Impulse water turbine, bucket, and bucket base

Abstract

This application relates to the field of hydropower technology, specifically to an impulse turbine, a bucket, and a bucket base. The bucket base is used to assemble the bucket onto the hub of the runner. The bucket base includes a thrust bearing base, which comprises a first bearing layer and a second bearing layer stacked circumferentially along the runner. The first bearing layer is disposed at the non-driving end of the thrust bearing base along the direction of runner rotation, and the second bearing layer is disposed at the driving end of the thrust bearing base along the direction of runner rotation. The thrust bearing base is configured to be connected to the hub via an assembled structure, and multiple identical thrust bearing bases can be tightly connected end-to-end along the outer circumferential edge of the hub. This fundamentally improves the load transmission path, effectively disperses local high stress, and significantly reduces dependence on the size of the hub forgings, thereby enabling the design and manufacture of larger, more reliable large runners capable of withstanding harsh operating conditions.

Description

Technical Field

[0001] This application relates to the field of hydropower technology, specifically to an impulse turbine, a water bucket, and a water bucket base. Background Technology

[0002] Under ultra-high head (greater than 800 meters) and ultra-large capacity (greater than 700 MW) conditions, impulse turbine runners and their hub connections face unprecedented technical challenges. Traditional designs that use welding to fix the buckets to the hub are ill-suited to handle the enormous pulsating impact loads and cyclic fatigue stresses generated by high-speed jets. This stress concentration is particularly pronounced at the weld root between the buckets and the hub, easily leading to structural deformation, microcrack initiation and propagation, ultimately causing serious accidents such as bucket fracture or even hub failure. Furthermore, to meet strength requirements, traditional designs have had to continuously increase the outer diameter and overall size of the hub, causing the weight and size of individual forgings to approach or even exceed the limits of modern manufacturing and heat treatment capabilities, becoming a key bottleneck restricting the increase in unit capacity.

[0003] The aforementioned structural reliability issues and manufacturing bottlenecks together limit the development of impulse turbines towards higher heads and larger capacities. Especially in sediment-laden watersheds, hard particles in the water flow exacerbate abrasion and corrosion at the bucket roots, further accelerating the welding fatigue failure process.

[0004] Therefore, the industry urgently needs a completely new connection structure to fundamentally improve the load transfer path, effectively disperse local high stress, and significantly reduce dependence on the size of the hub forgings, thereby making it possible to design and manufacture larger, more reliable large runners that can adapt to harsh operating conditions. Summary of the Invention

[0005] In view of this, embodiments of this application provide an impulse turbine, a bucket, and a bucket base, which can fundamentally improve the load transmission path, effectively disperse local high stress, and significantly reduce the dependence on the size of the hub forging, thereby making it possible to design and manufacture large runners with larger size, higher reliability, and the ability to adapt to harsh operating conditions.

[0006] A first aspect of this application provides a bucket base for an impulse turbine, the bucket base being used to assemble buckets onto the hub of the runner, the bucket base comprising:

[0007] The water bucket base is used to assemble the water buckets onto the hub of the runner, and the water bucket base includes:

[0008] A thrust bearing substrate, comprising a first bearing layer and a second bearing layer stacked together along the circumference of the rotor, wherein the first bearing layer is disposed at the non-driving end of the thrust bearing substrate along the rotation direction of the rotor, and the second bearing layer is disposed at the driving end of the thrust bearing substrate along the rotation direction of the rotor;

[0009] The thrust bearing base is configured to be connected to the hub via an assembly structure, and multiple identical thrust bearing bases can be tightly connected end to end along the outer circumferential direction of the hub.

[0010] In one embodiment, the circumferential thickness of the first tile layer is greater than the circumferential thickness of the second tile layer.

[0011] In one embodiment, the first tile layer is made of high-strength steel, including stainless steel or forged steel.

[0012] In one embodiment, the second tile layer is made of Babbitt alloy.

[0013] In one embodiment, the first tile layer and the second tile layer are composited by molding hot-melt welding or die casting to form the thrust tile substrate.

[0014] In one embodiment, the assembled structure is a mortise and tenon joint structure, and the root of the thrust bearing base is provided with a tenon for engaging with a mortise and tenon groove provided on the outer edge of the wheel hub.

[0015] In one embodiment, the thrust bearing substrate is provided with an interface structure for connecting water buckets, the interface structure being configured to be connected to one or more water bucket blades as a whole by welding or integral forging.

[0016] In one embodiment, the axial width of the thrust pad of the water bucket base, the circumferential thickness of the first pad layer, the circumferential thickness of the second pad layer, and the connection depth between the thrust pad and the hub are jointly determined by the water head, the circumferential surface pressure of the thrust pad, the number of water buckets, and the target value of the water bucket deflection.

[0017] A second aspect of this application provides an impulse turbine bucket, comprising:

[0018] Water bucket blades, and water bucket base as described above;

[0019] The water bucket blades are connected to the water bucket base.

[0020] A third aspect of this application provides an impulse turbine, comprising:

[0021] Hub, nozzle, and multiple impact turbine buckets as described above;

[0022] Multiple impact turbine buckets are assembled to the outer edge of the hub via their bucket bases, and the multiple bucket bases are connected end to end along the circumference of the hub.

[0023] The first aspect of this application provides a bucket base for an impulse turbine, the bucket base being used to assemble buckets onto the hub of a runner. The bucket base includes a thrust bearing base configured to be connected to the hub via an assembly structure. The thrust bearing base includes a first bearing layer and a second bearing layer stacked circumferentially along the runner. The first bearing layer is disposed at the non-driving end of the thrust bearing base along the runner's rotation direction, and the second bearing layer is disposed at the driving end of the thrust bearing base along the runner's rotation direction. The thrust bearing base is configured such that multiple identical thrust bearing bases are tightly connected end-to-end along the outer edge of the hub. This structure can transform the impact load concentrated at the root of a single bucket in a traditional welded connection into a band-shaped compressive-shear stress distributed along the outer edge of the hub, jointly borne by multiple tightly connected thrust bearing bases. This force transmission and diffusion mechanism fundamentally reduces stress concentration at the hub edge and significantly improves fatigue resistance. It not only solves the problems of load transfer and hydraulic stability of the runner of ultra-high head and ultra-large capacity impulse turbines, but also greatly reduces the requirements for the outer diameter of the hub by increasing the thickness of the thrust bearing. This allows for a 20% to 30% reduction in the outer diameter of the hub of ultra-high head (e.g., 1000m) and ultra-large capacity (e.g., 875MW to 1000MW) impulse turbines, significantly reducing the difficulty of hub manufacturing. Thus, while achieving a runner structure with higher stability and reliability, it also solves the problem of limiting the size of ultra-large impulse turbine hubs.

[0024] It is understandable that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect above, and will not be repeated here. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a water bucket base provided in one embodiment of this application;

[0027] Figure 2 This is a schematic diagram of the structure of the water bucket of an impulse turbine provided in one embodiment of this application;

[0028] Figure 3This is a schematic diagram of a water bucket and hub assembly forming a runner structure according to an embodiment of this application;

[0029] Figure 4 This is a schematic diagram of another angle of the rotor structure formed by assembling a water bucket and a hub according to an embodiment of this application;

[0030] Figure 5 This is a schematic diagram of the structure of an impulse turbine provided in one embodiment of this application. Detailed Implementation

[0031] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0032] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0033] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0034] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0035] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0036] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0038] like Figure 1 As shown in the embodiment of this application, a bucket base for an impulse turbine is provided. The bucket base is used to assemble the buckets 1 onto the hub 2 of the runner. The bucket base includes:

[0039] The thrust bearing base 16 is configured to be connected to the hub 2 via an assembly structure;

[0040] The thrust bearing substrate 16 includes a first layer 161 and a second layer 162 stacked together along the circumference of the rotor. The first layer 161 is disposed at the non-driving end of the thrust bearing substrate 16 along the rotation direction of the rotor, and the second layer 162 is disposed at the driving end of the thrust bearing substrate 16 along the rotation direction of the rotor.

[0041] The thrust bearing base 16 is configured such that multiple identical thrust bearing bases 16 can be closely connected end to end along the outer circumferential direction of the hub 2.

[0042] In application, the non-driving end is the backwater side 12 of the water bucket 1, and the driving end is the frontwater side 11 of the water bucket 1. Through the segmented thrust bearing base 16 connected end to end in the circumferential direction, the pulsating impact of the single bucket is converted into circumferential band shear stress, realizing the uniform transmission and diffusion of load from jet hydraulics to water bucket to thrust bearing to hub, significantly reducing the risk of local stress concentration and fatigue at the outer edge of the hub and the root of the water bucket.

[0043] This application's embodiment can transform the impact load concentrated at the root of a single bucket in a traditional welded connection into a banded compressive-shear stress distributed along the outer edge of the hub, borne jointly by multiple thrust bearing substrates tightly connected circumferentially. This force transmission and diffusion mechanism fundamentally reduces stress concentration at the hub edge and significantly improves fatigue resistance. It not only solves the problems of load transmission and hydraulic stability in ultra-high head and ultra-large capacity impulse turbine runners, but also greatly reduces the requirements for the hub's outer diameter by increasing the thickness of the thrust bearings. This allows for a 20%–30% reduction in the hub outer diameter of ultra-high head (e.g., 1000m) and ultra-large capacity (e.g., 875MW to 1000MW) impulse turbines, significantly reducing the difficulty of hub manufacturing. Thus, while achieving a runner structure with higher stability and reliability, it also solves the problem of limiting the size of ultra-large impulse turbine hubs.

[0044] In one embodiment, the circumferential thickness of the first tile layer 161 is greater than the circumferential thickness of the second tile layer 162.

[0045] In application, the thickness distribution of the two layers of the thrust bearing substrate 16 is determined according to the impact pressure of the jet (determined by the head h and flow rate Q) to ensure that the thick and thin tiles on both sides have sufficient rigidity and strength, as well as good wear resistance and elastic shaping performance. At the same time, the reasonable combination of the thickness δ1 of the Babbitt alloy thin tile and the δ2 ​​of the high-strength stainless steel thick tile can enable the water bucket impeller under this method to have good impact hydraulic performance, thereby ensuring the hydraulic efficiency of the water bucket.

[0046] In this embodiment, the circumferential thickness of the first tile layer is greater than that of the second tile layer. This ensures that the first tile layer, as the main load-bearing component, possesses sufficient stiffness and section modulus to efficiently transmit the enormous circumferential thrust, while the relatively thinner second tile layer focuses on utilizing its elastic deformation capacity to absorb impact energy. This combination of thick and thin layers optimizes the overall stiffness-flexibility ratio of the base and is a key structural parameter for achieving the synergistic effect of efficient load-bearing and effective buffering.

[0047] In one embodiment, the first tile 161 is made of high-strength steel, including stainless steel or forged steel.

[0048] In this embodiment, the first layer is made of high-strength steel, such as stainless steel or forged steel. The high yield strength and fatigue strength of high-strength steel ensure its structural integrity and dimensional stability under ultra-high thrust loads, while its excellent wear resistance effectively resists the erosion of water containing silt. It is particularly suitable for harsh working conditions where the non-driving end is subjected to compressive stress and fretting wear for a long time, ensuring the long-term durability of the base body.

[0049] In one embodiment, the second tile 162 is made of Babbitt alloy.

[0050] In this embodiment, the thrust bearing base is made of Babbitt alloy with a good elastic coefficient at the driving end (water-facing side of the bucket) and high-strength stainless steel or forged steel at the non-driving end (water-returning side of the bucket). Under the impact of the symmetrically distributed jets along the circumference, the buckets convert the jet impact load into a circumferential water thrust load, which is applied to the thrust bearing. The thrust bearings are connected end-to-end without gaps at the outer edge of the hub. That is, the thrust bearing connected to this bucket is both the bearing bearing of the previous bucket's thrust bearing and the load-bearing bearing of the next thrust bearing. By using the asymmetrical metal material thrust bearings with the above-mentioned gapless assembly structure as the bucket base, the compressive plasticity of the Babbitt alloy bearings can be utilized to absorb the pulsating load generated by the jets and high-speed rotation. The high strength and hardness of the stainless steel / forged steel can be used to transmit the ultra-large thrust load, driving the impact-type impeller to rotate at high speed. High-strength steel (stainless steel / forged steel) thick tiles (i.e., the first layer of tiles) ensure pressure resistance and dimensional stability, while Babbitt alloy thin tiles (i.e., the second layer of tiles) provide surface contact compliance and damping. The circumferential thrust tile has a more reasonable range of contact surface pressure (7.9-9.5MPa) and composite deflection (≈0.03 mm).

[0051] In this embodiment, the second layer is made of Babbitt alloy. Babbitt alloy is soft, tough, and has strong embedding properties. Its low elastic modulus and high damping characteristics enable it to effectively absorb and dissipate the high-frequency pulsating energy from the jet impact through a small amount of plastic deformation, thereby protecting the high-strength steel layer behind it and the hub connection interface, and greatly improving the smoothness of the entire transmission system under variable load.

[0052] In one embodiment, the first tile layer 161 and the second tile layer 162 are composited by molding hot melt welding or die casting to form the thrust tile substrate 16.

[0053] In this embodiment, the first and second tile layers are composited by molding hot-melt welding or die casting, ensuring a high-strength metallurgical bond or mechanical interlocking interface between the dissimilar materials. This robust composite method prevents peeling or loosening between the two layers under alternating loads, ensuring that thrust loads can be smoothly transferred from the Babbitt alloy layer to the high-strength steel layer. This is a key technological guarantee for achieving collaborative operation of the double-layer structure.

[0054] In one embodiment, the assembled structure is a mortise and tenon joint structure, and a tenon 14 is provided at the root of the thrust bearing base 16 for engaging with the mortise and tenon groove provided on the outer edge of the hub 2.

[0055] The assembled structure in this application embodiment is a mortise and tenon joint. The mortise and tenon joint achieves precise positioning and circumferential constraint of the thrust bearing base on the hub. Its multi-faceted contact characteristics can provide huge shear resistance to transmit torque, while allowing a certain degree of thermal expansion freedom in the radial and axial directions, avoiding the thermal stress generated by rigid connection, and the assembly process is also simpler and more reliable.

[0056] In one embodiment, the thrust bearing base 16 is provided with an interface structure for connecting the water bucket blades 15. The interface structure is configured to be connected to one or more water bucket blades 15 as a whole by welding or integral forging.

[0057] In application, the thrust bearing base 16 serves as the base or pedestal for the water bucket blades 15. The water bucket blades 15 are connected to the thrust bearing base 16 as a whole by welding or integral forging. One or two water bucket blades 15 can be connected to one thrust bearing base 16. The thrust bearing bases 16 are connected end to end without gaps and form a circle. The root of each thrust bearing base 16 is connected to the wheel hub, and in this embodiment, a mortise and tenon joint is used. In addition to the mortise and tenon joint, other assembly methods can also be used, and this embodiment is not limited to them.

[0058] The thrust bearing substrate of this application is provided with an interface structure for connecting the water bucket blades, and supports both welding and integral forging. This provides great flexibility in the manufacturing process. Welding facilitates the replacement and maintenance of the water bucket, while integral forging can achieve the ultimate performance of continuous streamlines and no weak interfaces. The most suitable manufacturing strategy can be selected according to different working conditions and usage concepts.

[0059] In one embodiment, the axial width of the thrust pad of the water bucket base, the circumferential thickness of the first pad layer 161, the circumferential thickness of the second pad layer 162, and the connection depth between the thrust pad and the hub 2 are jointly determined by the water head, the circumferential surface pressure of the thrust pad, the number of water buckets, and the target value of the water bucket deflection.

[0060] The key dimensional parameters of the water turbine base in this application embodiment are determined by the operating conditions such as water head and surface pressure, ensuring that the base of each turbine is not designed based on experience, but is a customized component that has been precisely calculated and optimized, so that its structural strength and elastic buffering performance can be perfectly matched with the specific hydraulic environment and power level, thereby achieving the optimal balance between safety and economy.

[0061] This application also provides an embodiment of an impulse turbine water bucket, such as Figure 2 As shown, it includes:

[0062] Water bucket blades 15, and a water bucket base as claimed in any one of claims 1 to 8;

[0063] The water bucket blade 15 is connected to the water bucket base.

[0064] This application embodiment integrates the water bucket base and water bucket blades into a complete water bucket assembly. This integrated design transforms the water bucket assembly into a standard modular unit that can be independently manufactured, tested, and replaced, greatly improving the maintainability of the water bucket while ensuring that the impact load borne by the water bucket blades can be directly introduced into the composite layer structure of the base through the optimal path.

[0065] This application also provides a runner structure for an impulse turbine, such as... Figure 3 , 4 As shown, it includes a hub 2 and a plurality of impulse turbine buckets as claimed in claim 9, wherein the plurality of impulse turbine buckets are assembled to the outer edge of the hub 2 via their bucket bases, and the plurality of bucket bases are connected end to end along the circumference of the hub 2.

[0066] This application also provides an impulse turbine, such as... Figure 5 As shown, it includes:

[0067] Hub 2, nozzle 3, and multiple impact turbine buckets as described in claim 9;

[0068] Multiple impulse turbine buckets are assembled to the outer edge of hub 2 via their bucket bases, and the multiple bucket bases are connected end to end along the circumference of hub 2.

[0069] The nozzle 3 is mounted on the water distribution coil 5, which is a ring-shaped high-pressure water pipe extending from the pressure steel pipe of the impulse turbine to the centerline elevation of the impulse turbine runner. Four or six nozzles are evenly distributed from the coil 5, providing powerful water pressure that, after passing through the nozzles (with internal nozzle adjustment), forms an impact jet 4, driving the water buckets to rotate the turbine hub at high speed. The turbine hub 2 and the water buckets 1 mounted on it together form the runner of the impulse turbine, which is driven to rotate by the impact jet 4.

[0070] In application, the hub 2 is an intermediate component connecting the water buckets of an impulse turbine runner and the main shaft, serving to transmit torque and support the water buckets. It has a disc-shaped or hub-shaped structure with a certain thickness and diameter to meet strength and rigidity requirements. It has a central hole for mounting with the main shaft and is fixed to the water buckets along its circumference by welding or bolting. The hub needs to withstand the enormous impact force and torque transmitted from the water buckets and is generally forged from high-strength alloy steel. Its working principle is as follows: high-speed water flow impacts the water buckets of the turbine, generating a rotational torque in the buckets due to the force of the water flow. This torque is transmitted to the main shaft through the hub, thereby driving the generator rotor to rotate and converting water energy into electrical energy.

[0071] In application, the main function of nozzle 3 is to convert the pressure energy of water into kinetic energy, forming a high-speed jet that impacts the turbine runner, causing it to rotate and thus converting water energy into mechanical energy. It consists of a nozzle body, a nozzle needle, and a throttling cone. The nozzle body is the water flow channel; its shape and size affect the speed and direction of the water flow. The nozzle needle is located inside the nozzle body; by adjusting its position, the nozzle's flow area can be changed, thereby controlling the water flow rate and jet velocity. The throttling cone is used to improve the flow characteristics of the water and reduce energy loss. Specifically, when pressurized water enters the nozzle, due to the nozzle's contraction, the water flow velocity gradually increases, and the pressure gradually decreases, converting the water's pressure energy into kinetic energy, forming a high-speed jet. This high-speed jet impacts the blades on the turbine runner, causing the runner to rotate, which in turn drives the generator to produce electricity.

[0072] Example 1

[0073] The axial width b of the thrust pad of the water bucket base, the circumferential thickness δ1 of the first pad layer (i.e., the thickness of the Babbitt alloy thin pad), the circumferential thickness δ2 of the second pad layer (i.e., the thickness of the high-strength steel thick pad), and the connection depth h (or tenon groove depth) between the thrust pad and the hub are jointly determined by the water head H, the circumferential surface pressure P of the thrust pad, the number of water buckets z, and the target value of the water bucket deflection δ. The specific determination method is as follows:

[0074] 1. Calculation of jet force and power based on hydraulics

[0075] For an impact bucket, according to the momentum theorem, the resultant force in the horizontal direction (circumferential direction) is:

[0076] F t =ρ Q j (Vu)[1+kcosφ];

[0077] Where ρ is the density of water (≈1000 kg / m³). 3 ); Q j V represents the flow rate of a single nozzle; V is the jet velocity = (2gH) 1 / 2 H is the water head (m); u is the circumferential linear velocity of the water bucket (rotor circumferential velocity); k∈(0,1) is the relative velocity coefficient (loss coefficient, taken as 0.85~0.95); φ is the deflection angle between the relative velocity leaving the water bucket and the reverse jet (usually taken as 10°~20°; cosφ≈0.94~0.98). Therefore, the single nozzle torque T = F t R, rotor power:

[0078] P=ΣF t u=Σρ Q j (Vu)[1+kcosφ]u;

[0079] For a given V (determined by the head H), the power is at its maximum at u = V / 2 when k and φ are approximately constant.

[0080] Based on the above analysis, the transmission path of the jet force along the water bucket-thrust bearing-hub is designed: the pulsating impact of the jet is converted into a circumferential thrust F by the water bucket. t The thrust is transmitted through the "water jet - composite thrust pad - hub" to the circumferentially segmented unidirectional elastic thrust pads (generated by corresponding single-sided Babbitt alloy thin pads). Because the thrust pads are connected end-to-end without gaps at the outer edge of the hub, the local impact from the circumferential nozzles is diffused along the circumference, forming a relatively uniform circumferential compressive-shear stress band, thereby reducing the local bending and torsional stress concentration at the outer edge of the hub; the Babbitt alloy thin pads provide compliant fit and damping of surface contact, dissipating the jet pulsating impact load; and the (stainless steel / forged steel) thick pads bear the main body's pressure and shear, ensuring strength and dimensional stability.

[0081] 2. Analyze the structural forces and dimensional formulas.

[0082] Let the impeller radius be R, each water bucket correspond to a circumferentially segmented thrust bearing (circumferential pitch p = 2πR / z, where z is the number of water buckets), the axial width of the thrust bearing be b, and its effective contact area be A = bp. Average surface pressure of a single nozzle on a single water bucket:

[0083] P ave =F t / A=F t / (b2πR / z)

[0084] Design constraints:

[0085] Babbitt surface pressure: P ave <[P]B (Babbitt metal dynamic load allowable load 8~12MPa);

[0086] Stainless steel / forged steel thick roof tile surface pressure: P ave <[P]s (High-strength steel has an allowable load of 120~200 MPa, which is 10~20 times that of Babbitt alloy).

[0087] Hub connection key: If each water bucket uses a mortise and tenon structure or shear key to transmit circumferential force, the shear stress of its single component is: τ t =F t / (nA) i ) < [τ]; ([τ]≈0.3-0.5·σ y ).

[0088] Thick / thin tile deflection matching: The thrust bearing can be considered as a composite layer of "thick plate + elastic surface layer (Babbitt metal)". Under uniform surface pressure P, the total compressive deflection θ on the double-sided contact side is:

[0089] θ=θ 厚瓦 +θ 弹性巴氏合金 =C plate pb2 / Es+pδ1 / E B ;

[0090] Where Es is the elastic modulus of stainless steel / forged steel, E B The equivalent modulus of Babbitt metal is approximately 30-60 GPa, δ1 is the thickness of the thin tile, and C is the equivalent modulus of Babbitt metal. plate The plate coefficient is related to the geometry of the thick tile (approximately 0.2~0.4 for circumferential strips). Design objective: θ is taken in the range of 0.05~0.2 mm, so that it can conform without softening.

[0091] Example 2

[0092] Taking a super-high head, large-capacity impulse turbine with a head of 1000m and a single unit capacity of more than 700MW as an example, the method described in this invention patent can achieve high adaptability, high strength, and high safety and reliability of the bucket-thrust bearing-hub structure. The specific implementation is as follows:

[0093] 1. Example of a 700 MW, 1000 m head impulse turbine (6 nozzles, z=20)

[0094] Given / take values ​​H = 1000m, γ = 0.90, ρ = 1000kg / m 3 g = 9.81 m / s 2 The total flow rate Q = P / (npgH) ≈ 79.3 m / s, and the nozzle flow rate Qj ≈ 13.2 m. 3 / s, jet velocity V = (2gH) 1 / 2 ≈ 140.1m / s.

[0095] Take u = 0.46V ≈ 64.4 m / s (based on the actual value of the project), relative exit angle p = 15°, k = 0.90 = [1 + kcosy ≈ 1.869].

[0096] Select the working circle radius of the impeller R=2.5 m (working diameter≈5 m); number of water buckets z=20; pitch p=2πR / x=0.785m; select the axial width of the thrust bearing b=0.25 m; initial values ​​for thin / thick bearings: δ1=60mm (Barcol), δ2=190 mm (stainless steel / forged steel).

[0097] Nozzle-water jet force:

[0098] F t =ρ Q j (Vu)[1+kcosφ]=1000·13.2·(140.1-64.4)·1.869≈1.87 MN;

[0099] The total tangential force of the nozzle is approximately 11.2 MN (acting on 6 receiving water buckets respectively).

[0100] Torque and verification power: T=R≈1.87 MN x2.5 m=4.67 MN;

[0101] The nozzle angular velocity w = u / R ≈ 25.77 rad / s;

[0102] P = ΣTω ≈ 6 x 4.67 x 25.77 MW ≈ 722 MW; that is, it meets the design target of 700 MW.

[0103] Surface pressure calculation (driving end Bacolatt thin tile): Contact area A = bp = ≈ 9.5 MPa;

[0104] The dynamic load of 9.5 MPa is within the commonly allowed range (8-12 MPa) for Babbitt metal; if the site experiences severe sand abrasion, b can be increased to 0.30 m (then P ave (≈ 7.9 MPa) to increase margin.

[0105] Deflection matching of thick / thin roof tiles (estimated)

[0106] Take Es = 200 GPa, E B =40 GPa, C plate =0.3, then:

[0107] θ=θ 厚瓦 +θ 弹性巴氏合金 =C plate pb 2 / Es+pδ1 / E B =0.012 mm+0.014 mm≈0.026mm;

[0108] The displacement is within the ideal range of "rigid yet flexible" (0.02~0.1 mm).

[0109] Hub connection depth (equivalent bolt length)

[0110] Each water bucket and its thick tile / hub base transmit force through n=4 high-strength bolts (or shear keys), and the shear force of a single component F ≈ / n ≈ 0.47MN.

[0111] Select 17-4PH stainless steel bolts, σ ​​≈ 900 MPa, and take the allowable shear stress [7| = 0.35σ ≈ 315 MPa, then the required effective shear section corresponds to a diameter d > V4A / π ≈ 44 mm. That is, the corresponding hub connection depth is approximately 50 mm.

[0112] With the use of thick-walled bearings, the wheel hub only needs to provide circumferential support and tenon-and-mortise shear key function. Its outer diameter is calculated as δ1= 60mm, δ2= 190mm, and the seat / transition is 20-30mm. Compared with the "one-piece bucket seat" type, the outer diameter of the wheel hub can be reduced by 560mm, which significantly reduces the difficulty of large-size forging and heat treatment. At the same time, because the circumferential force is supported by the segmented thrust bearings connected end to end, the maximum bending and torsional combined stress at the root of the wheel hub is significantly reduced, and the stress concentration factor is reduced by 30-40%.

[0113] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A bucket base for a pelton turbine, characterized in that, The water bucket base is used to assemble the water bucket (1) onto the hub (2) of the runner, and the water bucket base includes: The thrust bearing substrate (16) includes a first bearing layer (161) and a second bearing layer (162) stacked together along the circumference of the rotor. The first bearing layer (161) is disposed at the non-driving end of the thrust bearing substrate (16) along the rotation direction of the rotor, and the second bearing layer (162) is disposed at the driving end of the thrust bearing substrate (16) along the rotation direction of the rotor. The thrust bearing base (16) is configured to be connected to the hub (2) via an assembly structure, and multiple identical thrust bearing bases (16) can be tightly connected end to end along the outer circumferential direction of the hub (2); The first tile layer (161) is made of high-strength steel, including stainless steel or forged steel; The second layer (162) is made of Babbitt metal; The first layer is used to bear the pressure and shear of the main body, while the second layer is used to absorb and dissipate the pulsating energy from the jet impact through surface contact conformal fitting and plastic deformation.

2. The bucket base for a pelton turbine according to claim 1, wherein The circumferential thickness of the first tile layer (161) is greater than the circumferential thickness of the second tile layer (162).

3. The bucket base for a pelton turbine according to claim 1, wherein The first tile layer (161) and the second tile layer (162) are combined to form the thrust tile substrate (16) by molding hot melt welding or die casting.

4. The bucket base for a pelton turbine according to claim 1, wherein The assembled structure is a mortise and tenon connection structure. The root of the thrust bearing base (16) is provided with a tenon (14) for cooperating with the tenon groove provided on the outer edge of the hub (2).

5. The bucket base for a pelton turbine according to claim 1, wherein The thrust bearing base (16) is provided with an interface structure for connecting the water bucket blades (15), the interface structure being configured to be connected to one or more water bucket blades (15) as a whole by welding or integral forging.

6. The bucket base for a pelton turbine according to claim 1, wherein The axial width of the thrust pad of the water bucket base, the circumferential thickness of the first pad layer, the circumferential thickness of the second pad layer, and the connection depth between the thrust pad and the hub are determined by the water head, the circumferential surface pressure of the thrust pad, the number of water buckets, and the target value of the water bucket deflection.

7. A bucket for an impulse water turbine, characterized in that include: Water bucket blades (15), and water bucket base as described in any one of claims 1 to 6; The water bucket blades (15) are connected to the water bucket base.

8. A Pelton turbine, characterized by include: Hub (2), nozzle (3), and multiple impact turbine buckets as described in claim 7; Multiple impact turbine buckets are assembled to the outer edge of the hub (2) via their bucket bases, and the multiple bucket bases are connected end to end along the circumference of the hub (2).

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