Bionic water turbine runner for eliminating pressure pulsation hysteresis phenomenon and water turbine

Abstract

According to the bionic water turbine runner capable of eliminating the pressure pulsation hysteresis phenomenon and the water turbine, a bionic design area is designed on the head portion of a runner blade based on a tiger whale head molded line, a pressure surface side molded line of the runner blade forms a frontal-bulge-like structure, the thickness increasing trend is larger than that of a suction surface side molded line, flow separation can be restrained, and impact loss can be reduced; thickness distribution of a bionic area is accurately controlled through a formula, a conventional design area is arranged at the middle tail of the blade, and seamless connection is achieved between the blade and the conventional design area through a bionic transition area. According to the design, the resistance reduction and flow stabilization characteristics of natural evolution of the head of the whale are used for reference, hydromechanics optimization is combined, the inertial effect of vortex structure generation and development can be effectively restrained, the pressure pulsation hysteresis phenomenon is eliminated, and the pressure pulsation amplitude is reduced.

Description

Technical Field

[0001] This invention relates to the field of fluid machinery technology, and in particular to a biomimetic water turbine runner and water turbine that eliminates pressure pulsation hysteresis. Background Technology

[0002] The rapid development of new energy sources such as wind power and photovoltaics has placed higher demands on peak shaving and frequency regulation for conventional hydropower units. This makes turbine load regulation extremely frequent, requiring adjustments from small to large openings to respond to load increases, and from large to small openings to cope with load reductions. During this dynamic process, the turbine, especially in the low-load region, faces severe flow instability problems, particularly pressure pulsation hysteresis. This phenomenon refers to the fact that, during changes in operating conditions, the pressure pulsation curve as a function of load does not coincide with the curves when adjusting the guide vane opening from small to large and from large to small. Figure 1 As shown, the root cause lies in the strong inertial effect of the generation and evolution of the vortex structure within the turbine runner during the increase and decrease of the guide vane opening. This leads to a delayed collapse of the vortex structure during load increase and a delayed generation of the vortex structure during load decrease, resulting in differences in the corresponding broadband and low-frequency pressure pulsations, ultimately manifesting as pressure pulsation hysteresis. This hysteresis makes pressure pulsation prediction and control difficult, exacerbating unit fatigue damage.

[0003] Research has found that optimizing the runner, especially the runner head, can effectively weaken the inertial effect of the generation and development of vortex structures within the runner, thereby eliminating pressure pulsation hysteresis. In existing technologies, common methods for improving the head structure include using modern optimization algorithms and biomimetic design to optimize the head profile. Optimization algorithms, such as the conjugate gradient method or genetic optimization, often require extensive computation or model experiments, resulting in high costs. Biomimetic design methods are simpler, referencing structural forms formed through natural selection, such as the biomimetic humpback whale flipper-like protrusion structure. Chinese patent literature disclosed on June 22, 2022, a guide vane design method and a pump-turbine for improving the operational stability of a pump-turbine (publication number CN115081138B), which optimizes the movable guide vanes of the pump-turbine, effectively improving the pump-turbine's inverse S-shaped characteristics and enhancing operational stability. And the biomimetic dolphin head profile: Chinese patent document CN115306486A, published on September 19, 2022, discloses a biomimetic leading-edge slat, blade, and manufacturing method with a dolphin head profile. This invention is based on biomimetic passive control technology, designs a biomimetic leading-edge slat based on the characteristics of a dolphin's head, and directly connects the biomimetic leading-edge slat and the base blade through an adjustment device and slat connector. While ensuring that the overall shape of the base blade remains unchanged, it improves the aerodynamic performance of the blade to suppress the negative impact of flow separation and dynamic stall on the blade. However, the profile distribution pattern of the above method is significantly different from that of this patent and has not been applied to turbine blades. At the same time, existing biomimetic solutions have not been specifically designed for the pressure pulsation hysteresis phenomenon unique to turbines in dynamic load regulation.

[0004] Meanwhile, Chinese patent document CN113266504A, published on May 17, 2021, discloses a mixed-flow turbine with biomimetic tadpole-shaped blades. This blade can solve the problems of cavitation and pressure pulsation at the blade tip. However, it also does not consider the hysteresis characteristics to eliminate pressure pulsation and cannot meet the design requirements for operation with different rated heads.

[0005] In summary, existing turbine runner designs are unable to effectively eliminate pressure pulsation hysteresis and cannot significantly reduce the amplitude of pressure pulsation in the bladeless region. This, in turn, affects the operational stability of the turbine unit, increases the risk of unit vibration and fatigue damage, and restricts the development of turbines towards higher parameters and higher efficiency. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a biomimetic turbine runner and turbine with a head-shaped profile inspired by an orca to eliminate pressure pulsation hysteresis and reduce pressure pulsation in the bladeless region.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a biomimetic turbine runner that eliminates pressure pulsation hysteresis, wherein the head of the runner blade is designed with a biomimetic design area based on the head profile of an orca, and the biomimetic design area is constructed with a suction side profile and a pressure side profile, wherein the thickness increase trend of the pressure side profile of the biomimetic design area at the front end of the runner blade is greater than the thickness increase trend of the suction side profile; The thickness distribution patterns of the pressure surface side profile and the suction surface side profile of the biomimetic design region are shown in the formula:

[0008] in, δ P Indicates the thickness of the pressure surface in the biomimetic design area; δ S Indicates the thickness of the suction surface in the biomimetic design area; L m Indicates the flow direction of the biomimetic design area, 0≤ L m ≤ L h ; L h Indicates the length of the skeletal line in the biomimetic design area; L f Indicates the total length of the blade skeleton; H r Indicates the rated head; k This represents the control coefficient.

[0009] Furthermore, the biomimetic design area pressure surface profile forms a protruding structure similar to the forehead of an orca at the front end of the impeller blade.

[0010] Furthermore, the rotor blades have conventional design areas at the middle and tail.

[0011] Furthermore, the conventional design area includes the suction side profile and the pressure side profile of the conventional design area.

[0012] Furthermore, a biomimetic transition zone is provided between the biomimetic design zone and the conventional design zone. Furthermore, the biomimetic transition zone includes a suction side profile and a pressure side profile.

[0013] Furthermore, the suction surface side profile of the biomimetic transition zone smoothly connects the suction surface side profile of the biomimetic design zone and the suction surface side profile of the conventional design zone.

[0014] Furthermore, the pressure surface side profile of the biomimetic transition zone smoothly connects the pressure surface side profile of the biomimetic design zone and the pressure surface side profile of the conventional design zone.

[0015] Furthermore, the rotor blades are evenly distributed in a spiral pattern between the upper crown and the lower ring.

[0016] This invention also provides a water turbine with runner blades designed based on the head profile of an orca; the biomimetic design area comprises a suction side profile and a pressure side profile, and the thickness increase trend of the pressure side profile of the biomimetic design area at the front end of the runner blade is greater than that of the suction side profile; the thickness distribution law of the biomimetic design area of ​​the runner blade is shown in the following formula:

[0017] in, δ P Indicates the thickness of the pressure surface in the biomimetic design area; δ S Indicates the thickness of the suction surface in the biomimetic design area; L m Indicates the flow direction of the biomimetic design area, 0≤ L m ≤ L h ; L h Indicates the length of the skeletal line in the biomimetic design area; L f Indicates the total length of the blade skeleton; H r Indicates the rated head; k This represents the control coefficient.

[0018] In summary, the present invention has the following beneficial effects: (1) The present invention specifically adopts the head profile of the killer whale to design the biomimetic design area of ​​the rotor blades. The pressure surface profile forms a forehead-like bulge structure, and the blade thickness growth rate on the pressure surface side is greater than that on the suction surface side. This structure is naturally adapted to the underwater fluid flow characteristics, which can effectively optimize the flow field at the rotor inlet and suppress flow separation and impact loss. Combined with the parameter combination optimized by computational fluid dynamics, the inertial effect of vortex structure generation and evolution can be weakened from the source, eliminating the pressure pulsation hysteresis phenomenon and improving the accuracy of pressure pulsation prediction and control.

[0019] (2) This invention establishes the relationship between the thickness of the bionic design zone and key parameters such as rated head and bone line length through formula, so as to achieve precise quantitative control of thickness distribution and break through the limitation that existing bionic designs cannot adapt to different heads. By incorporating the rated head Hr as a key design parameter into the core law of profile thickness distribution of the bionic design zone, and combining it with targeted optimization of computational fluid dynamics, the bionic structure of the runner blade head can be dynamically adjusted according to the hydraulic characteristics of different rated heads. This design can flexibly adapt to various operating requirements from low to high heads. At the same time, through the optimized design of thickness gradient, the flow adaptability of the runner in the range of partial load to full load is improved, solving the problem of poor stability of existing runners under wide load conditions, and providing an efficient and universal runner design scheme for multi-condition turbines.

[0020] (3) The present invention sets up a bionic transition zone between the bionic design zone and the conventional design zone, and achieves seamless connection between the two zones through a smooth profile, avoiding local pressure pulsation caused by sudden flow changes; at the same time, the synergistic effect of the ridge-like protrusion and the thickness gradient can significantly reduce the pressure pulsation amplitude in the bladeless zone, reduce the risk of unit vibration and fatigue damage, and improve the long-term operational stability and service life of the turbine unit. Attached Figure Description

[0021] Figure 1 This is a typical rotor pressure pulsation curve.

[0022] Figure 2 This is a schematic diagram of the head shape of an orca.

[0023] Figure 3 This is a schematic diagram of a biomimetic water turbine runner.

[0024] Figure 4 This is a schematic diagram of a biomimetic leaf.

[0025] Figure 5 This is a graph showing the pressure pulsation of a biomimetic rotor.

[0026] The reference numerals in the attached drawings are explained as follows: 1. Upper crown; 2. Rotor blade; 3. Lower ring; 4. Bionic design area; 41. Side profile of the suction surface of the bionic design area; 42. Side profile of the pressure surface of the bionic design area; 5. Conventional design area; 51. Side profile of the suction surface of the conventional design area; 52. Side profile of the pressure surface of the conventional design area; 6. Bionic transition area; 61. Side profile of the suction surface of the bionic transition area; 62. Side profile of the pressure surface of the bionic transition area; 7. Rotor blade skeleton line. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments.

[0028] Example 1 This embodiment provides a biomimetic turbine runner that eliminates pressure pulsation hysteresis, such as Figure 2The biomimetic reference is based on the orca head profile. The head of the rotor blade 2 is designed based on the orca head profile to form a biomimetic design area 4. The biomimetic design area 4 is constructed with a biomimetic design area suction side profile 41 and a biomimetic design area pressure side profile 42. The biomimetic design area pressure side profile 42 forms a protruding structure similar to the orca forehead at the front end of the rotor blade 2 head. The thickness increase trend of the biomimetic design area pressure side profile 42 at the front end of the rotor blade 2 head is greater than the thickness increase trend of the biomimetic design area suction side profile 41.

[0029] Orcas are among the fastest and most agile marine animals, and their distinctive head shape, formed through a long process of natural selection, is beneficial for reducing drag and improving flow stability in underwater turbulence. This embodiment modifies the thickness distribution of the blade head by mimicking the orca's head profile. The orca's head profile, formed through millions of years of natural selection, is advantageous for underwater drag reduction and noise reduction. The orca-inspired blade head is thicker than conventional blade designs, and features a steeper bulge on the pressure side. This rapid increase in thickness suppresses flow separation at the pressure side, while the thickness change on the suction side is more gradual than that on the pressure side, reducing impact losses. This results in a smoother inlet flow for the biomimetic runner compared to conventional runners, better adapting to partial load conditions. Furthermore, this profile distribution takes into account the influence of the turbine's rated head, accommodating runner design requirements from low to high heads.

[0030] Example 2 This embodiment provides a biomimetic turbine runner that eliminates pressure pulsation hysteresis. The head of the runner blade 2 is designed with a biomimetic design area 4 based on the head profile of an orca. The biomimetic design area 4 has a biomimetic suction side profile 41 and a biomimetic pressure side profile 42. The biomimetic pressure side profile 42 forms a protruding structure similar to the forehead of an orca at the front end of the runner blade 2. The thickness increase trend of the biomimetic pressure side profile 42 at the front end of the runner blade 2 is greater than the thickness increase trend of the biomimetic suction side profile 41.

[0031] The orca head profile is applied to the head of the turbine runner blade 2. The bulging structure of the orca's brow allows the underwater flow to smoothly adhere to the bulging surface, avoiding the formation of a vortex shedding zone at the head. This characteristic is highly compatible with the water flow motion characteristics at the turbine runner inlet. In this embodiment, the brow-like bulge formed by the rapid increase in thickness on the pressure side allows the high-pressure water flow at the runner inlet to flow smoothly towards the middle of the blade along the pressure side, effectively avoiding flow separation caused by abrupt changes in the profile at the pressure side head. Meanwhile, the gentle thickness increase trend on the suction side can reduce the velocity gradient of the water flow on the suction side, reducing the local vortices generated by the water flow impacting the suction side of the blade, thus weakening the initial generation conditions of the vortex structure from the flow field source.

[0032] The thickness distribution patterns of the pressure surface side profile 42 and the suction surface side profile 41 in the biomimetic design region are shown in the formula:

[0033] in δ P Indicates the thickness of the side profile of the pressure surface in the biomimetic design area; δ S This indicates the thickness of the side profile of the suction surface in the biomimetic design area; L m Indicates the flow direction of the biomimetic design area, 0≤ L m ≤ L h ; L f Indicates the total length of the blade skeleton; L h Indicates the length of the skeletal line in the biomimetic design area; H r Indicates the rated head; k This represents the control coefficient.

[0034] The control coefficient k in the formula is selected based on multi-condition simulation optimization of the runner inlet flow field using computational fluid dynamics for different rated heads Hr. Suitable ranges are selected for low, medium, and high heads to ensure that the thickness distribution of the biomimetic design zone 4 adapts to the flow field characteristics under different heads. Furthermore, the formula correlates key hydraulic parameters such as rated head Hr and rib length with structural thickness parameters, achieving precise quantitative control of the thickness distribution of the biomimetic design zone 4. Compared to the qualitative description of traditional biomimetic design, quantitative design allows for the realization of structural flow field performance through numerical simulation.

[0035] The rotor blade 2 has conventional design areas 5 at its middle and tail sections. These conventional design areas 5 include a suction-side profile 51 and a pressure-side profile 52. To achieve a smooth transition between structure and performance, a biomimetic transition area 6 is provided between the rotor blade 2's head section (which mimics the shape of an orca's head) and the conventional design area 5. This biomimetic transition area 6 includes a smoothly connected suction-side profile 61 and pressure-side profile 62. This transition area achieves a smooth connection between the two design areas through the smoothly connected suction-side profile 61 and pressure-side profile 62.

[0036] In this embodiment, the head of the blade is a biomimetic design area 4 with a head-shaped profile similar to that of an orca. The thickness distribution of the biomimetic design area 4 is controlled by the above formula. The rotor head with the head-shaped profile similar to that of an orca is thicker than that of a conventional blade design, and the pressure surface side of the front end of the head has a steeper forehead feature, while the thickness change of the suction surface side is more gradual than that of the pressure surface side. The middle and tail of the blade adopt a conventional design area 5. A biomimetic transition area 6 is used to achieve a biomimetic transition area 6 between the biomimetic design area 4 and the conventional design area 5, which is composed of a smooth transition line.

[0037] Through the above methods, such as Figure 5 As shown, the pressure pulsation hysteresis phenomenon has disappeared. Therefore, this design can effectively eliminate the pressure pulsation hysteresis phenomenon, suppress the generation of vortex structures at the inlet, reduce pressure pulsation, improve the adaptability of the runner under wide load conditions, and enhance the operating stability of the turbine.

[0038] Example 3 This embodiment provides a water turbine, which includes a biomimetic water turbine runner having the pressure pulsation hysteresis elimination phenomenon described in Embodiment 1 or Embodiment 2, wherein the biomimetic runner is as follows: Figure 3 and Figure 4 As shown, it includes an upper crown 1 and a lower ring 3, with a plurality of rotor blades 2 evenly distributed in a spiral shape between the upper crown 1 and the lower ring 3. The thickness distribution law of the biomimetic design area 4 of the rotor blades 2 is shown in the following formula:

[0039] in, δ P Indicates the thickness of the pressure surface in the biomimetic design area; δ S Indicates the thickness of the suction surface in the biomimetic design area; L m Indicates the flow direction of the biomimetic design area, 0≤ L m ≤ L h ; L h Indicates the length of the skeletal line in the biomimetic design area; L f Indicates the total length of the blade skeleton; H r Indicates the rated head; k This represents the control coefficient.

[0040] The head profile is specifically designed to eliminate pressure pulsation hysteresis and offers superior hydraulic performance. Orcas are among the fastest and most agile marine animals, and their distinctive head shape, formed through long-term natural selection, is beneficial for reducing drag in underwater turbulence and improving flow stability. Based on the orca head profile, the runner blades 2, optimized using computational fluid dynamics simulations, effectively suppress flow instability at the runner inlet, weaken the inertial effects of vortex generation and development within the runner, thereby eliminating pressure pulsation hysteresis and reducing its amplitude. Furthermore, the design considers the influence of head, making it adaptable to turbine runner designs with varying rated heads, thus enhancing its versatility.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomimetic water turbine runner for eliminating pressure pulsation hysteresis, characterized in that, The head of the rotor blade (2) is designed with a biomimetic design area (4) based on the head profile of an orca. The biomimetic design area (4) is constructed with a biomimetic design area suction side profile (41) and a biomimetic design area pressure side profile (42). The thickness increase trend of the biomimetic design area pressure side profile (42) at the front end of the rotor blade (2) is greater than the thickness increase trend of the biomimetic design area suction side profile (41). The thickness distribution patterns of the pressure side profile (42) and the suction side profile (41) of the biomimetic design area are shown in the formula: in, δ P Indicates the thickness of the pressure surface in the biomimetic design area; δ S Indicates the thickness of the suction surface in the biomimetic design area; L m Indicates the flow direction of the biomimetic design area, 0≤ L m ≤ L h ; L h Indicates the length of the skeletal line in the biomimetic design area; L f Indicates the total length of the blade skeleton; H r Indicates the rated head; k This represents the control coefficient.

2. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 1, characterized in that, The biomimetic design area pressure surface profile (42) forms a convex structure similar to the forehead of an orca at the front end of the impeller blade (2).

3. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 1, characterized in that, The rotor blade (2) has a conventional design area (5) in the middle and tail.

4. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 3, characterized in that, The conventional design area (5) includes the suction side profile (51) and the pressure side profile (52) of the conventional design area.

5. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 3, characterized in that, A biomimetic transition zone (6) is provided between the biomimetic design zone (4) and the conventional design zone (5).

6. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 5, characterized in that, The biomimetic transition zone (6) includes the suction side profile (61) and the pressure side profile (62).

7. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 6, characterized in that, The biomimetic transition zone suction surface side profile (61) smoothly connects the biomimetic design zone suction surface side profile (41) and the conventional design zone suction surface side profile (51).

8. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 6, characterized in that, The biomimetic transition zone pressure surface side profile (62) smoothly connects the biomimetic design zone pressure surface side profile (42) and the conventional design zone pressure surface side profile (52).

9. The biomimetic turbine runner for eliminating pressure pulsation hysteresis according to claim 1, characterized in that, The rotor blades (2) are evenly distributed in a spiral pattern between the upper crown (1) and the lower ring (3).

10. A water turbine, characterized in that, The rotor blade (2) is designed based on the head profile of an orca; the biomimetic design area (4) is constructed with a suction side profile (41) and a pressure side profile (42). The thickness increase trend of the pressure side profile (42) of the biomimetic design area at the front end of the rotor blade (2) is greater than that of the suction side profile (41); the thickness distribution law of the biomimetic design area (4) of the rotor blade (2) is shown in the following formula: in, δ P Indicates the thickness of the pressure surface in the biomimetic design area; δ S Indicates the thickness of the suction surface in the biomimetic design area; L m Indicates the flow direction of the biomimetic design area, 0≤ L m ≤ L h ; L h Indicates the length of the skeletal line in the biomimetic design area; L f Indicates the total length of the blade skeleton; H r Indicates the rated head; k This represents the control coefficient.

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