Counter-rotating pump jet propeller

Abstract

The utility model provides a kind of to and fro pump jet propeller, including front rotor, rear rotor, guide pipe, guide vane and hub and propeller body, front rotor and rear rotor coaxial counter-rotation setting, the blade of front rotor rotates along clockwise direction, the blade of rear rotor rotates along counterclockwise direction, the input power of rear rotor is 1.2~1.5 times of front rotor input power;Guide pipe is annular cylindrical structure, its inner wall is fixedly connected with hub by radial support rib, outer wall covers the outer periphery of front rotor, rear rotor and guide vane, the inner diameter of guide pipe gradually reduces from front to back along axial direction, forms convergent section, for constraint radial water flow and reduce blade tip line speed, the utility model is integrated by guide pipe cavitation inhibition, guide vane rectification optimization, power dynamic distribution and heat dissipation system, while improving propelling efficiency and navigation stability, compactness and durability are considered, especially suitable for the power demand of high-speed underwater vehicle.

Description

Technical Field

[0001] This utility model relates to the field of underwater propulsion technology, and in particular to a counter-rotating pump-jet propulsion system suitable for the propulsion system of underwater vehicles with high speed and low cavitation risk. Background Technology

[0002] Traditional propeller propulsion systems are widely used in underwater vehicles, but they have significant drawbacks at high speeds. First, to meet high thrust requirements, single-propeller designs often require larger propeller diameters or higher rotational speeds, resulting in excessively large engines that compromise the overall compactness of the vehicle's structure. Furthermore, at high speeds, the linear velocity at the blade tips increases dramatically, causing a sudden drop in local pressure, which triggers water vaporization and cavitation. The impact force generated when these cavitation bubbles burst can cause erosion of the blade surface material, reducing propulsion efficiency and shortening equipment lifespan.

[0003] To alleviate cavitation, the existing technology proposes a counter-rotating propeller design, which distributes power by two sets of counter-rotating propellers to reduce the load on a single propeller and thus reduce the tip velocity. However, such designs still have the following problems: (1) the uneven power distribution between the front and rear rotors leads to an imbalance in circumferential torque, requiring the aircraft to frequently adjust the control surfaces to maintain directional stability, increasing energy loss; (2) when the speed exceeds the critical value, cavitation may still occur at the tip of the counter-rotating propeller, causing a sharp drop in propulsion efficiency; (3) the traditional duct structure only plays a simple guiding role and fails to effectively optimize the water flow distribution to suppress cavitation.

[0004] To address the aforementioned issues, a novel propulsion design is urgently needed that can solve the problems of torque imbalance and cavitation suppression through structural optimization while ensuring high speed, thereby improving energy utilization efficiency and navigation stability. Utility Model Content

[0005] This invention proposes a counter-rotating pump-jet propulsion system, which solves the problems of torque imbalance and cavitation that easily occur in existing underwater vehicles during high-speed navigation. The technical solution of this invention is achieved as follows: A counter-rotating pump-jet propulsion device includes a front rotor, a rear rotor, a duct, guide vanes and a hub, and a propulsion body. The front rotor and the rear rotor are coaxially arranged and rotate in opposite directions. The blades of the front rotor rotate clockwise and the blades of the rear rotor rotate counterclockwise. The drive shaft of the front rotor is connected to the engine's fuel pump and cooling water pump through a transmission mechanism. The fuel pump is used to deliver fuel to the engine, and the cooling water pump is used to circulate cooling water to cool the engine. The input power of the rear rotor is 1.2 to 1.5 times that of the front rotor to compensate for the power loss caused by the front rotor drive shaft driving the oil supply pump and cooling water pump, thereby balancing the circumferential torque of the front and rear rotors. The guide tube is an annular cylindrical structure. Its inner wall is fixedly connected to the hub by radial support ribs. The outer wall covers the outer periphery of the front rotor, rear rotor and guide vane. The inner diameter of the guide tube gradually decreases from front to back along the axial direction to form a converging section, which is used to constrain the radial water flow and reduce the tip linear velocity. The guide vane is fixedly installed at the tail of the rear rotor and includes multiple arc-shaped blades evenly distributed along the circumference. The curvature of the blade matches the circumferential circulation of the rear rotor outflow. The trailing edge of the guide vane extends to the outlet end of the guide tube and is welded and fixed to the inner wall of the guide tube. It is used to rectify the circumferential water flow at the outlet of the rear rotor into axial flow.

[0006] Furthermore, the transmission mechanism includes a gear set and a coupling. The gear set is located between the drive shaft of the front rotor and the oil supply pump and the cooling water pump, and the coupling is used to adjust the transmission torque.

[0007] Furthermore, the drive shaft of the rear rotor is embedded with a power compensation module. The power compensation module monitors the load changes of the front rotor in real time through sensors and dynamically adjusts the input power of the rear rotor to maintain the power difference between the front and rear rotors within the range of 1.2 to 1.5 times.

[0008] Furthermore, the hub has a tapered structure, with its front end connected to the drive shaft of the front rotor via a bearing, and its rear end fixed to the guide vanes via a flange. The hub surface is provided with guide grooves to guide cooling water to dissipate heat from the drive shaft.

[0009] Furthermore, the ratio of the number of blades between the front rotor and the rear rotor is 1:1.2~1.5, and the blade chord length of the rear rotor is 10~15% longer than that of the front rotor to adapt to power distribution requirements.

[0010] Furthermore, the converging section of the catheter is 1 / 3 to 1 / 2 of the total length of the catheter, the converging angle is 5 to 8°, and the inner wall surface is provided with an anti-cavitation coating, the coating material being a polyurethane-ceramic composite material.

[0011] Furthermore, the installation angle of the arc-shaped blades of the guide vane is 15~25°, and the distance between its leading edge and the trailing edge of the rear rotor blade is 0.2~0.3 times the chord length of the rear rotor blade, in order to avoid flow interference.

[0012] Furthermore, the drive shafts of the front and rear rotors rotate in opposite directions through a planetary gear set, with the transmission ratio of the planetary gear set set to 1:1.1~1.3 to match the power difference between the front and rear rotors.

[0013] Furthermore, an annular diffuser is provided at the outlet end of the conduit, with a diffusion angle of 3~5°, to further reduce the water flow velocity and suppress cavitation.

[0014] Compared with existing technologies, this solution has the following advantages: (1) Effective suppression of cavitation: The duct adopts a converging section design and a counter-rotating structure of the front and rear rotors, which effectively constrains the radial water flow, reduces the tip linear velocity, avoids the generation and rupture of cavitation bubbles on the blade surface under high-speed conditions, reduces the risk of material erosion, and extends the service life of the propeller. The annular diffuser at the outlet end of the duct further reduces the intensity of water flow turbulence, and increases the critical velocity for cavitation suppression by about 15% to 20%. (2) Improved torque balance and heading stability: The input power of the rear rotor is set to 1.2 to 1.5 times that of the front rotor to compensate for the power loss caused by the front rotor drive shaft driving the oil supply pump and cooling water pump. At the same time, the planetary gear set (transmission ratio 1:1.1 to 1.3) achieves counter-rotation, eliminating circumferential torque imbalance, reducing the frequency of aircraft control surface adjustment, and reducing energy waste. The power compensation module embedded in the rear rotor drive shaft can dynamically adjust the power difference and respond to load changes in real time to ensure the heading stability of the aircraft. (3) Optimization of propulsion efficiency: The guide vane adopts 6 to 8 arc-shaped blades (installation angle 15 to 25°), and its curvature is matched with the outflow circulation of the rear rotor, which efficiently converts the circumferential water kinetic energy into axial thrust, improving the propulsion efficiency by about 20 to 25%. The distance between the leading edge of the guide vane and the trailing edge of the rear rotor blade is set to 0.2 to 0.3 times the chord length to avoid flow interference and reduce energy loss; (4) Adaptive expansion: The blade parameters (number ratio 1:1.2~1.5, chord length difference 10%~15%, installation angle difference 3~5%) and the guide vane streamline thickness distribution (thick leading edge, thin trailing edge) are matched to different speed requirements, expanding the range of applicable operating conditions of the propeller. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the overall structure of a counter-rotating pump-jet propulsion device according to the present invention; Figure 2 This is a schematic diagram of the tail structure of a counter-rotating pump-jet propulsion device according to the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Front rotor; 2. Rear rotor; 3. Guide tube; 4. Guide vane; 5. Hub; 6. Propulsion body. Detailed Implementation

[0018] The technical solution of this utility model will be clearly and completely described below with reference to its embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0019] Reference Figure 1 This utility model provides a counter-rotating pump-jet propulsion device, including a front rotor 1, a rear rotor 2, a duct 3, guide vanes 4, a hub 5, and a propulsion body 6. The front rotor 1 and the rear rotor 2 are coaxially arranged and rotate counter-rotate. The blades of the front rotor 1 rotate clockwise. The drive shaft of the front rotor 1 is connected to the engine's fuel pump and cooling water pump through a transmission mechanism. The fuel pump is used to deliver fuel to the engine, and the cooling water pump is used to circulate cooling water to cool the engine. The duct 3 has an annular cylindrical structure, and its inner wall is connected to the hub 5 by radial support ribs. The guide vane 3 is fixedly connected, with its outer wall covering the outer periphery of the front rotor 1, rear rotor 2, and guide vane 4. The inner diameter of the guide vane 3 gradually decreases from front to back along the axial direction, forming a converging section to constrain the radial water flow and reduce the blade tip linear velocity. The guide vane 4 is fixedly installed at the tail of the rear rotor 2 and includes 6 to 8 arc-shaped blades evenly distributed along the circumference. The curvature of the guide vane 4 matches the circumferential circulation of the rear rotor 2. The trailing edge of the guide vane 4 extends to the outlet end of the guide vane 3 and is welded and fixed to the inner wall of the guide vane 3 to rectify the circumferential water flow at the outlet of the rear rotor 2 into axial flow.

[0020] The transmission mechanism can adopt the differential transmission structure commonly used in underwater vehicles. It only needs to be able to achieve an input power of 1.2 to 1.5 times that of the input power of the rear rotor 2, so as to compensate for the power loss caused by the front rotor 1 drive shaft driving the oil supply pump and cooling water pump, thereby balancing the circumferential torque of the front and rear rotors 2. The drive shaft of the rear rotor 2 is embedded with a power compensation module. The power compensation module adopts an embedded microcontroller (model STM32F407), which collects the torque signal of the front rotor (1) in real time through the Hall sensor, and dynamically adjusts the input voltage of the drive motor of the rear rotor (2) based on the PID algorithm, so that the power difference is stabilized at 1.2-1.5 times. Adaptably, the blade ratio of the front rotor 1 to the rear rotor 2 is 1:1.2~1.5, and the blade chord length of the rear rotor 2 is 10%~15% greater than that of the front rotor 1. The drive shafts of the front rotor 1 and the rear rotor 2 rotate in opposite directions through a planetary gear set. The transmission ratio of the planetary gear set is set to 1:1.1~1.3 to match the power difference between the front and rear rotors 2 and to adapt to power distribution requirements. This structure is not the main improvement of this utility model, and for the sake of protecting trade secrets, this solution is not fully disclosed. Only a common implementation is given: the transmission mechanism includes a gear set and a coupling. The gear set is located between the drive shaft of the front rotor 1 and the oil supply pump and the cooling water pump, and the coupling is used to adjust the transmission torque. Those skilled in the art can achieve the above effects through the above or other alternative solutions without creative effort.

[0021] Furthermore, the hub 5 has a conical structure, with its front end connected to the drive shaft of the front rotor 1 via a bearing, and its rear end fixed to the guide vane 4 via a flange. The surface of the hub 5 is provided with guide grooves to guide cooling water to dissipate heat from the drive shaft. The converging section of the duct 3 has a length of 1 / 3 to 1 / 2 of its total length, a convergence angle of 5 to 8°, and an anti-cavitation coating on its inner wall surface, the coating material being a polyurethane-ceramic composite material. The arc-shaped blades of the guide vane 4 have an installation angle of 15 to 25°, and the distance between its leading edge and the trailing edge of the blade of the rear rotor 2 is 0.2 to 0.3 times the chord length of the blade of the rear rotor 2 to avoid flow interference. An annular diffuser is provided at the outlet end of the duct 3, with a diffusion angle of 3 to 5°, to further reduce the water flow velocity and suppress cavitation.

[0022] Working principle explanation: High-speed navigation of an aircraft requires sufficient power. Using a single propeller would result in an excessively large engine, affecting the aircraft's overall size. Simultaneously, the propeller would also be relatively large, and at high speeds, the blade tips would experience high velocity, causing a decrease in pressure around the blades and leading to water vaporization. This vaporization generates numerous bubbles, which travel with the water flow to the propeller's pressure surface. The propeller's rotation, performing work on the water, causes these bubbles to burst. This results in erosion of the blade surface, a phenomenon technically called cavitation. In this design, the blades of the front rotor 1 rotate clockwise, while the blades of the rear rotor 2 rotate counterclockwise, effectively dividing the same power output into two parts. This also reduces the propeller diameter, thus lowering the blade tip linear velocity and minimizing the likelihood of cavitation.

[0023] However, this counter-rotating propeller design still has speed limitations. If the vehicle's speed increases to a certain critical value, this design will still cause cavitation in the propeller, leading to stall. To solve this problem, a duct 3 is added outside the propeller to constrain the water. This reduces the likelihood of cavitation at high speeds, representing a structural optimization design.

[0024] The reason why duct 3 suppresses cavitation: With the increase of radius, the circumferential linear velocity of a conventional propeller increases, and cavitation occurs when the propeller speed reaches a certain point. Therefore, in ordinary propellers, the load gradually decreases from 0.7 to 0.75 times the radius towards the blade tip, thus avoiding cavitation at high speeds. With the addition of duct 3, the duct can constrain the radial water flow. This eliminates the need for load reduction treatment on the rotor blades from the blade root to the blade tip. Consequently, under the same power conditions, the diameter of the propeller blades with duct 3 is smaller than that without duct 3, and the linear velocity at the blade tip is reduced at the same speed.

[0025] The reason for rectification: Guide vane 4 is designed to match the load changes of the front rotor 1 and the rear rotor 2. Since the power of the front rotor 1 is less than the power received by the rear rotor 2, the water flow passing through the rear rotor 2 still has a certain velocity in the circumferential direction. The function of guide vane 4 is to match the front and rear rotors 2 by having a certain curvature, which matches the circumferential velocity of the outflow from the rear rotor 2. In this way, the water flow passing through guide vane 4 can convert the circumferential velocity into axial velocity, thereby increasing energy utilization and improving the efficiency of the propeller.

[0026] This invention integrates cavitation suppression in the duct 3, rectification optimization in the guide vane 4, dynamic power distribution, and heat dissipation system. It improves propulsion efficiency and navigation stability while also ensuring structural compactness and durability, making it particularly suitable for the power requirements of high-speed underwater vehicles.

[0027] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A counter-rotating pump-jet propulsion device, comprising a front rotor (1), a rear rotor (2), a guide tube (3), guide vanes (4), a hub (5), and a propulsion body (6), characterized in that: The front rotor (1) and the rear rotor (2) are coaxially arranged to rotate in opposite directions. The blades of the front rotor (1) rotate clockwise, and the blades of the rear rotor (2) rotate counterclockwise. The drive shaft of the front rotor (1) is connected to the fuel pump and the cooling water pump of the engine through a transmission mechanism. The fuel pump is used to deliver fuel to the engine, and the cooling water pump is used to circulate cooling water to cool the engine. The input power of the rear rotor (2) is 1.2 to 1.5 times that of the input power of the front rotor (1) to compensate for the power loss caused by the drive shaft of the front rotor (1) driving the oil supply pump and the cooling water pump, thereby balancing the circumferential torque of the front and rear rotors. The duct (3) is an annular cylindrical structure. Its inner wall is fixedly connected to the hub (5) by radial support ribs. Its outer wall covers the outer periphery of the front rotor (1), the rear rotor (2) and the guide vane (4). The inner diameter of the duct (3) gradually decreases from front to back along the axial direction to form a converging section, which is used to constrain the radial water flow and reduce the blade tip linear velocity. The guide vane (4) is fixedly installed at the tail of the rear rotor (2), including multiple arc-shaped blades evenly distributed along the circumference. The curvature of the arc is matched with the circumferential circulation of the rear rotor (2). The tail edge of the guide vane (4) extends to the outlet end of the guide tube (3) and is welded and fixed to the inner wall of the guide tube (3). It is used to rectify the circumferential water flow at the outlet of the rear rotor (2) into axial flow.

2. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The transmission mechanism includes a gear set and a coupling. The gear set is located between the drive shaft of the front rotor (1) and the oil supply pump and the cooling water pump. The coupling is used to adjust the transmission torque.

3. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The drive shaft of the rear rotor (2) is embedded with a power compensation module. The power compensation module monitors the load change of the front rotor (1) in real time through a sensor and dynamically adjusts the input power of the rear rotor (2) to maintain the power difference between the front and rear rotors within the range of 1.2 to 1.5 times.

4. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The hub (5) is a conical structure. Its front end is connected to the drive shaft of the front rotor (1) through a bearing, and its rear end is fixed to the guide vane (4) through a flange. The surface of the hub (5) is provided with a guide groove to guide cooling water to dissipate heat from the drive shaft.

5. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The ratio of the number of blades in the front rotor (1) to the number of blades in the rear rotor (2) is 1:1.2 to 1.5, and the blade chord length of the rear rotor (2) is 10% to 15% longer than that of the front rotor (1) to adapt to power distribution requirements.

6. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The converging section of the conduit (3) is 1 / 3 to 1 / 2 of the total length of the conduit, the converging angle is 5° to 8°, and the inner wall surface is provided with an anti-cavitation coating.

7. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The arc-shaped blade of the guide vane (4) has an installation angle of 15° to 25°, and the distance between its leading edge and the trailing edge of the rear rotor (2) blade is 0.2 to 0.3 times the chord length of the rear rotor blade, so as to avoid flow interference.

8. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The drive shafts of the front rotor (1) and the rear rotor (2) rotate in opposite directions through a planetary gear set. The transmission ratio of the planetary gear set is set to 1:1.1 to 1.3 to match the power difference between the front and rear rotors.

9. The counter-rotating pump-jet propulsion device according to claim 1, characterized in that: The outlet end of the conduit (3) is provided with an annular diffuser with a diffusion angle of 3° to 5°, which is used to further reduce the water flow velocity and suppress cavitation.

Images