RU129079U1 - PROPELLER SCREW - Google Patents

Abstract

A rowing screw containing a hub and blades, each of which has through holes, characterized in that each blade is made in the form of a thin, preferably flat, elastic plate made with streamlined edges, while in the area adjacent to the hub, the blade is deformed to form folds in such a way that the blades are given a given slope to a plane perpendicular to the longitudinal axis of the hub, in addition, the design parameters of the blades are determined by the formula: W is the moment of resistance of the blade to torsion; B - blade width; D is the diameter of the ith hole; δ is the thickness of the blade, while the through holes are directed perpendicular to the working surfaces of the blades, in each longitudinal section of the blade the total area of the through holes does not exceed half the sectional area of the blade, and their diameter does not exceed 5 blade thicknesses .

Description

The utility model relates to the field of hydrodynamics and can be applied to modern high-speed devices moving in water, in whole or in part, at high-speed blade devices, which are used in various sectors of the national economy, mainly in shipbuilding, namely for propellers.

One of the most pressing problems in the operation of engines of small and large vessels is the cavitation of liquid during movement — the formation of gas bubbles under reduced pressure, which tend to compress with such force that dents and holes form as a result. The pressure difference along the edges of the blades occurs when the screw rotates, which distills the fluid from one pump chamber to another.

One of the reasons for cavitation of the propeller blades is surface heating, which significantly reduces the yield strength (stress corresponding to the onset of noticeable plastic deformations and accompanied by heating of the material).

Known screw propulsion device (see RF patent 2200113, IPC B63H 1/24, B64C 11/24, publication date 03/10/2003) containing hollow blades connected through an internal channel to the external environment and having a local outlet system on a suction surface.

The disadvantages of this design include the increased complexity of manufacturing.

As the closest analogue, a propeller is adopted (see RF patent 2094304, IPC B63H 1/18, B63H 1/26, publication date 10.27.1997) containing a hub with blades, each of which has through holes.

The disadvantages of the closest analogue are increased material consumption and heating of the surfaces of the propeller blades during operation.

The technical task of this utility model is the development of a propeller with improved performance.

The technical result achieved when solving the problem is expressed in increasing the efficiency of the propeller due to the following factors:

- lowering the surface temperature of the blades due to their elastic deformation;

- reduction of hydrodynamic resistance due to the formation of so-called artificial cavities in the form of through holes, creating the effect of retaining the boundary layer;

- the ability to determine the optimal location of through holes with a known direction of deformation can improve the reliability of the structure during long-term operation;

- reduction of labor and material consumption.

The problem is solved in that in the propeller containing the hub and the blades, in each of which through holes are made, each blade is made in the form of a thin, preferably flat, elastic plate made with streamlined edges, while the blade adjacent to the hub deformed with the formation of a fold in such a way that the blades are given a given slope to the plane perpendicular to the longitudinal axis of the hub, in addition, the design parameters of the blades are determined by the formula:

where W _t is the moment of resistance of the blade to torsion;

B is the width of the blade;

D _j is the diameter of the i-th hole;

δ is the thickness of the blade,

In this case, the through holes are directed perpendicular to the working surfaces of the blades, in each longitudinal section of the blade, the total area of the through holes does not exceed half the cross-sectional area of the blade, and their diameter does not exceed 5 blade thicknesses. Figure 1 shows the propeller in plan. Figure 2 shows a side view of the propeller blade. The drawings show the hub 1, on which the blades 2 are fixed, deformed to form a crease 3, and through holes 4 are made in each of the blades 2. The thickness of the propeller blade is conventionally shown.

The inventive device operates as follows. When the propeller is worn on a propeller shaft (not shown in the drawings), a pressure difference occurs on the discharge and suction surfaces of the blades 2, as a result of which a lifting force is formed, one of the components of which is directed opposite to the direction of movement of the vessel and creates an emphasis - the force pushing the vessel forward.

The through holes 4 through which the fluid flows from the blades 2 injecting onto the suction surfaces create the effect of retaining the boundary layer and thereby reduce cavitation, and the blades 2 being made in the form of thin, preferably flat, elastic plates allows lowering the temperature of the working surfaces.

Claims (1)

A rowing screw containing a hub and blades, each of which has through holes, characterized in that each blade is made in the form of a thin, preferably flat, elastic plate made with streamlined edges, while in the area adjacent to the hub, the blade is deformed to form folds so that the blades are given a given slope to a plane perpendicular to the longitudinal axis of the hub, in addition, the design parameters of the blades are determined by the formula $$W_t=\frac{B-{\sum }_{i=\mathrm{one}}^n{D}_i}{3}{\delta }^3$$

_, where W _t is the moment of resistance of the blade to torsion; B is the width of the blade; D _j is the diameter of the i-th hole; δ is the thickness of the blade, while the through holes are directed perpendicular to the working surfaces of the blades, in each longitudinal section of the blade, the total area of the through holes does not exceed half the cross-sectional area of the blade, and their diameter does not exceed 5 blade thicknesses.

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