Dual-ducted waterjet

Abstract

The application provides a double-diffuser water jet propeller, and belongs to the technical field of ship propulsion, and comprises a propelling body with a first end and a second end arranged oppositely, wherein the propelling body is further provided with a cavity, the propelling body is provided with a front inlet, a middle inlet, a tail outlet and a tail nozzle arranged in sequence from the first end to the second end, and the cavity is divided into a front flow channel and a rear flow channel; a power compartment is arranged at the first end; a front impeller is arranged in the front flow channel; a rear impeller is arranged in the rear flow channel; an outer shaft is arranged in the power compartment and the front impeller, and the outer shaft is used for driving the front impeller to rotate; an inner shaft is arranged in the power compartment and the rear impeller, and the inner shaft is used for driving the rear impeller to rotate; a first switch assembly is arranged in the power compartment, and the first switch assembly is used for opening or closing the front inlet; a second switch assembly is arranged in the middle inlet, and the second switch assembly is used for opening or closing the middle inlet; and a third switch assembly is arranged in the tail outlet, and the third switch assembly is used for opening or closing the tail outlet.

Description

Technical Field

[0001] This invention belongs to the field of ship propulsion technology, and specifically relates to a dual-duct waterjet propulsion device. Background Technology

[0002] Currently, waterjet propulsion is still in its development stage, and most of them adopt a single ducted propulsion structure and use only one power transmission device. With this design, waterjet propulsion is relatively ineffective in complex working environments. Summary of the Invention

[0003] In order to solve or improve at least one of the above-mentioned technical problems, the present invention aims to provide a dual-duct waterjet propulsion system.

[0004] To achieve the above objectives, the present invention provides a dual-duct waterjet propulsion device, comprising: a propulsion body having a first end and a second end disposed opposite to each other; the propulsion body further comprising a cavity; the propulsion body having a front inlet, a middle inlet, a tail outlet, and a tail nozzle arranged sequentially from the first end to the second end; the front inlet, the middle inlet, the tail outlet, and the tail nozzle all communicating with the cavity; the cavity being divided into a front flow channel and a rear flow channel; the front flow channel being a section within the cavity from the middle inlet to the front inlet; and the rear flow channel being a section within the cavity from the middle inlet to the tail nozzle; and a power chamber, disposed in... The first end comprises: a front impeller located in the front flow channel; a rear impeller located in the rear flow channel; an outer shaft passing through the power chamber and the front impeller, used to drive the front impeller to rotate; an inner shaft passing through the power chamber and the rear impeller, used to drive the rear impeller to rotate; a first switch assembly located in the power chamber, used to open or close the front inlet; a second switch assembly located at the middle inlet, used to open or close the middle inlet; and a third switch assembly located at the tail outlet, used to open or close the tail outlet.

[0005] According to the technical solution of the dual-duct waterjet propulsion device provided by the present invention, in the first aspect, the dual-duct waterjet propulsion device adopts a dual-duct propulsion structure and has two sets of power transmission devices. The first set drives the front impeller to rotate together through the outer shaft, and the second set drives the rear impeller to rotate together through the inner shaft. When one set of power transmission devices fails, the dual-duct waterjet propulsion device can still continue to move, and the operation reliability is high. In the second aspect, the first switch assembly is used to open or close the front inlet, the second switch assembly is used to open or close the middle inlet, and the third switch assembly is used to open or close the tail outlet. This design is beneficial to improving the flexibility of the dual-duct waterjet propulsion device and its adaptability under complex forward operating conditions. Due to the flexible and changeable propulsion method, the propulsion capacity of the dual-duct waterjet propulsion device can also be improved.

[0006] Specifically, the dual-duct waterjet propulsion system includes a propulsion body, a power chamber, a front impeller, a rear impeller, an outer shaft, an inner shaft, a first switch assembly, a second switch assembly, and a third switch assembly. The propulsion body has a first end and a second end positioned opposite each other. Optionally, the propulsion body has a first end and a second end positioned opposite each other along its length. Further, the propulsion body also has a cavity. The propulsion body is provided with a front inlet, a middle inlet, a tail outlet, and a tail nozzle arranged sequentially from the first end to the second end. The front inlet, middle inlet, tail outlet, and tail nozzle are all connected to the cavity. Optionally, the front inlet is located at the first end; the tail nozzle is located at the second end; the middle inlet and tail outlet are located between the first end and the second end, with the middle inlet closer to the first end and the tail outlet closer to the second end. Further, the cavity is divided into a front flow channel and a rear flow channel. The front flow channel is the section of the cavity from the middle inlet to the front inlet; the rear flow channel is the section of the cavity from the middle inlet to the tail nozzle.

[0007] Further, the power chamber is located at the first end of the propulsion body. The power chamber is fixed relative to the propulsion body. Further, the front impeller is located in the front flow channel; the rear impeller is located in the rear flow channel. Further, the outer shaft passes through the power chamber and the front impeller. The outer shaft is used to drive the front impeller to rotate. Optionally, the dual-duct waterjet propulsion device also includes a first driving member. The first driving member has a first drive shaft, which is connected to the outer shaft. The first driving member rotates the outer shaft through the first drive shaft, thereby driving the front impeller to rotate together. Optionally, the first drive shaft and the outer shaft are connected by a gear set. Optionally, the first drive shaft and the gear set have good precision, meshing, and transmission capacity, and the mounting point is protected by a good anti-vibration device to ensure structural integrity during speed changes. Optionally, the first driving member is located in the power chamber. Further, the inner shaft passes through the power chamber and the rear impeller. The inner shaft is used to drive the rear impeller to rotate. Optionally, the dual-duct waterjet propulsion device also includes a second driving member. The second drive unit has a second drive shaft connected to the inner shaft. The second drive unit rotates the inner shaft via the second drive shaft, thereby driving the rear impeller to rotate as well. Optionally, the second drive unit is located in the power compartment.

[0008] Optionally, the inner shaft passes through the outer shaft, allowing the inner shaft to rotate relative to the outer shaft. This design offers higher integration, improves space utilization, and optimizes spatial layout.

[0009] Further, a first switching assembly is located in the power compartment. The first switching assembly is used to open or close the front inlet. Optionally, the first switching assembly has a first station and a second station. When the first switching assembly is in the first station, it does not block the front inlet, and the front inlet is in an open state; when the first switching assembly is in the second station, it blocks the front inlet, and the front inlet is in a closed state. Optionally, the front inlet includes multiple first square openings, and these openings are arranged in a circumferential array at the first end of the propeller. Optionally, the first switching assembly includes a sliding valve mounted on the outside of the power compartment. Optionally, the first switching assembly also includes a slide rail structure located in the power compartment. The sliding valve can move relative to the front inlet via the slide rail structure to switch between the first station and the second station. Optionally, the sliding valve has a sealing layer to reduce fluid entry into the closed front inlet when the first switching assembly is in the second station. Optionally, the sealing layer is a layer structure formed of sealing material.

[0010] Further, a second switching assembly is located at the central inlet. The second switching assembly is used to open or close the central inlet. Optionally, the second switching assembly has a third station and a fourth station. When the second switching assembly is in the third station, it does not block the central inlet; at this time, the central inlet is open, and the second switching assembly is used to block the front and rear flow channels. When the second switching assembly is in the fourth station, it can block the central inlet; at this time, the central inlet is closed. Optionally, the central inlet includes multiple second square openings, and these openings are arranged in a circumferential array on the propeller. Optionally, the second switching assembly includes a first rotary valve installed at the central inlet. The second switching assembly also includes a first electromagnet installed on the front impeller and a second electromagnet installed at the central inlet. The first rotary valve can be switched between the third and fourth stations via the two electromagnets (the first and second electromagnets). Optionally, the first electromagnet, the second electromagnet, and the first rotary valve are all provided with a sealing layer to reduce fluid flow in the closed state. Optionally, the sealing layer is a layer structure formed of sealing material.

[0011] Further, a third switching assembly is located at the tail outlet. The third switching assembly is used to open or close the tail outlet. Optionally, the third switching assembly has a fifth position and a sixth position. When the third switching assembly is in the fifth position, it does not block the tail outlet; at this time, the tail outlet is open, and the third switching assembly is used to block the rear flow channel from the tail nozzle. When the third switching assembly is in the sixth position, it can block the tail outlet; at this time, the tail outlet is closed. Optionally, the tail outlet includes multiple third-sided shaped openings, and these openings are arranged in a circumferential array on the propeller. Optionally, the third switching assembly includes a second rotary valve installed at the tail outlet. Optionally, the third switching assembly also includes a third electromagnet installed on the rear impeller and a fourth electromagnet installed at the tail outlet. The second rotary valve can be switched between the fifth and sixth positions via the two electromagnets (the third and fourth electromagnets). Optionally, the third electromagnet, the fourth electromagnet, and the second rotary valve are all provided with sealing layers to reduce fluid flow in the closed state. Alternatively, the sealing layer is a layer structure formed of sealing material.

[0012] Optionally, the dual-duct waterjet propulsion unit also includes an electronic control device. The electronic control device is located in the power compartment. The first switch assembly, second switch assembly, third switch assembly, first drive component, and second drive component are all connected to the electronic control device. Optionally, the dual-duct waterjet propulsion unit has a first operating mode, a second operating mode, a third operating mode, and a fourth operating mode. In the first operating mode, the propulsion unit's speed is not less than a first threshold, and the propulsion unit is in a high-speed state. In the second operating mode, the propulsion unit's speed is not less than a second threshold and less than the first threshold, and the propulsion unit is in a medium-high speed state. In the third operating mode, the propulsion unit's speed is not less than a third threshold and less than the second threshold, and the propulsion unit is in a medium-speed state. In the fourth operating mode, the propulsion unit's speed is less than the third threshold, and the propulsion unit is in a low-speed state. The first threshold is greater than the second threshold, and the second threshold is greater than the third threshold.

[0013] Optionally, the outer casing of the propeller is coated with an anti-corrosion coating. The outer casing, front impeller, rear impeller, sliding valve of the first switching assembly, first rotary valve of the second switching assembly, and second rotary valve of the third switching assembly are made of composite materials to ensure strength and weight balance, offering the advantage of low cost. Optionally, both the outer and inner shafts are made of high-strength materials to ensure structural integrity when changing rotational speed. Optionally, the sliding mechanism of the first switching assembly is magnetically driven. Optionally, the sliding valve of the first switching assembly, the first rotary valve of the second switching assembly, and the second rotary valve of the third switching assembly are equipped with an anti-corrosion coating. Optionally, the sealing layer or other sealing structure in the dual-duct waterjet propeller uses waterproof rubber rings, providing excellent waterproof performance.

[0014] In the technical solution defined by this invention, firstly, the dual-duct waterjet propulsion device adopts a dual-duct propulsion structure and has two sets of power transmission devices. The first set drives the front impeller to rotate through the outer shaft, and the second set drives the rear impeller to rotate through the inner shaft. When one set of power transmission devices fails, the dual-duct waterjet propulsion device can still continue to move, resulting in high operational reliability. Secondly, the first switch assembly is used to open or close the front inlet, the second switch assembly is used to open or close the middle inlet, and the third switch assembly is used to open or close the tail outlet. This design improves the flexibility of the dual-duct waterjet propulsion device and its adaptability under complex forward operating conditions. Due to the flexible and varied propulsion methods, the propulsion capacity of the dual-duct waterjet propulsion device can also be improved.

[0015] In addition, the technical solution provided by the present invention may also have the following additional technical features:

[0016] In some technical solutions, the first switch assembly may optionally have a first station and a second station. When the first switch assembly is in the first station, the front inlet is in the open state; when the first switch assembly is in the second station, the front inlet is in the closed state.

[0017] In this technical solution, when the first switching assembly is in the first position, it does not block the front inlet, and the front inlet is in an open state. When the first switching assembly is in the second position, it blocks the front inlet, and the front inlet is in a closed state. Optionally, the front inlet includes multiple first square openings, and these openings are arranged in a circumferential array at the first end of the propulsion body. Optionally, the first switching assembly includes a sliding valve mounted on the outside of the power compartment. Optionally, the first switching assembly also includes a slide rail structure located in the power compartment. The sliding valve can move relative to the front inlet via the slide rail structure to switch between the first and second positions. Optionally, the sliding valve has a sealing layer to reduce fluid entry into the closed front inlet when the first switching assembly is in the second position. Optionally, the sealing layer is a layer structure formed of sealing material.

[0018] In some technical solutions, the second switch assembly may optionally have a third station and a fourth station. When the second switch assembly is in the third station, the middle inlet is in the open state, and the second switch assembly is used to block the front flow channel and the rear flow channel. When the second switch assembly is in the fourth station, the middle inlet is in the closed state.

[0019] In this technical solution, when the second switching assembly is in the third position, it does not block the central inlet, which is in an open state, and the second switching assembly is used to block the front and rear flow channels. When the second switching assembly is in the fourth position, it blocks the central inlet, which is in a closed state. Optionally, the central inlet includes multiple second square openings, which are arranged in a circumferential array on the propulsion body. Optionally, the second switching assembly includes a first rotary valve installed at the central inlet. The second switching assembly also includes a first electromagnet installed on the front impeller and a second electromagnet installed at the central inlet. The first rotary valve can be switched between the third and fourth positions via the two electromagnets (the first and second electromagnets). Optionally, the first electromagnet, the second electromagnet, and the first rotary valve are all provided with a sealing layer to reduce fluid flow in the closed state. Optionally, the sealing layer is a layer structure formed of sealing material.

[0020] In some technical solutions, the third switch assembly optionally has a fifth station and a sixth station. When the third switch assembly is in the fifth station, the tail outlet is in the open state, and the third switch assembly is used to block the rear flow channel from the tail nozzle. When the third switch assembly is in the sixth station, the tail outlet is in the closed state.

[0021] In this technical solution, when the third switching assembly is in the fifth position, it does not block the tail outlet, which is in an open state. The third switching assembly is used to block the rear flow channel from the tail nozzle. When the third switching assembly is in the sixth position, it blocks the tail outlet, which is in a closed state. Optionally, the tail outlet includes multiple third-sided shaped openings arranged in a circumferential array on the propulsion body. Optionally, the third switching assembly includes a second rotary valve installed at the tail outlet. Optionally, the third switching assembly also includes a third electromagnet installed on the rear impeller and a fourth electromagnet installed at the tail outlet. The second rotary valve can be switched between the fifth and sixth positions via the two electromagnets (the third and fourth electromagnets). Optionally, the third electromagnet, the fourth electromagnet, and the second rotary valve are all provided with sealing layers to reduce fluid flow in the closed state. Optionally, the sealing layer is a layer structure formed of sealing material.

[0022] In some technical solutions, the dual-duct waterjet propulsion system may optionally include: an electronic control device located in the power compartment, the electronic control device being electrically connected to a first switch assembly, an electronic control device being electrically connected to a second switch assembly, and an electronic control device being electrically connected to a third switch assembly.

[0023] In this technical solution, the dual-duct waterjet propulsion unit also includes an electronic control device. Specifically, the electronic control device is located in the power compartment. The electronic control device is electrically connected to the first switching assembly; the electronic control device is electrically connected to the second switching assembly; and the electronic control device is electrically connected to the third switching assembly. Based on the operating mode or travel speed of the dual-duct waterjet propulsion unit, the electronic control device controls the first switching assembly to be in the first or second position; based on the operating mode or travel speed of the dual-duct waterjet propulsion unit, the electronic control device controls the second switching assembly to be in the third or fourth position; and based on the operating mode or travel speed of the dual-duct waterjet propulsion unit, the electronic control device controls the third switching assembly to be in the fifth or sixth position.

[0024] In some technical solutions, the dual-duct waterjet propulsion system may optionally include: a first drive unit connected to the outer shaft and electrically connected to an electronic control device; and / or a second drive unit connected to the inner shaft and electrically connected to an electronic control device.

[0025] In this technical solution, the dual-duct waterjet propulsion unit also includes a first driving component. Specifically, the first driving component is connected to the outer shaft and is electrically connected to an electronic control device. The electronic control device controls whether the first driving component operates according to the operating mode or travel speed of the dual-duct waterjet propulsion unit, thereby controlling whether the front impeller rotates or not.

[0026] Furthermore, the dual-duct waterjet propulsion system also includes a second drive unit. Specifically, the second drive unit is connected to the inner shaft and is electrically connected to the electronic control device. The electronic control device controls whether the second drive unit operates according to the operating mode or travel speed of the dual-duct waterjet propulsion system, thereby controlling whether the rear impeller rotates or not.

[0027] It is worth noting that the dual-duct waterjet propulsion system may include only one of the first and second drive components, or it may include both the first and second drive components.

[0028] In some technical solutions, the inner shaft may optionally pass through the outer shaft, and the inner shaft may rotate relative to the outer shaft.

[0029] In this technical solution, the design approach has a higher degree of integration, which is conducive to improving space utilization and optimizing space layout.

[0030] In some technical solutions, optionally, the dual-duct waterjet propulsion system has a first operating mode and a travel speed not less than a first threshold. The outer shaft can drive the front impeller to rotate and the inner shaft can drive the rear impeller to rotate. The front inlet is in an open state, while the middle inlet and the tail outlet are both in a closed state.

[0031] In this technical solution, when the dual-duct waterjet propulsion system is in its first operating mode, its travel speed is not less than a first threshold, at which point the dual-duct waterjet propulsion system is in a high-speed state. In this state, the electronic control device controls both the outer and inner shafts to be operational; the outer shaft drives the front impeller to rotate, and the inner shaft drives the rear impeller to rotate. The electronic control device controls the first switch assembly to the first position, with the front inlet in the open state. The electronic control device controls the second switch assembly to the fourth position, with the middle inlet in the closed state. The electronic control device controls the third switch assembly to the sixth position, with both tail outlets in the closed state.

[0032] In some technical solutions, optionally, the dual-duct waterjet propulsion system has a second operating mode, wherein the traveling speed of the dual-duct waterjet propulsion system is not less than a second threshold and less than a first threshold, the second threshold is less than the first threshold, the outer shaft can drive the front impeller to rotate and the inner shaft can drive the rear impeller to rotate, the front inlet and the tail outlet are both in the open state, and the middle inlet is in the closed state.

[0033] In this technical solution, when the dual-duct waterjet propulsion system is in its second operating mode, its travel speed is not less than a second threshold and less than a first threshold; at this time, the dual-duct waterjet propulsion system is in a medium-to-high speed state. In this state, the electronic control device controls both the outer and inner shafts to be in operation; the outer shaft drives the front impeller to rotate, and the inner shaft drives the rear impeller to rotate. The electronic control device controls the first switch assembly to the first position, with the front inlet in the open state. The electronic control device controls the second switch assembly to the fourth position, with the middle inlet in the closed state. The electronic control device controls the third switch assembly to the fifth position, with both the tail outlets in the open state.

[0034] In some technical solutions, optionally, the dual-duct waterjet propulsion system has a third operating mode, in which the traveling speed of the dual-duct waterjet propulsion system is not less than a third threshold and less than a second threshold. When the third threshold is less than the second threshold, the outer shaft does not rotate, the inner shaft can drive the rear impeller to rotate, the front inlet and the tail outlet are both in a closed state, and the middle inlet is in an open state.

[0035] In this technical solution, when the dual-duct waterjet propulsion system is in its third operating mode, its travel speed is not less than the third threshold and less than the second threshold; at this time, the dual-duct waterjet propulsion system is in a medium-speed state. In this state, the electronic control device controls the outer shaft to be in a non-operating state, while the inner shaft is in an operating state. The outer shaft does not rotate, but the inner shaft can drive the rear impeller to rotate. The electronic control device controls the first switch assembly to the second position, with the front inlet in a closed state. The electronic control device controls the second switch assembly to the third position, with the middle inlet in an open state. The electronic control device controls the third switch assembly to the sixth position, with both the tail outlets in a closed state.

[0036] In some technical solutions, optionally, the dual-duct waterjet propulsion system has a fourth operating mode, in which the traveling speed of the dual-duct waterjet propulsion system is less than a third threshold, the outer shaft does not rotate, the inner shaft can drive the rear impeller to rotate, the front outlet is in a closed state, and the middle inlet and the tail outlet are both in an open state.

[0037] In this technical solution, when the dual-duct waterjet propulsion system is in its fourth operating mode, its travel speed is less than the third threshold, at which point the dual-duct waterjet propulsion system is in a low-speed state. In this state, the electronic control device controls the outer shaft to be inactive, while the inner shaft is inactive. The outer shaft does not rotate, but the inner shaft can drive the rear impeller to rotate. The electronic control device controls the first switch assembly to the second position, with the front inlet in the closed state. The electronic control device controls the second switch assembly to the third position, with the middle inlet in the open state. The electronic control device controls the third switch assembly to the fifth position, with both the tail outlets in the open state. Attached Figure Description

[0038] Figure 1A first schematic diagram of a dual-duct waterjet propulsion system according to an embodiment of the present invention is shown;

[0039] Figure 2 A schematic diagram of a dual-duct waterjet propulsion system in a first operating mode according to an embodiment of the present invention is shown.

[0040] Figure 3 A schematic diagram of a dual-duct waterjet propulsion system in a second operating mode according to an embodiment of the present invention is shown.

[0041] Figure 4 A schematic diagram of a dual-duct waterjet propulsion system in a third operating mode according to an embodiment of the present invention is shown.

[0042] Figure 5 A schematic diagram of a dual-duct waterjet propulsion system in a fourth operating mode according to an embodiment of the present invention is shown.

[0043] Figure 6 A second schematic diagram of a dual-duct waterjet propulsion system according to an embodiment of the present invention is shown;

[0044] Figure 7 A schematic diagram of a tail nozzle according to an embodiment of the present invention is shown.

[0045] in, Figures 1 to 7 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0046] 100: Dual-duct waterjet propulsion unit; 110: Propulsion body; 111: First end; 112: Second end; 113: Cavity; 1131: Front flow channel; 1132: Rear flow channel; 114: Front inlet; 115: Middle inlet; 116: Tail outlet; 117: Tail nozzle; 1171: Diverting port; 120: Power compartment; 131: Front impeller; 132: Rear impeller; 141: Outer shaft; 142: Inner shaft; 151: First switch assembly; 152: Second switch assembly; 153: Third switch assembly; 160: Electronic control device; 171: First drive component; 1711: First drive shaft; 172: Second drive component; 173: Gear set. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0048] In one embodiment of the invention, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the dual-duct waterjet propulsion system 100 includes a propulsion body 110, a power chamber 120, a front impeller 131, a rear impeller 132, an outer shaft 141, an inner shaft 142, a first switch assembly 151, a second switch assembly 152, and a third switch assembly 153. The propulsion body 110 has a first end 111 and a second end 112 disposed opposite to each other. Optionally, the propulsion body 110 has a first end 111 and a second end 112 disposed opposite to each other along its length. Further, the propulsion body 110 also has a cavity 113. The propulsion body 110 is provided with a front inlet 114, a middle inlet 115, a tail outlet 116, and a tail nozzle 117 arranged sequentially from the first end 111 to the second end 112. The front inlet 114, the middle inlet 115, the tail outlet 116, and the tail nozzle 117 are all connected to the cavity 113. Optionally, the front inlet 114 is located at the first end 111; the tail nozzle 117 is located at the second end 112; the middle inlet 115 and the tail outlet 116 are located between the first end 111 and the second end 112, with the middle inlet 115 closer to the first end 111 and the tail outlet 116 closer to the second end 112. Further, the cavity 113 is divided into a front flow channel 1131 and a rear flow channel 1132. The front flow channel 1131 is the section of the cavity 113 from the middle inlet 115 to the front inlet 114; the rear flow channel 1132 is the section of the cavity 113 from the middle inlet 115 to the tail nozzle 117.

[0049] Furthermore, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, the power chamber 120 is located at the first end 111 of the propulsion body 110. The power chamber 120 is fixed relative to the propulsion body 110. Further, a front impeller 131 is located in the front flow channel 1131; a rear impeller 132 is located in the rear flow channel 1132. Further, an outer shaft 141 passes through the power chamber 120 and the front impeller 131. The outer shaft 141 is used to drive the front impeller 131 to rotate. Optionally, the dual-duct waterjet propulsion device 100 also includes a first drive member 171. The first drive member 171 has a first drive shaft 1711, which is connected to the outer shaft 141. The first drive member 171 causes the outer shaft 141 to rotate via the first drive shaft 1711, thereby driving the front impeller 131 to rotate together. Optionally, the first drive shaft 1711 and the outer shaft 141 are connected by a gear set 173. Optionally, the first drive shaft 1711 and the gear set 173 have good precision, meshing, and transmission capacity, and the mounting point is protected by a good anti-vibration device to ensure structural integrity during gear shifting. Optionally, the first drive member 171 is located in the power chamber 120. Further, the inner shaft 142 passes through the power chamber 120 and the rear impeller 132. The inner shaft 142 is used to drive the rear impeller 132 to rotate. Optionally, the dual-duct waterjet propulsion unit 100 also includes a second drive member 172. The second drive member 172 has a second drive shaft, which is connected to the inner shaft 142. The second drive member 172 rotates the inner shaft 142 through the second drive shaft, thereby driving the rear impeller 132 to rotate together. Optionally, the second drive member 172 is located in the power chamber 120.

[0050] Optionally, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the inner shaft 142 passes through the outer shaft 141, and the inner shaft 142 can rotate relative to the outer shaft 141. This design method has a higher degree of integration, which is conducive to improving space utilization and optimizing space layout.

[0051] Furthermore, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, a first switch assembly 151 is disposed in the power compartment 120. The first switch assembly 151 is used to open or close the front inlet 114. Optionally, the first switch assembly 151 has a first station and a second station. When the first switch assembly 151 is in the first station, the first switch assembly 151 does not block the front inlet 114, and the front inlet 114 is in an open state; when the first switch assembly 151 is in the second station, the first switch assembly 151 can block the front inlet 114, and the front inlet 114 is in a closed state. Optionally, the front inlet 114 includes a plurality of first square openings, and the plurality of first square openings are circumferentially arrayed on the first end 111 of the propeller body 110. Optionally, the first switch assembly 151 includes a sliding valve mounted on the outside of the power compartment 120. Optionally, the first switch assembly 151 also includes a slide rail structure disposed in the power compartment 120. The sliding valve can move relative to the front inlet 114 through the slide rail structure to switch between the first station and the second station. Optionally, the sliding valve is provided with a sealing layer to reduce fluid entry into the closed front inlet 114 when the first switching assembly 151 is in the second position. Optionally, the sealing layer is a layer structure formed of sealing material.

[0052] Furthermore, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, a second switch assembly 152 is located at the central inlet 115. The second switch assembly 152 is used to open or close the central inlet 115. Optionally, the second switch assembly 152 has a third station and a fourth station. When the second switch assembly 152 is in the third station, it does not block the central inlet 115, and the central inlet 115 is in the open state, whereby the second switch assembly 152 blocks the front flow channel 1131 and the rear flow channel 1132. When the second switch assembly 152 is in the fourth station, it blocks the central inlet 115, whereby the central inlet 115 is in the closed state. Optionally, the central inlet 115 includes a plurality of second square openings, and the plurality of second square openings are circumferentially arrayed on the propeller body 110. Optionally, the second switch assembly 152 includes a first rotary valve installed in the central inlet 115. The second switch assembly 152 also includes a first electromagnet installed on the front impeller 131 and a second electromagnet installed in the central inlet 115. The first rotary valve can be switched between the third and fourth positions via two electromagnets (the first electromagnet and the second electromagnet). Optionally, the first electromagnet, the second electromagnet, and the first rotary valve are all provided with a sealing layer to reduce fluid passage in the closed state. Optionally, the sealing layer is a layer structure formed of sealing material.

[0053] Furthermore, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, a third switch assembly 153 is located at the tail outlet 116. The third switch assembly 153 is used to open or close the tail outlet 116. Optionally, the third switch assembly 153 has a fifth position and a sixth position. When the third switch assembly 153 is in the fifth position, it does not block the tail outlet 116, and the tail outlet 116 is in the open state. The third switch assembly 153 is used to block the rear flow channel 1132 from the tail nozzle 117. When the third switch assembly 153 is in the sixth position, it can block the tail outlet 116, and the tail outlet 116 is in the closed state. Optionally, the tail outlet 116 includes multiple third-party shaped openings, and these openings are arranged in a circumferential array on the propulsion body 110. Optionally, the third switch assembly 153 includes a second rotary valve installed at the tail outlet 116. Optionally, the third switching assembly 153 further includes a third electromagnet mounted on the rear impeller 132 and a fourth electromagnet mounted on the tail outlet 116. The second rotary valve can be switched between a fifth position and a sixth position via the two electromagnets (the third and fourth electromagnets). Optionally, the third and fourth electromagnets, as well as the second rotary valve, are provided with a sealing layer to reduce fluid flow in the closed state. Optionally, the sealing layer is a layer structure formed of sealing material.

[0054] Optionally, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6As shown, the dual-duct waterjet propulsion unit 100 also includes an electronic control device 160. The electronic control device 160 is located in the power compartment 120. The first switch assembly 151, the second switch assembly 152, the third switch assembly 153, the first drive member 171, and the second drive member 172 are all connected to the electronic control device 160. Optionally, the dual-duct waterjet propulsion unit 100 has a first operating mode, a second operating mode, a third operating mode, and a fourth operating mode. When the dual-duct waterjet propeller 100 is in the first operating mode, its travel speed is not less than a first threshold, and the dual-duct waterjet propeller 100 is in a high-speed state. When the dual-duct waterjet propeller 100 is in the second operating mode, its travel speed is not less than a second threshold and less than a first threshold, and the dual-duct waterjet propeller 100 is in a medium-high speed state. When the dual-duct waterjet propeller 100 is in the third operating mode, its travel speed is not less than a third threshold and less than a second threshold, and the dual-duct waterjet propeller 100 is in a medium speed state. When the dual-duct waterjet propeller 100 is in the fourth operating mode, its travel speed is less than a third threshold, and the dual-duct waterjet propeller 100 is in a low-speed state. The first threshold is greater than the second threshold, and the second threshold is greater than the third threshold. Optionally, the electronic control device 160 includes an electronic control unit (ECU) and multiple sensors. The multiple sensors are respectively located on the first switch assembly 151, the second switch assembly 152, the third switch assembly 153, the outer shaft 141, and the inner shaft 142. Multiple sensors are electrically connected to the electronic control unit (ECU). The ECU acquires main control signals and correction signals through these sensors. Based on these signals, the ECU controls the first switch assembly 151, the second switch assembly 152, the third switch assembly 153, the outer shaft 141, and the inner shaft 142.

[0055] Optionally, the outer casing of the propeller 110 is coated with an anti-corrosion coating. The outer casing of the propeller 110, the front impeller 131, the rear impeller 132, the sliding valve of the first switching assembly 151, the first rotary valve of the second switching assembly 152, and the second rotary valve of the third switching assembly 153 are made of composite materials to ensure a balance of strength and weight, offering the advantage of low cost. Optionally, both the outer shaft 141 and the inner shaft 142 are made of high-strength materials to ensure structural integrity when changing rotational speed. Optionally, the sliding mechanism of the first switching assembly 151 is magnetically driven. Optionally, the sliding valve of the first switching assembly 151, the first rotary valve of the second switching assembly 152, and the second rotary valve of the third switching assembly 153 are equipped with an anti-corrosion coating. Optionally, the sealing layer or other sealing structure in the dual-duct waterjet propeller 100 uses waterproof rubber rings, providing excellent waterproof performance.

[0056] In the technical solution defined by this invention, firstly, the dual-duct waterjet propulsion unit 100 adopts a dual-duct propulsion structure and has two sets of power transmission devices. The first set drives the front impeller 131 to rotate through the outer shaft 141, and the second set drives the rear impeller 132 to rotate through the inner shaft 142. When one set of power transmission devices fails, the dual-duct waterjet propulsion unit 100 can still continue to move, and its operational reliability is high. Secondly, the first switch assembly 151 is used to open or close the front inlet 114, the second switch assembly 152 is used to open or close the middle inlet 115, and the third switch assembly 153 is used to open or close the tail outlet 116. This design is beneficial to improving the flexibility of the dual-duct waterjet propulsion unit 100 and its adaptability under complex forward operating conditions. Due to the flexible and varied propulsion method, the propulsion capacity of the dual-duct waterjet propulsion unit 100 can also be improved.

[0057] In some embodiments, optionally, when the first switching assembly 151 is in the first position, the first switching assembly 151 does not block the front inlet 114, and the front inlet 114 is in an open state; when the first switching assembly 151 is in the second position, the first switching assembly 151 can block the front inlet 114, and the front inlet 114 is in a closed state. Optionally, the front inlet 114 includes a plurality of first square openings, and the plurality of first square openings are circumferentially arrayed on the first end 111 of the propeller body 110. Optionally, the first switching assembly 151 includes a sliding valve mounted on the outside of the power chamber 120. Optionally, the first switching assembly 151 also includes a slide rail structure disposed in the power chamber 120. The sliding valve can move relative to the front inlet 114 via the slide rail structure to switch between the first position and the second position. Optionally, the sliding valve is provided with a sealing layer to reduce fluid entry into the closed front inlet 114 when the first switching assembly 151 is in the second position. Optionally, the sealing layer is a layer structure formed of sealing material.

[0058] In some embodiments, optionally, when the second switching assembly 152 is in the third position, the second switching assembly 152 does not block the middle inlet 115, at which time the middle inlet 115 is in the open state, and the second switching assembly 152 is used to block the front flow channel 1131 and the rear flow channel 1132; when the second switching assembly 152 is in the fourth position, the second switching assembly 152 can block the middle inlet 115, at which time the middle inlet 115 is in the closed state. Optionally, the middle inlet 115 includes a plurality of second square openings, and the plurality of second square openings are distributed in a circumferential array on the propeller 110. Optionally, the second switching assembly 152 includes a first rotary valve installed in the middle inlet 115. The second switching assembly 152 also includes a first electromagnet installed on the front impeller 131 and a second electromagnet installed in the middle inlet 115. The first rotary valve can be switched between the third position and the fourth position by means of the two electromagnets (the first electromagnet and the second electromagnet). Optionally, the first electromagnet, the second electromagnet, and the first rotary valve are all provided with a sealing layer to reduce fluid flow in the closed state. Optionally, the sealing layer is a layer structure formed of sealing material.

[0059] In some embodiments, optionally, when the third switching assembly 153 is in the fifth position, the third switching assembly 153 does not block the tail outlet 116, at which time the tail outlet 116 is in the open state, and the third switching assembly 153 is used to block the rear flow channel 1132 and the tail nozzle 117; when the third switching assembly 153 is in the sixth position, the third switching assembly 153 can block the tail outlet 116, at which time the tail outlet 116 is in the closed state. Optionally, the tail outlet 116 includes a plurality of third-shaped openings, and the plurality of third-shaped openings are distributed in a circumferential array on the propeller 110. Optionally, the third switching assembly 153 includes a second rotary valve installed on the tail outlet 116. Optionally, the third switching assembly 153 also includes a third electromagnet installed on the rear impeller 132 and a fourth electromagnet installed on the tail outlet 116. The second rotary valve can be switched between the fifth position and the sixth position by means of the two electromagnets (the third electromagnet and the fourth electromagnet). Optionally, the third electromagnet, the fourth electromagnet, and the second rotary valve are all provided with a sealing layer to reduce fluid flow in the closed state. Optionally, the sealing layer is a layer structure formed of sealing material.

[0060] In some embodiments, the dual-duct waterjet propulsion unit 100 may optionally include an electronic control device 160. Specifically, the electronic control device 160 is located in the power compartment 120. The electronic control device 160 is electrically connected to the first switch assembly 151; the electronic control device 160 is electrically connected to the second switch assembly 152; and the electronic control device 160 is electrically connected to the third switch assembly 153. The electronic control device 160 controls the first switch assembly 151 to be in a first position or a second position according to the operating mode or travel speed of the dual-duct waterjet propulsion unit 100; the electronic control device 160 controls the second switch assembly 152 to be in a third position or a fourth position according to the operating mode or travel speed of the dual-duct waterjet propulsion unit 100; and the electronic control device 160 controls the third switch assembly 153 to be in a fifth position or a sixth position according to the operating mode or travel speed of the dual-duct waterjet propulsion unit 100.

[0061] In some embodiments, optionally, such as Figure 6 As shown, the dual-duct waterjet propulsion unit 100 also includes a first drive member 171. Specifically, the first drive member 171 is connected to the outer shaft 141 and is electrically connected to the electronic control device 160. The electronic control device 160 controls whether the first drive member 171 is working according to the working mode or travel speed of the dual-duct waterjet propulsion unit 100, thereby controlling whether the front impeller 131 rotates or not.

[0062] In some embodiments, optionally, such as Figure 6 As shown, the dual-duct waterjet propulsion unit 100 also includes a second drive member 172. Specifically, the second drive member 172 is connected to the inner shaft 142 and is electrically connected to the electronic control device 160. The electronic control device 160 controls whether the second drive member 172 operates according to the operating mode or travel speed of the dual-duct waterjet propulsion unit 100, thereby controlling whether the rear impeller 132 rotates or not.

[0063] In some embodiments, the inner shaft 142 may optionally pass through the outer shaft 141, and the inner shaft 142 may rotate relative to the outer shaft 141. This design offers higher integration, improves space utilization, and optimizes spatial layout.

[0064] In some embodiments, optionally, such as Figure 2As shown, when the dual-duct waterjet propulsion unit 100 is in the first operating mode, its travel speed is not less than a first threshold, at which point the dual-duct waterjet propulsion unit 100 is in a high-speed state. In this state, the electronic control device 160 controls both the outer shaft 141 and the inner shaft 142 to be in working condition. The outer shaft 141 can drive the front impeller 131 to rotate, and the inner shaft 142 can drive the rear impeller 132 to rotate. The electronic control device 160 controls the first switch assembly 151 to be in the first position, and the front inlet 114 is in the open state. The electronic control device 160 controls the second switch assembly 152 to be in the fourth position, and the middle inlet 115 is in the closed state. The electronic control device 160 controls the third switch assembly 153 to be in the sixth position, and both the tail outlet 116 are in the closed state.

[0065] In some embodiments, optionally, such as Figure 3 As shown, when the dual-duct waterjet propulsion unit 100 is in the second operating mode, its travel speed is not less than the second threshold and less than the first threshold. At this time, the dual-duct waterjet propulsion unit 100 is in a medium-to-high speed state. In this state, the electronic control device 160 controls both the outer shaft 141 and the inner shaft 142 to be in operation. The outer shaft 141 can drive the front impeller 131 to rotate, and the inner shaft 142 can drive the rear impeller 132 to rotate. The electronic control device 160 controls the first switch assembly 151 to be in the first position, with the front inlet 114 in the open state. The electronic control device 160 controls the second switch assembly 152 to be in the fourth position, with the middle inlet 115 in the closed state. The electronic control device 160 controls the third switch assembly 153 to be in the fifth position, with both the tail outlet 116 in the open state.

[0066] In some embodiments, optionally, such as Figure 4 As shown, when the dual-duct waterjet propulsion unit 100 is in the third operating mode, its travel speed is not less than the third threshold and less than the second threshold. At this time, the dual-duct waterjet propulsion unit 100 is in a medium-speed state. In this state, the electronic control device 160 controls the outer shaft 141 to be in a non-operating state and the inner shaft 142 to be in an operating state. The outer shaft 141 does not rotate, while the inner shaft 142 can drive the rear impeller 132 to rotate. The electronic control device 160 controls the first switch assembly 151 to be in the second position, and the front inlet 114 is in a closed state. The electronic control device 160 controls the second switch assembly 152 to be in the third position, and the middle inlet 115 is in a closed state. The electronic control device 160 controls the third switch assembly 153 to be in the sixth position, and both the tail outlet 116 and the tail outlet 116 are in a closed state.

[0067] In some embodiments, optionally, such as Figure 5As shown, when the dual-duct waterjet propulsion unit 100 is in the fourth operating mode, its travel speed is less than the third threshold, and the dual-duct waterjet propulsion unit 100 is in a low-speed state. In this state, the electronic control device 160 controls the outer shaft 141 to be in a non-operating state and the inner shaft 142 to be in an operating state. The outer shaft 141 does not rotate, while the inner shaft 142 can drive the rear impeller 132 to rotate. The electronic control device 160 controls the first switch assembly 151 to be in the second position, and the front inlet 114 is in a closed state. The electronic control device 160 controls the second switch assembly 152 to be in the third position, and the middle inlet 115 is in a closed state. The electronic control device 160 controls the third switch assembly 153 to be in the fifth position, and both the tail outlet 116 are in a closed state.

[0068] In some embodiments, optionally, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 7 As shown, the tail nozzle 117 has multiple rows of equidistant and uniformly arranged rotary opening and closing steering ports 1171 in multiple directions. Optionally, the multiple rows of rotary opening and closing steering ports 1171 are opened and closed by rotating vanes. Optionally, the rotating vanes are electrically connected to the electronic control device 160. The electronic control device 160 controls the rotating vanes. When a steering port 1171 in one direction is open, the dual-duct waterjet propeller 100 turns in that direction. The steering amplitude is controlled by controlling the number of rows of opening and closing steering ports 1171.

[0069] Optionally, the dual-duct waterjet propulsion unit 100 has a steering state. The rotating vane at the tail nozzle 117 is controlled by the electronic control device 160 to change the opening and closing of the steering port 1171, thus achieving steering. When the dual-duct waterjet propulsion unit 100 moves to the left, the rotating vane at the left steering port 1171 opens, and water is ejected to the left through pressure difference. The tail of the dual-duct waterjet propulsion unit 100 shifts to the right, and the forward direction becomes left. The steering amplitude can be changed by altering the number of opening and closing rows of the steering port 1171.

[0070] Optionally, the dual-duct waterjet propeller 100 has a lifting and lowering state. The rotating vane at the tail nozzle 117 is controlled by the electronic control device 160 to change the opening and closing of the steering port 1171, thus achieving steering. When the dual-duct waterjet propeller 100 rises, the rotating vane at the upper steering port 1171 opens, and water is sprayed upwards through the pressure difference. At this time, the tail of the dual-duct waterjet propeller 100 shifts downwards, and the forward direction is diagonally upwards, achieving lifting. Conversely, the lower nozzle opens and the propeller moves downwards. The lifting and lowering rate can be changed by controlling the number of opening and closing rows of the steering port 1171.

[0071] In the technical solution defined by this invention, firstly, the dual-duct waterjet propulsion unit 100 adopts a dual-duct propulsion structure and has two sets of power transmission devices. The first set drives the front impeller 131 to rotate via the outer shaft 141, and the second set drives the rear impeller 132 to rotate via the inner shaft 142. Even if one set of power transmission devices fails, the dual-duct waterjet propulsion unit 100 can still continue to move, exhibiting high operational reliability. Secondly, the first switch assembly 151 is used to open or close the front inlet 114, and the second switch assembly 152 is used to open... Alternatively, the middle inlet 115 can be closed, and the third switch assembly 153 is used to open or close the tail outlet 116. This design improves the flexibility of the dual-duct water jet thruster 100 and its adaptability under complex forward operating conditions. Due to the flexible and varied propulsion methods, the propulsion capacity of the dual-duct water jet thruster 100 can also be improved. Thirdly, the dual-duct water jet thruster 100 has a new steering design. Through the tail nozzle 117 and the multi-row rotary opening and closing steering port 1171, the steering amplitude or lifting rate can be effectively controlled, which helps to save costs.

[0072] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dual-duct waterjet propulsion system, characterized in that, include: The propulsion body (110) has a first end (111) and a second end (112) disposed opposite to each other. The propulsion body (110) also has a cavity (113). The propulsion body (110) is provided with a front inlet (114), a middle inlet (115), a tail outlet (116), and a tail nozzle (117) arranged sequentially from the first end (111) to the second end (112). The front inlet (114), the middle inlet (115), and the tail outlet (116) are... Both the inlet (116) and the tail nozzle (117) are connected to the cavity (113). The cavity (113) is divided into a front flow channel (1131) and a rear flow channel (1132). The front flow channel (1131) is a section in the cavity (113) from the middle inlet (115) to the front inlet (114). The rear flow channel (1132) is a section in the cavity (113) from the middle inlet (115) to the tail nozzle (117). The power compartment (120) is located at the first end (111). A front impeller (131) is provided in the front flow channel (1131). A rear impeller (132) is provided in the rear flow channel (1132). An outer shaft (141) is inserted through the power chamber (120) and the front impeller (131), and the outer shaft (141) is used to drive the front impeller (131) to rotate. An inner shaft (142) is inserted through the power chamber (120) and the rear impeller (132), and the inner shaft (142) is used to drive the rear impeller (132) to rotate. A first switch assembly (151) is provided in the power compartment (120), and the first switch assembly (151) is used to open or close the front inlet (114). A second switch assembly (152) is provided at the central inlet (115), and the second switch assembly (152) is used to open or close the central inlet (115). A third switch assembly (153) is provided at the tail outlet (116) for opening or closing the tail outlet (116).

2. The dual-duct waterjet propulsion system according to claim 1, characterized in that, The first switch assembly (151) has a first station and a second station. When the first switch assembly (151) is in the first station, the front inlet (114) is in the open state; when the first switch assembly (151) is in the second station, the front inlet (114) is in the closed state.

3. The dual-duct waterjet propulsion system according to claim 1, characterized in that, The second switch assembly (152) has a third station and a fourth station. When the second switch assembly (152) is in the third station, the middle inlet (115) is in the open state. The second switch assembly (152) is used to block the front flow channel (1131) and the rear flow channel (1132). When the second switch assembly (152) is in the fourth station, the middle inlet (115) is in the closed state.

4. The dual-duct waterjet propulsion device according to claim 1, characterized in that, The third switch assembly (153) has a fifth station and a sixth station. When the third switch assembly (153) is in the fifth station, the tail outlet (116) is in the open state. The third switch assembly (153) is used to block the rear flow channel (1132) from the tail nozzle (117). When the third switch assembly (153) is in the sixth station, the tail outlet (116) is in the closed state.

5. The dual-duct waterjet propulsion system according to any one of claims 1 to 4, characterized in that, Also includes: An electronic control device (160) is provided in the power compartment (120). The electronic control device (160) is electrically connected to the first switch assembly (151), the electronic control device (160) is electrically connected to the second switch assembly (152), and the electronic control device (160) is electrically connected to the third switch assembly (153).

6. The dual-duct waterjet propulsion device according to claim 5, characterized in that, Also includes: A first drive element (171) is connected to the outer shaft (141), and the first drive element (171) is electrically connected to the electronic control device (160); and / or The second drive unit (172) is connected to the inner shaft (142) and is electrically connected to the electronic control device (160).

7. The dual-duct waterjet propulsion system according to any one of claims 1 to 4, characterized in that, The inner shaft (142) passes through the outer shaft (141), and the inner shaft (142) is rotatable relative to the outer shaft (141).

8. The dual-duct waterjet propulsion system according to any one of claims 1 to 4, characterized in that, The dual-duct waterjet propulsion system has a first working mode and a travel speed not less than a first threshold. The outer shaft (141) can drive the front impeller (131) to rotate and the inner shaft (142) can drive the rear impeller (132) to rotate. The front inlet (114) is in an open state, and the middle inlet (115) and the tail outlet (116) are both in a closed state.

9. The dual-duct waterjet propulsion system according to any one of claims 1 to 4, characterized in that, The dual-duct water jet propulsion has a second working mode. The traveling speed of the dual-duct water jet propulsion is not less than a second threshold and less than a first threshold. The second threshold is less than the first threshold. The outer shaft (141) can drive the front impeller (131) to rotate and the inner shaft (142) can drive the rear impeller (132) to rotate. The front inlet (114) and the tail outlet (116) are both in the open state, and the middle inlet (115) is in the closed state.

10. The dual-duct waterjet propulsion system according to any one of claims 1 to 4, characterized in that, The dual-duct water jet propulsion has a third working mode. The traveling speed of the dual-duct water jet propulsion is not less than a third threshold and less than a second threshold. The third threshold is less than the second threshold. The outer shaft (141) does not rotate. The inner shaft (142) can drive the rear impeller (132) to rotate. The front inlet (114) and the tail outlet (116) are both closed. The middle inlet (115) is open.

11. The dual-duct waterjet propulsion system according to any one of claims 1 to 4, characterized in that, The dual-duct water jet propulsion system has a fourth operating mode. The travel speed of the dual-duct water jet propulsion system is less than the third threshold. The outer shaft (141) does not rotate. The inner shaft (142) can drive the rear impeller (132) to rotate. The front inlet (114) is in a closed state. The middle inlet (115) and the tail outlet (116) are both in an open state.

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