US2396159A - Elastic fluid turbine - Google Patents

Description

March 5, 1946. s. s. COIOKI ETAL 2,396,159

ELASTIC FLUID TURBINE Filed-July 14, 1945 Patented Mar. 5, 1946 H male Stanley Smith Cook and Louis Mortimer Douglas,

\ Wallsend-on-Tyne, England, assignors to The Parsons MarineSteam Turbine Company, Limited, Wallsend-on-Tyne, England Application July 14, 1943, serial No. 494,638

' In Great Britain July 30,1942

4Claims. (01.25340) r This invention relates to elastic fluid turbines of the kind comprising parallel-flow co-axial a1-' ternatively oppositely rotatingturbines, the flow of elastic fluid taking place axially through each turbine toward the other turbine to enter a common exhaust chamber disposed between the turbines. I

The invention consists in various features of construction and combinations of parts in an elastic fluid turbine of the kind set out above and for a full understanding of the invention a detailed description of a construction embodying the same in a preferred form will now be given in connection with the accompanying drawing forming a part of this specification and the invention then specifically pointed out in the claims.

Referring to the diagrammatic drawing accompanying this specification:

Figure l is a longitudinal sectional view of part of a steam turbine embodying the present invention in one form, and V Figure 2 is a developed plan thereof.

In carrying the invention into effect according to one convenient form illustrated by way of example in Figures 1 and 2, we provide a row of fixed blades K attached to a turbine stator, this lades and the profile of blades K is suchthat the steam impinges substantially normally on portionsof these blades so that its velocity is extin guished and the steam does not pass through these blades into the reversely rotating blades C of the astern turbine and cause frictionalloss and overheating, v I v High efiiciency is not of primary importance in the astern turbine but'it is desirable to develop as much power as possible with a. relatively small turbine and it will be seen that with the inter-' position of blades K the whole of the steam leav-r ing blades C impinges upon blades K and consequently has a fully reactive effect; whereas without them the path of the steam would be somewhat similar to that indicated by the dotted lines J and the reaction of that portion represented by row being disposed adjacent to the last row of I astern turbine blades C, the blades C being mount- H ed on a. rotor A carrying also a set of ahead turbine rotor blades D. The last moving row of astern blades 0 discharges steam towards the ahead section whilst the last moving row of ahead blades D discharges towards the astern section,

both discharging into a common chamber E enclosed by the turbine casing F.

A number of deflector devices to the blades K.

The steam leaving the radially inner portion of blades D tends to follow the path G" and that leaving the outer portion to follow the path G As these two paths converge, the steam leaving the blades D would have to compress to follow these paths, and as there is no 'force available to compress the steam, the path will be substantially M are attached 7 as indicated by the dotted lines H. It will be seen that if nothing is interposed between the'ahead and astern last moving rows, the portion indicated by dimension :1: would strike the rotor blades C and only that portion indicated by dimension 1 would impinge upon the stator, with the result that less than one quarter of this steam would be effective. ,7

The direction of the steam leaving blades D in a tangential plane is indicated by line B. from the root portion and '{I from the tip, portion of the I dimension w would be ineffective.

Furthermore, the steam leaving blades K is, in t the tangential plane, turned in the direction h with'a substantial component in the direction of astern rotation so that the portion represented by x which impingesupon the ahead rotor blades D will have a turning effect and actually increase the astern power over that developed in the normal astern blades. It frequently occurs that in turbines of the type described the area through the final moving row of blades of the astern turbine is insuflicient to accommodate expansion down to the pressure in the exhaust chamber, and the steam consequently leaves these blades at a higher pressure, the further expansion to the exhaust pressure taking place in the exhaust chamber itself, after leaving the blades. The blades K are so designed that the areas for steam flow through the blade passages are such that the passage of the steam through them does not cause any, or any substantial, increase in the pressure of the steam leaving blades C.

V The further expansion of the steam from the pressure at which it leaves blades C to the exhaust chamber, which expansion takes place in passing through or on leaving blades K causes the steam leaving the latter to have a very high velocity and if its path L has a substantial component in the direction of astern rotation and a considerable portion of the steam impinges upon the rotor in the direction indicated, this steam will add considerably to the power developed by the astern are also preferably disposed, in that plane, tangentially to the outer periphery of the row of blades C to conform to the path of the steam leaving these blades when rotating in the ahead direction.

The object of the ducts P is to ventilate this space between the blades C and K when running ahead, the blades C acting as a centrifugal pump to draw a cooling stream of steam over the blades, which steam can escape into the exhaust belt through the ducts P.

We claim:

1. An elastic fluid turbine of the kind comprising paralle1-flow co-axial alternatively oppositely rotating turbines, the fiow of elastic fluid taking place axially through each turbine towards the other turbine to enter a common exhaust chamber disposed between th turbines, said turbine having exhaust guiding blades between the common exhaust chamber and the last row of astern moving blades and including deflecting devices thereon having exhaust guiding surfaces to direct the astern exhaust steam with axial, radial and circumferential components against at least a portion of the last row of forward moving blades in a direction to give an additional turning efiect to the rotor in the astern direction.

2. An elastic fluid turbine as claimed in claim 1, wherein the exhaust guiding blades are disposed immediately succeeding in the direction of flow the last row of astern moving blades and said devices are fixed to and succeed the guiding blades and have guiding surfaces with axial, radial and circumferential components.

3. An elastic fluid turbine as claimed in claim 1, in which the exhaust guiding blades have passages for the exhaust steam flow occupying the greater partxof the :actual space occupied by the guiding blades and said passages, whereby a large and free flow of the astern exhaust through said blades is secured and loss of exhaust velocity in passing through the guiding blades reduced.

4. An elastic fluid turbine of the kind comprising parallel-flow co-axial alternately oppositely rotating turbines, the flow of elastic fluid taking place axially through each turbine towards the other turbine to enter a common exhaust chamber disposed between the turbines, having a row of fixed blades immediately succeeding in the direction of flow the last row of astern moving blades and wherein the space separating the said row of fixed blades from the last row of moving blades on the astern turbine is furnished with ducts serving to ventilate the space when the ahead turbine is in operative rotation.

STANLEY SMITH COOK. LOUIS MORTIMER DOUGLAS.

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