A pump-jet propeller rotor based on heterogeneously coupled blades and a design method

Abstract

The application provides a pump-jet propeller rotor based on heterogeneous coupling blades and a design method, which comprises multiple groups of rotor blades arranged in a staggered coupling mode along the circumference of a rotor hub, each group of rotor blades comprises long blades and short blades, the blade tips of each group of long blades are connected with the inner wall of a circular end ring, each group of short blades is arranged in a gap region between two adjacent long blades, and the blade roots of the short blades are fixed to the inner wall of the circular end ring. The application can apply torque to the rudder system of a scaled semi-hanging rudder during loading test, monitor the torque value of the rudder system, and complete corresponding no-load test, static load test and dynamic load test.

Description

Technical Field

[0001] This application relates to the technical field of ship propulsion devices, and more specifically, to a pump-jet propulsion rotor based on heterogeneous coupled blades and its design method. Background Technology

[0002] Modern ships place increasingly higher demands on their propulsion systems, requiring not only high efficiency but also lower vibration and noise. Research and development of low-noise ship propulsion systems has been a hot topic for ship design and operation departments both domestically and internationally. Pump-jet propulsion systems, a type of ducted propulsion system with forward / rear stators, offer excellent propulsion performance, cavitation characteristics, operational stability, and acoustic stealth, and are used in underwater vehicles and high-speed surface ships. However, complex gap flows inevitably occur in the blade tip region between the rotor and the inner wall of the duct, easily leading to tip cavitation and strong pressure pulsations, which significantly negatively impact the overall propulsion performance, structural vibration, and radiated noise characteristics of the propulsion system.

[0003] While current design methods such as rotor tip unloading and multi-blade design can improve the critical speed of the propeller, the dense arrangement of blades at the blade root and the resulting slat effect and tip unloading reduce the propulsion efficiency of the propeller, making it difficult to meet the requirements of high-efficiency, low-noise, cavitation-free navigation at higher speeds in the future. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a pump-jet propulsion rotor and design method based on heterogeneous coupled blades, which can significantly increase the critical speed of the propulsion while reducing the propulsion noise. It can be applied to the high-speed, low-noise design of various types of propulsion rotors.

[0005] The embodiments of this application are implemented as follows:

[0006] This application provides a pump-jet propulsion rotor based on heterogeneous coupled blades, characterized in that it includes multiple sets of rotor blades arranged in an alternating coupling along the circumference of the rotor hub. Each set of rotor blades includes long blades and short blades. The tip of each set of long blades is connected to the inner wall of a circular end ring. Each set of short blades is located in the gap area between two adjacent long blades. The root of the short blades is fixed to the inner wall of the circular end ring.

[0007] In some alternative implementations, the tips of the short blades are located at the inner radius of the rotor and are not connected to the rotor hub.

[0008] In some alternative embodiments, the circular end ring is embedded in the inner wall groove of the pump-jet propulsion duct, and the inner surface of the circular end ring smoothly transitions with the inner wall surface of the duct.

[0009] In some alternative embodiments, the chord length at the leaf root of the short leaf is longer than the chord length at the leaf tip, and the chord length decreases from the leaf root to the leaf tip.

[0010] In some alternative embodiments, a gap is provided between the outer wall surface of the circular end ring and the surface of the inner wall groove, and the gap distance does not exceed 10 mm.

[0011] A design method for a pump-jet propulsion rotor based on heterogeneous coupled blades, characterized by comprising the following steps:

[0012] Step a, determine the rotor configuration:

[0013] The rotor blades consist of two different types of blades, which are arranged in an alternating coupling along the circumference of the rotor hub. One type of rotor blade is longer in the radial direction, and the other type is shorter in the radial direction. The tip of the longer blade is fixed to the circular end ring, and the root of the blade is fixed to the rotor hub. The root of the shorter blade is fixed to the circular end ring, and the tip of the blade is not connected to the rotor hub.

[0014] Step b, rotor blade design:

[0015] Based on the determined rotor blade configuration, the number of blades and load distribution characteristics are determined according to the thrust, speed and critical speed of the propeller. Rotor blade airfoil matching design is carried out according to the load. The rotor blade design is completed by adjusting the airfoil of the short blades and their relative positions to the long blades in the circumferential and axial directions.

[0016] Step c, circular end ring design:

[0017] The circular end ring is embedded in the groove on the inner wall of the pump-jet propulsion duct, and the inner surface of the circular end ring along the axial direction is smoothly transitioned with the inner wall of the duct, so as to achieve smooth water flow inside the propulsion.

[0018] Step d, calculation of the propeller hydrodynamic performance:

[0019] After completing the rotor design, computational fluid dynamics was used to calculate the hydrodynamic performance of the propeller design scheme, taking into account the viscosity of the water flow. The propeller efficiency, cavitation, and acoustic performance were estimated, and some design parameters were optimized and adjusted based on the calculation results.

[0020] In some alternative implementations, the rotor blades adopt NACA airfoils, with the blade profile values ​​of the long and short blades remaining consistent within the range of 0.6D to 1.0D, where D is the rotor diameter. The chord length of the short blades decreases smoothly from 0.6D to a smaller radius, shortening to zero at a radius of 0.4D.

[0021] In some optional embodiments, the range of the axial position of the short blade relative to the long blade is 0 to 30% of the chord length of the short blade along the outflow direction. In the initial state of equal axial angle distribution, the short blade deflects towards the suction surface of the long blade by an angle not exceeding 20%*360 / N, where N is the number of rotor blades.

[0022] The beneficial effects of this application are: 1. This application provides a pump-jet propulsion rotor and design method based on heterogeneous coupled blades. By designing the structure of the coupled force unit of the blades, no rotor blade tip vortex is generated, which can significantly increase the critical speed of the propulsion while reducing the propulsion noise; 2. The addition of end rings not only significantly reduces the wing grid blocking effect near the rotor hub, but also enables a further increase in the number of rotor blades without reducing efficiency, which is beneficial to the improvement of blade cavitation energy and noise performance; 3. It can be applied to the design of rotors for various types of high-efficiency, high-speed, low-noise waterjet propulsion or pump-jet propulsion. The processing technology is mature and has good application prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the thruster structure according to an embodiment of this application;

[0025] Figure 2 This is a front view of the thruster rotor according to an embodiment of this application;

[0026] Figure 3 This is a cross-sectional view of the thruster according to an embodiment of this application;

[0027] Figure 4 This is a comparison chart of the open-water characteristic curves of the propeller in an embodiment of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0036] like Figure 1 , Figure 2 As shown, this invention proposes a pump-jet propulsion rotor based on heterogeneous coupled blades, comprising multiple sets of rotor blades arranged in a staggered coupling along the circumference of the rotor hub 1. Each set of rotor blades includes long blades 2 and short blades 3. The tips of the long blades in each set are connected to the inner wall of the circular end ring 4. Each set of short blades is located in the gap area between two adjacent long blades, and the root of the short blades is fixed to the inner wall of the circular end ring. The tips of the short blades are located at the inner radius of the rotor and are not connected to the rotor hub.

[0037] Adjacent long and short blades can form a set of blade coupled force units. By adjusting the blade shape of the short blade and its relative position to the long blade, the blade group can generate favorable load coordination distribution and interference characteristics. It can also suppress flow separation at the edge of the suction surface and reduce the overall unsteady excitation force of the rotor blade, thereby achieving the purpose of vibration reduction and noise reduction.

[0038] like Figure 3 As shown, the circular end ring is embedded in the groove 6 on the inner wall of the pump-jet propulsion duct 5. The inner surface of the circular end ring smoothly transitions with the inner wall of the duct, so as to achieve smooth water flow inside the propulsion.

[0039] By adding a circular end ring, not only is the blocking effect of the wing grid near the rotor hub significantly reduced, but the overall flow capacity and propulsion efficiency of the propeller can also be increased. Furthermore, the number of rotor blades can be further increased without reducing efficiency, reducing the load on a single blade and making the load on a single rotor blade more uniform, which is beneficial to improving the blade cavitation energy and noise performance.

[0040] A gap of no more than 10 mm is provided between the outer wall surface of the circular end ring and the surface of the inner groove. The rotor blade tip no longer has a blade tip gap with the guide tube, thus eliminating tip vortex cavitation. The outer radius of the rotor blade can then use a larger chord length and pitch compared to conventional rotor designs, further enhancing the thrust of the propeller.

[0041] Furthermore, the chord length at the base of the short leaf is longer than that at the tip, and the chord length decreases from the base to the tip.

[0042] Example 1

[0043] In this embodiment, taking a front-stator type pump-jet propulsion unit as an example, the rotor is arranged behind the stator blades of the propulsion unit. The specific design of the propulsion rotor is as follows:

[0044] (1) Based on the thruster duct profile and stator profile, the rotor blade design is carried out. First, the rotor configuration is determined. The thruster rotor blades consist of two different types of blades, arranged in a staggered coupling along the circumference. There is a circular end ring at the outer radius of the rotor (blade tip), which connects to each blade. One type of rotor blade is longer radially, fixed to the rotor hub at the inner radius (blade root), and fixed to the circular end ring at the outer radius; the other type of rotor blade is shorter radially, fixed to the circular end ring at the inner radius, and not connected to the rotor hub at the outer radius, contracting to approximately 0.4D (D is the rotor diameter). A long blade and a short blade form a set of coupled force-bearing units.

[0045] (2) Based on the determination of the rotor blade configuration, the number of blades and load distribution characteristics are determined according to the thrust, speed and critical speed of the propeller. The rotor blade airfoil matching design is carried out according to the load. The rotor blade design is completed by adjusting the airfoil of the short blade and its relative position to the long blade along the circumferential and axial directions.

[0046] The rotor blades adopt NACA airfoils, which have good hydrodynamic performance. The blade profile values ​​of the long and short blades remain consistent within the range of 0.6D to 1.0D. The chord length of the short blades decreases smoothly from 0.6D to a smaller radius, shortening to zero at a radius of approximately 0.4D. The airfoil pitch and tilt of the short blades are appropriately adjusted in the chord length contraction section to maintain a smooth flow transition.

[0047] The axial position of the short blades relative to the long blades is within a range of 0–30% of the chord length of the short blades along the outflow direction. In the initial state of uniform axial angular distribution, the short blades are deflected towards the suction surface of the long blades by an angle not exceeding 20% ​​* 360 / N (where N is the number of rotor blades) to suppress flow separation at the edge of the suction surface of the long blades. The axial movement of the short blades allows for effective load coordination within the blade assembly, thereby reducing the overall excitation force on the rotor blades.

[0048] (3) Finally, the circular end ring design is completed. The circular end ring is embedded in the inner wall groove of the pump-jet propulsion duct and the inner surface of the circular end ring along the axial direction is smoothly transitioned with the inner wall surface of the duct to achieve smooth water flow inside the propulsion. There is a gap between the outer wall surface of the circular end ring and the surface of the inner wall groove, and the gap distance does not exceed 10mm.

[0049] (4) After completing the rotor design, computational fluid dynamics is used to calculate the hydrodynamic performance of the propeller design scheme under the condition of considering the viscosity of water flow, and to estimate the propeller efficiency, cavitation and acoustic performance. Based on the calculation results, some design parameters are optimized and adjusted.

[0050] Under the same stator and duct design conditions, a numerical simulation comparison analysis was conducted on the hydrodynamic performance of the rotor design method described above and the conventional rotor blade design method. The open-water efficiency was improved by an average of 5% in the vicinity of the operating point (see...). Figure 4 Under autonomous driving conditions, the amplitude of the first-order unsteady force is reduced by more than 50%, and the critical speed is increased by more than 8 knots.

Claims

1. A pump-jet propulsor rotor based on heterogeneously coupled vanes, characterized by, The device includes multiple sets of rotor blades arranged in an alternating coupling along the circumference of the rotor hub. Each set of rotor blades includes long blades and short blades. The tip of each set of long blades is connected to the inner wall of a circular end ring. Each set of short blades is located in the gap between two adjacent long blades. The root of the short blades is fixed to the inner wall of the circular end ring. The tip of the short blades is located at the inner radius of the rotor and is not connected to the rotor hub. The chord length of the root of the short blade is longer than the chord length of the tip, and the chord length decreases from the root to the tip. The circular end ring is embedded in the groove of the inner wall of the pump-jet propulsion duct, and the inner surface of the circular end ring smoothly transitions to the inner wall of the duct.

2. A pump-jet propulsor rotor based on heterogeneously coupled blades according to claim 1, characterized in that, A gap is provided between the outer wall surface of the circular end ring and the surface of the inner wall groove, and the gap distance does not exceed 10mm.

3. A design method of a rotor for a pump-jet propeller based on hetero- coupled blades as claimed in one of the preceding claims 1 or 2, characterized in that, Includes the following steps: Step a, determine the rotor configuration: The rotor blades consist of two different types of blades, which are arranged in an alternating coupling along the circumference of the rotor hub. One type of rotor blade is longer in the radial direction and the other type is shorter in the radial direction. The tip of the longer blade is fixed to the circular end ring and the root of the blade is fixed to the rotor hub. The root of the shorter blade is fixed to the circular end ring and the tip of the blade is not connected to the rotor hub. Step b, rotor blade design: Based on the determined rotor blade configuration, the number of blades and load distribution characteristics are determined according to the thrust, speed and critical speed of the propeller. Rotor blade airfoil matching design is carried out according to the load. The rotor blade design is completed by adjusting the airfoil of the short blades and their relative positions to the long blades in the circumferential and axial directions. Step c, circular end ring design: The circular end ring is embedded in the groove on the inner wall of the pump-jet propulsion duct, and the inner surface of the circular end ring along the axial direction is smoothly transitioned with the inner wall of the duct, so as to achieve smooth water flow inside the propulsion. Step d, calculation of the propeller hydrodynamic performance: After completing the rotor design, computational fluid dynamics was used to calculate the hydrodynamic performance of the propeller design scheme, taking into account the viscosity of the water flow. The propeller efficiency, cavitation, and acoustic performance were estimated, and some design parameters were optimized and adjusted based on the calculation results.

4. A design method of a pump-jet propeller rotor based on heterogeneously coupled blades according to claim 3, characterized in that, The rotor blades adopt NACA airfoil. The blade profile values ​​of the long blades and short blades are consistent within the range of 0.6D to 1.0D, where D is the rotor diameter. The chord length of the short blades decreases smoothly from 0.6D to a smaller radius, and shortens to zero at a radius of 0.4D.

5. A design method of a pump-jet propeller rotor based on heterogeneously coupled blades according to claim 4, characterized in that, The range of the axial position of the short blade relative to the long blade is 0 to 30% of the chord length of the short blade along the outflow direction. In the initial state of equal axial angle distribution, the short blade deflects towards the suction surface of the long blade by an angle not exceeding 20%*360 / N, where N is the number of rotor blades.

Images