US1488582A - Elastic-fluid turbine - Google Patents

Description

April 1, 1924. R. C. ALLEN ELASTIC FLUID TURBINE Filed Jan. 15.

R.C.AII I E Patented Apr. 1, 1924.

nonnar 0.;ALLEN, or ESSINGTON, raNNsYnvaNIa, AssIeNoR 17o WESTINGHOUSE ELECTRIC &' MANUFACTURING COMPANY, A CORPORATION or PENNSYLVANIA.

ELASTIC-FLUID TURBINE.

Application filed January 13, 1922. .Serial No. 523,996.

To all whom it may concern:

Be itknown that I, ROBERT C. ALLEN, a citizen of the United States, and a resident of 541 Jansen Ave, Essington, in the county of Delaware and State of Pennsylvania,

have invented a new and useful Improvement inFilastic-Fluid Turbines, of which the following is a specification.

My invention relates to elastic-fluid turbines, and more particularly to the low-- pressure blading thereof, and it has for its object to provide apparatus of the character designated which shall be capable of operating at high speed to develop high power with el'licient utilization of the energy of the low-pressure motive fluid.

I In the drawings, Fig. 1 is a longitudinal sectional view of one form of turbine embodying my invention; Fig. 2 is a detailview of one of the blades of Fig. 1; Fig. 3 is a diagrammatic view added for explanatory purposes; and Fig. 1, an elevational view of the turbine of Fig. 1 drawn to smaller scale.

From a theoretical point of view, it would be better to construct a turbine to expand steam radially instead of axially; however, practically, the axial type possesses many advantages. One advantage of the radial type of turbine is that ample discharge area with small leaving angles may be provided, without any limitation as to blade height being imposed thereon, as is the case with axial-flow blading. With the axial-flow type of blading, a limitation is imposed upon the height of the blades by centrifugal force; in other words, since the height is limited, adequate discharge area is provided by having the blades arranged to discharge at large leaving angles, thereby resulting in low blade etliciency. From a practical standpoint, however, the construction of radial-flow turbines offers many practical and operational difiiculties, and, so far, only turbines of relatively smaller sizes have met with success. Appreciating the theoretical advantages of a turbine of the radial-flow type, I have provided a turbine of the axialfiow type with low-pressure blading which gradually changes the direction of flow from an axial to a radial direction. The cylinder or casing of the rotor is so shaped as to present curved surfaces which diverge toward a radial direction in proportion as the volume of the elastic fluid increases and as the pressure drops. Accordingly, I provide a low-pressure section which has stationary and moving rows of substantially] triangular or trapezoidal blades which have their bases firmly connected to the rotor and to the cylinder or casing. This design per-.-

mits of the construction of high blades with adequate strength; and, therefore, theblades may be made high enough to pass large volumes of low-pressure elastic fluid andto discharge the latter at small angles, thereby resulting in high blade efliciency.

Referring now to thedrawings for a more detailed description of my invention, I showa turbine comprising a rotor 10 and acylinder or casing 11 carrying suitable energyabstracting elements constituting a highpressure section 12 and a lowpressuresection 13. The high pressure section 12 is provided with energy-abstracting elements of any suitable type, for example, ISllO-W a multi-velocity impulse stage 14 followed by a plurality of fractional expansion stages 15, each of the latter-including stationary and moving rows of blades 16 and 17 carried respectively by the cylinder or casing- 11 and by the rotor 10.

The low-pressure section 13, which involves blading made in accordance with my present invention, includes a row of guide blades 18, followed by rows of blades 19,-

20 and 21, substantially triangular 'in outline, the row of blades 20 being carried by the casing or cylinder 11 and beinginterposed between the rows of blades 19 and 21 carried by the rotor 10.

The'rotor 10 and the cylinder 11 are so shaped as to present a diverging passage average direction of stream line flow, as indicated at 22 in Fig. 3; but, of course, this is impossible practically. I, therefore, have the rows of blades 16 and 17 arranged radially until the limit of height forzefficient moving blades 17 -within safe allowable stresses is reached; and, thereafter, if the moving rows are to be made taller, some provision must be made to make them stronger. The low-pressure section 13 is accordingly provided with the triangular blades 19, 20 and 21, which not only serve the purpose just mentioned, but also fill the diverging and outwardly curved blade space.

lhe moving blades 19 and 21 have their leaving or exit edges 23 and 24 disposed approximately normal to the direction of steam flow at said edges, as indicated in Figs. 1 and 3, this arrangement, from a theoretical standpoint, being the best to obtain the greatest efiect from the velocity energy of the expanding steam. The inlet edges 25 and 26 of blades 19 and 21 are arranged in radial planes, and the inlet and outlet edges 27 and 28 of the stationary row of blades 20 are disposed substantially parallel to the outlet edges 23 of the blades 19 and to the inlet edges 26 of the blades 21, respectively. It will be apparent that the moving blades do not overhang any of the stationary blades and that, therefore, the upper portion of the cylinder or casing 11 may be readily removed.

The contour of one of the triangular blades, for example, one of the blades 19, is indicated in Fig. 2. At the tip, the blade has any suitably curved cross-sectional shape so that when the blades are assembled suitable reaction passages are provided; and, as'the blade widens, the same degree of curvature is preserved at the edges 23 and 25, the intermediate portion 30 being substantially flat.

The blades 19, 20 and 21 are preferably provided with a plurality of curved guiding ribs 31 to assist in changing the direction of flow of the elastic fluid or steam from an axial toward a radial direction, thereby reducing losses due to eddying.

From the structure described, the operation of apparatus made in accordance with my invention will be apparent. Steam or elastic fluid is expanded and energy is abstracted by the elements of the highpressure section 12, and then the steam or elastic I fluid is discharged from the stationary row of guide blades 18 between the triangular reaction blades 19, the latter abstracting energy from the steam or elastic fluid and discharging it between the triangular guide blades 20 from which it is discharged to the last row of moving triangular reaction blades 21. The casing and rotor define a diverging and outwardly curved blade space, and this feature, together with the blading, serve togradually change the direction of flow from an axial toward a radial direction so that longer discharging reaction edges may be provided with the preservation of small exit or discharge angles, necessary for high blade efficiency. As the moving blades 19 and 21 are triangular, discharge edges of sufficient length may be provided without exceeding the limit of safe allowable stress for the material of the blades. The discharge edges 23 and 2% approximately are normal to the direction of steam flow so that the reactive effort of the expanding steam or elastic fiuid may be applied thereto with the greatest or'full effect. The cover of the cylinder or casing 11, with the blading carried thereby, may be readily removed, as the blading does not overhang.

From the foregoing, it will beapparent that I have devised a turbine in which the length of the leaving edges of the low-pressure blades is not limited by centrifugal effects, thereby permitting of the preservation of small leaving or exit angles. It is therefore, possible, with my construction, to build higl'ipower and high-speed turbine units in which the lowpressure blading operates with a high degree of eficiency.

lVhile l 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 other changes and modifications, without departing from the spirit thereof, and l 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

hat I claim is 1. In a turbine, a low-pressure section comprising a plurality of rows of approximately triangular blades.

2. In turbine, a plurality of rows of blades in which the inlet edge of the first row is substantially normal to the outlet edge of the last row.

.3. In a turbine, a plurality of rows of blades having adjacent parallel edges and the inlet edge of the first row being substantially normal to the outlet edge of the last row. 7 7

4C. In a turbine in which the direction of flow is changed from an axial to approximately a radial direction, a plurality of rows of stationary and moving blades, the latter blades having their discharge edges disposed approximately normal to the direction of steam flow at said edges.

5. In a turbine, a plurality of rows of stationary and moving blades having parallel adjacent edges, having the inlet edges of the moving blades arranged radially of the axis of rotation, and having the outlet edges of a plurality of the last rows of moving blades disposed at successively greater angles with respect to the inlet edges.

6. In a turbine, a low-pressure section including a plurality of rows of approximately triangular blades with complementally-shaped interposed guide blades, the inlet edges of the moving blades being disposed radially of the axis of rotation of the turbine and the outlet edge of a following row being disposed at a greater angle with respect to its inlet edge than a preceding row.

7. In a turbine, the combination of a casing and rotor together defining a diverging and outwardly curved blade space and a plurality of rows of approximately triangular blades in the space and carried by the casing and rotor.

8. In a turbine, the combination of a casing and rotor together defining a diverging and outwardly curved blade space and a plurality of rows of approximately triangular blades in the space and carried by the casing and rotor, the inlet edge of the first row of approximately triangular blades being normal to the outlet edge of the last row.

9. In a turbine, the combination of a casing and a rotor defining a diverging blade space curved from an axial toward a radial direction and a plurality of rows of blades in said space carried by said casing and rotor, the moving rows having discharge edges arranged substantially normal to the direction of steam flow at said edges.

10. In an elastic-fluid turbine, a lowpressure section comprising curved rotor and cylinder portions which together define a diverging blade space which extends outwardly from an axial toward a radial direction and a plurality of rows of blades having substantially parallel adjacent edges arranged in said blade space.

11. In an elastic-fluid turbine, a lowpressure section comprising rotor and cylinder portions curved outwardly defining a blade space extending from an axial toward a radial direction and including a plurality of rows of blades tapered in width to present substantially parallel adjacent edges.

12. In an elastic-fluid turbine, the-combination of a rotor and a cylinder curved outwardly at the low-pressure end to define a low-pressure blade space which diverges and extends from an axial toward a radial direction and a plurality of rows of approximately triangular low-pressure blades arranged in said space and carried by the rotor and casing.

13. In an elastic-fluid turbine, the combination of a cylinder or casing, a rotor, the low-pressure ends of the cylinder and the rotor being so shaped and curved as to define a blade space which diverges and extends froin an axial toward radial direction and a plurality of rows of blades tapering in width from the root ends toward the tips, the adjacent edges of said blades being substantially parallel.

14. In an elastic-fluid turbine, the combination of a cylinder or casing having upper and lower portions, a rotor, the lowpressure ends oi the cylinder and the rotor being so shaped and curved as to define a blade space which diverges and extends from an axial toward a radial direction, and a plurality of rows of blades tapering in width from the root ends toward the tips carried by saidrotor and casing, the adjacent edges of said blades being substantially parallel and the blades being so shaped that the edges of the stationary blades overhang the edges of the moving blades, whereby the upper portion of the cylinder may be readily removed.

15. In an elastic-fluid turbine, an axial flow portion and a portion in which the direction of steam is gradually changed from an axial to approximately a radial direction, said latter portion including a plurality of rows of tapered blades and each of the blades havinga radial edge and an edge approximately normal to the direction of steam flow at said edge. 7

In testimony whereof, I have hereunto subscribed my name this 10th day of January, 1922.

ROBERT C. ALLEN.

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