US1173097A - Turbine-blade. - Google Patents

Description

P. CHRISTLEIN & E. BROWN.

TURBIINE BLADE.

APPLICATION FILED MAR. 5. i915.

Patented Feb. 22, 1916.

C 1 I I 1 1 I I A l I 1 11 W IL L fiziiila l Paad PAUL CHRISTLEIN, OF BADEN, AND ERIC BROWN, 0]? BAHN HOFWEG, SWITZERLAND,

ASSIGNORS T0 AKTIENG-ESELLSCI-IAFT BROWN BOVERI & 0111, OF BADEN, SWIT- ZERLAND.

TURBINE-BLADE.

Application filed March 5, 19 15.

To all whom it may concern y Be it known that we, PAUL CHRISTLEIN, a subject of the German Emperor, and residing at Romerstrasse 7 Baden, Switzerland, and E1210 BROWN, a subject of the King of Great Britain and Ireland, and residing at Bahnhofweg, Baden, Switzerland, have invented certain new and useful Improvements in and Relating to Turbine-Blades, of which the following is a specification.

This invention relates to turbine blades and has for its object to provide an improved blade for steam or gas turbines or other purposes.

The invention consists in a conical turbine blade of constant or substantially constant strength, the section of'which blade is made of constant or approximately constant axial width with any desired entrance and exit angles, material being removed on the concave side of the blade at the place of greatest curvature which is situated on the entrance side to give the desired section.

In the accompanying diagrammatic drawings: Figure 1 illustrates an end view of a pair of adjacent blades according to one construction, and Fig. 2 is a longitudinal section corresponding to Fig. 1; Fig. 3 is an end view, 'and Fig. 4 a longitudinal section of a modified form of blade, and Fig. 4 is a view showing in rear elevation the form of invention illustrated in Figs. 3 and 4, and Figs. 5 and 6 are an end View and longitudinal section respectively of a further modification.

' In Figs. 1 and 2 the back of the blade is represented by the curve a b and. the concave side of the basis of the'blade, 2'. e.., of the body from which the blade is formed, by the curve 0 d. This body may be formed by any suitable means for instance rolling, drawing or milling from the solid bar. The angle y is suitably cut so that the steam or the like leaves the blade in the proper direction, and the angle 00 is cut so thatit enters without shock. I

As regards the exit angle the back edge a 6 must be parallel to the leading edge a d of the next blade for a certain distance m, and the construction indicated gives a proper exit even in the case where a large pitch comes into question, for instance where t=0.5 to 0.7 times the axial over-all length w (which may be from 20 to 40 millimeters) In order to give the blade the correct Specification of Letters Patent.

Patented Feb. 22, 1916.

Serial No. 12,404.

shape for it to have constant strength the material in the process of manufacture is removed from alongthe surface indicated by e at the concave side of the blades. Further material is removed from along the shaded part 7 at the entrance edge of the back of the blade in such a manner as to give themorrect entrance angle as indicated above, in order to insure entrance of the steam without shock, but at the same time as far as possible to give a constant axial width 'w along the blade.

In the form illustrated in Figs. 1 and 2, the inner curve of the blade section varies from its root to the tip (see especially Fig. 2.) 4

Fig. 3 shows a modification of blade, in which the inner curve'of the blade section is the same from the root to the tip. The removal of material from the surface 6 as before produces a shape giving approximately constant strength, the correct entrance and exit angles also being formed. Entrance without shock is obtained by milling a surface at the proper angle w from the tip to the root of the blade. Thus the entrance edge 0 0' crosses the exit edge d, d when viewed in rear elevation (see Fig. 4).

In the form shown in Figs. 3, 4, and 4 the removal of the materialfrom along the surface at the back of the blade on the en-. trance side produces a gradually tapering plane surface f (see Fig. 4), wider at the base than at the tip of the blade. The edges 0 0 may be radial or slightly inclined to the radius by suitably shaping the root of the blade.

In the modification shown in Figs. 5 and 6 the entrance angle diminishes progressively from the tip to the root of the blade by the amount d. As a result of this construction the tapering surface 7. formed by the removal of the material at the back of the blade on the entrance side will not lie in a single plane (as in the form shown in Figs. 3, 4 and 4) but will vary from root to tip by the amount represented by the angle d, which corresponds to the variation of the ratio between periphery velocity and steam velocity, as this ratio varies from the tip to the root of the blade. This is a very desirable construction when the ratio blade length to diameter of admission. is unfavorable and with wet steam in the low pressure part providing an entrance without shock corresponding to the highly variable ratio peripheral velocity to steam velocity referred to above.

In conclusion it may be stated according to the present invention one can obtain an improved efiiciency by reducing friction losses by regulated exit angles and by con-' tinuous guidance of the steam or the like. Further the following advantages can be gained: a diminished number of blades (because a larger pitch is permissible), smaller cost of the 'blading, less wear and tear, and lighter running rims and wheel bodies, which are particularly important for the low pressure wheels of fast running turbines. The advantage is also gained that vibrations of the long blades occur in a much less degree, because the blade passages are gradually filled and emptied by reason of the inclined entrance edges of the blades.

Having now described our invention what we claim as new and desire to secure by Letters Patent is 1. As a new article of manufacture a conical turbine blade having its concave side formed with the place of greatest curvature situated onthe'entrance side to produce a blade of substantially constant strength throughout its length.

2. As a new article of manufacture a conical turbine blade having its concave side formed with the place of greatest curvature situated on the entrance side to produce a blade of substantially constant strength and having a flat surface of tapering form formed atthe rear of the blade to produce the proper entrance angle.

3. As a new article of manufacture a conical turbine blade having its concave side formed with varying curvature throughout its length and being provided with a fiattened surface at the rear of the blade on the entrance side to provide the proper entrance angle. 7

4. As a new article of manufacture a conicalturbine blade having its side formed with the place of greatest curvature situated on the entrance side to provide a blade of substantially constant strength and being further provided at its rear side with a flattened surface on. the entrance side presenting a tapering surface, wider at the base than at the tip of the blade, to provide the proper entrance angle.

5. As a new article of manufacture two conical turbine blades having entrance and exit angles, such that the back of one blade is parallel with the face of the adjacent blade for a short distance at the exit end.

6. A turbine blade with a concave front face, the top and bottom of the concavity in a longitudinal section of the blade being represented by parallel straight lines both inclined toward the back of the blade from the root to the tip; the back of the blade being also formed with a surface which is inclined to said concavity and intersects it in a line running from the tip to the root of the blade.

In testimony whereof we aflix our signatures in presence of two witnesses.

DB. Inc. PAUL CHRISTLEIN. ERIC BROWN. Witnesses CARL GUBER. BERTHA C. Gnon.

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