US2291062A - Blade wheel propeller, particularly for watercraft - Google Patents

Description

July 28, 1942. SCHNEmER 2,291,062

BLADE WHEEL PROPELLER, PARTICULARLY FOR WATERCRAFT Filed March 7, 1940 s Sheets-Sheet 1 IN V ENTOR.

M ATTORNEY.

July 28, 1942.

E. SCHNEIDER 2,291,062 BLADE WHEEL PROPELLER, PARTICULARLY FOR WATERCRAFT Filed March 7, 1940 3 Sheets-Sheet 2 I IIIIlIJ'IIIII/ d 4 I I INVENTOR. Ewan fiims'zder M ,4 7 70mm July 2- E. SCHNEIDER I 2,291,062 I 5LADI17 WHEEL PROPELLER, PARTICULARLY FOR WATERCRAFT Filed March '7, i940 s Sheets-Sheet s w w mm? Patented July 28, 1942 BLADE WHEEL PROPELLEB, PARTICULARLY FOR WATERCRAFT Ernst Schneider, Vienna, Germany, assignor to Voith-Schneider Propeller Company, New York, N. Y., a corporation of New York Application March- 7, 1940, Serial No. 322,815

In Germany February 6, 1939 2 Claims.

This invention relates to blade wheel propellers for water or air crafts. In these propellers the blades are arranged upon a rotor, and the blades can feather about their axes while moving through their circular orbit. The blades are either at substantially right angles to the plane of rotation of the rotor, in which case they form' a cylindrical blade propeller, or the blades are the blades within the forward running blade semicircle equals approximately 1r. while the inclined at a small angle to the plane of rotation of the rotor, in which case they form a conical blade propeller. In either case, problems in regard to efiiciency of operation arise, and it is one of the objects of this invention'to so co-relate the blades of the rotor as to obtain the highest efiiciency of propelling action of the propeller, at the normal speed of rotation, the normal speed being usually the highest speed for which the propeller is designed.

For the proper understanding of the actions of blade wheel propellers, the circular orbit is divided into quadrants, formed by two diameters perpendicular to each other, one of these diameters being in line with the longitudinal axis of the boat or ship to which the propeller is applied, and the other being at right angles thereto and athwartship. Assuming the boat or ship to ,move forward, and provided the propeller rotates counter clockwise when looking down at it, the semicircle at the right hand of the longitudinal axis diameter and in which blades move in forward direction, is known as the forward running average pitch of the blades within the rearward running blade semicircle is slightly larger or smaller than 1r, and further in that pitches of the blades in the rearward semicircle are somewhat larger than the pitches of the blades in the corresponding'or reflective positions in t e forward semicircle.

The invention will be hereinafter further described, embodiments thereof shown in the drawings, and the invention will be finally pointed out in the claims.

In the accompanying drawings:

Figure 1 is a diagrammatic plan view showing the disposition of blades of 'a blade wheel propeller giving the highest efiiciency under normal speed conditions;

Figures 2 and 3 are similar views of a part of the number of the blades shown explain the actions of the blades under the designated pitch Jr; and

Figures 4 to 6 are diagrammatic plan views used to explain certain laws of action of the blades, which form the basic underlying concepts which led to the present invention.

Figure 'l is a plan view showing the positioning of the blades and the means for operating the same arranged in accordance with Figure 3,

Figure 7 being shown turned 90" in respect to blade semicircle and the semicircle at the left hand of said axis diameter in which the blades move in the rearward direction, is known as the rearward running blade semicircle. The semicircle forward of the athwartship diameter is known as the forward semicircle, and the semicircle aft of that diameter is known as the rearward semicircle. In-earlier disclosures, the varying actions of the water upon blades in different quadrants has been described. p

The particular part of this invention is to utilize factors of operation heretofore disclosed, and direct them in a special manner so as to obtain the highest efilciency of operation when operating at the normal speed of the operation. Under recognition of the principle that the most favorable pitch of a mechanical screw as regards efiiciency is obtained when H over D equals I, with H being the pitch, and D the diameter of the screw thread, the improved propeller embodies this principles for hydraulic uses.

The invention consists in disposing the blades of a. ,blade wheel propeller under conditions of Figure 3, and Figure 8 is a perspective view of Figure 7, with additional parts shown above the parts shown in Figure '7.

Fig. 9 is a plan view ing the curves through of the blades, as also' pass, when the normals of the forward moving blades intersect the .orbit and the diameter transof the blades and showwhich the center shaft verse to the direction of movement of the ship,

the normals of the other blades intersecting the extension of said diameter beyond the orbit.

Similar characters of reference indicate corresponding parts throughout the various views.

Referring to the drawings, and more particularly to Figures 1 and 2, the blade wheel orbit is shown by the circle K, the center of rotationof the blades by O, the direction of movement of the boat by the arrow T. and the direction of rotation of the blades, with the boat moving in the direction of the arrow T, by the arrow P. The semicircle cba is the forward running semicircle, and the semicircle cda is the rearward running semicircle. The semicircle deb is the forward semicircle and the semicircle (lab is the normal operations, so that the average pitch of aft or rearward semicircle. The diameter D in Figure 1, to.

their front and rear ends running extending from c through to a is'the diameter of the circle K, in alignment with or parallel with the longitudinal axis of the boat and the diameter D is at .right angles to D extending from d-through O to b or athwartship. The diameter D is the important diameter in respect to the present invention. Utilizing the known advantages of adjustable pitch in regard to magnitude as well as direction, and of blades having the same entrance edge all the time, the blade pitch of the blades S is equal to or approximately equal to 1, preferably for all of the blades.

The invention consists in making the pitch of the blades 8 while traveling inthe forward runing semicircle cba equal to r, and the pitch of the blades while running in the rearward running semicircle somewhat larger or smallerthan 1r. This pitch of the blades gives a most efllcient pitch, maintains the entrance edge of the blades, and gives arbitrary adjustability' of the blade pitch without having to accept the disadvantages of earlier proposals. The invention may also be defined by the blade normals of the blades. In Figure 1, the blade normals are indicated by the lines R, these normals being perpendicular in each case to the longitudinal axis of each blade, indicated by the lines B. The normals R of the tersect an extension D of the diameter D out-- intersect in some cases side of the circle K, or

the diameter D within the circle K. The normals of the blades oi' the forward running semicircle cba intersect nearer the blade circle K, than the normals of the blades of the rearward running semicircle 'cda. The pitch of the blades of the forward semicircle dob is somewhat smaller than the pitch of the blades in the rearward semicircle dab. The intersecting points N1 and Ni are at or in the vicinity of the circle K with the point N1 slightly greater in distance from the center 0 than N1. The intersecting points N: and N2 intersect, in the embodiment shown, the extension D of the diameter D, the intersecting point N1 being at a greater distance from the center 0 than the point N2.

Referring to Figure 2, the blade normals R of the blades inithe forward running semicircle cba intersect the diameter this embodiment directly the normals R of the blades with the rearward semicircle intersect an extension D of the diameter D at N: outside of the circle K. The distance of the point N: outside of the circle is dependent upon various considerations; one hand, this point must not be too far away from the blade circle, as otherwise the emciency D at the point N1, in

'''of that particular blade circle half decreases too much, and on the other hand, the must not be too close to the circle, require excessive forces to turn the their axis, inasmuch as the torque on the blade will be greater the tance between the intersecting intersecting as this would blades about to be imparted smaller the dis- DOint outside the blade circle and the circle. These considerations are Jembodied in the embodiment shown in Figure Referring t'oFigure 3, the intersection point N: of the blade normals of e the blades in the rearward running blade circle oda is located inside of-the circle K, whereby the distance of this point is dictated by similar consideration: as

at the circle K; and

onthe' blades in th forward running blade semicircle 'overDrequalsl.

those-which were set forth in connection with Figure 2, that is the efllciency and theacceleration forces required, for turning the blades must be taken into consideration in this blade wheel semicircle cda. The normals of blades 8 in the forward running semicircle cba intersect the diameter D at N1. Radial lines drawn from center 0 through the blade centers form an angle a of as shown in Figured, and the center line of this angle a is identical with the diameter D at its portion (10 and at high pitch values the relative velocity and therefore the work component influencing the efllciency are comparatively negligible. I

The emciency of a blade wheel built in accordance with the present invention may in a known manner be further improved by increasing the angles between the blade and tangent to the blade circle K through the blade axes in the rearward blade semicircle compared with the corresponding angles in the forward blade semicircle. This will effect a load increase in the rearward blade semicircle, thus equalizing the irregularities caused by the fact that the-flow velocity is larger in the rearward semicircle dab than in the forward half of the wheel dcb, due to the acceleration imparted on the fluid in the forward half of the wheel. This improvementof emciency may be effected by placing the intersection of the blade normals closer to the wheel center 0, when the blades move through the forward half dob. than the intersection points of the blade normals belon ing to the blades moving through the rearward wheel half dab.

The forego ng is based upon the following considerations:

As stated at the outset, the greatest emciency with a mechanical screw is obtained when H App n this to blade wheel propellers of either cylindrical or conical blade dispositions, this hydraulic maximum efficiency is reached if the entrance velocity of the fluid quals the peripheral velocity u of the blade wheel, that is, the relation of re over it equals 1. This condition is fulfilled ifthe blade normals, that is, the normals to the chords of the proflles of the blades through the blade centers intersecton the blade circle K. More precisely stated, the intersection takes place at or in proximity of the diameter D and the blade circle K. In designing ship propellers, the proportion of 11 over D designates the pitch of the propeller, in which H is the distance traveled by the blade wheel -per resolution under no-load condition (pitch) and D is the Between this ratio and the relation of are over it mentioned before, the following relation exists:

Hue

The blade normals R of blades 8 intersect in a point N located, on diameter D and blade wheel clrcleK. ThearrowPindlcatesthedisemicircle cda.

rection of rotation of the wheel and arrow T the direction of thrust, i. e., the direction of travel of the ship. This law of blade motion, as indicated in Figure- 4, requires that entrance and discharge edges of the blades alternate in such a way that, as illustrated in Figure 4, symmetrical profiles must be selected. These, however, do not permit to obtain the theoretically highest values of efficiency based on the most favorable blade pitch. A further disadvantage of these well not possible to realize the most efficient pitch 1r. The law of blade motion of these wheels is shown in Figure 5. This figure will be easily understood as the same reference charactershave been used as in Figure 4. The intersecting point N of the blade normals R lies outside of circle K on an extension D of diameter D. The peripheral velocity it under no-load condition in these blade wheels is smaller than velocity ve as may be seen from velocity triangle u, as, w, in Figure 5. A further known variety of blade wheels is shown in Figure 6. In this case the intersecting point N of the normals is located inside of the blade wheel circle. It may arbitrarily be shifted to various positions within the blade vcircle, permitting the propeller thrust to be varied in respect to its magnitudefrom a maximum to zero and in respect to its direction from ahead to astern, to starboard and to port, merely by shifting the intersecting point N of the normals. However, even in this case it is likewise impossible to obtain under normal conditions of operation the maximum values of pitch, inasmuch as the proportion ve/u does not equal 1, but must be smaller than 1, as can easily be seen from the velocity triangle u, ve, w, in Figure 6.

From the foregoing it is seen that this invention as described in connection with Figure 1, solved a problem by making thepitch of the blades exactly (substantially) equal to 1r, in forward running semicircle abc, and somewhat larger or smaller than 1r in the rearwardrunning Otherwise stated, the solution results from having the normals R of the forward running semicircle cba intersect the diameter D at or in proximity to its end point d, like Figure 2, and from having the normals of the semicircle cda intersect on an extension D of this diameter outside of the blade circle, or on the diameter inside of the blade circle, like Figure 3. Finally, the blade pitches in the aft semi are also known. But in these blade wheels it is 1 center 0. Concentric to the orbit abcd is a ring K which is rotatable with the blades in the orbit abcd; Another ring K when in initial position is concentric with ring K and with the orbit, and the orbit and the two rings are concentric. But the ring K is shiftable and inFigure 7 it is shown as shifted from its concentric position to an eccentric position in respect to ring K whereby 'the center 0 isshifted along the diameter db, as shown. The diameter db is also marked D and is trans- .verse to the longitudinal direction of the ship. The normals of the blades intersect the transverse diameter D as shown. To each blade or to a rod secured thereto, which rod in plan view is above the blade profiles, a link L is pivoted, the other end of which is pivoted to one end of an elbow lever L having its angle pivoted to the ring K 'The other leg of this elbow lever is arranged in a slide K pivoted to the ring K Thus by shifting the ring K into the position shown in the drawings in Figure 7, the forward moving blades in the semicircle abc, a little after and a little before the blades at the positions a and 0, have their perpendiculars pass through a point at the intersection of the orbit K and diameter D. The front end of all the blades pass through another orbit Y In Figure 1, the front end of the blades pass through the orbit Y shown in dot-dash line in Figure 1. The orbit Y in Figure 7 is that resulting from a disposition of the blades in accordance with Figure 3.

vThe intersection points N and N 1 are in the circular orbit K and in the diameter D, whereas the points N2 and N3 as also N 2 and N 3 are within the orbit, on the diameter D. In Figure '7 the ship moves in the direction of the arrow marked circle dab are somewhat larger than the blade pitches in the reflective or counterpart positions in forward semicircle deb, the counterpart being considered in respect to the athwart diameter D. This solution combines the advantages of the three known varieties of blade Wheels exemplified in Figures 4, 5 and 6, namely, most efficient pitch, maintains the entrance edge of the blades, and gives arbitrary adjustability of the blade pitch, without, however, having to accept the disadvantages of the types shown in Figures 4, 5

and 6.

In Fig. '7 is shown the orbit abcd, with the Forward and the blades rotate in the direction of the arrow marked P. The positioning of the blades in Figure 7 conforms to the pitches described hereinbefore. The criterion is the pitch of 1r as stated to give the highest efficiency under high speed or normal operation.

' It goes without saying that these data are to be considered on approximate basesonly, for, it -would be possible within the frame of this invention, on the one hand, to deviate from pitch 1E in-the forward running half circle within the limits of fairly high hydraulic efficiency, While on the other hand it would likewise be possible to select that section of the blade wheelcircle in which the blade normals intersect outside or inside the blade circles, larger or smaller than the half circle. I

In Fig. 9 isshown the blades S in the same position as shown'in Fig. 1. The center of each blade passes through the orbit K, and the tip of each blade through the path or curve Y, as in Figure 1. In Fig. 9 is also shown the path or curve through which the tail or rear end of each blade passes, which path 'or curve is necessarily a reverse curve to curve Y, and is indicated by Z. If now these paths or curves K, Y, and Z, be shaped into grooves as shown by the'double and spaced lines in Figure 9, stems on such blades as generally indicated by the small circles, will follow such grooves, when the blades are moved with their central shafts or stems in the orbit K. Any intermediate portion of a blade between those shown will necessarily be controlled by the same relationship. Thus when the rotor is supplied with such grooves Y, K and Z, and the blades moved by their stems in the orbit groove K, the tips and rears of the blades will take the positions shown, as long as their normals intersect the orbit at its intersection with the transverse diameter D in respect to the for- Reference is made'to my co-pending applica-.

tion, Serial No. 250,949, flled January 14, 1939,

and to U. 5. Letters Patents Nos. 1,681,500 of August 21, 1928; Voith 1,922,606 of August 15, 1933; and Ehrhart No. 2,037,069 of April 14, 1936.

I have described several embodiments of my invention, but it will be clear that changes may be made within the principle of the invention described, without departing from the scope of the subjoined claims.

I claim:

1. A blade wheel propeller having blades the axes of which in respect to theaxis of rotation of the propeller describes a cylinder or a cone, and having means to arbitrarily adjust the blades as to magnitude and blades moving on their axes in acircular orbit having a diameter disposed front to .aft and a diameter at right angles thereto, athwartship, with the semicircle at the right side of the iongitudinal diameter being-for the forward run ning blades and the semicircle at the left side of said longitudinal diameter being for the rear-.

ward running blades, the semicircle fore of the athwart diameter being the forward semicircle and the semicircle at the rear thereof being the aft semicircle, comprising means for axially shifting said blades during the rotation of the propeller for maintaining the blades while in forward running'position r, with their perpendicular; to the blade profiles intersecting said athwart diameter and said rearin the rearward running position 'at a pitch larger I direction of thrust, said at an average pitch of as to magnitude and directiomsaid blades mov ing on their axes in a circular orbit having a diameter disposed front to aft and a diameter at right angles thereto, athwartship, with the semicircle at therrigh't side of the longitudinal diameter being for the forward running blades and the semicircle at the left side of said longitudinal diameter being for the rearward running blades, the semicircle fore of the athwart diameter being the forward semicircle and the semicircle at the rear thereof being the aft semi circle, comprising means for axially shifting said blades during the rotation of the propeller for maintaining the blades'while inforward running position at an average pitch of 1r, with their perpendiculars to the blade profiles intersecting said athwart diameter and said rearward running semicircle of said orbit, means for simultaneously maintaining the blades while in the rearward rimning position at a pitch larger than r, with their perpendicular-s to the blade profiles intersectingsaid athwart diameter without said orbit, the blades in their forward semicircle being in advance of the blades in the aft semicircle while in the fluid current during the forward movement of the propeller as an entirety, and means for moving the pitch of the blades in the aft 40 semicircle of the blades, reflective thereof or counterpart thereto, in the forward semicircle.

SCHNEIDER.

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