Runner blade capable of reducing pressure pulsation of vaneless area

Abstract

The utility model discloses a runner blade for reducing pressure pulsation in a vaneless area, which relates to the technical field of fluid mechanical equipment and comprises a runner and a blade, the runner consists of an upper crown and a lower ring, one end of the blade is connected with the upper crown, the other end of the blade is connected with the lower ring, the blade consists of a pressure surface and a suction surface, one side of the pressure surface is a low-pressure side, and the other side of the pressure surface is a suction surface. By changing the shape of the high-pressure side of the original runner, namely the water inlet edge of the blade under the working condition of the water turbine, on one hand, the radius of the partial flow surface of the high-pressure side is reduced, and on the other hand, the distribution rule of the wrap angle of the blade is redesigned; the strength of water flow vortexes caused by the rotating wheel can be restrained to a certain extent, the range of vortexes is reduced, the amplitude of pressure pulsation of a vaneless area is reduced, and serious safety production accidents caused by unit vibration are avoided.

Description

Technical Field

[0001] This utility model relates to the field of fluid machinery equipment technology, and in particular to a rotor blade that reduces pressure pulsation in the bladeless zone. Background Technology

[0002] Compared to conventional hydropower stations, pumped storage power stations offer advantages such as peak shaving and valley filling, and improved renewable energy absorption capacity. Their full utilization of water energy significantly enhances the economic efficiency of power grid operation. However, in recent years, dangerous accidents such as generator vibration and damage to flow components have seriously affected the safe and stable operation of pumped storage power stations, drawing considerable attention to the stability of pump-turbines. Numerous studies have shown that pressure pulsation between the pump-turbine runner and guide vanes (referred to as the "bladeless zone") is closely related to generator vibration. Therefore, providing a runner that can reduce pressure pulsation in the bladeless zone and improve the operational stability of pumped storage power stations has significant engineering implications.

[0003] In the prior art, patent publication number CN118881497A discloses a water pump turbine runner blade suitable for rapid transition processes, comprising several long blades, several short blades, and several gradually changing airfoil trailing edges. The long blades and the short blades are installed inside the runner. The long blades are equidistantly arranged circumferentially along the axis of the lower ring of the runner. One end of each long blade and one end of each short blade is connected to the inner wall of the lower ring of the runner. There is a gap between the other end of each long blade and the other end of each short blade and the axis of the lower ring of the runner. The gradually changing airfoil trailing edges are located at the trailing edges of the long blades. This comparative technology is a conventional runner, which has uneven pressure distribution during rotation, affecting the overall performance. Utility Model Content

[0004] The purpose of this invention is to address the issue that, in turbine or pump operation, the dominant frequency of pressure pulsation in the bladeless zone is mostly the blade frequency. Due to the disturbance of water flow caused by the high-pressure side of the runner, the pressure distribution in the bladeless zone is uneven. The greater the unevenness of the pressure distribution, the larger the amplitude of pressure pulsation in the bladeless zone and the more obvious the unit vibration. This new runner improves the flow vortex on the high-pressure side of the blades by changing the geometry of the original runner, thereby reducing the amplitude of pressure pulsation in the bladeless zone and preventing serious safety accidents caused by unit vibration. It provides a runner blade that can reduce pressure pulsation in the bladeless zone.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a rotor blade for reducing pressure pulsation in the bladeless region, comprising a rotor and blades. The rotor is composed of an upper crown and a lower ring. One end of the blade is connected to the upper crown, and the other end is connected to the lower ring. The blade is composed of a pressure surface and a suction surface. One side of the pressure surface is a low-pressure side, and one side of the suction surface is a high-pressure side. The high-pressure side is concave.

[0006] Preferably, the blade has n laminar surfaces, and the difference in the wrap angle φn between adjacent laminar surfaces is between 1.5° and 4.5°. The wrap angle φn is the angle between the two axial surfaces at the intersection of the design streamline and the blade inlet and blade outlet edges, where n = (1, 2, 3, 4, 5).

[0007] Preferably, the upper crown and the lower ring are trumpet-shaped structures.

[0008] Preferably, the S-shape of the high-pressure side edge extends from the middle of the blade to the lower ring portion, and the high-pressure side gradually bends towards the pressure surface.

[0009] Preferably, the high-pressure side of the blade has a radius of Ra near the upper crown, a mid-section radius of Rb, and a radius of Rc near the lower ring, where Ra = Rc and Rb = 0.97 * Ra.

[0010] Preferably, the S-shaped concave edge of the high-voltage side has a smaller wrap angle.

[0011] Preferably, the blade has a span of 0 near the upper crown, a span of 1 near the lower ring, and a span of 0.5 in the middle.

[0012] Preferably, the high-pressure side radius of the blade is the same near the upper crown and the lower ring.

[0013] Preferably, the radius of the blade decreases and then increases along the high-pressure side from the upper crown to the lower ring, with the blade having the smallest radius at the middle Span = 0.5.

[0014] Preferably, the blade is a three-dimensional twisted blade.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: By changing the shape of the original high-pressure side of the runner, that is, the water inlet edge of the blades in the turbine operating condition, this utility model reduces the radius of the flow surface on the high-pressure side on the one hand, and redesigns the distribution law of the blade wrap angle on the other hand. To a certain extent, it can suppress the intensity of the water flow vortex caused by the runner, reduce the range of the vortex, reduce the amplitude of the pressure pulsation in the bladeless area, and avoid serious safety accidents caused by unit vibration. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of a rotor blade for reducing pressure pulsation in the bladeless zone according to the present invention.

[0017] Figure 2 This is an enlarged schematic diagram (C) of the high-pressure side of a rotor blade for reducing pressure pulsation in the bladeless region according to this utility model.

[0018] Figure 3 This is a flow channel diagram of a rotor blade for reducing pressure pulsation in the bladeless region according to this utility model.

[0019] Figure 4 This is a schematic diagram of the flow surface of a rotor blade to reduce pressure pulsation in the bladeless region according to the present invention.

[0020] Figure 5 This is a schematic diagram of the wrap angle φ of a rotor blade for reducing pressure pulsation in the bladeless zone according to this utility model.

[0021] Figure 6 This is a schematic diagram of a blade located in a rotor according to the present invention.

[0022] In the diagram: 1. Pressure surface; 2. Suction surface; 3. Low-pressure side; 4. High-pressure side; 5. Blade; 6. Runner; 61. Upper crown; 62. Lower ring; 7. Blade inlet; 8. Blade outlet. Detailed Implementation

[0023] The technical solution of this utility model will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. The described embodiments are only some embodiments of this utility model, and not all embodiments.

[0024] The table below shows the relationship between the span and the wrap angle of this utility model.

[0025] Table 1

[0026] Span 0 0.25 0.50 0.75 1 Corner 82.2 82.0 80.6 78.6 79.5

[0027] Example 1: Refer to Figures 1 to 5 This invention modifies the high-pressure side of the pump-turbine runner by combining a concave shape with an "S" shape, thus forming a new pump-turbine blade 5. This modified design has shown certain advantages in practical applications. In principle, the concave structure can change the flow direction and velocity distribution of water on the surface of the blade 5, while the "S" shape design further optimizes the flow path of the water, making the flow on the surface of the blade 5 more stable and reducing pressure pulsation caused by water flow impact and separation. In actual tests, the modified blade 5 can reduce the pressure pulsation amplitude in the bladeless region to a certain extent, providing a strong guarantee for the stable operation of the unit.

[0028] The blade 5 has a concave center, which allows for a uniform transition in the high-pressure side radius. This feature effectively reduces dynamic and static interference between the runner and the movable guide vane. During the operation of the pump-turbine, interference between the relative motion of the runner and the movable guide vane can cause additional pressure pulsations and vibrations, affecting the normal operation of the unit. By making the blade 5 concave center and achieving a uniform transition in the high-pressure side radius, this interference can be effectively avoided, thereby further improving the stability of the unit's operation. The upper crown 61 and the lower ring 62 are trumpet-shaped structures.

[0029] Meanwhile, the wrap angle of blade 5 near the lower ring is slightly smaller than that of the remaining flow surface. This design detail also plays a role in improving the "S" characteristic of the pump-turbine. The "S" characteristic is an important characteristic during the operation of the pump-turbine, and its poor performance can lead to unstable operation of the unit under certain operating conditions. By designing the wrap angle of blade 5 near the lower ring to be slightly smaller, the flow state of the water in this area can be optimized, thereby improving the "S" characteristic. In particular, the wrap angle of the concave part of the "S" shape is small, but in order to ensure that its impact on the flow state at the runner inlet of the turbine is minimal, the blade has n laminar surfaces, and the difference in the wrap angle φn between adjacent laminar surfaces is between 1.5° and 4.5°. The wrap angle φn is the angle between the two axial surfaces at the intersection of the design streamline and the blade inlet 7 and the blade outlet 8, n = (1, 2, 3, 4, 5), so as to fully play the role of improving the "S" characteristic and further reduce the pressure pulsation amplitude in the bladeless region.

[0030] In turbine or pump operation, the dominant frequency of pressure pulsation in the bladeless zone is mostly the blade frequency. This is due to the disturbance of the water flow by the high-pressure side of the runner. When the high-pressure side of the runner disturbs the water flow, it causes uneven pressure distribution in the bladeless zone. The greater the degree of pressure unevenness, the larger the amplitude of pressure pulsation in the bladeless zone, leading to more pronounced unit vibration and potentially causing serious safety accidents. This new type of runner effectively improves the flow separation vortex phenomenon on the high-pressure side of the blades by changing the geometry of the original runner. Flow separation vortices are a significant factor leading to intensified pressure pulsation. By reducing the occurrence of flow separation vortices, the amplitude of pressure pulsation in the bladeless zone can be significantly reduced, thereby avoiding serious safety accidents caused by unit vibration and ensuring the safety and stability of the pump-turbine throughout the entire operation process.

[0031] Example 2: Refer to Figures 1 to 5 This embodiment relates to a rotor, and more particularly to a rotor that can effectively reduce pressure pulsation in the bladeless region. Its unique structural design has significant advantages in related fields and provides a strong guarantee for the efficient and stable operation of fluid machinery.

[0032] The most crucial part of this impeller lies in the design of its blades 5. Blades 5 consist of a pressure surface 1 and a suction surface 2, this basic double-sided structure providing the foundation for subsequent specialized designs. One side of the pressure surface 1 is the low-pressure side 3, while the other side of the suction surface 2 is the high-pressure side 4. Uniquely, the high-pressure side 4 is concave. This shape helps guide the flow direction and velocity of the fluid, playing a preliminary role in reducing pressure pulsation. During fluid machinery operation, changes in the flow direction and velocity of the fluid are important factors affecting pressure pulsation. Traditionally, the high-pressure side of blades 5 is mostly flat or convex, which makes fluid flow on the blade surface prone to separation, thus exacerbating pressure pulsation. However, the concave high-pressure side in this embodiment allows the fluid to flow more closely to the blade surface, reducing flow separation and effectively reducing pressure pulsation. The blades 5 are mounted on the impeller 6.

[0033] The high-pressure side 4 features an S-shaped edge design, which is not arbitrary; it follows a specific pattern from the middle of blade 5 to the lower ring. Starting from the middle of blade 5, the high-pressure side 4 gradually bends towards the pressure surface 1 as it extends downwards. This gradual bending structure allows the fluid to transition more smoothly on the surface of blade 5, reducing pressure fluctuations caused by fluid impact. In the middle of blade 5, the fluid flow velocity and direction are relatively complex. The S-shaped edge design effectively guides the fluid, creating smoother streamlines on the surface of blade 5, reducing the local velocity gradient and thus minimizing pressure pulsations. As blade 5 extends downwards, the S-shaped edge gradually bends towards the pressure surface 1. This change further optimizes the fluid flow path, making the flow more stable in the lower ring of blade 5 and preventing pressure pulsations caused by fluid impact on the lower ring.

[0034] The blade 5 itself also employs a three-dimensional twisted design. This complex shape allows the blade 5 to better adapt to the fluid flow characteristics at different locations. In fluid machinery, fluid flow characteristics vary at different locations, such as flow velocity, flow direction, and pressure. The three-dimensional twisted blade 5 can adaptively adjust to these different flow characteristics, ensuring that the blade 5 maintains good hydraulic performance at all positions. Moreover, the blade 5 consists of several flow surfaces, each of which has been carefully designed and calculated to ensure that the entire blade 5 operates efficiently and stably during operation. Through the precise design of each flow surface, the blade 5 can maintain a good flow state under different positions and operating conditions, reducing pressure pulsations caused by poor fluid flow.

[0035] The dimensional parameters of blade 5 are also subject to strict and precise specifications. The radius of the upper crown on the high-pressure side of blade 5 is Ra, its central radius is Rb, and its lower ring radius is Rc, where Ra = Rc and Rb = 0.97 * Ra. This proportional relationship of radii makes the curvature variation of blade 5 more reasonable in different parts, further optimizing the fluid flow state and playing a key auxiliary role in reducing pressure pulsation in the bladeless region. The same radius for the upper crown and lower ring ensures the structural symmetry of blade 5 at these two key positions, making the fluid flow characteristics more consistent at the upper crown and lower ring, and reducing pressure pulsation caused by local structural differences. The central radius is slightly smaller than the radii of the upper crown and lower ring, allowing blade 5 to form an appropriate curvature variation in the middle, further optimizing the fluid flow path, making the fluid flow in the middle of blade 5 more stable, and reducing the generation of pressure pulsation.

[0036] The design of the wrap angle φ is also an important detail in this embodiment. The wrap angle φ refers to the angle between the two axial surfaces at the intersection of the design streamline and the inlet / outlet edges of the blade 5. At the S-shaped concave edge of the high-pressure side 4, the wrap angle is smaller, which facilitates concentrated fluid flow in this area and reduces the generation of undesirable phenomena such as eddies. A smaller wrap angle allows the fluid to flow more concentratedly at the S-shaped concave, avoiding the generation of eddies and other undesirable phenomena in this area, thereby reducing pressure pulsations caused by eddies. The difference in wrap angle Δφ between adjacent laminar flow blades is between 1.5° and 4.5°. This precise control ensures the consistency and coordination of fluid flow characteristics at different levels of the entire blade 5, thereby comprehensively reducing pressure pulsations in the bladeless region. Through precise control of the wrap angle variation at each level, the fluid flow characteristics of the blade 5 at different levels can be made more consistent and coordinated, further optimizing the fluid flow state and reducing the generation of pressure pulsations.

[0037] The design of blade 5 is one of the core features of this rotor. Near the upper crown, the span of blade 5 is 0; near the lower ring, the span is 1; and in the middle of blade 5, the span is 0.5. This setting provides a basic coordinate reference for the design of other parameters of blade 5, allowing for more precise subsequent design. By clearly defining the span values ​​at different positions on blade 5, targeted design and optimization of various parts of blade 5 can be achieved, resulting in the best effect of reducing pressure pulsation in the bladeless area.

[0038] Regarding the high-pressure side radius design of blade 5, the high-pressure side radius 4 of blade 5 near the upper crown and lower ring is the same, which helps to maintain the balance and stability of the impeller during operation. When fluid flows through blade 5, this symmetrical radius design allows the fluid to experience similar forces at the upper crown and lower ring, thereby reducing pressure fluctuations caused by local structural differences and further reducing pressure pulsation in the bladeless region.

[0039] The radius of blade 5 decreases and then increases along the high-pressure side from the upper crown to the lower ring, with the smallest radius at the middle Span = 0.5. This variation trend is carefully designed and calculated. Starting from the upper crown, the high-pressure side radius gradually decreases as it transitions towards the middle of blade 5, causing the fluid velocity to gradually increase while the pressure gradually decreases in this region. When it reaches the middle Span = 0.5, the radius reaches its minimum value, at which point the fluid velocity is fastest and the pressure is lowest. Subsequently, transitioning from the middle to the lower ring, the high-pressure side radius gradually increases again, the fluid velocity gradually decreases, and the pressure gradually increases. This radius variation design, which first decreases and then increases, makes the fluid flow on the surface of blade 5 more stable, effectively avoiding pressure pulsations caused by abrupt changes in fluid velocity and pressure, and plays a key role in reducing pressure pulsations in the bladeless region.

[0040] Furthermore, the turbine inlet side is concave. This concave inlet side design better guides the fluid into the runner, allowing the fluid to contact the blades 5 more smoothly upon entering the runner, reducing pressure loss and pressure fluctuations caused by fluid impact. At the same time, the concave inlet side also increases the flow path length of the fluid within the runner, giving the fluid more time and space for energy conversion, thus improving the runner's operating efficiency.

[0041] At point 3 on the low-pressure side, the arrangement is similar to that of conventional blades. This is because the primary consideration on the low-pressure side is the flow stability and pressure distribution uniformity of the fluid in this region. Adopting a conventional arrangement ensures that the fluid flow characteristics on the low-pressure side are consistent with existing mature technologies, avoiding uncertainties and risks caused by excessive innovation. Simultaneously, this provides a stable reference basis for the overall design of the impeller, allowing designers to focus more on optimizing key components such as the high-pressure side to achieve the goal of reducing pressure pulsation in the bladeless region.

[0042] In summary, the impeller in this embodiment, which reduces pressure pulsation in the bladeless zone, can significantly reduce pressure pulsation in the bladeless zone and improve the working efficiency and stability of the impeller in practical applications through the special structural design of its blades 5 and precise parameter control. It has broad market application prospects and important technical value.

[0043] For those skilled in the art, the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention.

Claims

1. A runner blade for reducing pressure pulsations in a bladeless region, characterized by, The turbine wheel is composed of an upper crown and a lower ring, and the blade is connected to the upper crown at one end and to the lower ring at the other end, and the blade is composed of a pressure surface and a suction surface, one side of the pressure surface is a low pressure side, and one side of the suction surface is a high pressure side, and the high pressure side is concave.

2. A runner blade for reducing pressure pulsations in a bladeless region according to claim 1, wherein The blade has n laminar flow surfaces, and the included angle φn between adjacent laminar flow surfaces is between 1.5° and 4.5°, the included angle φn is the included angle between the two axial surfaces at the intersection point of the designed streamline and the blade inlet and blade outlet edge, and n=(1, 2, 3, 4, 5).

3. A runner blade for reducing pressure pulsations in a bladeless region according to claim 1 or 2, wherein The upper crown and the lower ring are in a trumpet shape.

4. A runner blade for reducing pressure pulsations in a bladeless region according to claim 1 or 2, wherein The S-shaped edge of the high pressure side is from the middle of the blade to the lower ring part, and the high pressure side gradually bends towards the pressure surface.

5. A runner blade for reducing pressure pulsations in the bladeless region according to claim 1 or 2, wherein The high pressure side of the blade near the upper crown has a radius Ra, the middle part has a radius Rb, and the part near the lower ring has a radius Rc, wherein Ra=Rc and Rb=0.97*Ra.

6. A runner blade for reducing pressure pulsations in the bladeless region according to claim 5, wherein The included angle of the S-shaped concave part of the high pressure side edge is small.

7. A runner blade for reducing pressure pulsations in the bladeless region according to claim 1 or 6, wherein The blade has a Span=0 near the upper crown, a Span=1 near the lower ring, and a Span=0.5 in the middle part.

8. A runner blade for reducing pressure pulsations in the bladeless region according to claim 7, wherein, The high pressure side radius of the blade near the upper crown and the lower ring is the same.

9. A runner blade for reducing pressure pulsations in the bladeless region according to claim 7, wherein The high pressure side radius of the blade along the upper crown to the lower ring first decreases and then increases, and the radius of the blade at the middle part Span=0.5 is the smallest.

10. A runner blade for reducing pressure pulsations in the bladeless region according to claim 1 or 9, wherein The blade is a three-dimensional twisted blade.

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