Pump jet propeller

Abstract

The application relates to a pump-jet propeller, which comprises an annular conduit, a first stator, a rotor and a hub, the first stator, the rotor and the hub are arranged inside the annular conduit, the first stator is close to a trailing edge of the annular conduit, the first stator and the rotor are connected with the hub, the first stator is connected with an inner wall of the annular conduit, the trailing edge of the annular conduit is provided with a plurality of sawtooth assemblies which are arranged at intervals along the circumferential direction of the annular conduit, the sawtooth assemblies are located between two adjacent stator blades, the sawtooth assemblies comprise at least one sawtooth structure, the first stator comprises a plurality of stator blades; the rotor is used for rotating and generating a water power so as to make the pump-jet propeller generate a forward thrust; the sawtooth assemblies are used for interfering with a wake field of the pump-jet propeller to reduce vibration and noise, and can improve the problems of large thrust loss caused by continuous distributed sawtooth structures and poor noise reduction effect.

Description

Technical Field

[0001] The present application relates to the field of ship propulsion technology, and in particular to a pump-jet propulsion system. Background Art

[0002] Pump-jet propulsion, as a high-efficiency, low-noise combined propulsion device, is becoming the main mechanical propulsion device for underwater equipment. The pump-jet propulsion device is mainly composed of an annular duct and a rotor and stator inside the duct.

[0003] As underwater equipment continues to develop in the direction of high speed and quietness, more stringent requirements are placed on the performance of pump-jet propulsion. As the main working component of underwater equipment, the hydrodynamic performance and noise performance of the pump-jet propulsion significantly affect the speed and acoustic stealth of underwater equipment. Therefore, it is of great significance to improve the hydrodynamic performance and noise performance of the propeller. At present, the performance control methods of pump-jet propulsion mainly focus on the structural improvement of the pump-jet rotor, duct, and stator. Among them, the method of applying a bionic structure to the trailing edge of the duct has the advantage of convenient processing and manufacturing compared with other methods.

[0004] However, the above-mentioned pump-jet propulsion system has the problem that the hydrodynamic performance and noise performance cannot be controlled at the same time. Summary of the Invention

[0005] Based on this, it is necessary to provide a pump-jet propulsion system that can take into account both the regulation of hydrodynamic performance and noise performance in order to address the above technical issues.

[0006] In a first aspect, the present application provides a pump-jet propulsor, comprising: an annular duct, a first stator, a rotor, and a hub, wherein the first stator, the rotor, and the hub are all disposed within the annular duct, the first stator being adjacent to a trailing edge of the annular duct, the first stator and the rotor being connected to the hub, and the first stator being connected to an inner wall of the annular duct, the trailing edge of the annular duct being provided with a plurality of sawtooth assemblies spaced apart along the circumference of the annular duct, the sawtooth assemblies being located between two adjacent stator blades, the sawtooth assemblies comprising at least one sawtooth structure, and the first stator comprising a plurality of stator blades;

[0007] a rotor, configured to rotate and generate hydrodynamic force so as to enable the pump-jet propeller to generate forward thrust;

[0008] The sawtooth assembly is used to interfere with the wake field of the pump-jet propulsor to reduce vibration and noise.

[0009] In one embodiment, the serration assemblies are arranged at equal intervals along the circumference of the trailing edge of the annular duct, and the coverage area of ​​the serration assemblies is the area between the suction surface of one of the two adjacent stator blades and a preset position, where the preset position is a position determined based on the middle position between the two adjacent stator blades.

[0010] In one embodiment, the number of the serration assemblies is equal to the number of stator blades.

[0011] In one embodiment, the height of the sawtooth structure does not exceed 0.1 times the chord length of the annular duct, and does not exceed the axial distance between the trailing edge of the first stator and the trailing edge of the annular duct.

[0012] In one embodiment, the ratio of the height of the sawtooth structure to the width of the sawtooth structure is not less than 2 and not greater than 4.

[0013] In one embodiment, the pump-jet propulsor further includes a second stator, which is disposed inside the annular duct. The second stator is respectively connected to the hub and the inner wall of the annular duct, and the second stator is away from the trailing edge of the annular duct.

[0014] In one embodiment, surfaces of the annular duct, the first stator, the rotor and the second stator are provided with sliding surfaces.

[0015] In one embodiment, the sliding lengths of the sliding surfaces corresponding to the annular duct, the first stator, the rotor, and the second stator are the same or different.

[0016] In one embodiment, the slip length is 20 -500 between.

[0017] In one embodiment, the sliding surface includes at least one of a carbon-based coating surface and a fluorine-containing coating surface.

[0018] The pump-jet propeller comprises an annular duct, a first stator, a rotor, and a hub. The first stator, rotor, and hub are all disposed within the annular duct. The first stator is located near the trailing edge of the annular duct. The first stator and rotor are connected to the hub. The first stator is connected to the inner wall of the annular duct. The trailing edge of the annular duct is provided with a plurality of sawtooth assemblies spaced apart along the circumference of the annular duct. The sawtooth assemblies are located between two adjacent stator blades and include at least one sawtooth structure. The rotor is configured to rotate and generate hydrodynamic forces to cause the pump-jet propeller to generate forward thrust. The first stator includes a plurality of stator blades. The sawtooth assembly is configured to interfere with the wake flow field of the pump-jet propeller to reduce vibration and noise. By providing a plurality of sawtooth assemblies spaced apart along the circumference of the annular duct on the trailing edge of the annular duct, and positioning the sawtooth assemblies between two adjacent first stators, the discontinuous distribution of the sawtooth assemblies on the trailing edge of the annular duct can improve the problems of large thrust loss and poor noise reduction caused by the continuous distributed sawtooth structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 Schematic diagram of the structure of a pump-jet propulsion system in one embodiment;

[0021] Figure 2 is a schematic structural diagram of a pump-jet propulsion system in another embodiment;

[0022] Figure 3 Schematic diagram of the sawtooth aspect ratio of a pump-jet propulsor in one embodiment;

[0023] Figure 4 Schematic diagram of a curve showing the effect of a sawtooth structure on thrust coefficient in one embodiment;

[0024] Figure 5 A schematic diagram of a curve showing the effect of a sawtooth structure on propulsion efficiency in one embodiment;

[0025] Figure 6 Schematic diagram of a curve showing the effect of a sawtooth structure on the change in sound pressure level in the xy vertical plane in one embodiment;

[0026] Figure 7 Schematic diagram of a curve showing the effect of a sawtooth structure on the change in the sound pressure level in the xz vertical plane in one embodiment;

[0027] Figure 8 Schematic diagram of a curve showing the effect of a sawtooth structure on a change in the total sound pressure level in the xy vertical plane in one embodiment;

[0028] Figure 9 Schematic diagram of a curve showing the effect of a sawtooth structure on the change in the total sound pressure level in the xz vertical plane in one embodiment;

[0029] Figure 10 Schematic diagram of a curve showing the effect of the coupling between the sawtooth structure and the sliding surface on the thrust coefficient in one embodiment;

[0030] Figure 11 A schematic diagram of a curve showing the effect of the coupling between the sawtooth structure and the sliding surface on the propulsion efficiency in one embodiment;

[0031] Figure 12 Schematic diagram of the effect of the coupling between the sawtooth structure and the sliding surface on the change in the sound pressure level in the xy vertical plane in one embodiment;

[0032] Figure 13Schematic diagram of the effect of the coupling between the sawtooth structure and the sliding surface on the change in the sound pressure level in the xz horizontal plane in one embodiment;

[0033] Figure 14 Schematic diagram of the effect of the coupling between the sawtooth structure and the sliding surface on the change in the total sound pressure level in the xy vertical plane in one embodiment;

[0034] Figure 15 Schematic diagram of the effect of the coupling between the sawtooth structure and the sliding surface on the change in the total sound pressure level in the xz vertical plane in one embodiment;

[0035] Figure 16 Schematic diagram showing comparison of pump jet noise performance under small sawtooth working conditions in one embodiment;

[0036] Figure 17 Schematic diagram of comparison of pump jet noise performance under large sawtooth working conditions in one embodiment.

[0037] Description of reference numerals:

[0038] Pump-jet propeller 01; annular duct 10;

[0039] stator blades 20; rotor 30;

[0040] Hub 40; Sawtooth assembly 50;

[0041] Sawtooth structure 500 ; Second stator 60 . DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0043] Pump-jet propulsion, as a highly efficient and low-noise combined propulsion system, is becoming the primary mechanical propulsion device for underwater equipment. Pump-jet propulsion mainly consists of an annular duct with a rotating blade cascade (rotor) and a fixed blade cascade (stator) inside the duct.

[0044] As underwater equipment continues to evolve toward higher speeds and quieter operation, increasingly stringent performance requirements are being placed on pump-jet propulsion. In terms of hydrodynamic performance, the annular duct, stator, and rotor all generate thrust, and the stator and rotor generate torque, impacting the pump-jet's propulsion efficiency. In terms of flow noise performance, the duct and stator primarily contribute broadband noise, while the rotor primarily contributes line-spectrum noise. Therefore, controlling the duct, stator, and rotor will impact both the pump-jet's hydrodynamic and flow noise performance.

[0045] At present, the performance control methods of pump-jet propulsion mainly focus on the structural improvements of the pump-jet rotor, annular duct, and stator, such as adding end rings to the rotor blade tips, applying grooves to the inner wall of the annular duct, setting the trailing edge of the annular duct or stator as a porous medium, and applying a bionic structure to the trailing edge of the duct. However, since the above structures will have an adverse effect on the hydrodynamic performance while reducing the pump-jet noise, it is difficult to simultaneously control the pump-jet hydrodynamics and flow noise performance. Among them, the method of applying a bionic structure to the trailing edge of the annular duct has the advantage of convenient processing and manufacturing compared to other methods, and therefore has the possibility of further improvement. However, the above-mentioned pump-jet propulsion has the problem that the hydrodynamic performance and noise performance cannot be controlled at the same time. The present application aims to provide a new type of pump-jet propulsion to solve the above problems.

[0046] After introducing the background technology of the pump-jet propulsion provided by the embodiment of the present application, the following focuses on introducing the pump-jet propulsion proposed in this solution.

[0047] In one embodiment, Figure 1 As shown, a pump-jet propulsor 01 is provided, which includes an annular duct 10, a first stator, a rotor 30, and a hub 40. The first stator, the rotor 30, and the hub 40 are all arranged inside the annular duct 10. The first stator is close to the trailing edge of the annular duct 10. The first stator and the rotor 30 are connected to the hub 40. The first stator is connected to the inner wall of the annular duct 10. The trailing edge of the annular duct 10 is provided with a plurality of sawtooth assemblies 50 arranged at intervals along the circumference of the annular duct 10 (see Figure 2 ), the sawtooth assembly 50 is located between two adjacent stator blades 20, the sawtooth assembly 50 includes at least one sawtooth structure 500, and the first stator includes a plurality of stator blades 20;

[0048] The rotor 30 is configured to rotate and generate hydrodynamic force to enable the pump-jet propeller 01 to generate forward thrust;

[0049] The sawtooth assembly 50 is used to interfere with the wake field of the pump-jet propulsor 01 to reduce vibration and noise.

[0050] The annular duct 10 is a torus-like structure with unequal radii at both ends, wherein the end with the smaller radius is the trailing edge of the annular duct 10 , and the end with the larger radius is the non-trailing edge of the annular duct 10 .

[0051] Generally speaking, the pump-jet propulsor 01 may include only one stator or two stators; when the pump-jet propulsor 01 includes only one stator, the stator may be close to the trailing edge of the annular duct 10 and be arranged on the hub 40, or it may be away from the trailing edge of the annular duct 10 and be arranged on the hub 40; and, when the pump-jet propulsor 01 includes two stators, the two stators may be respectively close to the trailing edge position of the annular duct 10 and the non-trailing edge position of the annular duct 10, and be arranged on the hub 40.

[0052] Furthermore, when the stator in the pump-jet propulsor 01 is disposed near the trailing edge of the annular duct 10, the rotor 30 is disposed away from the trailing edge of the annular duct 10 and is disposed on the hub 40. When the stator in the pump-jet propulsor 01 is disposed away from the trailing edge of the annular duct 10, the rotor 30 is disposed near the trailing edge of the annular duct 10 and is disposed on the hub 40. In addition, when the pump-jet propulsor 01 includes two stators, one near the trailing edge of the annular duct 10 and one near the non-trailing edge of the annular duct 10, the rotor 30 is located between the two stators and is disposed on the hub 40. When the motor drives the rotor 30 to rotate, water flows into the non-trailing edge of the annular duct 10, thereby generating huge hydrodynamic forces. The rotation of the rotor 30 generates forward thrust, thereby causing the pump-jet propulsor 01 to generate forward thrust.

[0053] The first stator in the pump-jet propulsor 01 provided in the embodiment of the present application is a stator close to the trailing edge of the annular duct 10. One end of the first stator is fixed to the inner wall of the annular duct 10, and the other end of the first stator is fixed to the hub 40 to ensure that the annular duct 10, the first stator and the hub 40 are fixed and do not move.

[0054] It should be noted that a first stator is provided in the pump-jet propulsor 01 to recover the rotational energy in the wake of the rotor 30 and improve the overall efficiency of the pump-jet propulsor 01, but its noise is relatively high. In addition, the blades of the first stator are subjected to a force opposite to the incoming flow, generating thrust and having the function of balancing torque.

[0055] See also Figure 2 The trailing edge of the annular duct 10 is provided with a plurality of sawtooth assemblies 50 arranged at intervals along the circumference of the annular duct 10. The sawtooth assemblies 50 are located between two adjacent stator blades 20 and include at least one sawtooth structure 500. The sawtooth assembly 50 has the advantages of simple structure and easy processing. It should be noted that the sawtooth assembly 50 should be obtained by removing material from the original annular duct 10, rather than by adding material to the trailing edge of the original annular duct 10. The reason is that removing material can ensure higher structural strength and avoid the situation where the sawtooth assembly 50 oscillates under large hydrodynamic loads, thereby avoiding the situation where the added sawtooth assembly 50 causes a surge in noise.

[0056] The pump-jet propeller provided in the embodiments of the present application sets multiple sawtooth assemblies arranged at intervals in the circumferential direction of the annular duct on the trailing edge of the annular duct, and the sawtooth assemblies are located between two adjacent stator blades, so that the non-continuous sawtooth assemblies on the trailing edge of the annular duct can improve the problem of large thrust loss and poor noise reduction effect caused by the continuous sawtooth structure.

[0057] In one embodiment, the arrangement area of the sawtooth assembly 50 also needs to be further limited, each sawtooth assembly 50 is arranged at intervals in the circumferential direction of the annular duct 10, and the coverage area of the sawtooth assembly 50 is the area between the suction surface of one of the two adjacent stator blades 20 and the preset position, and the preset position is a position determined according to the middle position between the two adjacent stator blades 20.

[0058] The first stator includes multiple stator blades 20, each stator blade 20 includes a convex curved surface and a concave curved surface, and the suction surface of the stator blade 20 is the convex curved surface of the stator blade 20.

[0059] Generally, the central position between the two stator blades 20 in the first stator can be determined first, and the sawtooth assembly 50 is arranged between the central position between the two stator blades 20 and the suction surface of any one of the two stator blades 20. It should be noted that each sawtooth assembly 50 is arranged at intervals in the circumferential direction of the trailing edge of the annular duct.

[0060] The pump-jet propeller provided in the embodiments of the present application sets the sawtooth assembly between any two stator blades of the first stator, thereby improving the problem of large thrust loss and poor noise reduction effect caused by the continuous sawtooth structure, and interfering with the wake field of the pump-jet propeller to reduce vibration and noise.

[0061] In one embodiment, the number of sawtooth assemblies 50 is equal to the number of stator blades 20. Generally, the first stator of the pump-jet propeller 01 provided in the embodiments of the present application has 13 stator blades 20, that is, 13 sawtooth assemblies 50 are arranged in the circumferential direction of the trailing edge of the annular duct 10.

[0062] The pump-jet propeller provided in the embodiments of the present application sets the sawtooth assembly equal to the number of stator blades, which can adaptively improve the problem of large thrust loss and poor noise reduction effect caused by the continuous sawtooth structure, and interfere with the wake field of the pump-jet propeller to reduce vibration and noise.

[0063] In one embodiment, the height of each sawtooth structure 500 also needs to be limited, referring to Figure 2 and Figure 3The height of the sawtooth structure 500 is not more than 0.1 times the chord length of the annular duct 10, and is not more than the axial distance between the position of the trailing edge of the first stator and the position of the trailing edge of the annular duct 10.

[0064] The position of the trailing edge of the first stator is the position of the outer edge of each stator blade 20 in the first stator, and the position of the outer edge is close to the position of the trailing edge of the annular duct 10.

[0065] The pump-jet propeller provided by the embodiment of the present application further limits the height of the sawtooth structure, provides data basis for manufacturing the sawtooth structure, and thus realizes vibration reduction and noise reduction of the wake field of the pump-jet propeller.

[0066] In one embodiment, the relationship between the height of each sawtooth structure 500 and the width of the sawtooth structure 500 needs to be limited, as shown in Figure 3 The ratio of the height of the sawtooth structure 500 to the width of the sawtooth structure 500 is not less than 2 and not more than 4.

[0067] It should be noted that each sawtooth structure 500 can be a triangle-like structure, for example, a triangle with a ratio of height to width of 2-4, for example, a sine shape with a ratio of height to width of 2-4, or other shapes with a ratio of height to width of 2-4, which are not limited in the embodiment of the present application.

[0068] The pump-jet propeller provided by the embodiment of the present application further limits the ratio between the height of the sawtooth structure and the width of the sawtooth structure, provides data basis for manufacturing the sawtooth structure, and thus realizes vibration reduction and noise reduction of the wake field of the pump-jet propeller.

[0069] In one embodiment, as shown in Figure 1 The pump-jet propeller 01 further includes a second stator 60, which is arranged inside the annular duct 10, and is connected with the hub 40 and the inner wall of the annular duct 10, and is away from the trailing edge of the annular duct 10.

[0070] One end of the second stator 60 is connected with the hub 40, and the other end is connected with the inner wall of the annular duct 10, so that the second stator 60 is fixedly connected with the hub 40 and the annular duct 10. In addition, the second stator 60 is arranged in the pump-jet propeller 01 to provide pre-rotation for the rotor 30, improve the working conditions of the rotor 30, thereby improve the propelling efficiency of the rotor 30, and effectively reduce the radiation noise.

[0071] The pump-jet propeller provided by the embodiment of the present application sets the second stator to provide a basis for further noise reduction.

[0072] In one embodiment, the surfaces of the annular duct 10, the first stator, the rotor 30 and the second stator 60 in the pump-jet propeller 01 are all provided with slip surfaces.

[0073] In the embodiments of the present application, the surfaces of the annular duct 10, the first stator, the rotor 30 and the second stator 60 in the pump-jet propeller 01 are provided with slip surfaces, so that the fluid in contact with the surfaces generates a certain slip velocity when flowing through the surfaces, thereby reducing the velocity gradient at the near-wall surface, and reducing the shear stress and frictional resistance at the fluid-solid interface. At the same time, the slip can change the pressure distribution of the surfaces of the annular duct, the first stator, the second stator and the rotor, reduce the pressure difference resistance, and improve the profile airfoil lift, thereby improving the overall thrust and efficiency of the pump-jet propeller, and achieving the improvement of the pump-jet hydrodynamic performance.

[0074] Alternatively, the slip surfaces can be provided only on the surfaces of the annular duct 10, or only on the surfaces of the first stator, or only on the surfaces of the rotor 30, or only on the surfaces of the second stator 60, or on the surfaces of the annular duct 10 and the first stator, or on the surfaces of the annular duct 10 and the rotor 30, or on the surfaces of the annular duct 10 and the second stator 60, or on the surfaces of the first stator and the rotor 30, or on the surfaces of the first stator and the second stator 60, or on the surfaces of the rotor 30 and the second stator 60, or on the surfaces of any three of the annular duct 10, the first stator, the rotor 30 and the second stator 60, or on the surfaces of the annular duct 10, the first stator, the rotor 30 and the second stator 60. It should be noted that the present application does not limit the position of the slip surface.

[0075] In one embodiment, the slip lengths of the corresponding slip surfaces of the annular duct 10, the first stator, the rotor 30 and the second stator 60 in the pump-jet propeller 01 can be the same or different.

[0076] It should be noted that the slip surface is measured by the slip length, and the slip length is defined as the normal distance corresponding to the extension of the slip velocity along the velocity gradient at the near-wall surface to zero velocity to the inside of the solid.

[0077] In the embodiment of the present application, by arranging sliding surfaces with a certain sliding length on the annular duct, the first stator, the rotor and the second stator of the pump-jet propulsor, and arranging a plurality of serration components arranged at intervals along the circumference of the annular duct on the trailing edge of the annular duct, that is, coupling the discontinuously distributed local serration components with the sliding surface, the pump-jet thrust loss caused by the serration structure can be overcome, the hydrodynamic performance of the pump-jet can be significantly improved, the pump-jet efficiency can be improved, and the pump-jet noise can be further reduced on the basis of the serration structure, thereby showing significant advantages over the existing technology.

[0078] In one embodiment, the above-mentioned sliding length is 20 -500 and the sliding surface includes at least one of a carbon-based coating surface and a fluorine-containing coating surface.

[0079] It should be noted that the slip surface can be realized by selecting a coating that does not significantly change the surface roughness of the pump spray, such as a carbon-based coating, a fluorine-containing coating, etc., which can be applied to the surface of various pump spray components by spraying or coating, and has the advantages of easy implementation and strong durability.

[0080] Optionally, the following provides two matching relationships between the sizes of sawtooth structures and the sliding surfaces, including: one is a large sawtooth structure, that is, the height of the sawtooth structure is 6 mm, not exceeding 0.1 times the chord length of the annular duct, and not exceeding the axial distance between the trailing edge of the second stator and the trailing edge of the annular duct, and the corresponding width of the sawtooth structure is 3 mm; the other is a small sawtooth structure, the height of the sawtooth structure is half the height of the large sawtooth structure, that is, 3 mm, and the corresponding width of the sawtooth structure is 1.5 mm. Among them, the large sawtooth structure can start from the suction surface of the second stator and be arranged circumferentially along the trailing edge of the annular duct of the pump-jet propulsor, with 4 teeth arranged at each location, and a total of 13 locations arranged along the circumference, for a total of 52 teeth. The small sawtooth structure also starts from the suction surface of the second stator and is arranged circumferentially along the trailing edge of the annular duct of the pump-jet propulsor, with 8 teeth arranged at each location, and a total of 13 locations arranged along the circumference, for a total of 104 teeth. The sliding surface is set on the duct, the first stator, and the second stator, and the sliding length is set to 100 The pump-jet propulsor with the local sawtooth structure and the sliding surface controlled simultaneously is recorded as “6-3-local-100 ”, “3-1.5-local-100 ”.

[0081] In one embodiment, a "6-3-local-100 ”, “3-1.5-local-100 The simulation results of the pump-jet propulsor are as follows:

[0082] For the pump-jet propulsion system in the above embodiment, a fluid domain is established and a fluid grid is divided to calculate its hydrodynamic and noise performance at the self-propulsion operating point under non-uniform incoming flow. First, SST k- The model performs steady-state flow field calculations. After the calculations are stable, the IDDES method is used for transient calculations. The calculation time step is set to 1 rotation of the pump-jet rotor. Corresponding to the time, the transient calculation time step is 5400 steps (i.e., the rotor rotates 15 times). Furthermore, after the IDDES method calculation is stable, the FW-H model is turned on to calculate and collect noise signals, and the collection time step is 5400 steps (i.e., the rotor rotates 15 times). After the calculation is completed, the hydrodynamic and noise data of the last 15 weeks are collected for subsequent analysis. Among them, the hydrodynamic performance of the pump-jet propulsion system is mainly measured by the thrust coefficient and propulsion efficiency. The thrust coefficient is the ratio of the thrust exerted on each component and the whole of the pump-jet to the product of the fluid density, the square of the speed, and the fourth power of the diameter. The flow noise performance is measured by the sound pressure level index, i.e., the i-th frequency The sound pressure level (SPL) at is expressed in the following formula (1):

[0083]

[0084] in, is the reference sound pressure. = 1 10 -6 Pa, Indicates the i-th frequency The corresponding sound pressure.

[0085] The calculation formula for the Overall Sound Pressure Level (OASPL) is as follows (2):

[0086]

[0087] It should be noted that during the simulation process, the noise receiving points and azimuth angles must be defined as follows: With the center of the pump-jet propulsor's rotor as the center, noise receiving points are set on the circumference of the xy vertical plane, xz horizontal plane, and yz cross-section at a distance of 1 meter from the center of the pump-jet propulsor's rotor. Within the xy vertical plane, the positive x-axis corresponds to an azimuth of 0°, and the positive y-axis corresponds to an azimuth of 90°; within the xz horizontal plane, the positive x-axis corresponds to an azimuth of 0°, and the negative z-axis corresponds to an azimuth of 90°; within the yz cross-section, the negative z-axis corresponds to an azimuth of 0°, and the positive y-axis corresponds to an azimuth of 90°. Therefore, the 0° and 90° azimuth angles within the yz cross-section correspond to the 90° azimuth angle within the xz horizontal plane and the 90° azimuth angle within the xy vertical plane, respectively. Therefore, subsequent analysis will primarily be conducted within the xy vertical plane and the xz horizontal plane.

[0088] Furthermore, in order to effectively compare the technical effects of the technical solutions provided in the embodiments of the present application, the hydrodynamic and flow noise performances of the basic pump-jet propulsor model without slip and serration, the pump-jet propulsor model with a continuously arranged serration structure, and the pump-jet propulsor model with a locally arranged serration structure in the present application are compared. The specific results are as follows (it should be noted that the operating conditions of the pump-jet propulsor model with a locally arranged serration structure in the present application are consistent with the operating conditions of the pump-jet propulsor model with both a locally arranged serration structure and a sliding surface in Example 2):

[0089] Example 1:

[0090] Effect of sawtooth structure on the hydrodynamic performance of pump-jet propulsor Figure 4 and Figure 5 It can be seen that the serration structure causes a decrease in duct thrust, and thus in the overall thrust of the pump-jet. Larger serration structures cause greater thrust loss in the duct and pump-jet as a whole, while smaller serration structures cause less thrust loss in the duct and pump-jet as a whole. Furthermore, the thrust loss caused by the local serration structure is less than that of the circumferentially continuously arranged serration structure. The continuously arranged serration structures "6-3" and "3-1.5" cause 93.2% and 35.1% thrust loss in the duct, respectively, corresponding to 1.8% and 0.8% overall thrust losses, respectively. The local serration structures "6-3-local" and "3-1.5-local" cause 57.6% and 12.3% thrust loss in the duct, respectively, corresponding to 1.3% and 0.2% overall thrust losses, respectively. Therefore, the local serration-type pump-jet has superior hydrodynamic performance compared to the existing continuously arranged serration-type pump-jet.

[0091] Effect of sawtooth structure on flow noise performance of pump-jet propulsor Figure 6 and Figure 7, it can be seen that the "3-1.5" sawtooth structure and the "6-3-local" sawtooth structure can significantly reduce the line spectrum sound pressure level of the pump-jet rotor at a 90° azimuth angle in the xy vertical plane and the xz horizontal plane, reducing the rotor line spectrum sound pressure level by 3.6 dB and 5.7 dB in the xy vertical plane, and by 4.8 dB and 5.2 dB in the xz horizontal plane, respectively. The overall line spectrum level of the pump-jet is reduced by 3.9 dB and 4.2 dB in the xy vertical plane, and by 6.3 dB and 6.0 dB in the xz horizontal plane, respectively. However, the "6-3" and "3-1.5-local" sawtooth structures have limited effect on suppressing the line spectrum noise of the pump-jet rotor, with the reduction in line spectrum sound pressure level within 1.0 dB.

[0092] The effect of sawtooth structure on the total sound pressure level of pump-jet propulsion can be found in Figure 8 and Figure 9 It can be seen that at the 90° azimuth angle in the xy vertical plane, the large zigzag structures "6-3" and "6-3-local" cause a reduction of 1.7 dB and 1.8 dB in the total duct sound pressure level, respectively, while the small zigzag structures "3-1.5" and "3-1.5-local" reduce the total duct sound pressure level by less than 0.5 dB; at the 90° azimuth angle in the xz horizontal plane, the large zigzag structures "6-3" and "6-3-local" cause a reduction of 2.5 dB and 3.2 dB in the total duct sound pressure level, respectively, while the small zigzag structures "3-1.5" and "3-1.5-local" reduce the total duct sound pressure level by 1.2 dB and 1.8 dB, respectively. That is, the effect of the serrated structure on the total sound pressure level of the duct is stronger in the xz horizontal plane than in the xy vertical plane, and in the xz horizontal plane, the local serrated structure shows a noise reduction advantage over the circumferentially continuously arranged serrated structure.

[0093] The sawtooth structure also causes the total rotor sound pressure level to decrease in the xy vertical plane and the xz horizontal plane, see Figure 8 and Figure 9 At a 90° azimuth angle in the xy vertical plane, the "3-1.5" and "6-3-local" sawtooth structures reduce the rotor's total sound pressure level by 1.6 dB and 2.1 dB, respectively. At a 90° azimuth angle in the xz horizontal plane, the reductions are 2.1 dB and 2.0 dB, respectively. The effects of both the "3-1.5-local" and "6-3" sawtooth structures on the rotor's total sound pressure level are within 1.0 dB.

[0094] For the total sound pressure level of the pump jet as a whole, see Figure 8 and Figure 9It can be seen that in the xy vertical plane and the xz horizontal plane, the "6-3-local" zigzag structure has the greatest reduction in the overall total sound pressure level of the pump-jet. At an azimuth angle of 90° in the xy vertical plane and the xz horizontal plane, the "6-3-local" zigzag structure causes a reduction in the overall total sound pressure level of the pump-jet of approximately 2.2 dB and 2.6 dB, respectively. The reductions of the other three zigzag structures are relatively small.

[0095] The above simulation results show that the "6-3-local" sawtooth structure has the best effect in reducing the overall sound pressure level of the pump jet. In addition, the "6-3-local" sawtooth structure only causes an efficiency loss of about 0.7% in the overall efficiency of the pump jet, and the impact on the pump jet's hydrodynamic performance is relatively small. This shows that the local sawtooth structure has an advantage over the continuous arrangement sawtooth structure in simultaneously regulating hydrodynamic and flow noise performance, making the pump jet have relatively better overall performance.

[0096] Example 2:

[0097] Next, we introduce 100 The dynamic performance of pump jet under the coupling effect of slip length and four sawtooth structures, see Figure 10 The application of the sliding interface improves the degradation of the pump water jet dynamic performance caused by the sawtooth structure, which increases the thrust coefficients of the duct and the rear stator, reduces the drag coefficient of the front stator, increases the torque coefficient of the rear stator, and 100 The coupling of slip length and different sawtooth structures has little effect on the increase in thrust coefficient of the rear stator and the decrease in drag coefficient of the front stator, which are around 20% and 38% respectively. However, the coupling of interface slip and different sawtooth structures has a certain effect on the increase in thrust coefficient of the duct. The percentage increase in thrust coefficient of the duct has the following relationship: "3-1.5-100 - Local">"3-1.5-100 ">“6-3-100 - Local">"6-3-100 ", corresponding to an increase in catheter thrust of 217%, 196%, 166% and 132% respectively.

[0098] The increase in the thrust coefficient of the annular duct significantly affects the overall thrust coefficient of the pump-jet, and thus affects the overall propulsion efficiency of the pump-jet. Figure 11 It can be seen that "3-1.5-100 - Local", "3-1.5-100 ”, “6-3-100 - Local" and "6-3-100 The four coupling control schemes correspond to increases in pump-jet efficiency of 7.7%, 7.4%, 6.9%, and 6.4%, respectively, which increase the overall propulsion efficiency of the pump-jet to 80.7%, 80.4%, 79.8%, and 79.4%, respectively. It can be seen that the effects of interface slip and sawtooth structure on the pump-jet hydrodynamic performance have a simple superposition relationship, and interface slip significantly improves the pump-jet hydrodynamic performance loss caused by the sawtooth structure, thereby greatly improving the pump-jet hydrodynamic performance.

[0099] Furthermore, the effect of interface slip and discontinuous sawtooth structure coupling on the flow noise performance of pump-jet propulsion can be found in Figure 12 and Figure 13 , we can know that “3-1.5-100 - Local" and "6-3-100 -local" coupling control scheme has a more significant effect on reducing the rotor line spectrum sound pressure level. At the 90° azimuth angle in the xy vertical plane, the rotor line spectrum sound pressure level is reduced by 13.7 dB and 15.3 dB respectively, and at the 90° azimuth angle in the xz horizontal plane, the rotor line spectrum sound pressure level is reduced by 12.4 dB and 13.8 dB respectively. At the same time, it also causes a significant reduction in the overall line spectrum sound pressure level of the pump jet. The "6-3-100 The coupling control scheme causes an increase of about 1.5 dB in the rotor line spectrum sound pressure level, resulting in a 1.2 dB increase and a negligible 0.2 dB decrease in the overall line spectrum sound pressure level of the pump jet in the xy vertical plane and the xz horizontal plane.

[0100] See also Figure 14 and Figure 15 , 100 The total sound pressure level of the duct under the coupling effect of interface slip and four bionic structures is reduced, and the total sound pressure level of the duct corresponding to the coupling of interface slip and different bionic structures is not much different. The total sound pressure level reduction of the pump jet duct in the xy vertical plane is in the range of 4.0-4.4 dB, while at the 90° azimuth angle in the xz horizontal plane, the "3-1.5-100 ” and “6-3-100 -local" coupling regulation has a relatively high reduction in the total sound pressure level of the duct, which is 5.6 dB and 5.2 dB respectively. For the rear stator, 100 Under the coupling effect of interface slip and four bionic structures, the total sound pressure level is reduced to a certain extent, and the reduction is relatively large in the xy vertical plane, with a total sound pressure level reduction of 1.2-2.1 dB at the 90° azimuth angle, while the reduction is smaller in the xz horizontal plane, with a total sound pressure level reduction of 0.7-1.4 dB at the 90° azimuth angle. The coupling of interface slip and bionic structure will also have a certain impact on the total sound pressure level of the rotor. Figure 14 、 Figure 15 It can be seen that "6-3-100 "The coupling control scheme causes the total sound pressure level of the rotor to increase, while the other three coupling control schemes all reduce the total sound pressure level of the rotor, and the "3-1.5-100" coupling of the local sawtooth structure and the sliding surface -Partial", "6-3-100 The "-local" scheme has a better control effect, with a reduction effect of 2.8 dB and 2.2 dB in the rotor total sound pressure level at an azimuth angle of 90° in the xy vertical plane, and a reduction effect of 3.0 dB and 2.1 dB in the rotor total sound pressure level at an azimuth angle of 90° in the xz horizontal plane.

[0101] For the overall sound pressure level of the pump jet, the four coupling control schemes all showed a reduction in the total sound pressure level, and the local sawtooth structure and sliding surface coupling control effect was better, "3-1.5-100 - Local" and "6-3-100 The "-local" coupling control scheme has a total sound pressure level reduction of 3.7 dB and 3.3 dB at an azimuth angle of 90° in the xy vertical plane, and a total sound pressure level reduction of 4.3 dB and 4.2 dB at an azimuth angle of 90° in the xz horizontal plane. Therefore, 100 Among the four coupling control schemes of interface slip and sawtooth structure, “3-1.5-100 - Local" and "6-3-100 - Local" scheme has a lower overall pump spray sound pressure level, "3-1.5-100 "The second is the "6-3-100 "The scheme will have an adverse effect on the overall sound pressure level of the pump jet, indicating the significant advantages of the local sawtooth structure and sliding surface coupling control scheme proposed in this invention.

[0102] At this point, the technical advantages of the technical solution proposed by the present invention are basically clear. The total sound pressure level and the corresponding line spectrum sound pressure level of the pump-jet propulsion system under the interaction of interface slip with the four bionic structures of "3-1.5", "6-3", "3-1.5-local", "6-3-local" and their coupling. Figure 16 and Figure 17 It can be seen that among the nine control schemes of only interface slip control, only sawtooth structure control and the two coupled control, “3-1.5-100 -Partial", "6-3-100 - local" coupling control scheme has lower pump-jet overall sound pressure level and line spectrum sound pressure level, and the "6-3-100 -local" coupling control scheme has the lowest line spectrum sound pressure level. Furthermore, it can be seen from Table 1 below that "3-1.5-100 - Local" and "6-3-100 The "local" coupling control scheme significantly improves the propulsion efficiency of the pump-jet, with efficiency improvements of 7.7% and 6.8% respectively compared to the basic pump-jet.

[0103] Table 1 Comparison of pump water jet dynamic performance under different control schemes

[0104]

[0105] Therefore, "3-1.5-100 - Local" and "6-3-100 Both the "local" coupling control schemes significantly improve the hydraulic and flow noise performance of the pump jet, which has significant technical advantages compared to the continuous arrangement of sawtooth structures in the prior art, which causes a decrease in the hydraulic performance of the pump jet and has limited noise reduction effects. In addition, compared with the continuous arrangement of sawtooth structures in the prior art, the local bionic structure proposed in the present invention can significantly reduce processing time and costs due to the removal of less material, and has less impact on the overall mechanical properties of the pump jet conduit. The sliding surface can be achieved through plating or spray coating, which has the advantages of easy implementation and strong durability.

[0106] From the above analysis, it can be seen that compared with the existing technology, the beneficial effect of the present invention is that the new type of pump-jet propulsion proposed by the present invention can further improve the noise reduction effect of the serration structure while reducing the loss of pump-jet water dynamic performance caused by the continuous distributed serration structure. Furthermore, the pump-jet propulsion proposed by the present invention, which couples the local serration structure with the sliding surface, makes it possible to take into account both the improvement and regulation of the pump-jet water dynamic performance and the flow noise performance, and the improvement effect is significant, which has significant technical advantages over the existing technology. In addition, the technical solution proposed by the present invention can reduce processing time and processing costs, and has less impact on the overall mechanical properties of the annular duct of the pump-jet propulsion, and has broad application prospects in the fields of surface ships, underwater navigation bodies, etc.

[0107] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0108] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A pump-jet propulsion system, characterized in that: The pump-jet propulsor comprises an annular duct, a first stator, a rotor and a hub, wherein the first stator, the rotor and the hub are all arranged inside the annular duct, the first stator is close to the trailing edge of the annular duct, the first stator and the rotor are connected to the hub, the first stator is connected to the inner wall of the annular duct, the trailing edge of the annular duct is provided with a plurality of sawtooth assemblies arranged at intervals along the circumference of the annular duct, the sawtooth assembly is located between two adjacent stator blades, the sawtooth assembly comprises at least one sawtooth structure, and the first stator comprises a plurality of stator blades; The rotor is used to rotate and generate hydrodynamic force to enable the pump-jet propeller to generate forward thrust; The sawtooth assembly is used to interfere with the wake field of the pump-jet propulsor to reduce vibration and noise.

2. The pump-jet propulsion system according to claim 1, characterized in that: Each of the serration assemblies is arranged at equal intervals along the circumference of the trailing edge of the annular duct, and the coverage area of ​​the serration assemblies is the area between the suction surface of one of the two adjacent stator blades and a preset position, and the preset position is a position determined according to the middle position between the two adjacent stator blades.

3. The pump-jet propulsion device according to claim 1 or 2, characterized in that: The number of the sawtooth assemblies is equal to the number of the stator blades.

4. The pump-jet propulsion device according to claim 1 or 2, characterized in that: The height of the sawtooth structure does not exceed 0.1 times the chord length of the annular duct, and does not exceed the axial distance between the trailing edge of the first stator and the trailing edge of the annular duct.

5. The pump-jet propulsion device according to claim 4, characterized in that: The ratio of the height of the sawtooth structure to the width of the sawtooth structure is not less than 2 and not more than 4.

6. The pump-jet propulsion system according to claim 1, characterized in that: The pump-jet propulsor further includes a second stator, which is disposed inside the annular duct. The second stator is respectively connected to the hub and the inner wall of the annular duct, and the second stator is away from the trailing edge of the annular duct.

7. The pump-jet propulsion device according to claim 6, characterized in that: Surfaces of the annular duct, the first stator, the rotor, and the second stator are provided with sliding surfaces.

8. The pump-jet propulsion device according to claim 7, characterized in that: The sliding lengths of the sliding surfaces corresponding to the annular duct, the first stator, the rotor, and the second stator are the same or different.

9. The pump-jet propulsion device according to claim 8, characterized in that: The slip length is 20 -500 between.

10. The pump-jet propulsion device according to any one of claims 7 to 9, characterized in that: The slip surface includes at least one of a carbon-based coating surface and a fluorine-containing coating surface.

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