US1853136A - Runner blading - Google Patents

Description

April 12, 1932.- L. F MOVODY 1,853,136

' RUNNER BLADING Filed Feb. 8, 1928 2 Sheets-Sheet l April 12, 1932. F. MOODY 1,853,136

RUNNER BLADING Filed Feb. 8, 1928 2 Sheets-Sheet 2 Patented Apr. 12, 1932 UNITED staresv LEWIS FERRY MOODY, OF PHILADELPHIA, PENN SYLVANIA Runner. BLADING Application filed February 8, 1928. Serial No. 252,858.

have complicated shapes involving a large number of indeterminate variables. Each new problem of des gn has therefore been met largely by judgement rather than definite,

calculation, and the net result has depended to a considerable extent upon the personal preference of individual designers. It has been difiicult to foretell the performance of a new design of runner from the known operation of prior runners and this has sometlmes led to uncertainties and failures to meet requirements.

The chief object of this invention is to overcome these objections to prior runners and provide a system of runner blade surfacing which while efliciently utilizing the water flow involves relatively simplesurface contours based on regular geometric lines and surfaces. The runner blades of this invention have helicoidal surfaces or the like which are geometrically determinable with precision. Such geometrically regular surface contours reduce the number of variable factors involved in the design so that theobserved characteristics of known runners may be intelligently used to predetermine the characteristicsof different but analogous designs for other installations. This permits a simplification and standardization of the forms of runner blades to a much greater extent than is now possible while at the same time improving the characteristics of individpermits higher speeds to be realized and greatly improves the efiiciency, since in turbines of high specific speed the loss due to surface friction is an important factor. The

invention also attains a more exact agree the power rating is required and hydraulic corrosion is reduced on account of the greater smoothness and regularity of the general surface contour resulting from machining, for the local bumps and hollows frequent in the usual cast surfaces tend to cause corrosion.

In the accompanying drawings illustrating the invention,

Figs. 1, 2 and 8 are elevational views of runners having blades shaped inaccordance with this invention and showing by diagrammatic outline apparatus adapted for the machining of the blades.

Figs. at and 5 are, respectively, vertical and horizontal sections of a turbineinstallation embodying my runner.

In the specific embodiment of the invention shown in Fig. 1 the runner 2 is mounted on a rotatable mandrel 3, the blades 4 of the runner being shown extending at substantially right angles to the runner axis so that the runner is of the axial flow type. During the machining of each blade the mandrel 3 oscillates through an angle sufficient to carry the cutting tool 5 completely across the blade from edge to edge, the tool being simultaneously oscillated around the axis a by the I worm wheel segment 6 driven by worm 7 on shaft 8 ear-connected to the mandrel drive (see ig. 3) so that the oscillating movement of the tool is proportional to the oscillatory movement of theblade. The tool carrier 9 is fed along the arm 10 of the oscillating segment 6 by screw 11 after each cut and thus the tool progresses from tip to hub of the blade on increasingly larger arcs correspondingly increasing the pitch of the blade surface toward the center. This method of surfacing produces a helicoidal surface with the'blade pitch greater at the hub and gradually decreasing toward the tips and by varying the ratio'of oscillation of the mandrel and tool arm and variously positioning the axis a with respect tothe mandrel axis a variety of blade surfaces may be produced adapted for dilferent runners. In each case it is seen that the axis a for each blade is remote from the runner and lies in a circular line concentric to the runner axis.

In order to provide an additional variation of the contour of the blade surface a special former may be used to additionally control the tool movement and thus ive a wider variability. For instance as shown in Fig. 1 the yoke 12 carrying the worm 7 may be slidably mounted and moved by a cam 13 on the mandrel 3, the roller 1d of the yoke member 12 being normally held against said cam by fluid pressure, or by weight or spring, etc. By suitably shaping the peripheral contour of the cam 13 the shape of the blade surface may be varied from a helicoid and in particularvthe rear surface of the blades may be givena relatively convex shape to strengthen the blade.

In Fig. 2 the runner 2 has its blades 4 of the diagonally inward flow type with their axes inclined to the runner axis. Such blades may be machined by an oscillating tool of the type shown in Fig. 1 (see Fig. 3) or as shown in Fig. 2 the tool 5 may be reciprocated back and forth with the reciprocatory carrier 15 driven back and forth by the screw drive 16 intergeared with the mandrel 3, a screw feed 17 for the tool carriage 18 being Iprovided to feed the tool lengthwise of the lade. The helicoidal surface produced by this method will have a constant pitch from the hub to the tip of the blade.

In Fig. 3 a runner 2" of the diagonal inward flow type is shown .with apparatus adapted to machine the blade surfaces along a helicoidal pitch increasing toward the hub. In this figure the blades are mounted to rotate around an axis tt and the tool arm 51 is pivotally mounted on an axis perpendicular to the runner axis but oflset from it. The rotation of the tool arm is made proportional to that of the blade 50 by a set of gears comprising the worm gear 52, worm 53, worm 55 and worm gear 56 with intermediate change gears 54 to suit different pitches. The feed motion of tool carrier 57 IS in a radial direction from the axis a. The tool 58 describes increasingly larger arcs it progresses toward the hub and thus correspondingly increases the pitch of the blade surface toward the center.

While in Figs. 1, 2 and 3 the axis of rotation of the supporting mandrel coincides with the axis of the runner, this axis of rotation of the mandrel during machining of the blades may be separated from the runner axis if desired to produce a proper configuration of the blade surface with relation to the runner axis. In either Fig. 2 or Fig. 3 additional variation of the tool movement may be provided by a. suitable template or cam variation of the tool feed as indicated for instance in connection with the tool feed of Fig. 1.

By the use of a simple form of surface,

such as the helicoidal surfaces here proposed, a highly desirable simplification and standardization of the forms of runner blades is made possible. For example, if a series of runners is built with helicoidal surfaces, the blade contours can all be of similar form such, for example, as straight or elliptical edges but of different relative widths; and it then becomes possible to specify the blade form completely by a small number of numerical factors such as the pitch ratio of the helicoid and width or area ratio of the blade surface. The standardization can be carried still further and made to cover the form of blade section and variation of thickness. For example, if the back of the blade is given the form of a circular arc, in cross section, in all runners of a set, the form of bladesection is thus standardized. lVhile the invention has been described with particular reference to turbine runners of the diagonal inward flow and axial flow type, it is also applicable to runners of the diagonal outward flow type, but either type would have an intake and discharge generally indicated at 60 and 61 respectively and preferably adjustable guide vanes 63 adapted to impart whirl to the inflowing fluid would be used. The runner tips are close to the ring 62 shown in Figs. 4 and 5. These figures also showing that the blades are more horizontal at the tips than at the hub for it will be noted that the circumferential extent of the blade tips, Fig. 5, is greater than the axial extent of the blade tips, Fig. 4, whereas adjacent the hub the circumferential extent of the blades more nearly approaches their axial extent, Fig. 4. Inasmuch as the slope of the blades with respect to a plane normal to the runner axis is the ratio between the axial extent and the circumferential extent it is seen that the slope is less at the blade tips than at the hub. The principle of the invention is not confined to the specific examples shown but is intended to cover any modifications within the scope of the appended claims. This application is a continuation in part of my copending application, Serial No. 578,388, filed July 29, 1922, now Patent No. 1,733,671, of October 29, 1929.

I claim:

1. In combination, a high specific speed propeller type hydraulic turbine runner having blade surfaces formed as a special type of helicoidal surface having straight line elements disposed in successive meridian planes and progressively changing in inclination to the runner axis in passing from one such meridian plane to the next, all of said straight line elements intersecting a common circular line contained in a plane normal to the runner axis and having a radius greater than the largest radial extent of the runner; means forming an intake and discharge for said runner including a casing surrounding the runner and disposed adjacent the blade tips and means for whirling the flow to said runner.

2. In combination, a high specific speed propeller type turbine runner having blades with a surface of special helicoidal form gen-' erated by a straight line intersecting and diagonal to the runner axis and having a generating movement at an angle to said axis simultaneouslywith a movement of rotation about said axis, said surface having machine finish thereby providing a surface of accurately smooth hydraulic form, means forming an intake and discharge for saidrunner including a casing surrounding the runner and disposed adjacent the blade tips and means for whirling the flow to said runner. v

3. In combination in a high specific speed propeller type rotary hydraulic machine, a

runner having machine-surfaced blade surfaces formed 'as special helicoidal surfaces generated by moving, a generating point along a series of concentric circular arcs in a merldlan plane Wh1le simultaneously rotatlng sald meridian plane about the runner axis, said generating point in successive arcs falling on a straight line in the meridian plane; means forming an intake and discharge for said runner including a casing surrounding the runner and disposed adjacent the blade tips and means for whirling the flow to said runner.

4. A turbine rotor as set forth in claim 2 having at least four blades.

5. The combination in a hydraulic turbine, comprlsing a runner having blade sur- LEWIS FERRY MOODY.

Images