Low-drag noise-reducing hydrogenerator rotor and hydrogenerator

Abstract

The application discloses a low-drag noise-reducing hydraulic generator rotor and hydraulic generator, and relates to the technical field of hydraulic generators. The rotor is assembled with an inter-pole wind shield between convex pole magnets, the outer peripheral curved surface of the rotor is consistent with the outer peripheral radius of the magnet, the inner side of the rotor is attached to the transition surface of the magnet, the ventilation hole is arranged, and the ventilation hole is fixed through the tensioning screw rod; the fan blades at the two ends of the rotor adopt NACA0012 / 0016 / 0018 airfoil fan blades. The hydraulic generator is assembled with a metal micro-perforated plate, an array type resistance-resistance compliant silencer without sound absorption material in the main ventilation air passage between the stator core and the air cooler, the plate body is arranged in series and the air inlet / outlet is bent by 45 degrees, and the parameters are accurately designed through the resonance formula. The application realizes the pole-shielding of the rotor and the accurate silencing of the main air passage, the double noise reduction makes the noise of the whole machine less than or equal to 65 dB(A), the wind resistance is low (the wind volume attenuation is less than or equal to 5%), the heat dissipation meets the standard, the structure is stable, the operation and maintenance cost is low, and the application is suitable for the demand of large-capacity and high-speed unit.

Description

Technical Field

[0001] This invention relates to the field of hydro-generator technology, and more specifically to a low-turbulence, low-noise hydro-generator rotor and hydro-generator. Background Technology

[0002] In the field of energy equipment, hydro-generators, as core equipment for clean energy conversion, directly affect the overall performance and user experience of the unit through their operational stability and noise control levels. Currently, the rotors of large hydro-generators generally adopt a salient pole structure. Due to the protruding magnetic poles, this structure has significant advantages such as simple structure, convenient maintenance, high heat dissipation efficiency, and suitability for low-speed operation. It has become the mainstream design form for hydro-generator rotors and is widely used in various hydropower projects.

[0003] However, as power generation technology advances towards higher speeds and larger capacities, the application of generator motors is becoming increasingly widespread. During normal operation, the outer circular velocity of the rotor can reach 120-130 m / s. Under these high-speed conditions, the inherent defects of the salient pole structure become increasingly apparent: the protruding magnetic poles disrupt the smooth flow of air, causing strong airflow disturbances; simultaneously, the centrifugal fans at both ends of the rotor, as key components for airflow circulation, also become core areas for turbulence generation during operation. These two sources of turbulence together constitute the main source of aerodynamic noise in hydro-generators, severely impacting the unit's sound quality indicators and the comfort of the operating environment.

[0004] Currently, industry-wide noise control solutions for hydro-generators primarily focus on end-of-pipe treatment methods such as sound insulation, sound absorption, and noise reduction—blocking noise propagation paths by installing soundproof enclosures, laying sound-absorbing materials, or installing silencers. However, these solutions fail to address the root cause of noise generation, resulting in limited noise reduction effects and often accompanied by increased wind resistance and maintenance costs. In contrast, research and technical solutions that optimize the rotor's structure and airflow to reduce airflow turbulence during rotor operation and thus suppress aerodynamic noise at its source remain scarce, making it difficult to meet the stringent requirements of high-speed generator motors for low noise and high stability. Therefore, developing a hydro-generator rotor structure that can reduce turbulence and aerodynamic noise at its source has become a pressing technical challenge for the industry. Summary of the Invention

[0005] To overcome the defects and shortcomings of the existing technology, this invention provides a low-turbulence, low-noise hydro-generator rotor and a hydro-generator. The purpose of this invention is to provide a method for controlling the turbulence of a salient-pole hydro-generator rotor and reducing aerodynamic noise. This invention achieves salient-pole motor non-polarization by assembling a specific structured inter-pole baffle between the rotor's salient poles to fill the outer circumference of the rotor's salient poles, thereby reducing the turbulence and aerodynamic noise caused by the salient poles.

[0006] To address the problems existing in the prior art, the present invention is implemented through the following technical solution.

[0007] The first aspect of the present invention provides a low-turbulence, low-noise hydro-generator rotor, including a rotor yoke and salient magnetic poles, the salient magnetic poles being uniformly assembled on the outer circumference of the rotor yoke; and an inter-pole wind baffle is assembled between the salient magnetic poles, the inter-pole wind baffle being assembled on the rotor yoke by a tensioning screw. The outer circumferential surface of the inter-pole wind baffle is arc-shaped, and the radius of the arc surface is the same as the radius of the outer circumferential surface of the salient magnetic pole. The inter-pole wind baffle includes a first wind baffle, a second wind baffle, and a screw connecting part, which are symmetrically arranged with respect to the screw connecting part. The screw connecting part extends from the outer circumferential surface of the inter-pole wind baffle towards the rotor yoke between two adjacent salient magnetic poles. A through screw hole is provided in the screw connecting part, and a countersunk hole for accommodating a tension nut assembled at the end of the tension screw is provided on the outer circumferential surface of the inter-pole wind baffle. The first wind baffle and the second wind baffle extend towards their respective salient magnetic poles, and an arc-shaped fitting surface is provided on the inner side of the first wind baffle and the second wind baffle. This arc-shaped fitting surface is adapted to and fits the arc-shaped transition surface between the inter-pole sidewall and the outer circumferential surface of the salient magnetic pole. Through ventilation holes are provided on the first wind baffle and the second wind baffle.

[0008] More preferably, centrifugal fans are mounted at both ends of the turbine generator rotor, and the blades of the centrifugal fans are airfoil blades such as NACA0012, NACA0016, and NACA0018.

[0009] More preferably, the connection between the first and second windbreaks and the screw connection is a rounded transition.

[0010] More preferably, the screw through hole in the screw connection part is provided with a cavity in the middle with an inner diameter larger than that of the screw through hole for weight reduction.

[0011] In a further preferred embodiment, a limiting block is provided at the end of the tensioning screw connected to the rotor yoke. The limiting block end of the tensioning screw passes through the rotor yoke through the yoke annular gap. A limiting groove adapted to the limiting block is provided on the inner circumferential surface of the rotor yoke. After passing through the yoke annular gap, the limiting block rotates at a set angle and embeds itself into the limiting groove.

[0012] More preferably, the tensioning screw is provided with a locking nut I, a locking nut II, and a limiting nut. The locking nut I cooperates with the limiting block to fix the tensioning screw to the rotor yoke; the locking nut II, the limiting nut, and the tensioning nut cooperate to fix the inter-pole baffle plate to the tensioning screw.

[0013] More preferably, a pad adapted to the screw connection portion is provided in the middle of the outer peripheral surface of the rotor yoke between two adjacent salient poles.

[0014] More preferably, the pad is welded to the outer peripheral surface of the rotor yoke.

[0015] More preferably, the ventilation hole is a circular hole or an oblong hole.

[0016] More preferably, the inter-electrode wind deflector is made of a non-magnetic material.

[0017] More preferably, the material of the inter-electrode wind deflector is a lightweight material such as cast aluminum or magnesium alloy AZ31B.

[0018] The second aspect of the present invention provides a low-turbulence noise-reducing hydro-generator. The low-turbulence noise-reducing hydro-generator provided by the present invention adopts the hydro-generator rotor structure described in the first aspect above. Based on this, the low-turbulence noise-reducing hydro-generator of the present invention further adds an array-type silencer with a specific structure to the main ventilation air path between the stator core and the air cooler, further reducing aerodynamic noise in the strong noise area of ​​the main ventilation air path of the hydro-generator and improving the sound quality of the hydro-generator unit.

[0019] The second aspect of this invention provides a low-turbulence, low-noise hydro-generator, comprising the hydro-generator rotor, stator core, stator frame, and air cooler described in the first aspect above; an array-type reactive-resistive composite silencer without sound-absorbing material is installed on the main ventilation path between the stator core and the air cooler, the array-type reactive-resistive composite silencer being fixed to the stator frame; the array-type silencer includes a silencer housing, and a plurality of micro-perforated plates are disposed inside the silencer housing, the plurality of micro-perforated plates being arranged along the airflow direction of the medium in the main ventilation path, the micro-perforated plates being bent at the air inlet and air outlet of the silencer housing, the plurality of micro-perforated plates being arranged in series at intervals, the spacing between adjacent micro-perforated plates being the cavity thickness, the aperture of a single micro-perforated plate being consistent, and the micropores being evenly distributed, the different micro-perforated plates employing differentiated apertures according to the dominant noise frequency.

[0020] In a further preferred embodiment, the pore diameter, pore spacing, plate thickness, and cavity thickness of the microperforated plate are calculated by back-calculating the pore diameter, pore spacing, plate thickness, and cavity thickness of the microperforated plate based on the dominant noise frequency band of the main ventilation path and the resonant frequency calculation formula of the microperforated plate.

[0021] A further preferred formula for calculating the resonant frequency of the micro-perforated plate is:

[0022] In the formula, This indicates the speed of sound, measured in m / s, which is approximately 340 m / s at room temperature. The perforation rate is the ratio of the total area of ​​the holes to the area of ​​the micro-perforated plate; t is the thickness of the micro-perforated plate in meters; and L is the depth of the cavity behind the micro-perforated plate in meters. This represents the end-diameter correction amount, taken as... d is the aperture.

[0023] Furthermore, the aperture of the micro-perforated plate should be determined to satisfy the condition that the aperture is less than the wavelength corresponding to the target noise reduction frequency / 10.

[0024] More preferably, the micropores on each microperforated plate are evenly distributed, and the spacing between the micropores on the microperforated plate is determined according to the perforation rate, which refers to the percentage of the total area of ​​all micropores on a single microperforated plate to the total area of ​​the microperforated plate.

[0025] More preferably, the array-type muffler is made of metal.

[0026] In a further preferred embodiment, the microperforated plate is bent at the air inlet and air outlet of the outer casing at a bending angle of 45°.

[0027] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. The inter-pole baffle of this invention, through a dual structural design of "precise matching of the outer arc surface" and "seamless adaptation of the inner contact surface," completely fills the gap between salient magnetic poles, constructs a smooth and continuous rotor outer circumference profile, and realizes the functional transformation of the salient pole structure into a "quasi-hidden pole structure." Its outer circumferential arc radius is completely consistent with the outer circumferential radius of the salient magnetic pole, which can eliminate the cutting and obstruction of airflow by the protruding magnetic pole at high speeds (120~130m / s). When a traditional salient pole rotor is running, the protruding part of the magnetic pole will cause the airflow to generate violent flow and eddies, forming high-intensity aerodynamic noise. However, the hidden polarization design of this invention allows the airflow to flow smoothly along the outer circumference of the rotor, reducing the airflow disturbance intensity in the magnetic pole area by 50%~70%, corresponding to an aerodynamic noise reduction of 15~22dB(A), fundamentally solving the inherent noise defects of the salient pole structure under high-speed conditions. Meanwhile, the inner arc-shaped contact surfaces of the first and second windbreaks are precisely fitted with the inter-pole sidewalls and outer arc-shaped transition surfaces of the magnetic poles, preventing secondary eddies from being generated at the connection gap between the magnetic poles and the windbreaks, further reducing local turbulence noise, and ensuring the integrity and stability of the airflow field on the outer circle of the rotor.

[0028] 2. While filling the gap between magnetic poles to reduce noise, the inter-pole baffle, through the through-holes (circular or oblong) in the first and second baffle sections, provides an efficient flow channel for rotor cooling air, preventing heat dissipation failure due to structural enclosure. Specifically, the size and distribution of the ventilation holes match the rotor yoke's original ventilation system, guiding the cooling air smoothly through the magnetic pole gap. This forms a closed loop with the ventilation holes of the rotor yoke laminations and the heat dissipation channels of the magnetic pole coils, ensuring that heat from core heat-generating components such as salient poles and magnetic pole coils is promptly dissipated. Actual measurement data shows that after assembling this inter-pole baffle, the rotor temperature rise is controlled within the design limit (≤65K). Compared with traditional rotors without baffles, the heat dissipation efficiency decreases by only 3%~5%, fully meeting the thermal management requirements of high-speed generator motors and breaking the technical contradiction that "noise reduction inevitably increases resistance, and increased resistance inevitably affects heat dissipation."

[0029] 3. The inter-pole baffle plate is rigidly connected to the rotor yoke via a tensioning screw, and its multi-layered structural design ensures stability at high speeds. Firstly, the screw connection extends from the outer periphery of the inter-pole baffle plate towards the rotor yoke, shortening the tensioning screw's lever arm and reducing the torque load under centrifugal force. The countersunk hole design of the screw's through-hole fully accommodates the tensioning nut, preventing it from protruding and creating additional turbulence, while also preventing the nut from loosening during high-speed rotation. Secondly, the connection between the tensioning screw and the rotor yoke employs a locking structure of "limiting block + yoke annular gap + limiting groove"—the limiting block passes through the yoke annular gap and rotates at a set angle to embed into the limiting groove, quickly achieving axial positioning of the screw. Combined with the multiple fixing mechanisms of locking nuts I, II, and the limiting nut, the maximum radial displacement of the inter-pole baffle plate at a linear velocity of 120~130 m / s is ≤0.1 mm, eliminating the risk of structural loosening or resonance and meeting the stringent strength requirements of rotor components under high-speed operating conditions.

[0030] 4. The structural design of the inter-pole baffle plate fully considers engineering feasibility, adopting a modular disassembly and convenient assembly logic: each baffle plate corresponds to a set of adjacent magnetic poles and can be installed or replaced independently without disassembling core components such as the rotor yoke and magnetic poles; the assembly method of inserting the tensioning screw through the magnetic yoke annular gap eliminates the need for additional complex mounting holes on the rotor yoke, utilizing only the original annular gap of the yoke for fixation, greatly simplifying the assembly process and shortening unit maintenance time (maintenance efficiency improved by 40%~60%). Simultaneously, the inter-pole baffle plate uses non-magnetic lightweight materials such as cast aluminum or magnesium alloy AZ31B, which not only avoids interference with the rotor magnetic circuit but also reduces the overall weight of the rotor (the weight of a single baffle plate is 30%~40% lighter than steel components), reducing rotor centrifugal load and drive energy consumption; the materials are widely available, the processing technology is mature (it can be die-cast), and the cost is controllable after large-scale production, possessing strong engineering applicability.

[0031] 5. The centrifugal fans at both ends of the rotor are the core source of end turbulence and aerodynamic noise in traditional hydro-generators, and the cross-sectional shape of their blades directly determines the intensity of airflow disturbance. The NACA0012 / 0016 / 0018 airfoil blades used in this invention have a streamlined profile with a "rounded front and pointed rear, smooth transition" compared to traditional rectangular cross-section blades, which can guide the airflow to flow smoothly along the blade surface: on the one hand, the large curvature arc at the leading edge of the blade can avoid the impact noise generated by the vertical impact of the airflow, so that the airflow is gently split, and the impact noise intensity is reduced by 8~12dB(A); on the other hand, the gentle curved surface design from the maximum thickness point to the trailing edge can significantly reduce the phenomenon of airflow boundary layer separation, avoiding the large number of vortices formed by boundary layer separation in traditional rectangular blades, and reducing vortex noise by 10~15dB(A). Actual measurements show that, at a rotor outer circular velocity of 120-130 m / s, the centrifugal fan with NACA airfoil blades reduces the total aerodynamic noise by 18-25 dB(A) compared to traditional fans, completely solving the problem of "strong turbulence and high noise" at the rotor end.

[0032] 6. The NACA0012 / 0016 / 0018 airfoils are aerodynamically optimized standardized cross sections. Their streamlined structure can effectively reduce airflow resistance. At the same rotational speed, the drag coefficient of NACA airfoil fan blades is 30%~40% lower than that of rectangular fan blades. This not only reduces energy loss during fan operation (fan power is reduced by 15%~20%), but also outputs a more stable airflow. Traditional rectangular fan blades are prone to airflow fluctuations due to airflow turbulence (fluctuation range can reach 10%~15%), while NACA airfoil fan blades can control airflow fluctuations within 3%, ensuring that cooling air can be evenly introduced into the ventilation gaps of the rotor yoke and magnetic poles, avoiding local heat dissipation dead zones. Meanwhile, the differentiated thickness design of the three airfoils (NACA0012 thickness 12%, NACA0016 thickness 16%, NACA0018 thickness 18%) can be adapted to hydro generators of different power levels: NACA0012 (low resistance priority) is selected for small power units, and NACA0018 (strength priority) is selected for large power units, taking into account both ventilation efficiency and structural adaptability, and ensuring that the temperature rise of the rotor core components (magnetic poles, coils) is controlled within the design limit (≤65K).

[0033] 7. During the operation of high-speed generator-motor systems, centrifugal fan blades must withstand enormous centrifugal forces and vibration loads. Traditional rectangular fan blades are prone to breakage due to stress concentration. The NACA0012 / 0016 / 0018 airfoil fan blades exhibit a more uniform stress distribution across their cross-section: the design of the maximum thickness point (located at 20%~30% of the chord length) effectively disperses centrifugal forces. Combined with the rounded transition between the blade root and the rotor end plate, this reduces the maximum stress on the blade by 25%~35%, far below the allowable stress of the material (≤215MPa when using high-strength alloys). Simultaneously, the streamlined profile reduces the alternating impact of airflow on the blades, lowering the blade vibration acceleration by 40%~50%, thus preventing structural fatigue failure due to resonance. At high speeds of 120~130m / s, NACA airfoil fan blades can achieve long-term stable operation (service life ≥40 years) without deformation, breakage, or noise attenuation, fully meeting the stringent operating requirements of high-speed generator-motor systems.

[0034] 8. This invention's hydro-generator utilizes a dual-technology combination of rotor structure optimization and a reactive-resistive composite silencer for the main ventilation path, forming a comprehensive noise reduction solution covering rotor turbulence noise and main ventilation path aerodynamic noise. Specifically, the reactive-resistive composite silencer precisely targets the main ventilation path between the stator core and the air cooler—a region with strong aerodynamic noise radiation from the hydro-generator. Traditional technologies, due to the high wind resistance of the silencer and its inability to adapt to the main ventilation path, fail to effectively control noise in this area. The reactive-resistive composite silencer of this invention, through the design without sound-absorbing materials and precise parameter optimization, can achieve high transmission loss over a wider frequency band, and achieve targeted attenuation of 5~7dB(A) for main airflow noise. After synergistic effect with rotor structure optimization (noise reduction of 20~25dB(A)), the overall noise can be reduced to below 65dB(A), meeting the Class I environmental noise limit in GB / T10069.1-2008. It completely solves the problem of the superposition of "rotor turbulence noise + main airflow noise" in high-speed hydro generators, and significantly improves the unit's sound quality indicators and the comfort of the operating environment.

[0035] 9. Traditional main airflow silencers rely on sound-absorbing materials (such as glass wool), which suffer from high wind resistance, severe airflow attenuation, and the easy dispersal and pulverization of the sound-absorbing materials, leading to failure and contamination. They are unsuitable for main ventilation ducts (requiring at least 80% of the total airflow without contamination). In contrast, this invention's array-type reactive-resistive composite silencer achieves a balance between "silencing" and "ventilation" through a triple design: First, it employs a metal micro-perforated plate structure without sound-absorbing materials, avoiding the obstruction of airflow by material fibers; second, the micro-perforated plate features a 45° bend design. The system guides the airflow to enter smoothly, reducing local eddies. Combined with parameter optimization of "aperture < target frequency wavelength / 10" (0.5~4mm micro-aperture), the airflow pressure loss is controlled to ≤200Pa and the airflow attenuation ≤5%, fully meeting the ventilation efficiency requirements of the main airflow path and ensuring that the heat dissipation of the stator core and air cooler is not affected (stator coil temperature rise ≤65K). Thirdly, a reactive-resistive composite silencer is used, achieving high transmission loss over a wider frequency band and significantly increasing noise reduction. Fourthly, the resonant frequency formula... By reverse-engineering the aperture, spacing, thickness, and cavity thickness of the micro-perforated plate, the resonant frequency of the micro-perforated plate is precisely matched with the dominant noise frequency of the main airflow path, increasing the noise reduction coefficient to 0.8~0.9 (compared to 0.5~0.6 for traditional silencers), achieving efficient noise reduction under low wind resistance.

[0036] 10. Noise in the main ventilation path typically includes two or more frequency peaks (e.g., 200-500Hz low-to-mid frequency and 1000-3000Hz mid-to-high frequency). Traditional silencers, due to their fixed parameters, can only reduce noise in a single frequency band, resulting in poor broadband performance. This invention achieves broadband coverage through multiple design features: Firstly, a single micro-perforated plate adopts a "same aperture + optimized perforation rate" design to ensure efficient attenuation of the target single frequency band (e.g., noise reduction ≥12dB(A) in the 1000Hz frequency band); secondly, different layers of micro-perforated plates within the silencer employ differentiated apertures (e.g., the first layer is 2mm for 500Hz, and the second layer is 1mm for 2000Hz), ultimately achieving effective suppression of broadband noise in the 200-3000Hz range. This overcomes the limitation of traditional silencers' "narrow frequency adaptation" and adapts to the noise spectrum differences in the main ventilation path of turbine generators with different power and speed.

[0037] 11. The array-type reactive-resistive composite silencer is manufactured as a single piece of metal, possessing three reliability advantages: First, the material has strong compatibility with the stator frame and can be firmly fixed to the stator frame by welding or flanges, with no risk of loosening under unit vibration conditions (10~100Hz, acceleration ≤10m / s²); Second, the metal material (such as steel plate, aluminum alloy, etc.) is temperature resistant, humidity resistant, and corrosion resistant, combined with the micro-perforated plate laser drilling process (hole diameter tolerance ±0.05mm, smooth hole wall) The burrs prevent dust accumulation and blockage caused by rough hole walls, and the service life is consistent with the metal parts of the unit (≥40 years). Unlike traditional sound-absorbing material silencers, it does not need to be replaced regularly (once every 3 to 5 years), reducing operation and maintenance costs by more than 85%. Thirdly, the sealing design (rubber sealing gasket) between the silencer shell and the micro-perforated plate ensures that the airflow leakage is ≤5% of the total air volume, avoiding short circuits of un-silenced airflow that affect the noise reduction effect, and ensuring that the noise reduction performance decays by ≤10% during long-term operation, with stability far exceeding that of traditional silencers.

[0038] 12. The array-type silencer's dimensions are precisely designed according to the internal installation space of the stator frame, eliminating the need to alter the original main ventilation path layout of the hydro-generator (such as the stator core and air cooler positions). It can be directly assembled into the stator frame, featuring a compact structure and small footprint (100~300mm thickness). This design is suitable for both new unit synchronous designs and noise reduction retrofits of existing units. Retrofitting only requires reserving an installation interface on the stator frame between the stator core and air cooler, without disassembling core components of the unit. The retrofit cycle is shortened to 7~10 days (compared to over 150 days for traditional retrofits), significantly reducing downtime losses. Furthermore, the muffler's modular design (with independently replaceable micro-perforated plates) facilitates later maintenance, further enhancing its engineering application value. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the cross-sectional structure of the turbine generator rotor of the present invention; Figure 2 This is a schematic cross-sectional view of the wind baffle plate between the poles of the turbine generator rotor of the present invention; Figure 3 This is a schematic diagram of the centrifugal fan structure on the rotor of the hydro-generator of the present invention; Figure 4 for Figure 2 View from AA direction; Figure 5 This is a schematic diagram of the assembly structure of the interpole wind baffle plate of the hydro-generator rotor of the present invention, which is assembled on the rotor yoke by a pad block. Figure 6 This is a schematic diagram of the assembly structure of the tension screw and rotor yoke in the rotor of the hydro-generator of the present invention; Figure 7 This is a schematic diagram of the assembly process of the tension screw and rotor yoke in the rotor of the hydro-generator of the present invention; Figure 8 This is a schematic diagram showing the assembly and fixation of the tension screw and the rotor yoke in the rotor of the hydro-generator of the present invention; Figure 9 This is a schematic diagram of the assembly and fixing of the interpole wind baffle, tensioning screw and rotor magnetic yoke of the hydro-generator rotor of the present invention; Figure 10 This is a schematic diagram showing a circular hole on the outer circumferential surface of the interpole wind baffle plate in the rotor of the hydro-generator of the present invention; Figure 11 This is a schematic diagram showing the oblong hole on the outer circumferential surface of the interpole wind baffle plate in the rotor of the hydro-generator of the present invention; Figure 12 This is a schematic diagram of the structure of the hydro-generator of the present invention; Figure 13 This is a top view of the structure of the hydro-generator of the present invention; Figure 14 This is a schematic diagram of the stator core, stator frame, and air cooler structure in the hydro-generator of the present invention; Figure 15 This is a schematic diagram of the assembly structure of the stator core, stator frame, array silencer and air cooler in the hydro-generator of the present invention; Figure 16 This is a schematic diagram of the three-dimensional structure of the array-type muffler of the present invention; Figure 17 This is a schematic diagram of the micro-perforated plate arrangement structure in the array-type muffler of the present invention; Figure 18 This is a schematic diagram of different micro-perforated plate combinations in the array-type muffler of the present invention; Figure 19 This is a schematic diagram of the arrangement of micro-perforated plates in the array-type muffler of the present invention; Reference numerals: 1. Hydro-generator rotor; 2. Rotor yoke; 3. Salient pole; 4. Inter-pole windbreak plate; 5. Tensioning screw; 6. Outer circumferential surface of the inter-pole windbreak plate; 7. Outer circumferential surface of the salient pole; 8. First windbreak section; 9. Second windbreak section; 10. Screw connection section; 11. Screw through hole; 12. Tensioning nut; 13. Countersunk hole; 14. Arc-shaped mating surface; 15. Inter-pole sidewall; 16. Arc-shaped transition surface; 17. Ventilation hole; 18. Centrifugal fan; 9. Fan blade; 20. Arc transition; 21. Cavity; 22. Limiting block; 23. Magnetic yoke annular gap; 24. Inner circumferential surface of rotor magnetic yoke; 25. Limiting groove; 26. Locking nut I; 27. Locking nut II; 28. Limiting nut; 29. ​​Spacer block; 30. Outer circumferential surface of rotor magnetic yoke; 31. Stator core; 32. Stator frame; 33. Air cooler; 34. Main ventilation air duct; 35. Array-type silencer; 36. Silencer housing; 37. Micro-perforated plate. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0041] Example 1 As a preferred embodiment of the present invention, please refer to the appendix to the specification. Figure 1 and attached Figure 2 As shown, this embodiment discloses a low-turbulence, low-noise hydro-generator rotor, including a rotor yoke and salient poles. The salient poles are uniformly assembled on the outer circumference of the rotor yoke. An inter-pole wind baffle is assembled between the salient poles, and the inter-pole wind baffle is assembled on the rotor yoke by a tensioning screw. The outer circumferential surface of the inter-pole wind baffle is arc-shaped, and the radius of the arc surface is the same as the radius of the outer circumferential surface of the salient magnetic pole. The inter-pole wind baffle includes a first wind baffle, a second wind baffle, and a screw connecting part, which are symmetrically arranged with respect to the screw connecting part. The screw connecting part extends from the outer circumferential surface of the inter-pole wind baffle towards the rotor yoke between two adjacent salient magnetic poles. A through screw hole is provided in the screw connecting part, and a countersunk hole for accommodating a tension nut assembled at the end of the tension screw is provided on the outer circumferential surface of the inter-pole wind baffle. The first wind baffle and the second wind baffle extend towards their respective salient magnetic poles, and an arc-shaped fitting surface is provided on the inner side of the first wind baffle and the second wind baffle. This arc-shaped fitting surface is adapted to and fits the arc-shaped transition surface between the inter-pole sidewall and the outer circumferential surface of the salient magnetic pole. Through ventilation holes are provided on the first wind baffle and the second wind baffle.

[0042] In this embodiment, the inter-pole baffle plate of the present invention completely fills the gap between salient magnetic poles through the dual structural design of "precise matching of the outer arc surface" and "seamless adaptation of the inner contact surface", constructs a smooth and continuous rotor outer circle profile, realizes the functional transformation of the salient pole structure to "quasi-hidden pole structure", and eliminates the cutting and obstruction of airflow by the convex magnetic poles at high speeds (120~130m / s).

[0043] Example 2 As another preferred embodiment of the present invention, this embodiment is a further detailed supplement and explanation of the technical solution of the present invention based on the above embodiment 1.

[0044] As one implementation method of this embodiment, please refer to the appendix to the specification. Figure 2 As shown, the connection points between the first and second windshield sections and the screw connection section are rounded. This rounded transition design reduces stress at the connection points between the first and second windshield sections and the screw connection section.

[0045] As another embodiment of this invention, please refer to the appendix to the specification. Figure 2 As shown, a cavity with an inner diameter larger than the screw through hole in the screw connection part is provided in the middle for weight reduction, so as to reduce the weight of the inter-electrode baffle, thereby reducing the centrifugal force of the inter-electrode baffle and reducing the centrifugal force of the inter-electrode baffle on the tension screw.

[0046] As another embodiment of this invention, please refer to the appendix to the specification. Figure 6 Appendix Figure 7 Appendix Figure 8 and attached Figure 9 As shown, a limiting block is provided at the end of the tensioning screw connected to the rotor yoke. The limiting block end of the tensioning screw passes through the yoke annular gap and then through the rotor yoke. A limiting groove adapted to the limiting block is provided on the inner circumferential surface of the rotor yoke. After passing through the yoke annular gap, the limiting block rotates at a set angle and embeds itself into the limiting groove. The tensioning screw is provided with a locking nut I, a locking nut II, and a limiting nut. The locking nut I cooperates with the limiting block to fix the tensioning screw to the rotor yoke. The locking nut II, the limiting nut, and the tensioning nut cooperate to fix the inter-pole baffle plate to the tensioning screw.

[0047] As another embodiment of this invention, please refer to the appendix to the specification. Figure 5 As shown, a pad adapted to the screw connection portion is provided at the center of the outer peripheral surface of the rotor yoke between two adjacent salient poles. As an example, the pad is welded to the outer peripheral surface of the rotor yoke.

[0048] As another embodiment of this invention, please refer to the appendix to the specification. Figure 10 and attached Figure 11 As shown, the ventilation holes on the inter-element wind deflector are either circular or oblong.

[0049] The inter-electrode wind baffle is made of a non-magnetic material. Furthermore, the material of the inter-electrode wind baffle is cast aluminum or magnesium alloy AZ31B.

[0050] Example 3 As another preferred embodiment of the present invention, this embodiment is a further detailed supplement and explanation of the technical solution of the present invention based on the above-described Embodiment 1 or Embodiment 2. In this embodiment, reference is made to the appendix to the specification. Figure 3 and attached Figure 4As shown, centrifugal fans are mounted at both ends of the turbine generator rotor. The blades of the centrifugal fans are airfoil blades such as NACA0012, NACA0016, or NACA0018. The centrifugal fans at both ends of the rotor are the core source of end turbulence and aerodynamic noise in traditional turbine generators, and the cross-sectional shape of their blades directly determines the intensity of airflow disturbance. The NACA0012 / 0016 / 0018 airfoil blades used in this invention have a streamlined profile with a "rounded front and pointed rear, smooth transition" compared to traditional rectangular cross-section blades. This can guide the airflow to flow smoothly along the blade surface: on the one hand, the large curvature arc at the leading edge of the blade can avoid the impact noise generated by the vertical impact of the airflow, so that the airflow is gently split, and the impact noise intensity is reduced by 8~12dB(A); on the other hand, the gentle curved surface design from the maximum thickness point to the trailing edge can significantly reduce the phenomenon of airflow boundary layer separation, avoiding the large number of vortices formed by boundary layer separation in traditional rectangular blades, and reducing vortex noise by 10~15dB(A). Actual measurements show that, at a rotor outer circular velocity of 120-130 m / s, centrifugal fans using NACA airfoil blades reduce total aerodynamic noise by 18-25 dB(A) compared to traditional fans, completely solving the problem of "strong turbulence and high noise" at the rotor end.

[0051] Example 4 As another preferred embodiment of the present invention, please refer to the appendix to the specification. Figure 12 Appendix Figure 13 Appendix Figure 14 Appendix Figure 15 Appendix Figure 16 Appendix Figure 17 Appendix Figure 18 and attached Figure 19 As shown, this embodiment discloses a low-turbulence noise-reducing hydro-generator, including the hydro-generator rotor, stator core, stator frame, and air cooler described in the first aspect above; an array-type reactive-resistive composite silencer without sound-absorbing material is installed on the main ventilation airway between the stator core and the air cooler, and the array-type silencer is fixed on the stator frame; the array-type silencer includes a silencer shell, and a plurality of micro-perforated plates are arranged inside the silencer shell. The plurality of micro-perforated plates are arranged along the airflow direction of the medium in the main ventilation airway, and the micro-perforated plates are bent at the air inlet and air outlet of the silencer shell. The plurality of micro-perforated plates are arranged in series at intervals, and the distance between adjacent micro-perforated plates is the cavity thickness. The aperture of a single micro-perforated plate is consistent, and the micro-holes are evenly distributed. Different micro-perforated plates adopt different apertures according to the dominant noise frequency.

[0052] As an example of this embodiment, the pore diameter, pore spacing, plate thickness, and cavity thickness of the micro-perforated plate are calculated by back-calculating the pore diameter, pore spacing, plate thickness, and cavity thickness of the micro-perforated plate based on the dominant noise frequency band of the main ventilation path and the resonant frequency calculation formula of the micro-perforated plate.

[0053] Furthermore, the formula for calculating the resonant frequency of the micro-perforated plate is as follows:

[0054] In the formula, This indicates the speed of sound, measured in m / s, which is approximately 340 m / s at room temperature. The perforation rate is the ratio of the total area of ​​the holes to the area of ​​the micro-perforated plate; t is the thickness of the micro-perforated plate in meters; and L is the depth of the cavity behind the micro-perforated plate in meters. This represents the end-diameter correction amount, taken as... d is the aperture.

[0055] As another example of this embodiment, the diameter of the micro-holes on the micro-perforated plate is set according to the noise frequency of the main ventilation path. Specifically, the determination of the micro-hole diameter satisfies the condition that the micro-hole diameter is less than the wavelength corresponding to the target noise reduction frequency / 10.

[0056] The micropores on each microperforated plate are evenly distributed. The spacing between the micropores on the microperforated plate is determined according to the perforation rate, which refers to the percentage of the total area of ​​all micropores on a single microperforated plate to the total area of ​​the microperforated plate.

[0057] The micro-perforated plate is bent at the air inlet and air outlet of the silencer housing at a bending angle of 45°.

[0058] As another example of this embodiment, the diameter of the micropores is selected from 0.5 to 4 mm according to the noise frequency of the main ventilation path.

[0059] As another example of this embodiment, several micro-perforated plates are arranged in series at intervals to form a reactive-resistive composite silencer.

[0060] As another example of this embodiment, the array-type silencer is made of metal.

[0061] Example 5 As another preferred embodiment of the present invention, this embodiment is a further detailed supplement and explanation of the technical solution of the hydro-generator described in the above embodiment 4, based on the above embodiment 4.

[0062] Through simulation, theoretical calculation, or actual measurement of turbine generator noise and airflow data under different operating conditions; specifically including the following: Analyze the noise frequency distribution and noise spectrum characteristics, identify the dominant frequency bands of the hydro-generator noise, and record the peak sound pressure level corresponding to each frequency band; study the intrinsic relationship between operating conditions and this type of noise, clarify the noise change law under different operating conditions, and combine the overall noise limit of the hydro-generator to deduce the minimum noise reduction amount to be achieved, thus forming a quantitative noise reduction target. Focusing on the noise generation mechanism of hydro-generators, this study quantifies the contribution of turbulence, vortex shedding, boundary layer, and pole mechanisms to the total aerodynamic noise; it also locates the specific positions of each noise generation mechanism within the stator frame and clarifies the noise propagation path; and it acquires basic airflow data for the main ventilation path, including total flow rate, average airflow velocity, and the unit's allowable pressure loss threshold and airflow attenuation limit.

[0063] In this embodiment, the noise reduction strategy is determined based on the noise generation mechanism, noise characteristics, and noise spectrum distribution at different locations: Among them, the noise generation mechanism should be clearly defined: whether it is electromagnetic force noise, aerodynamic noise, or mechanical force noise; Noise characteristics and spectrum analysis: Based on the noise spectrum and the generation mechanism, determine whether the noise is high-frequency or low-frequency, discrete pure tone or broadband random noise, and thus determine its propagation path (propagation medium). Noise reduction approach: Different noise reduction solutions are needed for different noise generation mechanisms.

[0064] This application mainly addresses the noise characteristics of the main ventilation path between the stator core of a hydro turbine generator and the air cooler, by installing an array-type reactive-resistive combined silencer without sound-absorbing cotton to significantly reduce noise.

[0065] This application reduces aerodynamic noise through improvements to the rotor structure.

[0066] Aerodynamic noise mainly originates from the cooling fan and rotor rotation, and is directly related to the air outlet. This is the most significant aerodynamic noise source for large and medium-sized motors. Due to differences in their generation mechanisms and characteristics, it can be further subdivided into three types: One of them is eddy noise (wideband noise): When the fan blades rotate, they create eddies in the air around them. These eddies are constantly forming and breaking up, causing air pressure pulsations and generating noise. Its characteristics and spectrum: wideband noise, with a very wide spectrum distribution, from tens of Hz to tens of thousands of Hz. —Secondly, there is rotational noise (discrete noise): this is caused by the periodic beating of air by the blades, resulting in air pressure pulsations. When the passing frequency of the blades coincides with a certain structural characteristic frequency, a strong "whistling" sound (steam whistle effect) is produced. Its characteristics and spectrum are discrete single tones, with the fundamental frequency being the number of blades multiplied by the rotational speed, accompanied by higher harmonics. There are obvious peaks in the spectrum; Thirdly, there is the issue of eddy current shedding and surge noise: When airflow passes through the narrow and complex air ducts inside the motor (especially near the air outlet), separation and eddy currents will occur, causing pressure pulsations and noise. When the airflow path is obstructed, surge will occur, producing a low-frequency roar.

[0067] The array-type reactive-resistive composite silencer in this invention is mainly used to reduce noise in the main ventilation path.

[0068] Aerodynamic noise reduction strategies (based on mechanism and spectrum): 1) Source control (core): Through optimized fan design and air duct optimization; 2) Airflow path treatment (key measure for air outlets): Install silencers; Reactive silencers: These primarily reduce noise through the reflection and interference of sound waves, and are particularly effective against low-to-mid-frequency noise (such as the fundamental frequency of rotating noise). Internal structures include expansion chambers and resonant cavities. Resistive silencers: lined with sound-absorbing materials (such as glass wool, mineral wool, rock wool, etc.), they convert sound energy into heat energy through friction, and are most effective against mid-to-high frequency noise (such as broadband eddy current noise). Composite silencer: Combining reactive and resistive structures to achieve full-band noise reduction. This proposal introduces a novel, high-efficiency, sound-absorbing cotton-free reactive-resistive composite silencer, which achieves high transmission loss over a wider frequency band; Design considerations: The design of a muffler must balance noise reduction, aerodynamic performance (low pressure loss), and size.

[0069] Mechanical noise (mainly originating from bearings and rotors): The generation mechanisms include bearing friction, frame vibration, improper assembly, etc.; or rotor dynamic imbalance, where the rotor's center of mass does not coincide with its center of rotation, generating periodic centrifugal force, leading to vibration and noise. Its noise characteristics and spectrum distribution: Bearing noise is a high-frequency "hissing" or "rumbling" sound with a wide spectrum, but usually includes characteristic frequencies determined by the bearing's geometry; rotor imbalance noise is a low-frequency "rumbling" sound (the frequency is consistent with the rotor's rotational frequency). Noise reduction strategies: Select high-precision, low-noise bearings, ensure good lubrication, and improve the machining and assembly accuracy of bearing components; add weight to the rotor and perform dynamic and static balancing corrections.

[0070] Electromagnetic noise (mainly originating from the interaction between the stator and rotor magnetic fields): Electromagnetic noise is radiated noise generated by the vibration of the stator and rotor structure caused by the alternating electromagnetic force in the air gap. Tooth frequency vibration noise is the most significant, mainly manifested as discrete noise caused by the 5th, 7th, 11th, and 13th order electromagnetic harmonics, fractional harmonic noise, 100Hz vibration noise caused by rotor eccentricity and stator non-roundness, and rotational frequency noise caused by rotor non-roundness. Specific control methods include selecting a reasonable pole-slot ratio, controlling manufacturing and installation quality, and conducting dynamic balancing tests on the rotor. Currently, electromagnetic design is relatively mature, and manufacturing and installation quality are generally well controlled, resulting in relatively low electromagnetic noise, which accounts for a very small proportion of the overall unit noise.

[0071] The design method of the array-type silencer in this invention is as follows: S1, the pre-parameter acquisition step, which involves ventilation simulation of the main ventilation path between the stator core of the hydro-generator and the air cooler, theoretical calculation of the ventilation system, or actual measurement of unit noise data and airflow data under different operating conditions; specifically including the following: (1) Analyze the noise frequency distribution and noise spectrum characteristics, identify the dominant frequency range of aerodynamic noise in the main ventilation path, and record the peak sound pressure level corresponding to each frequency range; study the intrinsic relationship between the working conditions and this type of noise, clarify the noise change law under different working conditions, and combine the overall noise limit of the hydro-generator to back-calculate the minimum noise reduction amount to be achieved, and form a quantitative noise reduction target. (2) Focus on the aerodynamic noise generation mechanism in the main ventilation duct, quantify the contribution ratio of turbulence mechanism, vortex shedding mechanism, boundary layer mechanism and pole mechanism in the total aerodynamic noise; at the same time, locate the specific location of each noise generation mechanism inside the stator frame, and clarify the noise propagation path; obtain basic airflow data of the main ventilation duct, including total flow rate, average airflow velocity and allowable pressure loss threshold and airflow attenuation limit of the unit; S2. Determine the noise reduction strategy and core structure scheme steps. Based on the aerodynamic noise generation mechanism, noise characteristics and spectrum distribution of the main ventilation air path as defined in step S1, determine the noise reduction strategy and lock in the core structure of the array silencer. S3. Determine the external dimensions and preliminary airflow calculation steps of the array-type silencer. Based on the design drawings or measured data of the stator frame of the hydro-generator, and combined with the airflow requirements of the main ventilation path, clarify the physical size constraints and preliminary ventilation feasibility of the silencer. The preliminary airflow calculation refers to the preliminary calculation of ventilation resistance and airflow attenuation based on the determined external dimensions and the basic airflow data of the main ventilation path obtained in step S1. This is to avoid the external design from compromising ventilation safety and convenience. If the requirements are not met, return to adjust the external dimensions. S4. Initial Scheme Design Steps: Based on the advantageous frequency band, noise mechanism and contribution ratio, and quantified noise reduction target determined in step S1, the core structure of the array-type muffler determined in step S2, and the external dimensional constraints and preliminary airflow parameters in step S3, combined with the micro-perforated silencing theory, the initial scheme design of the array-type muffler is carried out; including the aperture, thickness, hole spacing, and cavity thickness of the micro-perforated plate of the array-type muffler. S5. Simulation Analysis and Optimization Steps: Based on the initial scheme of the array-type silencer determined in step S4, a three-dimensional model of the array-type silencer is established. ANSYS is used to build a noise reduction scheme model and set boundary conditions. First, the flow field of the airflow through the array-type silencer in the main ventilation path is simulated using the fiuent module to obtain pressure data as initial parameters. Then, the Mechanical model is imported to simulate fluid noise and noise reduction effect, and the noise reduction amount in different frequency bands is analyzed. By comprehensively adjusting the aperture, spacing, thickness, and spatial thickness of the micro-perforated plate, ventilation performance is optimized, pressure loss and airflow attenuation are reduced while ensuring the silencing effect, resulting in a better parameter combination and noise reduction effect. S6. Accurate calculation of fluid parameters and solution locking: Based on the optimal parameter combination obtained in step S5, calculate the core airflow parameters of the main ventilation path. If the air volume and pressure loss exceed the air volume attenuation limit and pressure loss threshold in step S2, adjust the micro-perforated plate aperture, hole spacing, plate thickness and / or space thickness, and repeat steps S5-S6 until the optimal parameter combination and noise reduction effect are obtained, and finally lock in the design solution that meets the dual requirements of ventilation and noise reduction.

[0072] In step S2, based on the aerodynamic noise generation mechanism, noise characteristics, and spectral distribution of the main ventilation path as defined in step S1, a noise reduction strategy is determined, specifically: To address broadband eddy current noise, a resistive sound absorption technology is employed, which converts sound energy into heat energy through the frictional viscosity effect of micro-perforated plates, thereby achieving broadband noise reduction. To address discrete rotational noise, a resonant silencing technology approach is adopted. By matching the parameters of the micro-perforated plate, the resonant frequency of the silencer is aligned with the peak frequency of the noise, and the energy is canceled out by sound wave interference. To address eddy shedding and surge noise, a technical approach combining flow field optimization and noise reduction is adopted. This involves reducing airflow separation through structural design and simultaneously weakening noise through noise reduction structures.

[0073] In step S2, locking the core structure of the array silencer specifically means determining that the micro-perforated plate array is the core carrier, and achieving full-frequency coverage through the combination of multiple plates in series and / or in parallel. In the series direction, micro-perforated plates with different parameters are arranged along the airflow path to match different mid-to-high frequency bands respectively; in the parallel direction, differentiated cavity regions are divided in the synchronization plane to cover the low-frequency band, forming a multi-dimensional silencer array.

[0074] For flow field optimization, bends are incorporated into the micro-perforated plates at the muffler's inlet and outlet. These bends are configured to guide a smooth airflow transition and control ventilation resistance. As an example, the micro-perforated plates are bent at the inlet and outlet of the housing at a bend angle of 45°.

[0075] In step S4, the initial design of the array-type silencer specifically refers to, based on the dominant noise frequency band determined in step S1, and combined with the formula for calculating the resonant frequency of the micro-perforated plate, back-calculating the aperture, spacing, plate thickness, and cavity thickness of the micro-perforated plate.

[0076] As an example, the formula for calculating the resonant frequency of a micro-perforated plate is:

[0077] In the formula, This indicates the speed of sound, measured in m / s, which is approximately 340 m / s at room temperature. The perforation rate is the ratio of the total area of ​​the holes to the area of ​​the micro-perforated plate; t is the thickness of the micro-perforated plate in meters; and L is the depth of the cavity behind the micro-perforated plate in meters. This represents the end-diameter correction amount, taken as... d is the aperture.

[0078] In step S4, the aperture of the micro-perforated plate must be determined to satisfy the condition that the aperture is less than the wavelength corresponding to the target noise reduction frequency / 10. The apertures of the micro-holes on a single micro-perforated plate are uniform. In step S4, the micro-holes on each micro-perforated plate are evenly distributed, and the spacing between the holes on the micro-perforated plate is determined based on the perforation rate, which refers to the percentage of the total area of ​​all micro-holes on a single micro-perforated plate to the total area of ​​the micro-perforated plate.

[0079] In a preferred embodiment of this invention, step S4 involves defining and determining the parameters in the initial design of the array-type muffler: Design logic: First, determine the resonant frequency of the structure based on the peak frequency of the target noise to be controlled, and then calculate or optimize a set of feasible parameters using formulas. Step 1: Determine the target frequency: Based on the previous noise spectrum analysis, identify the main noise components that need to be suppressed, such as the peak frequency of the air outlet noise; design the resonant frequency of the micro-perforated plate structure to be near this peak. Step 2: Calculation and Selection of Key Parameters: The resonant frequency of the micro-perforated plate is mainly determined by the acoustic mass (determined by the micropores) and acoustic compliance (determined by the cavity). The approximate calculation formula is as follows:

[0080] a. Resonance frequency formula (determines frequency tuning) Where: The resonant frequency (Hz) represents the frequency with the highest sound absorption coefficient, and δ is the end correction factor, typically taken as 0.8~1.0. The cavity thickness adjusts the resonant frequency. The most sensitive parameter. The greater the thickness, The lower the value, the higher the perforation rate. It will also increase. However, it primarily affects the sound absorption coefficient and bandwidth. Plate thickness and aperture: (t+δ·d) can be considered as the "effective plate thickness," and the larger its value, the greater the effect. The lower.

[0081] b. Calculation of perforation rate: The perforation rate is the ratio of the total area of ​​the holes to the total area of ​​the plate. For a square array of holes: the hole diameter and the hole spacing together determine the perforation rate.

[0082] c. Determine the specific plate thickness, hole diameter, perforation rate, and cavity thickness. This is a multi-objective optimization process without a single unique solution. Selection and balancing within a reasonable range are necessary, while also considering the manufacturing process. Aperture: The core requirement is to meet the "micro-perforation" condition, meaning the aperture is much smaller than the wavelength to ensure sufficient acoustic resistance. The smaller the aperture, the greater the acoustic resistance, the narrower the sound absorption bandwidth, and the more difficult the manufacturing process.

[0083] Plate thickness: Related to aperture, generally too thin and the mechanical strength is insufficient, too thick and the acoustic impedance is too high.

[0084] Perforation rate: Generally between 0.5% and 3%. If the perforation rate is too small, the acoustic impedance is too large, resulting in poor sound absorption; if the perforation rate is too large, the acoustic impedance is too small, and the structure is close to being completely transparent, resulting in poor sound absorption.

[0085] Cavity thickness: calculated by reversing the resonant frequency formula. For example, the target... With a frequency of 800Hz, assuming a perforation rate of 1%, a plate thickness of 1mm, and a hole diameter of 0.8mm, the cavity thickness can be calculated to be approximately 20mm to 50mm. This thickness must be matched to the existing space of the mounting base. If the calculated cavity thickness is too large, other parameters need to be adjusted (such as increasing the perforation rate) or a different... .

[0086] 2) The relationship between the number of microplates and the space (basic logic): a. Single-cavity structure: a single layer of micro-perforated plate + a rear cavity. This is a Helmholtz resonator array, which is highly efficient at absorbing sound in only a narrow frequency band.

[0087] b. Multi-cavity series / parallel structure: To broaden the sound absorption frequency band, common practices are: Parallel: Using micro-perforated plate structures with different parameters (mainly different cavity depths) in the same plane, each structure targeting a specific frequency band. Series: Arranging multiple micro-perforated plate silencing units with different resonant frequencies in the airflow direction to form a "resistive-reactive" composite silencer structure, which can achieve high transmission loss over a wider frequency band (our approach is based on this).

[0088] Therefore, the number of microperforated plates directly determines the bandwidth that can be covered and the overall noise reduction. A larger number of microperforated plates increases the difficulty of design and manufacturing, and may also increase the airflow pressure drop. A trade-off needs to be struck based on the complexity of the noise spectrum and the noise reduction objectives.

[0089] Estimation of transmission loss: The core mechanism of micro-perforated panel silencing is resonant sound absorption, converting sound energy into heat energy for dissipation rather than reflection. A micro-perforated panel structure with a cavity at the back can be considered a mass-acoustic compliance-acoustic impedance (MAR) system. Its acoustic characteristics can be described by acoustic impedance. Substituting the acoustic impedance of the micro-perforated panel into the more general acoustic transmission matrix method allows for accurate calculation of its transmission loss. For micro-perforated panel structures, a more commonly used performance evaluation index is the "absorption coefficient," which describes how much incident sound energy is absorbed rather than reflected. After designing specific micro-perforated panel parameters, the curve of its absorption coefficient versus frequency can be obtained through theoretical calculation or software simulation. Then, by placing this sound-absorbing structure in a channel or silencer and combining it with boundary conditions, the transmission loss of the entire device can be calculated.

[0090] Step S3 clarifies the physical dimensional constraints of the muffler, specifically by measuring the internal space dimensions of the stator frame in the main ventilation path between the stator core and the air cooler to ensure that the muffler does not interfere with the stator core and air cooler after installation. Based on the aforementioned internal space dimensions and the micro-perforated plate array structure determined in step S2, the dimensions of the muffler housing are designed. The dimensions of the housing match the flow cross-section of the main ventilation path, and the length is adapted to the structural requirements of multiple plates connected in series.

[0091] Choosing micro-perforated panels offers significant advantages over traditional resistive sound-absorbing materials: 1) High temperature and airflow resistance; the high temperature and fast flow rate of the cooling airflow from generators and motors easily cause traditional sound-absorbing materials such as glass wool to be blown away and pulverized, leading to failure and pollution; 2) Micro-perforated panels are made of metal, making them sturdy and durable; 3) Environmentally friendly, with no fiber pollution; 4) Excellent mid-to-high frequency sound absorption performance: through careful design, it can effectively cover the main frequency bands of motor aerodynamic and electromagnetic noise; 5) Compact structure: it can be integrated with the base structure; 6) High operability: using common materials and conventional processing methods, it is easy to implement.

[0092] Its core sound absorption mechanism is a resonant sound absorber. When sound waves are incident, they force air to move back and forth in the micropores. Due to the small size of the pores, the friction and viscosity between the air and the pore walls are very significant, which efficiently converts sound energy (mechanical energy) into heat energy.

[0093] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0094] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A low-turbulence, noise-reducing hydro-generator rotor, comprising a rotor yoke and salient poles, the salient poles being uniformly assembled on the outer circumference of the rotor yoke; an inter-pole windbreak plate is assembled between the salient poles, the inter-pole windbreak plate being assembled on the rotor yoke by a tensioning screw; characterized in that: The inter-pole baffle plate fills the gap between adjacent salient magnetic poles, filling the outer circumference between adjacent salient magnetic poles to construct a smooth and continuous rotor outer circumference profile, thus achieving salient rotor non-polarization. The outer circumferential surface of the inter-pole baffle plate is an arc surface, the radius of which is the same as the radius of the outer circumferential surface of the salient magnetic pole. The inter-pole baffle plate includes a first baffle part, a second baffle part, and a screw connection part, the first and second baffle parts being symmetrically arranged with respect to the screw connection part. The screw connection part extends from the outer circumferential surface of the inter-pole baffle plate towards the rotor yoke between two adjacent salient magnetic poles. A through screw hole is provided inside the screw connection part, and the outer surface of the inter-pole baffle plate... The circumferential surface is provided with a countersunk hole for accommodating the tension nut assembled at the end of the tensioning screw. The tension nut is completely accommodated in the countersunk hole, preventing the tension nut from protruding from the countersunk hole and forming additional turbulence. The first windbreak and the second windbreak extend towards their respective salient magnetic poles. The inner sides of the first windbreak and the second windbreak are provided with arc-shaped fitting surfaces. These arc-shaped fitting surfaces are adapted to and precisely fitted with the arc-shaped transition surface between the interpole sidewall and the outer circumferential surface of the salient magnetic pole, preventing the airflow from generating secondary eddies at the connection gap between the magnetic pole and the interpole windbreak plate. The first windbreak and the second windbreak are provided with through ventilation holes.

2. The low-turbulence, noise-reducing hydro-generator rotor as described in claim 1, characterized in that: Centrifugal fans are mounted at both ends of the rotor of the hydro-generator, and the blades of the centrifugal fans are NACA0012, NACA0016 or NACA0018 airfoil blades.

3. A low-turbulence, noise-reducing hydro-generator rotor as described in claim 1 or 2, characterized in that: The connection between the first and second windbreaks and the screw connection is a rounded transition.

4. A low-turbulence, noise-reducing hydro-generator rotor as described in claim 1 or 2, characterized in that: The screw connection part has a cavity with an inner diameter larger than the screw through hole in the middle for weight reduction.

5. A low-turbulence, noise-reducing hydro-generator rotor as described in claim 1 or 2, characterized in that: The tensioning screw is connected to the end of the rotor yoke with a limiting block. The limiting block end of the tensioning screw passes through the yoke ring gap and passes through the rotor yoke. The inner circumferential surface of the rotor yoke is provided with a limiting groove that matches the limiting block. After passing through the yoke ring gap, the limiting block rotates at a set angle and embeds itself into the limiting groove.

6. The low-turbulence, noise-reducing hydro-generator rotor as described in claim 5, characterized in that: The tensioning screw is equipped with a locking nut I, a locking nut II, and a limiting nut. The locking nut I cooperates with the limiting block to fix the tensioning screw to the rotor yoke. The locking nut II, the limiting nut, and the tensioning nut cooperate to fix the inter-pole baffle plate to the tensioning screw.

7. The low-turbulence, noise-reducing hydro-generator rotor as described in claim 5, characterized in that: A pad adapted to the screw connection part is provided in the middle of the outer peripheral surface of the rotor yoke between two adjacent salient poles.

8. The low-turbulence, noise-reducing hydro-generator rotor as described in claim 7, characterized in that: The pad is welded to the outer peripheral surface of the rotor yoke.

9. A low-turbulence, noise-reducing hydro-generator rotor as described in claim 1 or 2, characterized in that: The ventilation holes are either circular or oblong.

10. A low-turbulence, noise-reducing hydro-generator rotor as described in claim 1 or 2, characterized in that: The inter-electrode windbreak is made of a non-magnetic material.

11. A low-turbulence, noise-reducing hydro-generator rotor as described in claim 10, characterized in that: The material of the inter-electrode wind deflector is aluminum alloy or magnesium alloy AZ31B.

12. A low-turbulence, noise-reducing hydro-generator, characterized in that: The invention comprises a hydro-generator rotor, stator core, stator frame, and air cooler as described in any one of claims 1-11; an array-type silencer without sound-absorbing material is installed on the main ventilation path between the stator core and the air cooler, the array-type silencer being fixed on the stator frame; the array-type silencer includes a silencer housing, and a plurality of micro-perforated plates are disposed inside the silencer housing, the plurality of micro-perforated plates being arranged along the airflow direction of the medium in the main ventilation path, the micro-perforated plates being bent at the air inlet and air outlet of the silencer housing, the plurality of micro-perforated plates being arranged in series at intervals, the spacing between adjacent micro-perforated plates being the cavity thickness, the aperture of a single micro-perforated plate being consistent, and the micropores being evenly distributed, the different micro-perforated plates adopting differentiated apertures according to the dominant noise frequency.

13. A low-turbulence, low-noise hydro-generator as described in claim 12, characterized in that: The pore diameter, pore spacing, plate thickness, and cavity thickness of the microperforated plate are calculated by inversely using the formula for calculating the resonant frequency of the microperforated plate, based on the dominant noise frequency band of the main ventilation path.

14. A low-turbulence, low-noise hydro-generator as described in claim 13, characterized in that: The formula for calculating the resonant frequency of a micro-perforated plate is: In the formula, This indicates the speed of sound, measured in m / s, which is approximately 340 m / s at room temperature. The perforation rate is the ratio of the total area of ​​the holes to the area of ​​the micro-perforated plate; t is the thickness of the micro-perforated plate in meters; and L is the depth of the cavity behind the micro-perforated plate in meters. This represents the end-diameter correction amount, taken as... d is the aperture.

15. A low-turbulence, noise-reducing hydro-generator as described in claim 14, characterized in that: The aperture of the micro-perforated plate must be determined to meet the requirement that the aperture diameter is less than the wavelength corresponding to the target noise reduction frequency / 10.

16. A low-turbulence, low-noise hydro-generator as described in claim 13, characterized in that: The micropores on each microperforated plate are evenly distributed. The spacing between the micropores on the microperforated plate is determined according to the perforation rate, which refers to the percentage of the total area of ​​all micropores on a single microperforated plate to the total area of ​​the microperforated plate.

17. A low-turbulence, low-noise hydro-generator as described in any one of claims 12-16, characterized in that: The array-type silencer is made of metal.

18. A low-turbulence, low-noise hydro-generator as described in any one of claims 12-16, characterized in that: The micro-perforated plate is bent at the air inlet and air outlet of the outer casing at a bending angle of 45°.

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