected by my invention; as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which: The single figure on the drawing is a fragmentary transverse section through a portion of a turbine inwhich my invention is embodied.

- Referring now in detail to the construction illustrated, it will be observed that I have shown a portion of an axial-flow elastic-fluid turbine including two blade-carrying members Ill and H, respectively. Insofar as my invention is concerned, either of these members may be considered as the rotor and the other the cylinder. However, for the purpose of description, I will callthe member ID the rotor or spindle of the turbine and the member H the cylinder thereof.

Secured to the rotor it and extending radially therefrom are a plurality of spaced rows of reaction blades identified by the reference characters I2, l3, and M, respectively. Arranged in cooperative relationship with the rotating blades are a series of stationary blades indicated by the reference numerals l5, and 16, respectively; the stationary blades being carried by the cylinder I i as shown. The elastic fluid, for example, steam, flows in an axial direction successively through the turbine blades as indicated by the arrow; and

as the steam flows through each row of blades, the pressure thereof is reduced, as is well known in the art.

An annular shroud I1 is secured to each row of rotating blades, and an axially-extending annular packing strip I8 is carried by each shroud l1 and extends toward the opposing cylinder II to provide an axial packing clearance IQ for the purpose of restricting the escape of steam around the ends of the blades. shroud 20 is secured to each row of stationary blades and each shroud 20 is providedwith an annular packing strip 2|,the outer end 2.2 of which extends axially and in a direction opposite to that of the strip l8 and cooperates with an annular shoulder 23 on the'rotor III to provide a packing clearance 24 which serves to restrict the escape of steam around the ends ofthe stationary blades.

It will be observed that the packing strip l8 extends axially from the outer high pressure edge of each row of moving blades. With such an arrangement, the velocity of the motive fluid escaping through the packing clearance 19 is sub stantially lowered, because the escaping fluid enters a relatively large annular space 25 surrounding the tips of the moving blades before it enters the main stream of motive fluid at the low pressure side. 7

Likewise, the packing clearance 24 is also arranged adjacent'the high pressure side of the stationary blades and, therefore, the velocity of motive fluid escaping therethroughis dissipated in the relatively larger space 26 surrounding each row of stationary blades. A further feature of the construction of the packing clearance 24 is that the shoulder 23 and the outer end 22 of the packing strip 2| are so arranged that steam escaping through the clearance 24 is directed radially toward the shroud 26. On account of this arrangement, the escaping motive fluid is caused to turn corners in the relatively large space 26 before reaching the main stream at the low pressure side of the blade, and, therefore, the velocity of the escaping steam is further reduced.

It will also be observed that the outer end 22 of the packing strip 2! extends in a direction opposite to that of the packing strip i8; By reason of this construction; adjustment of the packing clearances i9 and 24 may be had by an endwise movement of the rotor. 10.. 'That is to say, movement of the rotor in the direction of elastic fluid fiow increases the packing clearance i9 and 24 and, conversely, movement of the rotor in' the opposite direction decreases the packing clearances.

From the above description, it will be seen that I have provided a construction wherein the detrimental eddying effects caused by the high velocities of the escaping motive fluid are eliminated and at the same time one wherein the packing clearances may be adjusted during normal turbine operation to reduce the amount of escaping motive fluid.

Likewise, an annular While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims. I

; What I claim is:

1. In a turbine, a rotor and a stator having spaced radial faces, stationary and moving rows of blades carried by the stator and by the rotor, respectively, shrouds carried by the stationary and moving rows of blades, and cylindrical packing elements connected to the high pressure sides of the shrouds and cooperating with the radial faces to define relatively close clearances, the cy- I lindrical packing elements connected to the shrouds of the moving rows of blades extending forwardly of the high pressure sides of the latter to cooperate with radial faces on the stator and the cylindrical packing elements joined to the shrouds of the stationary rows of blades extending rearwardly from the high pressure sides of the latter to cooperate with radial faces on the rotor.

2. The combination as claimed in claim 1 wherein the stator andthe rotor are provided with circumferential spaces arranged outwardly of the moving blade shrouds and inwardly of the stationary blade shrouds and into which steam escaping from between the fine clearances is discharged. V

3. In a turbine, a rotor and a statorhaving spaced radial faces, stationary and moving rows of blades carried by the stator and by the rotor, respectively, shrouds carried by the moving rows of'blades and extending forwardly of the high pressure sides thereof to define close clearances with respect to the stator radial faces, and shrouds carried by the stationary blades and having portions springing from the high pressure sides thereof and extending outwardly and rear-- wardly to define relatively close clearances with respect to said rotor'radial faces. 7 f4. In a turbine, a rotor and a stator having spaced radial faces, stationary and moving rows of blades carried by the stator and by the rotor, respectively, shrouds carried by the moving rows of blades and extending forwardly of the high pressure sides thereof to define relatively close clearances with respect to the stator radial faces, shrouds carried by the stationary blades, and annular packing members including inner radial portions joined to the high pressure sides of the last-named shrouds and cylindrical portions joined to and extending rearwardly from said radial portions to define relatively close clearances with respect to said rotor radial faces.

ERIC ZETTERQI TIST.