FI95226B - Propeller for boats and ships - Google Patents

Description

95226

PROPELLER FOR BOATS AND SHIPS

The invention relates to a propeller for boats and ships, which can be used in principle in all ships in which currently known propellers are used. The structure of the propeller according to the invention 5 comprises a substantially cylindrical body to be attached to the shaft of the ship and propeller holes fixed to this body. The propeller according to the invention differs from the structure of the current propeller mainly in that the propeller blades are arranged helically in the body 10 so that the propeller blade following the previous propeller blade is placed behind the previous blade on the pressure side so that the axial symmetrical circular blades the angles of the sectors form a total of 15 full circles of 360 °. The better operation of such a propeller is based on the fact that there is no "empty space" between the propeller blades, so there is no water slip in the propeller either. Water slippage is precisely the worst factor in lowering the efficiency of current propellers, so the propeller of the invention achieves better efficiency than any currently used propellers with a peak efficiency of just over 70%. In practice, however, the efficiency of existing propellers is much lower, especially on heavy-duty cargo ships 25, which can only have an efficiency of about 20-30%, mainly due to the considerable slip. With the propeller according to the invention, an efficiency of up to more than 90% can be achieved and the efficiency remains almost constant even with heavy loads, because the propeller has no slip at all. The propeller according to the invention thus considerably saves energy or correspondingly increases the speed of ships.

The more than 2000-year-old Archimedean screw, which has been known for more than 2,000 years, has been tried on several occasions as a so-called continuous propeller for the ship. However, this propeller has never worked properly.

The reason for the poor operation of this propeller becomes clear when compared to the very similar structure of the cowardly propeller of the invention. In a continuous propeller, the water mass initially coming to the propeller has to partially rotate around the propeller shaft and new water can only enter the propeller blades from 5 sides. In a propeller according to the invention, which could be called a semi-continuous propeller, each propeller blade "takes in and leaves" the incoming water mass as linearly as possible so that as little energy as possible is used to "rotate" and turbulence the water mass. In this case, the efficiency of the propeller is also as high as possible.

The propellers in use today are also propellers, and their first versions were developed hundreds of years ago, 15 combining the good qualities of Archimedes' screw and windmill. In the beginning, the efficiency of the propellers was modest, but even with the current technology, the efficiency of the propellers can only be obtained at a maximum of about 70%.

The main reason for the low efficiency is the "mandatory empty space" between the propeller blades 20 and the resulting water slip. The magnitude of the slip is usually well over 20% of the energy applied to the shaft. Attempts have been made to reduce the slip, for example, by building tunnels around the propeller; by building rotary-blade propellers; and by placing ‘25 propellers rotating in opposite directions on the shaft. These measures have often led to slightly better results, but efficiency has remained low and investment costs have risen accordingly. The propeller according to the invention does not have it. Due to the structure, there is no slip at all, so its efficiency is only reduced by different flow resistances and cavitation. However, the overall impact of these losses is quite small as they consume only about 4-8% of the total energy entering the propeller. Thus, with the propeller 35 according to the invention, efficiencies of more than 90% can be achieved. In order to achieve the above effect, the invention is mainly characterized by the features set out in claim i.

In the following, the invention will be explained in detail with reference to the accompanying drawing in which:

Figure 1 shows a side view of a four-blade propeller 5 according to the invention.

Figure 2 shows the propeller of Figure 1 when projected onto a plane perpendicular to the axis. For clarity, the propeller blades are separated by two lines from one station.

1C Figure 3 shows a projection pattern of a cowardly six-bladed propeller of the invention when the blades are hydrodynamically shaped better than circular sector shaped blades.

Figure 1 shows a side view of a four-bladed propeller according to the invention. The propeller includes a strong, cylindrical 15 fixed body 1. Four completely symmetrical circular sector propeller blades 2 are welded or otherwise very firmly attached to the outer surface of the body in a helical position perpendicular to the axis. Blades 2 are set and bent to a certain desired pitch 2 (propeller pitch) so that, viewed axially, all the different blades of the propeller are side by side, i.e. their sectors form o a complete circle 360.

When the propeller is viewed tangentially in the direction of the surface of the propeller blade 2, a small gap 3 of approximately 3-4 times the average thickness of the propeller blade is left between the blades 2. These slots 3 form a completely essential factor for the operation of the entire propeller, since they enable each blade 2 of the propeller to operate completely independently and the other propeller blades do not interfere with the operation of one. The slots 3, mentioned in Fig. 1, divide the propeller into four blades. The co-operation of the blades results in the best possible efficiency for the propeller. The propeller can be fitted with 3 blades, but preferably 4 or 5, or -5 more if necessary, when the hull diameter is large.

4 95226

Figure 2 shows a pattern projected axially in a plane perpendicular to the body 1 of a four-blade propeller. However, for the sake of clarity in the figure, the propeller blades are slightly separated from each other by drawing the lateral points of the blades 2 5 with two lines. A mounting cylinder 4 on the shaft is also drawn in the middle inside the body 1. The blades of the propeller 2 are marked so that the first blade is represented by number 2a and the subsequent blades by numbers 2b, 2c and 2d.

The operation of the propeller according to the invention is mainly based on three main principles, which are explained in the following: 1. The propeller blades 2 always take in free water and likewise remove the water they take in the free water. In practice, this means that the normal ordinal pressure wave vector of the differential surface of any propeller does not hit the inner surface of the next 15 blades. Due to the helical structure of the propeller, such a situation can only arise in connection with the first and last blades of the propeller. However, it is easily eliminated by making the distance between the first platform 2a and the last platform 2d large enough. In Fig. 1, 20 pressure wave vectors are shown by the vector λΓ, which clearly bypasses the last blade 2d of the propeller. This happens whenever the distance between the front edge of the first blade of the propeller and the rear edge of the last blade is greater than the diameter of the propeller. 1 2 3 4 5 6 2. When the propeller is viewed in the direction of its axis, all its blades 2 are adjacent to each other, i.e. the sum of the sectors 3 formed by the blades is 360 °. In practice, this means 4 that the propeller has a maximally large pushing area over the entire 5 ascent path, and thus there is no empty space 6 causing slippage between the propeller blades. Because no slip occurs, only fluid flow resistances and cavitation reduce propeller efficiency. Their effect, especially at low speeds, is relatively small, so the efficiency of the propeller can rise to more than 90%. A particularly important feature of the propeller 5 95226 is that even if the propeller speed is increased, its efficiency remains almost constant. In this case, the often very low efficiencies of heavy cargo ships can even be doubled.

5 3. The overall operation of the propeller consists of the co-operation of separate, independent, independent symmetrical blades 2a, 2b, 2c and 2d. This operation is effected in the propeller by placing the blades helically on the body so that the blade of the propeller 10 following the propeller blade is placed behind the previous blade on the pressure side so that a suitable gap 3 is left between them, between which water can flow. At slot 3, the previous blade ceases to function and, correspondingly, the next shoulder begins to operate, cutting new water over the blade.

15 As the ship sets in motion, a rotating propeller generates a flow of water that causes a thrust on the propeller blades. The magnitude of this force depends on the propeller diameter, pitch, and speed, and its magnitude is directly proportional to the weight of the water mass displaced by the propeller per unit time. In addition, a force is applied to the propeller which is dependent on the internal flow resistance of the liquid caused by the water leaving the propeller. The propeller according to the invention displaces water in each revolution into a cylindrical water column, the base of which is formed by the projected surface area of the propeller (Fig. 2) and the pitch of the propeller. A current propeller, which would have the pitch and diameter of the previous propeller and have half the space between the blades, would form a water column like the previous one, but with a volume of only half of the previous one. Correspondingly, the thrust from the 30 propellers would also be only half of the previous one. In practice, circular sector shaped propeller blades are not optimal and due to rotational motion, better efficiency is achieved when the blades are hydrodynamically shaped so that the leading edge of the blades cuts water along its entire length while the projected surface area of the blades covers the largest possible area of propeller rotation. as ta. Such pallets 5 are shown in Figure 3.

6 95226

A propeller for ships and boats, in which three, four or more symmetrical propeller blades (2) are fixed to a certain propeller blade body (1) in a cylindrical propeller body (1) so that a gap of 3 to A times the propeller blade thickness ( 3) characterized in that, viewed in the direction of the propeller axis, all propeller blades are so adjacent to each other that the hydrodynamically shaped blades (5) fill a substantially large part of the propeller rotation area and where the distance between the first blade (2a) and the last blade (2d) is larger than the diameter of the propeller so that no pressure wave vector in the normal direction of the differential surface of the first blade hits the inner surface of the last blade.

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Claims (2)

95226 1. A ship and ship propeller, on which the cylindrical propeller body (1) has been attached three, four or more symmetrical propeller blades (2) at each angle of inclination screwlike so that from the side there will be a gap (3) between the blades, which are 3 - k times equal to the thick propeller blade, characterized by the fact that all the propeller blades seen in the longitudinal direction of the shaft are tangential to each other so much that the blades made in hydrodynamic form fill a substantially large part of the rotational surface of the propeller and at what distance between the first blade (2a) and the last blade (2d) is larger than the diameter of the propeller, so that no pressure path vector in the normal direction from the differential surface of the first propeller blade hits the inner surface of the last propeller blade.