CN108163171B

CN108163171B - Ship propeller

Info

Publication number: CN108163171B
Application number: CN201810121526.3A
Authority: CN
Inventors: 王坤坤; 王守仁; 王勇; 刘文涛; 王成; 于琪琪; 禄心强; 吴戍戌
Original assignee: University of Jinan
Current assignee: University of Jinan
Priority date: 2018-02-07
Filing date: 2018-02-07
Publication date: 2023-06-23
Anticipated expiration: 2038-02-07
Also published as: CN108163171A

Abstract

The invention discloses a ship propeller, comprising: an inner duct; an outer duct which is sleeved outside the inner duct and is coaxial with the inner duct, an interlayer flow passage is formed between the outer duct and the inner duct, and the outer duct is longer than the inner duct by a given length at the tail end; the propeller is arranged in the inner duct. The ship propeller duct according to the present invention is relatively short but efficient.

Description

Ship propeller

Technical Field

The invention relates to a ship propeller.

Background

The ship propeller is a kind of ship propeller, and is a mechanism for pushing the ship forward, mainly pushing the water by the propeller through the rotation generated by the turbine, for example, so that the ship obtains forward power based on recoil. The ship propeller is mainly a propeller type ship propeller, and the propeller type ship propeller is mainly two types, namely an unducted propeller type propeller and a ducted propeller type ship propeller, and the ship propeller related to the invention belongs to the latter type ship propeller.

The ducted propeller is referred to as a ducted propeller for short, and refers to a propeller system surrounded by a duct. Compared with an unducted propeller, the ducted propeller system has higher efficiency, and has the characteristics of small noise and high safety.

The thrust of the ducted propeller is related to the flow rate of fluid through the disk and the flow rate inside and outside the duct, and due to the complexity of the mutual interference between the ducts and the propeller, the design of the ducted propeller generally requires a relatively large amount of experience and a relatively long time, and any and even partial slight modification thereof may have a relatively large influence on the efficiency thereof.

Chinese patent CN107284652a discloses an integrated ducted propeller having one duct and a propeller installed in the duct, which is different from the known ducted propeller duct-fixing structure in which the duct is fixedly connected with the blades of the propeller, and is intended to reduce impact noise and improve efficiency by such an integrated structure. However, by the unitary construction, the resulting structure has a relatively large bypass ratio, relatively short acceleration times for the fluid, and limited fluid diversion by the relatively short bypass. In addition, the integral structure does provide the structural strength of the whole ducted propeller, but the ducts rotating together inevitably increase extra energy consumption, especially the liquid resistance is relatively large, and the efficiency is reduced.

The Chinese patent document CN104773279A discloses a curve ducted marine propeller, wherein the diameter of an inlet port of a duct is larger, the diameter of an outlet port of the duct is smaller, the duct is constructed into a variable-diameter structure based on the diameter matching of the inlet port and the outlet port, the front edge of the duct can generate larger resistance, the static pressure of a water absorption area in the front edge of the duct is increased, and meanwhile, the propeller also adopts a structure that blades are connected with the duct into a whole. In contrast, its equivalent bypass ratio depends on the outlet end caliber, so that its bypass ratio is much smaller. The bypass bus structure is relatively complex, and has high requirements on the processing technology. And it employs a single propeller having a plurality of lead lengths, it is known that the efficiency of the propeller is related to a plurality of factors, two of which are loss of axial induced speed and loss of circumferential induced speed, the plurality of lead length propellers significantly increasing the water flow twist, i.e. producing a larger loss of circumferential induced speed, which is why the blades of current propellers are typically employed in a plurality, and at most in a half of the lead length. And the maximum speed of the propeller capable of accelerating the water flow is determined because the rotating speed of the propeller is basically determined, and the acceleration effect of the overlong screw is limited.

Chinese patent CN104859820a discloses a two-stage ducted marine propeller, which also adopts a structure that a blade and a duct are fixed together, and is essentially equivalent to adopting a two-stage accelerating structure, unlike chinese patent CN104773279a, which adopts two sets of driving devices to accelerate two sets of propellers respectively, that is, the former stage has a lower speed, the latter stage has a higher speed, and in fact, the latter stage further accelerates the fluid that has generated a certain speed. As described above, the chinese patent document CN104773279a indicates that the static pressure area at the front end is larger, which is beneficial to the improvement of efficiency, in other words, the two-stage acceleration actually loses the efficiency of the latter-stage acceleration, and the overall energy consumption is larger. And the overall duct length is bigger, and for the boat with the rear propeller, the difficulty of installing the propeller on the boat body can be obviously increased.

Disclosure of Invention

In view of the above, it is an object of the present invention to provide a ship propeller with relatively short ducts but relatively high efficiency.

A ship propeller comprising:

an inner duct;

an outer duct which is sleeved outside the inner duct and is coaxial with the inner duct, an interlayer flow passage is formed between the outer duct and the inner duct, and the outer duct is longer than the inner duct by a given length at the tail end;

the propeller is arranged in the inner duct.

The ship propeller is characterized in that the inner duct and the outer duct are conical ducts with the caliber of the head end being larger than that of the tail end.

Optionally, the taper of the outer culvert is greater than the taper of the inner culvert.

Optionally, the inner culvert is coplanar with the head end of the outer culvert;

providing a prepositive cylinder connected with the head end of the inner culvert, wherein the prepositive cylinder is a cylindrical cylinder, and the inner diameter of the cylindrical cylinder is the same as the caliber of the head end of the inner culvert;

the front cylinder is coaxial with the inner channel.

Optionally, the length of the front cylinder is one sixth to one fifth of the inner diameter thereof.

Optionally, the given length is 0.4-0.7 times of the caliber of the tail end of the inner channel.

Optionally, the caliber of the tail end of the outer duct is 0.75-0.92 times of the caliber of the tail end of the inner duct.

Optionally, rib plates are arranged in the circumferential direction of the interlayer flow channel;

the centripetal end of the rib plate is connected with the outer surface of the inner duct, and the centrifugal end of the rib plate is connected with the inner surface of the outer duct.

Alternatively, the process may be carried out in a single-stage, the rib plates are radial panels based on the inner ducts;

the rib has six total ribs.

Optionally, the outer surface circumference of the outer duct is provided with dorsal fins, and the dorsal fins form a radial panel of the outer duct.

According to an embodiment of the invention, the ship has an inner duct and an outer duct which is sleeved outside the inner duct, wherein a propeller is arranged in the inner duct, and recoil force required for forward movement of the ship is generated by pushing fluid towards the tail end of the duct. The propeller forms a vortex in the backward liquid discharge process, the backward component in the vortex belongs to a beneficial component, and the rotation component in the vortex belongs to a harmful component. However, it is found that both components generate an absorbing effect on the low pressure area based on the venturi effect, the fluid pressure in the interlayer flow passage between the two ducts is lower than the fluid pressure ejected by the inner duct, the beneficial components generate the absorbing effect, and the rotating components also have the absorbing effect, so that part of the rotational kinetic energy of the fluid can be converted into the backward kinetic energy of the fluid in the interlayer flow passage, and the efficiency of the ship propeller is improved. In addition, the inner and outer nested ducts do not need to be increased in efficiency by multi-stage or multi-stage spirals, the overall length is relatively short, and the ratio of the ducts is increased but still within an acceptable range.

Drawings

Fig. 1 is a schematic view showing a main sectional structure of a ship propeller according to an embodiment of the present invention.

Fig. 2 is a schematic top view of the structure corresponding to fig. 1.

Fig. 3 is a schematic perspective view of a ship propeller.

In the figure: 1. the rib plate, the fin plate, the outer duct, the inner duct, the front cylinder, the propeller and the interlayer flow passage are arranged in sequence.

Detailed Description

For a ship propeller, the head and tail of the ship propeller are matched with the head and tail of the ship, namely, the direction of the ship head is also the head side of the ship propeller, and the side opposite to the head side is the rear side or the tail side is matched with the ship tail of the ship.

In general, the main profile of the duct is a revolution body having a defined axis, also a revolution axis of the revolution body, based on which the duct has a defined radial, axial and circumferential direction, with a defined centrifugal and centripetal direction.

Referring to the description, 1-3 of the drawings, a ship propeller is provided with two ducts, namely an inner duct 4 and an outer duct 3 shown in the drawings, wherein the two ducts are coaxial, and high coaxiality of the two ducts needs to be ensured during assembly.

In general, the outer culvert 3 may be directly installed on the bottom of the ship, and fixedly disposed, and the inner culvert 4 may be installed on the bottom of the ship by a portion extending axially out of the outer culvert 3, or may be connected to the outer culvert 3 by a radial connector.

Wherein, the inner channel 4 is used for arranging the screw propeller 6, the screw propeller 6 is not required to be provided with an independent mounting bracket, but is directly connected with a screw propeller shaft, the propeller 6 is connected and supported by the output shaft of the power equipment, so that the propeller 6 maintains a given coaxiality with the internal channel.

The outer duct 3 is coaxial with the inner duct 4, and under the assembly condition, the outer duct 3 is positioned outside the inner duct 4, and the thrust to the fluid generated by the propeller 6 has less direct influence on the outer duct 3.

In contrast, in normal use, the inlet end of the duct is the head end thereof, for example, the inner duct 4, and when the propeller 6 is operating normally, water flows in from the head end of the inner duct 4 and is discharged from the tail end thereof, and the head end of the inner duct 4 is the upper end as shown in fig. 1.

On the section plane taking the axis of the culvert as the normal, the diameter of the inner circle of the section plane of the outer culvert 3 is larger than the diameter of the outer circle of the section plane of the inner culvert 4, an interlayer flow channel 7 is determined between the inner culvert 4 and the outer culvert 3, and when the ship is moving forwards, fluid flows through the interlayer flow channel 7, and as the fluid flowing through the interlayer flow channel 7 is not directly accelerated by the screw propeller 6, compared with the fluid in the inner culvert 4, the water head pressure at the outlet end of the interlayer flow channel 7 is smaller than the water head pressure at the outlet end of the inner culvert 4, so that a Venturi effect can be generated.

The venturi effect, also known as venturi effect, is found by the spammer venturi (Giovanni Battista Venturi), and is therefore named by its name. This effect is manifested in the phenomenon that when a restricted flow passes through a reduced flow cross-section, the flow velocity of the fluid increases, with the flow velocity being inversely proportional to the flow cross-section. Whereas, as known from bernoulli's law, an increase in flow rate is accompanied by a decrease in fluid pressure, a common venturi phenomenon. This effect is colloquially referred to as creating a low pressure in the vicinity of the fluid flowing at high velocity, thereby creating an adsorption effect.

The water flow discharged from the inner channel 4 is a high-speed fluid, and the two streams have a certain flow velocity difference, so that the high-speed fluid formed at the outlet end of the inner channel 4 can attract the interlayer channel 7, thereby further accelerating the fluid in the interlayer channel 7. The acceleration is not only reflected in the axial component of the flow rate of the water discharged from the inner channel 4, but also in the circumferential component thereof, and the rotation component in the vortex generated by the liquid discharged from the inner channel 4 can also form negative pressure to generate attraction to the fluid in the interlayer flow channel 7, so that part of the flow rate of the rotation component can be converted into the axial component of the fluid, harmful components are reduced, and the useful component is improved, thereby improving the efficiency of the ship propeller.

The outer duct 3 is also adapted to be longer at the end than the inner duct 4 by a given length L, which essentially provides a transition space where a venturi tube is formed.

Based on the foregoing configuration, the loss of the circumferential induction speed, that is, the water flow torsion loss can be reduced.

In addition, due to the constraint of the double-layer duct, cavitation is further reduced, and noise of the spiral 6 can be further reduced.

Referring to fig. 1 and 3 of the specification, it can be seen that the inner duct 4 and the outer duct 3 are tapered ducts with a caliber of the head end being larger than that of the tail end. Based on the above, reference may be made to chinese patent document CN104773279a, in which the duct is configured to have a larger inlet port diameter and a smaller outlet port diameter, and the duct is configured to have a variable diameter structure based on the matching of the inlet port and outlet port diameters, so that the front edge of the duct can generate a larger resistance, thereby increasing the static pressure of the water absorption region in the front edge of the duct, and being beneficial to improving the efficiency.

In the embodiment of the invention, the double-bypass structure is adopted, the inner bypass 4 based on the conical structure can generate stronger injection speed, so that stronger injection capacity can be generated, and the efficiency is further improved based on the Venturi effect.

Further, the taper of the outer duct 3 is larger than that of the inner duct 4, the distance between the outer duct 3 and the inner duct 4 is gradually reduced in the axial direction of the duct from the beginning to the end, a closing-in is formed, and the Venturi effect can be further enhanced.

Furthermore, as mentioned above, the tapered duct structure is advantageous for increasing the static pressure in the water absorbing region at the front edge of the duct, but if the front ends of the inner duct 4 are flush, the suction force at the inlet of the inner duct 4 is relatively large, which affects the fluid entering the inter-layer flow channel 7, and thus, in the structure shown in fig. 1, the inner duct 4 is coplanar with the front end of the outer duct 3. Then, a front cylinder 5 is arranged at the front end of the inner duct 4, so that the inflow interference to the interlayer flow channel 7 can be reduced.

Further, referring to fig. 1 of the specification, it can be seen that the front cylinder 5 is a cylindrical cylinder, the inner diameter of the cylindrical cylinder is the same as the caliber of the head end of the inner channel 4, the front cylinder 5 and the inner channel 4 are directly connected by an end face, and the front cylinder 5 and the inner channel 4 are coaxial.

The front cylinder 5 is not too long nor too short, and if too long, a large boundary friction is generated, and a large loss of axial induction speed is generated. The front cylinder 5 is not too short, otherwise the inner duct 4 is attracted more strongly to influence the water flow entering the interlayer flow channel 7, and the length of the front cylinder 5 is one sixth to one fifth of the inner diameter.

In addition, in view of the substantially same considerations, the given length L is not excessively large, and it is only necessary to generate a venturi effect, that is, to satisfy the venturi structure, and it is apparent that too long a length increases the loss of the axial induction speed. Meanwhile, the structure of the venturi tube is considered, and the given length L is 0.4-0.7 times of the caliber D1 of the tail end of the inner channel 4.

In addition, the rotation of the vortex can be further weakened based on boundary friction so as to reduce the inclination of the ship body caused by the back flushing of the vortex, and the boundary friction can be further enhanced based on a conical structure, so that the back flushing caused by the vortex and the momentum generated by the impact of the vortex on the wall surface of the outer culvert 3 can be counteracted to a certain extent, and the inclination of the ship is reduced. Therefore, considering this factor, the tail end caliber D2 of the outer duct 3 is 0.75 to 0.92 times the tail end caliber D1 of the inner duct.

In the above description, it is mentioned that the inner duct 4 may be connected to the outer duct 3, and that the loss of the circumferential induction speed may be suppressed to some extent based on the arrangement of the inner and outer ducts. In the structure shown in fig. 1-3, rib plates 1 are all arranged in the circumferential direction of the interlayer flow channel 7, the rib plates can inhibit vortex flow, and based on the conical duct structure shown in fig. 1, in the through flow of water flow from the beginning to the end, the rib plates 1 and the inner duct and the outer duct form a closing-in structure, so that vortex flow generation is inhibited, and the suction effect is more obvious.

Therefore, the swirling ejection action of the swirling ejected from the inner channel 4 to the interlayer flow path 7 can be effectively suppressed.

Correspondingly, the centripetal end of the rib plate 1 is connected with the outer surface of the inner duct 4, and the centrifugal end of the rib plate 1 is connected with the inner surface of the outer duct 3.

Further, the rib 1 is a radial panel based on the inner duct 4.

Preferably, the rib 1 has six total ribs.

In addition, as shown in fig. 1 to 3, the outer surface of the outer duct 3 is circumferentially provided with dorsal fins, such as the fin 2 shown in fig. 1, which constitute radial panels of the outer duct 3. The fin plates 2 are mainly used for rectifying water flow outside the culvert, so that resistance is reduced.

Claims

1. A ship propeller, comprising:

an inner duct;

the propeller is arranged in the inner duct;

the inner duct and the outer duct are both conical ducts with the caliber of the head end being larger than that of the tail end;

the taper of the outer duct is larger than that of the inner duct;

the inner duct is coplanar with the head end of the outer duct;

the front cylinder is coaxial with the inner channel;

the length of the front cylinder is one sixth to one fifth of the inner diameter of the front cylinder;

the given length is 0.4-0.7 times of the caliber of the tail end of the inner channel;

the caliber of the tail end of the outer culvert is 0.75-0.92 times of that of the tail end of the inner culvert.

2. The ship propeller of claim 1, wherein rib plates are arranged in the circumferential direction of the interlayer flow channel;

3. The ship propeller of claim 2, wherein the rib plate is an inner duct-based radial panel;

the rib has six total ribs.

4. The ship propeller of claim 1, wherein the outer surface of the outer duct is circumferentially provided with dorsal fins, the dorsal fins forming radial panels of the outer duct.