Impulse water turbine, bucket and mortise and tenon connection structure for bucket and hub

Abstract

The application relates to the technical field of hydroelectric power generation, in particular to an impulse water turbine, a water bucket and a mortise-and-tenon connection structure for the water bucket and a wheel hub. The water bucket comprises a water bucket blade and a tenon head arranged at the root of the blade; the shape of the tenon head is configured to be movably assembled with a mortise groove arranged on the wheel hub of the water turbine in a manner with a matching gap. The structure can realize the movable assembly manner with the matching gap, can make the water bucket have limited displacement in the gradually changing gap under different jet impact load conditions, and thus changes the original traditional rigid connection into a flexible movable connection. The water bucket can be reliably connected with the wheel hub without relying on welding or bolt fixation, and the problem that the water head and the wheel hub weld seam are easily broken under high-strength water impact force in the original mode is solved.

Description

Technical Field

[0001] This application relates to the field of hydropower technology, specifically to an impulse turbine, a water bucket, and a tenon-and-mortise connection structure for the water bucket and the hub. Background Technology

[0002] At high heads, especially those exceeding 700m, impulse turbines are generally used. The runner head of larger capacity, high-speed impulse turbines is typically rigidly connected to the hub by welding. Because the runner of an impulse turbine bears the force of a high-speed jet, long-term operation under the powerful impact of the water flow easily leads to fatigue at the welded joint between the runner head and the hub. Especially since the impulse runner rotates at high speed in the air, and with a certain number of nozzles evenly distributed along the circumference, the load on the runner is discontinuous and intermittent. This accelerates fatigue at the runner-hull connection, causing the welded impulse runner head to easily fracture from the root after prolonged operation. This is a current challenge and limitation for high-head, large-capacity impulse turbines, significantly affecting their operational reliability and even limiting their selection for larger capacity, higher head applications.

[0003] Under conditions of larger capacity and higher head, such as head > 1000m and capacity > 800MW, if the turbine runner buckets adopt a welded rigid connection method, the stress conditions at the head root will further deteriorate, making bucket breakage not only difficult to avoid but also significantly shortening the cycle, making it difficult to meet the requirements for long-term safe and reliable operation. Summary of the Invention

[0004] In view of this, embodiments of this application provide an impulse turbine, a water bucket, and a tenon-and-mortise connection structure for the water bucket and the hub, to solve the problems of easy breakage and short service life of the water bucket in existing impulse turbines.

[0005] A first aspect of this application provides an impulse turbine bucket, including a bucket and a tenon disposed at the root of the bucket; The tenon is shaped to be movable and fitted with a mortise and tenon provided on the turbine hub with a fitting clearance.

[0006] In one embodiment, the surface of the tenon that mates with the mortise is a toothed surface.

[0007] In one embodiment, the tenon has a first toothed surface on the water-facing side and a second toothed surface on the back side along the rotation direction of the wheel after assembly, the first toothed surface and the second toothed surface having different tooth profile parameters.

[0008] In one embodiment, the upper surface of the tooth of the first tooth surface has a first inclination angle, and the upper surface of the tooth of the second tooth surface has a second inclination angle, wherein the first inclination angle is greater than the second inclination angle; The tooth depth of the first tooth surface is greater than the tooth depth of the second tooth surface.

[0009] In one embodiment, the center trajectory of the tooth-shaped surface is any one of a circle, an ellipse, or a parabola.

[0010] The second aspect of this application provides a mortise and tenon connection structure for the bucket and hub of an impulse turbine, including a mating tenon and a mortise groove. The tenon is located at the base of the water bucket; The tenon groove is provided on the outer circumference of the wheel hub; The tenon is movably fitted into the mortise with a fitting clearance.

[0011] In one embodiment, the tenon has a first toothed sidewall adapted to the shape of a first toothed surface of the tenon, and a second toothed sidewall adapted to the shape of a second toothed surface of the tenon. A first toothed mating gap is formed between the first toothed surface and the first toothed sidewall, and a second toothed mating gap is formed between the second toothed surface and the second toothed sidewall. The toothed depth of the first toothed mating gap is greater than the toothed depth of the second toothed mating gap.

[0012] In one embodiment, the line connecting the two side walls of the tenon groove and the direction of water flow, and the line connecting the two toothed surfaces of the tenon and the direction of water flow, both form a certain angle, and the angle is an acute angle.

[0013] In one embodiment, the lower end of the tenon is provided with a centrifugal sand discharge chute; The centrifugal sand discharge chute is configured to use the centrifugal force generated when the wheel rotates to throw out mud and sand that may enter the gap between the tenon and the mortise.

[0014] A third aspect of this application provides an impulse turbine, including a hub, nozzles, and a plurality of water buckets evenly distributed on the hub, wherein the plurality of water buckets are assembled on the hub by a mortise and tenon connection structure as described in the second aspect of this application.

[0015] The first aspect of this application provides an impact turbine bucket, including bucket blades and tenons disposed at the root of the bucket blades; the tenons are configured to be movably assembled with a tenon groove disposed on the turbine hub with a fitting clearance. By providing a tenon structure of a specific shape at the root of the bucket blades, a movable assembly with the hub tenon groove is achieved. This structure enables a movable assembly with a fitting clearance, allowing the bucket to undergo restricted (non-free) displacement in a gradually changing gap under different jet impact loads, thereby transforming the original traditional rigid connection into a flexible movable connection. This allows the bucket to be reliably connected to the hub without relying on welding or bolt fixing, solving the common problem of easy breakage of the head and hub welds under high-intensity water impact forces in the original method.

[0016] 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

[0017] 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.

[0018] Figure 1 This is a three-dimensional structural schematic diagram of the water bucket of an impulse turbine provided in an embodiment of this application; Figure 2 This is a schematic diagram of the assembly of the bucket and hub of an impulse turbine according to an embodiment of this application; Figure 3 This is a schematic diagram of a tenon-and-mortise connection structure between a bucket and a hub for an impulse turbine, provided in one embodiment of this application. Figure 4 This is a top view of the turbine runner assembled using a mortise and tenon joint structure, as provided in an embodiment of this application. Figure 5 yes Figure 4 Schematic diagram of the inclined setting of the tenon groove; Figure 6 yes Figure 4 Enlarged schematic diagram of the centrifugal sand discharge chute in the middle; Figure 7 This is a schematic diagram of an impulse turbine structure provided in one embodiment of this application; Figure 8 yes Figure 7 A schematic diagram of the runner structure of a medium-impact turbine. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] like Figure 1 As shown in the figure, an embodiment of this application provides an impulse turbine bucket, which includes bucket blades 15 and tenons 14 disposed at the root of the bucket blades 15; The tenon 14 is shaped to be movablely assembled with a mortise 21 provided on the turbine hub in a manner with a mating clearance.

[0027] In application, the water-facing surface 11 and the water-repellent surface 12 of this embodiment are two surfaces of an integrally formed water bucket, which is made of high-strength stainless steel or forged steel.

[0028] In applications, the water jet is a key component used to withstand the impact of water flow and convert water flow energy into mechanical energy. It typically consists of jet blades, a jet back, and a water-dividing blade, evenly distributed around the hub. In this embodiment, the water jet blades are double-bowl shaped to accommodate the impact of the water flow and the energy conversion. The water-dividing blade is located at the center of the water jet blades, dividing the jet into two parts, which enter the two halves of the water jet respectively. When high-speed water is ejected from the nozzle and impacts the water-dividing blade of the water jet, the water flow is divided into two parts, which enter the two halves of the water jet respectively. During the flow of water within the water jet, the speed and direction of the water flow change due to the shape and curvature of the water jet, thus generating an impact force on the water jet. This impact force drives the water jet to rotate through the hub, driving the impeller and main shaft to rotate, converting the kinetic energy of the water flow into mechanical energy. The water jet is made of high-strength, high-toughness materials, such as stainless steel, to withstand the impact and wear of the high-speed water flow.

[0029] In application, when high-speed water impacts the water-facing surface of the bucket, the jet impact force is transmitted to the tenon at the root of the bucket blades, causing it to enter the toothed tenon groove and fit tightly against the inner surface of the groove along the direction of the wheel's rotation, thus transferring the impact load to the hub. Depending on the magnitude of the impact load, under different operating conditions (i.e., different water heads), the length of the toothed gap occupied by the tenon varies. That is, the greater the impact load, the deeper the tenon enters the mortise groove, and the larger the proportion of the fit clearance occupied, and vice versa.

[0030] This application embodiment achieves a movable assembly with the hub tenon groove by setting a specifically shaped tenon structure at the root of the water bucket blade. This allows the water bucket to reliably connect to the hub without relying on welding or bolt fixing, fundamentally avoiding the risk of weld fatigue fracture. This structure enables a movable assembly method with a fitting clearance, allowing the water bucket to undergo restricted (non-free) displacement within the gradually changing gap under different jet impact loads, thus transforming the original traditional rigid connection into a flexible movable connection. Due to its self-adaptive, weld-free, boltless, and fixed connection characteristics, the rigid root of the water head and hub is also eliminated, fundamentally solving the problem of easy fracture of the water head and hub welds under high-intensity water impact forces common in the original method.

[0031] In one embodiment, the surface of the tenon 14 that mates with the mortise 21 is a toothed surface.

[0032] The tooth profile of this application significantly increases the contact area, enabling impact loads to be uniformly transmitted through multiple tooth surfaces, effectively dispersing stress concentration. At the same time, the tooth meshing effect can also generate a self-locking effect during high-speed rotation, enhancing the stability of the connection.

[0033] In one embodiment, the tenon 14 has a first toothed surface 141 on the water-facing side and a second toothed surface 142 on the back side along the rotation direction of the wheel after assembly, the first toothed surface 141 and the second toothed surface 142 having different tooth profile parameters.

[0034] In application, the tenon teeth are larger on the water-facing side of the hub or bucket and smaller on the water-repellent side. This fit clearance method allows for adjustment of the tenon's occupation of the mortise tooth clearance length under different operating conditions (i.e., different water heads) based on the magnitude of the jet impact load. That is, the greater the jet impact load, the deeper the tenon enters the mortise, and the larger the proportion of the toothed fit clearance.

[0035] This application's embodiments achieve asymmetrical force characteristics by differentiating the tooth profile parameters of the upstream and downstream sides. This allows the upstream side of the water bucket to provide a larger bearing area and interlocking force when subjected to impact loads, while the downstream side maintains appropriate flexibility, thereby optimizing the load distribution.

[0036] In one embodiment, such as Figure 3 As shown, the upper surface of the tooth head of the first tooth surface 141 has a first tilt angle θ1, and the upper surface of the tooth head of the second tooth surface 142 has a second tilt angle θ2. The first tilt angle θ1 is greater than the second tilt angle θ2. The tooth depth of the first tooth surface 141 is greater than the tooth depth of the second tooth surface 142.

[0037] In application, the toothed surfaces of the mortise and tenon structure are asymmetrically distributed along the rotation direction of the wheel (θ1 > θ2). The biting force is proportional to the sine of the centrifugal force at an angle θ between the tooth surface and the tangential direction of rotation. The component of the centrifugal force perpendicular to the tooth surface is the biting force, F. 咬合 =F 离心 ×sinθ, the structural coefficient (k=sinθ) is determined by the slope of the toothed gap. When θ1 is 3°~8° (corresponding to k≈0.052~0.139), the tenon and mortise interlocking force generated by centrifugal force is greater than the nozzle jet impact force, which meets the requirements for safe and stable operation.

[0038] The embodiments of this application use a larger water-facing tilt angle to help guide the tenon to wed into the mortise more smoothly under impact load, while the differential tooth depth design ensures that the optimal contact state can be maintained under different load conditions, realizing adaptive matching between load and structural response.

[0039] In one embodiment, the trajectory line of the tooth center of the tooth surface is any one of a circle, an ellipse, or a parabola.

[0040] Circular, elliptical, and parabolic shapes are all curves with good mechanical properties, which can optimize stress transmission paths and reduce local stress concentration. At the same time, these shapes are also easy to manufacture with precision, ensuring fitting accuracy and reliability.

[0041] This application also provides a mortise and tenon connection structure for the bucket and hub of an impulse turbine, such as... Figures 2-4 As shown, it includes a mating tenon 14 and a mortise 21; Tenon 14 is set at the root of water bucket blade 15; The tenon 21 is provided on the outer circumference of the hub 2; The tenon 14 is movably assembled in the mortise 21 with a fitting clearance.

[0042] The mortise and tenon connection structure of this application embodiment ensures the force balance of the impact impeller, significantly reducing the unbalanced eccentric force of the impeller under high-head impact. With multiple nozzles evenly distributed along the circumference, the water buckets indirectly bear the impact of the nozzle jets. During fixed welding, any unbalanced force generated for various reasons acting on the impeller becomes a harmful eccentric force, which can severely affect the shaft stability of the impact unit. The mortise and tenon connection structure with progressive clearance allows the water buckets evenly distributed along the circumference of the impeller hub to self-adjust the fit clearance of the tenon in the mortise under unbalanced force conditions, thereby offsetting the eccentric force of the shaft and causing the impeller to regain circumferential equilibrium. The mortise and tenon structure has the ability to automatically adjust the fit clearance under high-speed rotation and impact water loads, allowing the tenon and mortise to adapt to the impact load and ensuring a balanced force distribution, avoiding the problem or defect of concentrated weld stress leading to failure and fracture under rigid welding methods. Because of the adoption of a movable assembly mortise and tenon structure with no welding or bolt fixing, the water bucket and its hub can withstand greater and higher impact loads and head conditions in principle, and are easier to assemble and maintain. This greatly improves the hydraulic performance and safety performance of the impulse turbine, and also significantly increases the range of head and single-unit capacity of the impulse turbine.

[0043] In applications, mortise and tenon joints can be made of forged steel, which possesses a certain degree of elasticity. When subjected to high-speed rotation or impact water flow loads, relative movement and stress occur between the tenon and mortise. Due to the elastic deformation of steel, the mortise and tenon joint can automatically adjust the fit clearance within a certain range. For example, under impact loads, the steel undergoes compression or tension deformation, temporarily increasing or decreasing the gap between the tenon and mortise to adapt to load changes. Compared to rigid welding, mortise and tenon joints offer a degree of flexibility, absorbing and buffering impact energy and reducing structural damage. The anisotropic properties of forged steel also play a positive role in stress distribution. Forged steel exhibits different mechanical properties in different directions. Mortise and tenon joint designs typically consider the anisotropic properties of steel, ensuring that the load is transmitted along the direction of higher strength in the forged steel, thereby improving the structure's load-bearing capacity and stress balance, and avoiding the problem of stress concentration and potential failure / fracture in welds.

[0044] Therefore, the above connection method creates a non-rigid force transmission path, which allows for small relative displacement through the fitting gap, thereby absorbing impact energy, avoiding stress concentration, and completely avoiding the material property degradation problem caused by welding.

[0045] In one embodiment, the tenon 21 has a first toothed sidewall that matches the shape of the first toothed surface 141 of the tenon 14, and a second toothed sidewall that matches the shape of the second toothed surface 142 of the tenon 14. There is a first toothed fitting gap between the first toothed surface 141 and the first toothed sidewall, and there is a second toothed fitting gap between the second toothed surface 142 and the second toothed sidewall. The toothed depth d1 of the first toothed fitting gap is greater than the toothed depth d2 of the second toothed fitting gap.

[0046] In application, the shapes of the tenon and mortise are set with a non-toothed fit clearance according to the combination of constant centrifugal force generated by high-speed rotation and intermittent jet impact force in the direction of rotation. This ensures that the tenon clamping force generated by centrifugal force is greater than the safety threshold of instability (vibration, displacement, deformation) of intermittent jet, thus guaranteeing that the impact impeller and water bucket with tenon and mortise connection can operate safely and stably under minimum and maximum working conditions.

[0047] In application, because the tooth depth of the first toothed fit is greater than that of the second toothed fit, an asymmetrical gap is formed between the bucket and the hub in the direction of rotation. The centrifugal force generated by the high-speed rotation of the impeller causes the tenon at the root of the bucket to tightly mesh with the hub along the asymmetrical toothed gap. This meshing force is proportional to the centrifugal force. When the rotation speed is greater than 200 r / min and the outer diameter of the hub is greater than 2 m, the meshing force generated by the centrifugal force is 22.38 tn. This fastening force is sufficient to offset the effect of the wave-like impact force generated by 4 or 6 nozzles. Under the combined action of high-speed jet and centrifugal force, the tenon and mortise of the bucket fit tightly in the direction of rotation, maintaining high stability under various working conditions, generating strong torque, driving the impeller of the impulse turbine to rotate, and without producing in-slot vibration or harmful displacement or deformation.

[0048] The mortise and tenon structure in this embodiment employs a special tooth-like shape, which generates a self-locking effect or adaptive adjustment capability under stress. When subjected to lateral loads, the wedge-shaped portion of the tenon fits tightly with the mortise. As the load increases, the tenon further weaves into the mortise, thereby automatically adjusting the gap and enhancing the stability of the connection. This mortise and tenon structure effectively disperses the load. When subjected to impact loads, the contact surface between the tenon and the mortise is large, allowing the load to be transferred and dispersed through multiple contact surfaces, avoiding the generation of concentrated stress.

[0049] This application's embodiments achieve a progressive load transfer mechanism by limiting the difference in the fit clearance between the mortise sidewall and the tenon tooth surface. This allows the tenon to embed deeper into the mortise when the impact load increases, automatically increasing the effective contact area and thus keeping the stress level within a safe range.

[0050] In one embodiment, such as Figure 5As shown, the line connecting the two side walls of the tenon 21 and the direction of water flow, and the line connecting the two toothed surfaces of the tenon 14 and the direction of water flow, all form a certain angle θ3, which is an acute angle.

[0051] In application, the tenon groove on the hub forms a certain angle θ3 with the horizontal center line of the hub according to the direction of water flow from the impeller, and the tenon at the root of the bucket adopts the same inclination angle. The centrifugal force generated by the high-speed rotation of the impact impeller in a fixed direction causes the bucket to generate a clamping force in the tenon groove through the oblique angle θ3 distributed on the hub. This force, together with the biting force generated by the large and small teeth θ1 and θ2 mentioned above, works to ensure the good hydraulic and mechanical performance of the bucket.

[0052] Because the tenon at the base of the water bucket is directly assembled at a certain angle in the direction of rotation into the hub tenon groove with the same inclination angle at the top opening and bottom stop, under operating conditions, the tenon of the water bucket automatically finds and adjusts its position in the tenon groove through the combined action of centrifugal force and water flow impact force, via the aforementioned hub tenon groove distribution inclination angle θ3, the tenon teeth and the inclination angles θ1 and θ2 of the water-facing / backwater-facing surfaces, that is, automatically adjusts the fit clearance.

[0053] The embodiments of this application utilize an angled design to enable the mortise and tenon joint to generate a clamping effect through centrifugal force during rotation. This self-tightening structure ensures that the connection will not loosen under high-speed conditions, while the inclined arrangement also facilitates drainage and sand removal, keeping the interface clean.

[0054] In one embodiment, such as Figure 6 As shown, a centrifugal sand discharge chute 211 is provided at the lower end of the tenon 21; The centrifugal sand discharge chute 211 is configured to use the centrifugal force generated when the wheel rotates to throw out the mud and sand that may enter the gap between the tenon 14 and the mortise 21.

[0055] In application, the tenon groove adopts a centrifugal sand discharge chute. By setting a centrifugal chute at the lower end of the tenon groove in the direction of the impeller rotation, the powerful centrifugal force generated by the high-speed rotation of the impact turbine is used to throw the mud and sand in the gap of the tenon structure to the bottom of the impeller along the centrifugal chute. This ensures that the gap fit of the tenon structure is not adversely affected by the high mud and sand operating conditions. At the same time, by reasonably setting the angle of the centrifugal sand discharge chute, it is ensured that the centrifugal sand discharge of the tenon groove will not affect the impeller, thus ensuring the safe operation of the impeller of the tenon-and-mortise connection method.

[0056] The centrifugal sand discharge chute design of this application embodiment cleverly utilizes the centrifugal force generated by the rotation of the impeller. The chute structure can promptly throw out silt particles that have intruded into the mating gaps, preventing jamming or wear caused by silt deposition, and ensuring the long-term reliable operation of the tenon and mortise connection in sandy water flow.

[0057] This application also provides an impulse turbine, such as... Figure 7 As shown, it includes a hub 2, a nozzle 3, and multiple water buckets 1 evenly distributed on the hub 2. The multiple water buckets 1 are assembled on the hub 2 by the mortise and tenon connection structure as described above.

[0058] Among them, nozzle 3 is installed on water distribution coil 5, which is a ring-shaped high-pressure water pipe from the water pressure steel pipe of the impulse turbine to the center line elevation of the impulse turbine runner, and leads out the above-mentioned 4 or 6 evenly distributed nozzles, providing strong water pressure to form an impact jet 4 after passing through the nozzles (with internal spray needle adjustment), driving the water bucket to drive the hub to rotate at high speed. Figure 8 As shown, the hub 2 and the water bucket 1 mounted on the hub 2 together form the runner of the impulse turbine, which is driven to rotate by the impulse jet 4.

[0059] 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.

[0060] 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.

[0061] Example 1 The centrifugal force interlocking force principle and analysis of the above-mentioned impulse turbine assembled based on the mortise and tenon joint structure are as follows: I. Analysis Theory and Formulas 1. Basic formula for centrifugal force The centrifugal force generated when the water bucket rotates with the hub is: F 离心 =m⋅ω 2⋅r; in: m is the mass of a single water bucket (kg); ω is the angular velocity of the wheel (rad / s), ω=2πn / 60, where n is the rotational speed (r / min); r is the distance (m) from the center of mass of the water bucket to the axis of rotation, which is approximately half the outer diameter of the hub, i.e., r = D / 2, where D is the outer diameter of the hub (m).

[0062] 2. Mechanical transformation of interlocking force in mortise and tenon joints Since the tooth-like gaps in the mortise and tenon structure are asymmetrically distributed (from large to small) along the direction of rotation, let θ be the angle between the tooth surface and the tangential direction of rotation. The component of the centrifugal force perpendicular to the tooth surface is the meshing force F. 咬合 :F 咬合 =F 离心 ⋅sinθ; Or, to simplify, it can be expressed as a relationship proportional to centrifugal force: F 咬合 =k⋅F 离心 ; Where k is the structural coefficient, which is determined by the slope of the toothed gap, k=sinθ, and θ is usually taken as 3°~8° (corresponding to k≈0.052~0.139).

[0063] II. Calculation 1. Known parameters Rotational speed n = 200 r / min; If the outer diameter of the hub is D = 2.4m, then the radius of rotation is r = D / 2 = 1.2m; The mass of a single water bucket is m = 150 kg (assuming it is made of cast steel and has a volume of approximately 0.02 m³). 3 ); The tooth surface inclination angle θ = 5°, corresponding to k = sin5° ≈ 0.087.

[0064] 2. Centrifugal force calculation Angular velocity: ω = (2π / 60) × 200 ≈ 20.94 rad / s; Centrifugal force: F 离心 =150×(20.94) 2 ×1.2≈150×438.5×1.2=78930N.

[0065] 3. Calculation of bite force F 咬合 =kF 离心 =0.087×78930≈6867N≈0.6867tf (ton-force, 1tf=9800N); F 咬合 ≈0.6867tf≈0.673tN.

[0066] 4. Total bite force of multiple water buckets Assuming the impeller has Z=20 buckets, the total bite force is: F 总咬合 =Z⋅F 咬合 =20×0.6867≈13.73tf.

[0067] III. Impact Force Comparison and Verification 1. Calculation of impact force of a single nozzle Assume the nozzle jet velocity is v = 80 m / s (high head condition), and the flow rate of a single nozzle is 0.5 m³ / s. 3 The impact force is: F 冲 =ρQv=1000×0.5×80=40000N=4.08tf; Where F = ΔtΔmv = ρQv, ρ is the water density and Q is the flow rate.

[0068] 2. Total impact force of the four (4) nozzles F 总冲-4喷嘴 =4 × 4.08 = 16.32tf; At this point, the total bite force of 13.73tf needs to be combined with a safety factor K ≥ 1.2. In actual design, the bite force can be increased by increasing the tooth inclination angle or the mass of the water bucket. If θ = 8° (k = 0.139), then the bite force of a single water bucket is: F 咬合 =0.139×78930≈10971N≈1.119tf; The total bite force is 20 × 1.119 = 22.38 tf > 16.32 tf, which meets the requirement of offsetting the impact force.

[0069] IV. Main conclusions of the above principle analysis 1. Relationship between bite force and centrifugal force: The bite force is directly proportional to the centrifugal force. When the rotational speed n and the hub radius r increase, the bite force increases quadratically (because ω∝n, F_centrifugal ∝ω²r).

[0070] 2. Influence of structural parameters: The tooth surface inclination angle θ directly determines the biting force conversion efficiency. During the design, the tooth surface stress needs to be verified through finite element analysis to avoid overload deformation (θ ≤ 10° is recommended).

[0071] 3. Safety margin: The bite force should be at least 1.2 to 1.5 times the peak impact force, which can be achieved by adjusting the water bucket mass, tooth inclination angle or hub diameter.

[0072] 4. Engineering Applications: When n=200r / min, D=2.4m, m=150kg, and θ=8°, the bite force of a single water jet is approximately 1.12tf, and the total bite force of 20 water jets reaches 22.4tf, which is sufficient to offset the wave-like impact of a 4-nozzle system (and still meets the requirements after considering the dynamic coefficient). If the friction coefficient of the toothed structure (μ≈0.15~0.2) is considered to enhance the bite force, it can be further increased accordingly.

[0073] Example 2 In this embodiment, an impulse turbine has four nozzles evenly distributed around its circumference, a runner radius R = 2m, and 20 water buckets evenly distributed around the runner hub. The flow rate of each nozzle jet is Q = 1m³. 3 Taking a jet velocity v0 = 50 m / s and a rotating wheel angular velocity ω = 10 rad / s as an example, a comparative analysis is conducted with a structure without mortise and tenon joints (fixed welding): 1. Calculate the impact force of the nozzle jet on the water bucket. According to the momentum theorem, neglecting friction within the water bucket, assume the jet's velocity drops to v1 = 5 m / s (approximate value) after impacting the bucket, and the density of water ρ = 1000 kg / m³. 3 .

[0074] The impact force F of a single nozzle jet on the water bucket 冲击 By the momentum theorem: F=Δp / Δt, Δp=ρQ(v0-v1), then F 冲击 =ρQ(v0-v1)=1000×1×(50-5)=45000N.

[0075] 2. Calculate the centrifugal force. Let the mass of each water bucket be m, and assume that the mass of each water bucket is m = 100 kg. The centrifugal force is F. 离心 =mω 2 Substituting m = 100kg, ω = 10rad / s, and R = 2m into the equation, we can obtain F. 离心 =100×10 2 ×2 = 20000N.

[0076] 3. Analysis of unbalanced eccentric forces in structures without mortise and tenon joints (fixed welding) Because the water buckets indirectly bear the impact of the nozzle jet, unbalanced forces may occur in the case of fixed welding. Assume that due to manufacturing or installation errors, one water bucket experiences an impact force 10% greater than the others, i.e., the impact force F experienced by that water bucket... 冲击1 =1.1×45000 = 49500N, other water buckets withstand the impact force F 冲击2=45000N.

[0077] At this moment, the unbalanced eccentric force F on the rotor 偏 Considering the circumferential distribution of the impact force, taking the bucket with the larger force as the reference point, and assuming the angle between adjacent buckets is θ = 2π / 20 = 0.1π, the influence of the unbalanced force is analyzed by taking the moment about the center of the impeller. Due to the complexity of the force distribution, the calculation is simplified here, considering only the radial component of the impact force.

[0078] Let the angle between the impact force direction and the radial direction be α (assuming α = 30°), and the unbalanced eccentric force F 偏 Radial component F 偏r =(F 冲击1 -F 冲击2 )×cosα=(49500 - 45000)×cos30≈3897N; This unbalanced eccentric force will cause the runner to generate additional vibrations, affecting the stability of the shaft system.

[0079] 4. Force balance analysis for structures with mortise and tenon joints With a mortise and tenon joint structure featuring progressive clearance, the water bucket can self-adjust the fit clearance of the tenon within the mortise and tenon under unbalanced stress conditions.

[0080] When a water bucket is subjected to a large impact force, the tenon undergoes a slight displacement within the mortise, altering the stress state of the water bucket. Assume that through this self-adjustment, the impact force borne by this water bucket is redistributed to the surrounding water buckets.

[0081] After redistribution, the impact force experienced by each water bucket tends to be uniform, assuming they are all close to the average value: F 冲击平均 = (4 × 45000) / 20 = 9000 N. At this time, the unbalanced eccentric force is greatly reduced, assuming it is reduced to 10% of the original value, i.e., F 偏r新 =0.1×3897 = 389.7N.

[0082] As can be seen from the above calculations, the mortise and tenon joint structure with progressive clearance ensures the force balance of the impact impeller in principle, greatly reduces the unbalanced eccentric force of the impeller under high head impact mode, and helps to ensure the stability of the shaft system of the impact unit.

[0083] 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 water bucket for an impulse turbine, characterized in that, Includes a water bucket blade (15) and a tenon (14) disposed at the root of the water bucket blade (15); The tenon (14) is configured to be movablely assembled with a mortise (21) provided on the turbine hub in a manner with a fitting clearance; The surface of the tenon (14) that mates with the mortise (21) is toothed; The tenon (14) has a first toothed surface (141) on the water-facing side and a second toothed surface (142) on the back side along the rotation direction of the wheel after assembly. The first toothed surface (141) and the second toothed surface (142) have different tooth profile parameters. The upper surface of the tooth head of the first tooth surface (141) has a first inclination angle, and the upper surface of the tooth head of the second tooth surface (142) has a second inclination angle, wherein the first inclination angle is greater than the second inclination angle; The tooth depth of the first tooth surface (141) is greater than the tooth depth of the second tooth surface (142); The first tilt angle is in the range of 3° to 8°. The first tilt angle is the angle between the first tooth surface (141) and the rotation tangent. The second tilt angle is the angle between the second tooth surface (142) and the rotation tangent.

2. The impulse turbine bucket as described in claim 1, characterized in that, The trajectory line of the tooth-shaped center of the tooth surface is any one of a circle, an ellipse, or a parabola.

3. A tenon-and-mortise connection structure for the bucket and hub of an impulse turbine, used for the bucket of an impulse turbine as described in claim 1 or 2, characterized in that, Including the mating tenon (14) and mortise (21); The tenon (14) is set at the root of the water bucket blade (15); The tenon (21) is provided on the outer circumference of the hub (2); The tenon (14) is movably fitted into the mortise (21) with a fitting clearance.

4. The mortise and tenon connection structure as described in claim 3, characterized in that, The tenon (21) has a first toothed sidewall that matches the shape of the first toothed surface (141) of the tenon (14) and a second toothed sidewall that matches the shape of the second toothed surface (142) of the tenon (14). There is a first toothed fit gap between the first toothed surface (141) and the first toothed sidewall, and there is a second toothed fit gap between the second toothed surface (142) and the second toothed sidewall. The toothed depth of the first toothed fit gap is greater than the toothed depth of the second toothed fit gap.

5. The mortise and tenon connection structure as described in claim 3, characterized in that, The line connecting the two sides of the tenon (21) forms a certain angle with the direction of water flow, and the angle is an acute angle.

6. The mortise and tenon connection structure as described in claim 3, characterized in that, The lower end of the tenon (21) is provided with a centrifugal sand discharge chute (211). The centrifugal sand discharge chute (211) is configured to use the centrifugal force generated when the wheel rotates to throw out the mud and sand that may enter the gap between the tenon (14) and the mortise (21).

7. An impulse turbine, characterized in that, It includes a hub (2), a nozzle (3) and a plurality of water buckets (1) evenly distributed on the hub (2), the plurality of water buckets (1) being assembled on the hub (2) by a tenon and mortise connection structure as described in any one of claims 3 to 6.

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