Device for inhibiting cavitation of pump-jet propeller and reducing noise

Abstract

The invention provides a device for inhibiting cavitation of a pump-jet propeller and reducing noise, and belongs to the technical field of underwater vehicle propelling, energy conservation and noise reduction, the device comprises a guide pipe, a rotor, a propeller hub and a porous stator, the rotor and the porous stator are mounted on the propeller hub, the guide pipe is supported by the porous stator, the porous stator is of a porous structure, and the rotor is connected with the porous stator. The porous structure is used for improving the flow field of the rotor and improving the performance of the rotor and is located at the rear edge of the stator. The rear edge of the stator is provided with the porous structure, the porous structure is a plurality of small holes with different sizes, the porous structure restrains the trailing vortex of the stator in a micropore seepage mode, the inflow pressure of the rotor is greatly increased, the low-pressure area of the suction surface of the rotor is reduced, therefore, cavitation of the surface of the rotor is restrained, and the service life of the rotor is prolonged. The multi-hole structure scatters the trailing vortex, and the pulsating pressure amplitude of a rotor area is obviously weakened, so that the generation of broadband noise is effectively inhibited, and the radiation noise level of the pump-jet propeller is reduced.

Description

Technical Field

[0001] This invention belongs to the field of underwater vehicle propulsion and energy-saving noise reduction technology, specifically relating to a device for suppressing cavitation and reducing noise in pump-jet propulsion. Background Technology

[0002] As the core power system of the new generation of underwater equipment, the performance of pump-jet propulsion directly affects the efficiency of deep-sea resource development. Compared with traditional propellers, pump-jet propulsion, with its integrated duct-rotor-stator design, has advantages such as high thrust density, low vibration and noise, and deep-sea adaptability.

[0003] Cavitation occurs during the efficient operation of pump-jet propulsion systems. This phenomenon significantly restricts the hydrodynamic performance, service life, and stealth capabilities of pump-jet propulsion systems. When cavitation covers part of the blade area, rotor efficiency drops sharply, and the collapse of cavitation bubbles on the rotor blade surface triggers microjets that impact the rotor structure, leading to material cavitation failure and shortening the lifespan by more than 60%. Furthermore, the initiation, evolution, and collapse of cavitation generate enormous cavitation noise, producing characteristic line spectrum peaks in the 100-500Hz frequency band, which increases the acoustic signal exposure distance of underwater platforms several times. Existing stators suffer from the following defects: strong tip vortices / hub vortices are generated at the trailing edges of solid stator blades, placing the rotor within the stator's vortex structure, resulting in high surface pressure and inducing cavitation in the rotor's low-pressure region. Summary of the Invention

[0004] The purpose of this invention is to provide a device for suppressing cavitation and reducing noise in pump-jet propulsion, further improving the hydrodynamic performance of pump-jet propulsion under different operating conditions, reducing the excitation force and noise of pump-jet propulsion, and improving the stealth performance of underwater vehicles.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A device for suppressing cavitation and reducing noise in a pump-jet propulsion system includes: a duct, a rotor, a hub, and a porous stator. The rotor and the porous stator are mounted on the hub. The duct is supported by the porous stator. The porous stator has a porous structure to improve the rotor flow field and enhance rotor performance. The porous structure is located at the trailing edge of the stator.

[0007] Furthermore, the porous structure of the porous stator is a micropore array with a diameter ≤ 1 mm.

[0008] Furthermore, the porous structure of the porous stator is located in the 30% chord length region of the trailing edge of the stator blade.

[0009] Furthermore, the pore density of the porous structure of the porous stator is higher at the tip of the blade than at the root.

[0010] Furthermore, the diameters of the micropores in the porous structure vary.

[0011] Furthermore, the duct is either an acceleration duct or a deceleration duct; when an acceleration duct is used, the rotor thrust is increased, thereby improving the hydrodynamic performance of the pump-jet propulsion system; when a deceleration duct is used, the velocity distribution of the rotor suction surface is changed, thereby improving the rotor's cavitation performance.

[0012] Furthermore, the rotor is located at the radial center of the suppressor pump-jet propulsion unit, and the rotor is located behind the porous stator.

[0013] Furthermore, the rotor is located at the radial center of the conduit, and is axially positioned downstream and rearward, behind the porous stator.

[0014] Furthermore, the number of blades of the rotor and the porous stator should be coprime, and the porous stator should have more blades than the rotor to disperse the noise spectrum and reduce the peak value of the discrete spectrum.

[0015] The beneficial effects of this invention are as follows:

[0016] This invention adds a porous structure to the stator of the pump-jet propulsion system to disperse the stator wake vortex, improve the downstream flow field of the stator, and solve the problem of adverse interference to the rotor caused by the shedding of the stator wake vortex in the prior art.

[0017] The porous structure in the porous stator of this invention suppresses stator wake vortices through micropore permeation, significantly increasing the rotor inflow pressure. This reduces the low-pressure zone on the rotor suction surface, thereby suppressing cavitation on the rotor surface. It fundamentally solves the erosion problems on the rotor surface caused by cavitation initiation and collapse, thus improving the rotor's service life.

[0018] The porous stator of this invention disperses the wake vortex through its porous structure, significantly reducing the amplitude of pulsating pressure in the rotor region, thereby effectively suppressing the generation of broadband noise and reducing the radiated noise level of the pump-jet propulsion system. Attached Figure Description

[0019] Appendix Figure 1 This is a schematic diagram of the structure of the present invention;

[0020] Appendix Figure 2 This is a schematic diagram of the inside of the catheter of the present invention;

[0021] Appendix Figure 3 This is the front view of the present invention;

[0022] Appendix Figure 4 This is a schematic diagram of the porous structure of the porous stator of the present invention.

[0023] In the attached diagram: 1. Conduit, 2. Rotor, 3. Hub, 4. Porous stator. Detailed Implementation

[0024] The present invention will now be further described with reference to the accompanying drawings.

[0025] This invention provides a device for suppressing cavitation and reducing noise in pump-jet propulsion systems, applicable to underwater vehicles, as shown in the attached figure. Figure 1-3 As shown, it includes: a duct 1, a rotor 2, a hub 3, and a porous stator 4. The rotor 2 and the porous stator 4 are mounted on the hub. The duct 1 is supported by the porous stator 4. The porous stator 4 has a porous structure to improve the rotor flow field and enhance rotor performance. The porous structure is located at the trailing edge of the stator.

[0026] The duct 1 is a stationary component that improves the flow field around the rotor 2; the duct can assist the stator in improving the incoming flow conditions to the rotor. Depending on the specific situation, different airfoil profiles can be used to improve different rotor performances. If an acceleration duct is used, the rotor thrust can be increased, thereby improving the hydrodynamic performance of the pump-jet propulsion system; if a deceleration duct is used, the velocity distribution on the rotor's suction surface can be changed, thereby improving the rotor's cavitation performance.

[0027] Furthermore, the duct is located at the outermost radial end of the entire pump-jet propulsion system and requires stator support. This protects internal components and integrates the flow field. Different cross-sectional shapes can also provide different performance enhancements to the pump-jet propulsion system. Acceleration-type ducts can accelerate the passing fluid, according to the momentum theorem... As velocity increases, thrust increases; therefore, accelerating ducts can improve the hydrodynamic performance of pump-jet propulsion systems. Decelerating ducts, on the other hand, can improve the velocity distribution on the rotor surface and reduce the incoming flow velocity. According to Bernoulli's equation... As speed decreases, pressure increases. When the rotor surface pressure is lower than the saturated vapor pressure of water, cavitation occurs. Therefore, the deceleration duct can delay cavitation by increasing the rotor surface pressure, thereby improving the cavitation performance of the pump-jet propulsion system.

[0028] The rotor 2 is a rotating component supported by the hub 3. It is the main output component, receiving energy from the outside and providing thrust to the underwater vehicle.

[0029] The hub 3 is used to fix the rotor 2 and the porous stator 4.

[0030] As attached Figure 4As shown, the porous stator 4 is a stationary component used to support the duct 1 and improve the rotor flow field, thereby enhancing rotor performance. The porous stator 4 improves the incoming flow to the rotor, increasing its work capacity and thus improving the overall efficiency of the pump-jet propulsion system. Furthermore, the porous structure suppresses flow separation and vortex shedding within the stator itself, weakens the wake vortex intensity, and reduces pressure pulsation, indirectly improving the rotor inflow quality and thus suppressing rotor cavitation.

[0031] The diameter of the holes in the porous rotor should be strictly ≤1mm, and holes are prohibited in the leading edge region of the blades. Because there are local high-pressure peaks in the high angle of attack region of the leading edge, opening holes will cause high-speed jet disturbance, disrupt the attached flow state, and induce cavitation.

[0032] In terms of the structure of the porous stator, if the porous structure is to improve the rotor cavitation performance, the position of the openings at the trailing edge must be precisely located. The porous position should be in the 30% chord length region of the stator's trailing edge, which can suppress flow separation and thus reduce eddy intensity. The pore density at the blade tip should be higher than that at the blade root, which can more significantly disturb the stability of the vortex core and disrupt secondary flow accumulation, thereby breaking up tip vortices and weakening hub vortices, and reducing stator pressure pulsation.

[0033] The porous stator should be located upstream of the rotor, which is beneficial for interfering with the downstream flow field where the rotor is located and improving its flow field environment.

[0034] In this embodiment, the number of blades of the stator and rotor of the device should be coprime, and the number of blades of the stator should be greater than that of the rotor, in order to disperse the noise spectrum and reduce the peak value of the discrete spectrum.

[0035] The rotor 2 of this invention is connected to the drive shaft via the hub 3. The drive shaft provides the rotational speed to drive the rotor to rotate, creating a pressure difference before and after the blade to generate thrust. The porous stator 4 is located upstream of the rotor, and its blade trailing edge 30% chord length region is provided with a micro-pore array with a diameter ≤1mm. Figure 4 (As shown), the blade tip pore density is higher than the blade root. The duct 1 is supported by the rotor hub 3 and connected to the rotor 2. The duct 1 is located on the outermost side of the device, and its airfoil profile can be either an acceleration type (to increase thrust) or a deceleration type (to improve cavitation). The microporous structure of the porous stator actively intervenes in the flow field through low-speed seepage: when the fluid flows through the trailing edge of the stator suction surface, the seepage energy released by the micropores inhibits boundary layer separation, reduces the trailing edge vortex shedding intensity, effectively weakens the vortex core stability of the tip vortex and hub vortex, disperses the vortex structure, and destroys the coherence of pressure pulsation. This flow field reconstruction can significantly reduce the inflow non-uniformity of the rotor and improve the flow field distribution on the rotor surface. The minimum pressure on the rotor suction surface is increased by 22%, which greatly delays the cavitation initiation moment, thereby weakening the impact of cavitation on the performance of the pump-jet propulsion system. The duct 1 assists in flow field optimization through rectification: if a deceleration type duct is used, due to the Bernoulli effect, it further increases the rotor surface pressure, and in synergy with the porous stator, it can further improve the cavitation performance of the pump-jet propulsion system.

[0036] As can be seen from the above technical solutions, the above embodiments of the present invention provide a device for suppressing cavitation and reducing noise in pump-jet propulsion. By using a porous stator to reconstruct the rotor inflow environment with microflow control, the device optimizes the cavitation performance of pump-jet propulsion from three perspectives: vortex source suppression, pressure field optimization, and pulsation force reduction. This provides underwater equipment with a propulsion device that features low cavitation, low noise, and long service life.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for suppressing cavitation and reducing noise in a pump-jet propulsion system, characterized in that, include: The components are: duct (1), rotor (2), hub (3), and porous stator (4). The rotor (2) and porous stator (4) are mounted on the hub. The duct (1) is supported by the porous stator (4). The porous stator (4) has a porous structure to improve the rotor flow field and enhance rotor performance. The porous structure is located at the trailing edge of the stator.

2. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 1, characterized in that, The porous structure of the porous stator (4) is a micropore array with a diameter ≤ 1 mm.

3. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 2, characterized in that, The porous structure of the porous stator (4) is located in the 30% chord length region of the trailing edge of the stator blade.

4. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 3, characterized in that, The pore density of the porous structure of the porous stator (4) is higher at the leaf tip than at the leaf root.

5. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 4, characterized in that, The porous structures have different micropore diameters.

6. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 1, 2, 3, or 4, characterized in that, The duct (1) is an acceleration duct or a deceleration duct; when an acceleration duct is used, the rotor thrust is increased, thereby improving the hydrodynamic performance of the pump-jet propulsion device; when a deceleration duct is used, the velocity distribution of the rotor suction surface is changed, thereby improving the cavitation performance of the rotor.

7. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 6, characterized in that, The rotor (2) is located at the radial center of the suppressor pump-jet propulsion unit, and the rotor (2) is located behind the porous stator (4).

8. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 7, characterized in that, The rotor (2) is located at the radial center of the conduit (1), and is located downstream and rearward in the axial direction, behind the porous stator (4).

9. The device for suppressing cavitation and reducing noise in a pump-jet propulsion system according to claim 7 or 8, characterized in that, The number of blades of the rotor (2) and the porous stator (4) should be prime numbers, and the porous stator (4) should have more blades than the rotor (2) in order to disperse the noise spectrum and reduce the peak value of the discrete spectrum.

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