Hyperbolic blade for francis runner, manufacturing method and francis runner

Abstract

A hyperbolic blade for a Francis runner, a manufacturing method and a Francis runner, belonging to the technical field of water turbines. The hyperbolic blade comprises a blade head (1) and a blade tail (2), wherein the blade head (1) and the blade tail (2) are integrally formed; the blade head (1) is in a gradual transition configuration, the blade head (1) comprises an upper transition section (3), a middle transition section (4) and a lower transition section (5), the upper transition section (3), middle transition section (4) and lower transition section (5) being sequentially connected end to end and integrally formed. The present invention takes into account both the operating parameters of the unit and the geometric parameters of a runner blade inlet, so as to obtain the distribution pattern of the maximum thickness of a blade inlet airfoil section, thereby effectively improving the flow regime at the blade inlet, meeting the requirements for large head variation and wide load operation; this improves the flow uniformity at the runner inlet between the crown (6) and band (7) under off-design conditions, reduces the value of pressure pulsation in a vaneless region under off-design conditions, enhances the overall stiffness and strength of the runner, and improves the operational stability of the unit.

Description

Double-curved mixed-flow runner blade, preparation method and mixed-flow runner TECHNICAL FIELD

[0001] The present application relates to the technical field of water turbines, in particular to a double-curved mixed-flow runner blade, a preparation method and a mixed-flow runner. BACKGROUND

[0002] In recent years, new energy such as wind power and photovoltaic power has developed rapidly, but due to the inflexible characteristics of these new energy power, conventional hydroelectric generating units have become increasingly important for ensuring the safety and stability of the power grid. Both power grid dispatchers and power plant operators need hydroelectric generating units to have a wide and efficient stable operating range to adapt to peak shaving and frequency modulation.

[0003] However, the existing mixed-flow water turbine has a fixed runner, which is a single-regulating water turbine. When the unit deviates from the optimal point of the water turbine, the impinging flow at the inlet of the runner and the circulation at the outlet of the runner will produce complex flow disturbance phenomena such as flow separation vortex, draft tube vortex, blade passage vortex, Karman vortex street, secondary flow or runner outlet backflow. For water turbines with large water head and variable amplitude, the more the optimal condition deviates, the more serious the flow separation, and the more obvious the low pressure area formed at the head of the blade, especially near the back of the blade and the lower ring, which induces the occurrence of cavitation at the head of the blade. The more serious the cavitation, the more likely it is to cause cavitation erosion damage to the blade. Related studies have shown that optimizing the geometric parameter distribution of the runner blade inlet and the blade head airfoil is beneficial to suppressing the flow separation at the back of the runner blade inlet and adapting to the outlet flow of the movable guide vane, thereby delaying the initiation and development of the blade passage vortex caused by the flow separation at the back of the runner blade in the low flow area, reducing the cavitation level at the head of the blade, and thus expanding the efficient and stable operating range of the unit. At the same time, the overall rigidity level of the real machine runner and the irregular thickness distribution of the runner blade airfoil have a great relationship, and how to design a special runner blade airfoil thickness rule to effectively avoid the occurrence of cracks at the connection between the upper crown and the lower ring is required. The best match of the operating parameters and geometric parameters of the wide load running unit. Therefore, it is crucial to design and develop a mixed-flow runner blade that can adapt to the requirements of large water head and wide load operation.

[0004] Chinese patent document No. CN113266504A, published on August 17, 2021, discloses a mixed-flow water turbine with bionic tadpole-type blades, which includes a spiral case, a fixed guide vane and a movable guide vane installed downstream of the spiral case, a runner installed at the outlet of the movable guide vane, a draft tube installed below the runner, and bionic tadpole-type blades installed in the runner.

[0005] The mixed flow water turbine with the biomimetic tadpole type blade disclosed in the patent document increases the thickness of the runner inlet blade by designing the biomimetic tadpole type runner blade, reduces the flow angle, reduces the separation vortex intensity, increases the pressure of the vortex center, and reduces the low-speed area and low-pressure area. However, the thickness distribution of the biomimetic tadpole type blade is determined by defining a polynomial function related to the streamline position, which is only applicable to the runner with a specific parameter level. The design of the runner of the water turbine requires the input of external parameters, such as the water head section of the hydropower station, the output level of the unit, the water head amplitude, and the stability index requirement, which will affect the determination of the geometric parameters, such as the relative guide vane height, the nominal diameter of the runner, and the length of the runner blade, and in turn will affect the range of the streamline position defined in the above patent document. Therefore, the accuracy of the thickness distribution of the designed biomimetic tadpole type blade is easily affected, which affects the flow uniformity of the runner inlet between the upper crown and the lower ring under the influence of the working condition, and the overall rigidity level of the runner, and cannot be applied to the requirements of large water head amplitude and wide load operation. SUMMARY

[0006] In order to overcome the defects of the prior art, the present application provides a hyperbolic mixed flow runner blade, a preparation method and a mixed flow runner. The present application obtains the maximum thickness distribution rule of the blade inlet airfoil section by comprehensively considering the unit operating parameters and the runner blade inlet geometric parameters, which can effectively improve the flow state of the blade inlet, is suitable for large water head amplitude and wide load operation requirements, improves the flow uniformity of the runner inlet between the upper crown and the lower ring under the influence of the working condition, reduces the pressure pulsation value of the bladeless area under the influence of the working condition, improves the overall rigidity level of the runner, and improves the operating stability of the unit.

[0007] The present application is realized by the following technical scheme:

[0008] A hyperbolic mixed flow runner blade, comprising a blade head and a blade tail, the blade head and the blade tail are integrally formed, the blade head is a gradual change type, the blade head comprises an upper gradual change section, a middle gradual change section and a lower gradual change section, and the upper gradual change section, the middle gradual change section and the lower gradual change section are integrally formed in sequence.

[0009] The blade head gradually changes in space, specifically, the blade head airfoil section of the upper gradual change section near the upper crown is thick, the blade head airfoil section of the lower gradual change section near the lower ring is thick, and the blade head airfoil section of the middle gradual change section is thin.

[0010] The gradual change refers to that the maximum thickness distribution of the blade head airfoil section presents thick at the upper crown and the lower ring in the spanwise direction, and thin in the middle.

[0011] The maximum thickness refers to the maximum value of the distance between the front profile of the blade head airfoil section and the blade skeleton line, or the maximum value of the distance between the back profile of the blade head airfoil section and the blade skeleton line.

[0012] The spanwise direction refers to the height direction of the blade.

[0013] The upper transition section refers to the position of the axial plane projection of the blade head airfoil section in the spanwise direction 0≤ 0.35, the middle transition section is located between the upper transition section and the lower transition section, and the middle transition section refers to the position of the axial plane projection of the blade head airfoil section in the spanwise direction 0.35≤ 0.75, and the lower transition section refers to the position of the axial plane projection of the blade head airfoil section in the spanwise direction 0.75< 1.

[0014] The maximum thickness of the blade head airfoil section includes the maximum thickness of the front airfoil section and the maximum thickness of the back airfoil section.

[0015] The maximum thickness of the front airfoil section refers to the maximum value of the distance between the front profile line of each airfoil section of the blade and the blade skeleton line.

[0016] The maximum thickness of the back airfoil section refers to the maximum value of the distance between the back profile line of each airfoil section of the blade and the blade skeleton line.

[0017] The maximum thickness of the front airfoil section is calculated by formula 1;

[0018] Formula 1;

[0019] Wherein, Tf is the maximum thickness of the front airfoil section, S is the spanwise direction, i.e. the position of each blade head airfoil section relative to the upper crown, Hmax is the maximum water head, Hmin is the minimum water head, L is the length of the maximum thickness of the front airfoil section of each airfoil section of the blade along the flow direction of the blade airfoil, β is the blade inlet installation angle, θ is the blade inlet wrap angle, R is the inlet radius of the blade head airfoil section, N* is the optimal unit speed, Nmax is the maximum unit speed.

[0020] The maximum thickness of the back airfoil section is calculated by formula 2;

[0021] Formula 2;

[0022] Wherein, Tb is the maximum thickness of the back airfoil section, L is the length of the maximum thickness of the back airfoil section of each airfoil section of the blade along the flow direction of the blade airfoil, is the minimum unit speed.

[0023] The unit speed is calculated by formula 3;

[0024] Formula 3;

[0025] wherein, is the unit speed, is the rotational speed, is the nominal diameter of the runner inlet, is the water head.

[0026] The connection between the upper gradual section and the middle gradual section is a smooth transition.

[0027] The connection between the middle gradual section and the lower gradual section is a smooth transition.

[0028] The maximum thickness of the upper gradual section is greater than the maximum thickness of the lower gradual section.

[0029] The maximum thickness of the lower gradual section is greater than the maximum thickness of the middle gradual section.

[0030] A preparation method of a hyperbolic mixed-flow runner blade, comprising the following steps:

[0031] S1, obtaining unit operation parameters and blade inlet geometric parameters;

[0032] S2, calculating and determining the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil;

[0033] S3, processing a gradual blade head according to the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil and the maximum thickness of the blade head airfoil section, and integrally forming a blade tail with the gradual blade head.

[0034] In the S1, the unit operation parameters include water head amplitude, relative guide vane height, unit speed and unit flow, the unit speed includes minimum unit speed, optimal unit speed and maximum unit speed, and the unit flow includes rated unit flow and optimal unit flow.

[0035] The relative guide vane height is the ratio of the guide vane height to the runner throat diameter.

[0036] The unit operation parameters further include the ratio of the rated unit flow to the optimal unit flow.

[0037] In the S1, the blade inlet geometric parameters include guide vane height, inlet radius of the blade head airfoil section, blade inlet wrap angle and blade inlet setting angle.

[0038] The distribution ratio in S2 refers to a ratio of a length of the maximum thickness of the front surface profile section of each profile section of the blade along a flow direction of the blade profile to a length of the blade profile.

[0039] The distribution ratio in S2 includes a distribution ratio of the maximum thickness of the front surface profile section of each profile section of the blade along the flow direction of the blade profile and a distribution ratio of the maximum thickness of the back surface profile section of each profile section of the blade along the flow direction of the blade profile.

[0040] The distribution ratio of the maximum thickness of the front surface profile section of each profile section of the blade along the flow direction of the blade profile refers to a ratio of a length of the maximum thickness of the front surface profile section of each profile section of the blade along the flow direction of the blade profile to the length of the blade profile.

[0041] The distribution ratio of the maximum thickness of the back surface profile section of each profile section of the blade along the flow direction of the blade profile refers to a ratio of a length of the maximum thickness of the back surface profile section of each profile section of the blade along the flow direction of the blade profile to the length of the blade profile.

[0042] The distribution ratio of the maximum thickness of the front surface profile section of each profile section of the blade along the flow direction of the blade profile is calculated by formula 4.

[0043] Formula 4;

[0044] wherein, is the length of the maximum thickness of the front surface profile section of each profile section of the blade along the flow direction of the blade profile, is the length of the blade profile, is a spanwise direction, i.e., a position of each profile section of the blade head relative to the upper crown, is a coefficient, and the value is , is a guide vane height, is a runner throat diameter, is a blade inlet setting angle, is a maximum water head, is a minimum water head, is a rated unit flow rate, is an optimal unit flow rate.

[0045] The distribution ratio of the maximum thickness of the back surface profile section of each profile section of the blade along the flow direction of the blade profile is calculated by formula 5.

[0046] Formula 5;

[0047] wherein, is the length of the maximum thickness of the back surface profile section of each profile section of the blade along the flow direction of the blade profile, is a coefficient, and the value is .

[0048] The unit flow rate is calculated by formula 6.

[0049] Formula 6;

[0050] wherein, is the unit flow rate, is the flow rate.

[0051] A mixed flow runner comprises an upper crown and a lower ring, and a plurality of hyperbolic mixed flow runner blades are arranged between the upper crown and the lower ring.

[0052] The hyperbolic mixed flow runner blades are 13-17, and the hyperbolic mixed flow runner blades are uniformly distributed in a spiral shape on the upper crown.

[0053] The beneficial effects of the present application mainly manifest in the following aspects:

[0054] 1. In the present application, the maximum thickness distribution law of the blade inlet airfoil section is obtained by comprehensively considering the unit operation parameters and the inlet geometric parameters of the runner blade, which can effectively improve the flow state of the blade inlet, is suitable for large water head amplitude and wide load operation requirements, improves the flow uniformity of the runner inlet between the upper crown and the lower ring under partial working conditions, reduces the pressure pulsation value of the bladeless area under partial working conditions, improves the overall rigidity and strength level of the runner, and improves the operation stability of the unit.

[0055] 2. In the present application, the maximum thickness distribution law of the gradually changing blade head can well adapt to large water head amplitude operation, effectively reduce the flow angle, increase the adaptability of the runner to the flow, guide the water flow to flow more smoothly, reduce the internal vortex generated by the flow separation at the blade inlet, improve the operation efficiency of the runner, and reduce the possibility of cavitation near the back of the blade inlet and the lower ring.

[0056] 3. In the present application, the pressure pulsation value of the bladeless area under partial working conditions can be effectively reduced, and the stable operation range of the unit can be significantly widened.

[0057] 4. In the present application, the maximum thickness of the upper gradually changing section is greater than the maximum thickness of the lower gradually changing section. According to engineering experience and actual operation of the hydroelectric generator, the risk of cracks at the connection between the blade and the upper crown is higher than that at the connection between the blade and the lower ring of the runner. Therefore, by setting the maximum thickness of the upper gradually changing section to be greater than the maximum thickness of the lower gradually changing section, the overall thickness of the upper crown airfoil section is increased, and the rigidity and strength level and the fatigue damage resistance of the runner are improved.

[0058] 5. In the present application, the maximum thickness of the lower gradually changing section is greater than the maximum thickness of the middle gradually changing section, and in the spanwise direction, the maximum thickness of the middle gradually changing section is less than the maximum thickness of the lower gradually changing section, which can avoid disturbing the uniformity of the flow and reduce the pressure pulsation of the bladeless area.

[0059] 6. In the present application, the maximum thickness distribution law of the blade airfoil head in different spanwise directions is defined, which is suitable for runner design of different water head sections and different optimal unit parameter levels, and has better applicability.

[0060] 7. Compared with the current turbine runner design scheme of old power plants, this invention adopts a gradient blade tip maximum thickness distribution pattern under the same runner parameter level, which increases the airfoil thickness at the upper crown and lower ring, thereby improving the overall rigidity and strength level of the runner and its resistance to fatigue damage, and effectively reducing the risk of runner cracks.

[0061] 8. This invention has good adaptability to the inflow at the outlet of the active guide vane at any guide vane height, and can reduce the large pressure gradient changes inside the runner caused by the flow separation on the back side of the blade inlet. The initial formation of blade passage vortex in the low load area and the development of blade passage vortex can be further away from the long-term stable operation area, thus ensuring the stability of runner operation.

[0062] 9. In this invention, since the flow separation phenomenon on the back side of the turbine blade inlet is very sensitive to changes in unit speed, a gradually changing maximum thickness distribution pattern at the blade head is adopted. This allows the turbine to move the flow separation line on the back side further away from the normal operating range, which is beneficial to ensuring the reliability of the runner operation.

[0063] 10. In this invention, the airfoil thickness at the upper crown and lower ring is further increased, which significantly improves the rigidity of the rotor and further reduces the risk of rotor cracking.

[0064] 11. This invention fully considers the limitations of turbine design boundaries under different head sections, different operating ranges, and optimal unit parameter levels, further enhancing adaptability to incoming flow and reducing unstable flow in non-optimal operating conditions. This enables it to meet the current operating requirements of hydropower stations with wide head ranges and wide loads, and improves the flexibility of power station peak shaving and frequency regulation.

[0065] 12. In this invention, since the lower the water head and the higher the guide vane height, the greater the difference in the flow of water from the outlet of the movable guide vane to the inlet of the impeller in the spanwise direction, a specific design of the impeller blade head can effectively increase the adaptability to the incoming flow. Attached Figure Description

[0066] The present invention will now be further described in detail with reference to the accompanying drawings and specific embodiments:

[0067] Figure 1 is a schematic diagram of the structure of the hyperbolic mixed-flow impeller blade of the present invention;

[0068] Figure 2 is a schematic diagram of the axial projection of the airfoil section at the tip of the hyperbolic mixed-flow turbine blade of the present invention;

[0069] Figure 3 is a schematic diagram of the airfoil section at the head of the hyperbolic mixed-flow rotor blade of the present invention;

[0070] Figure 4 is a schematic diagram of the structure of the hyperbolic mixed-flow impeller blade of the present invention;

[0071] Figure 5 is a structural schematic diagram of the mixed-flow runner of the present application;

[0072] Figure 6 is a schematic diagram of the maximum thickness variation of the blade head portion in the perspective A in Figure 4;

[0073] Figure 7 is an enlarged view of the portion C in Figure 4;

[0074] Marked in the figure: 1, blade head portion, 2, blade tail portion, 3, upper gradual transition section, 4, middle gradual transition section, 5, lower gradual transition section, 6, upper crown, 7, lower ring;

[0075] is the position of each blade head portion airfoil section relative to the upper crown in the spanwise direction; is the blade inlet setting angle; is the blade inlet wrap angle; is the inlet radius of the blade head portion airfoil section; is the runner inlet nominal diameter; is the runner throat diameter; is the guide vane height; is the maximum thickness of the front airfoil section; is the length of the maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil; is the maximum thickness of the back airfoil section; is the length of the maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil; is the length of the blade airfoil. Embodiment of the present application

[0076] Example 1

[0077] Referring to Figures 1-7, a double-curved mixed-flow runner blade includes a blade head portion 1 and a blade tail portion 2, which are integrally formed, the blade head portion 1 is of a gradual transition type, and the blade head portion 1 includes an upper gradual transition section 3, a middle gradual transition section 4, and a lower gradual transition section 5, which are integrally formed in sequence.

[0078] This embodiment is the most basic embodiment, and the blade inlet airfoil section maximum thickness distribution law is obtained by comprehensively considering the unit operating parameters and the runner blade inlet geometric parameters, which can effectively improve the flow state of the blade inlet, is suitable for large water head amplitude and wide load operation requirements, improves the flow uniformity of the runner inlet between the upper crown 6 and the lower ring 7 under partial working conditions, reduces the pressure pulsation value of the bladeless area under partial working conditions, improves the overall rigidity and strength level of the runner, and improves the operating stability of the unit.

[0079] Example 2

[0080] Referring to Figs. 1-7, a double-curved mixed-flow runner blade includes a blade head 1 and a blade tail 2, which are integrally formed, the blade head 1 is of a gradual change type, the blade head 1 includes an upper gradual change section 3, a middle gradual change section 4 and a lower gradual change section 5, which are integrally formed in sequence.

[0081] Preferably, the blade head 1 is gradually changed in space, specifically, the blade head airfoil section of the upper gradual change section 3 near the upper crown 6 is thick, the blade head airfoil section of the lower gradual change section 5 near the lower ring 7 is thick, and the blade head airfoil section of the middle gradual change section 4 is thin.

[0082] This embodiment is a preferred embodiment, the maximum thickness distribution law of the gradual change type blade head can well adapt to large water head amplitude operation, effectively reduce the flow angle, increase the adaptability of the runner to the flow, guide the water flow to flow more smoothly, reduce the internal vortex generated by the blade inlet flow separation, improve the runner operation efficiency, and reduce the possibility of cavitation near the lower ring 7.

[0083] Embodiment 3

[0084] Referring to Figs. 1-7, a double-curved mixed-flow runner blade includes a blade head 1 and a blade tail 2, which are integrally formed, the blade head 1 is of a gradual change type, the blade head 1 includes an upper gradual change section 3, a middle gradual change section 4 and a lower gradual change section 5, which are integrally formed in sequence.

[0085] The blade head 1 is gradually changed in space, specifically, the blade head airfoil section of the upper gradual change section 3 near the upper crown 6 is thick, the blade head airfoil section of the lower gradual change section 5 near the lower ring 7 is thick, and the blade head airfoil section of the middle gradual change section 4 is thin.

[0086] The gradual change refers to that the maximum thickness distribution of the blade head airfoil section is thick at the upper crown 6 and the lower ring 7 in the spanwise direction, and thin in the middle.

[0087] The maximum thickness refers to the maximum value of the distance between the front profile of the blade head airfoil section and the blade skeleton line or the maximum value of the distance between the back profile of the blade head airfoil section and the blade skeleton line.

[0088] The spanwise direction refers to the height direction of the blade.

[0089] This embodiment is another preferred embodiment, which can effectively reduce the pressure pulsation value of the bladeless area under partial working conditions, and significantly expand the stable operation range of the unit.

[0090] Embodiment 4

[0091] Referring to Figs. 1-7, a double-curved mixed-flow runner blade includes a blade head 1 and a blade tail 2, which are integrally formed, the blade head 1 is of a gradual change type, the blade head 1 includes an upper gradual change section 3, a middle gradual change section 4 and a lower gradual change section 5, which are integrally formed in sequence.

[0092] The blade head 1 is gradually changed in space, specifically, the blade head airfoil section of the upper gradual change section 3 near the upper crown 6 is thick, the blade head airfoil section of the lower gradual change section 5 near the lower ring 7 is thick, and the blade head airfoil section of the middle gradual change section 4 is thin.

[0093] The gradual change means that the maximum thickness of the blade head airfoil section is distributed in the spanwise direction to show that the upper crown 6 and the lower ring 7 are thick and the middle is thin.

[0094] The maximum thickness means the maximum value of the distance between the front profile of the blade head airfoil section and the blade skeleton line or the maximum value of the distance between the back profile of the blade head airfoil section and the blade skeleton line.

[0095] The spanwise direction means the height direction of the blade.

[0096] Further preferably, the upper gradual change section 3 specifically means the blade head airfoil section whose axial plane projection position is in the spanwise direction 0≤ < 0.35, the middle gradual change section 4 is located between the upper gradual change section 3 and the lower gradual change section 5, the middle gradual change section 4 means the blade head airfoil section whose axial plane projection position is in the spanwise direction 0.35≤ ≤ 0.75, and the lower gradual change section 5 means the blade head airfoil section whose axial plane projection position is in the spanwise direction 0.75< 1.

[0097] The maximum thickness of the blade head airfoil section includes the maximum thickness of the front airfoil section and the maximum thickness of the back airfoil section.

[0098] The maximum thickness of the front airfoil section means the maximum value of the distance between the front profile of each airfoil section of the blade and the blade skeleton line.

[0099] The maximum thickness of the back airfoil section means the maximum value of the distance between the back profile of each airfoil section of the blade and the blade skeleton line.

[0100] The maximum thickness of the front airfoil section is calculated by Formula 1;

[0101] Formula 1;

[0102] wherein, is the maximum thickness of the front airfoil section,​ Hmax is the maximum water head, Hmin is the minimum water head, Hmin is the minimum water head, L is the length of the maximum thickness of the face of each airfoil section along the flow direction of the airfoil, is the inlet setting angle of the blade, is the inlet wrap angle of the blade, is the inlet radius of the head airfoil section, Nopt is the optimum unit speed, Nmax is the maximum unit speed.

[0103] The maximum thickness of the back airfoil section is calculated by equation 2;

[0104] Equation 2;

[0105] wherein, Tb is the maximum thickness of the back airfoil section, L is the length of the maximum thickness of the back of each airfoil section along the flow direction of the airfoil, Nmin is the minimum unit speed.

[0106] The unit speed is calculated by equation 3;

[0107] Equation 3;

[0108] wherein, N is the unit speed, N is the speed, D is the nominal diameter of the runner inlet, H is the water head.

[0109] The connection between the upper transition section 3 and the middle transition section 4 is a smooth transition.

[0110] The connection between the middle transition section 4 and the lower transition section 5 is a smooth transition.

[0111] The maximum thickness of the upper transition section 3 is greater than the maximum thickness of the lower transition section 5.

[0112] The maximum thickness of the lower transition section 5 is greater than the maximum thickness of the middle transition section 4.

[0113] The maximum thickness of the upper gradual change section 3 is greater than the maximum thickness of the lower gradual change section 5. According to engineering experience and actual operation of the water turbine of the power station, the risk of cracks at the connection between the blade and the upper crown 6 is higher than the risk of cracks at the connection between the blade and the lower ring 7. Therefore, by setting the maximum thickness of the upper gradual change section 3 to be greater than the maximum thickness of the lower gradual change section 5, the overall thickness of the airfoil section of the upper crown 6 is increased, and the rigidity level and fatigue damage resistance of the runner are improved.

[0114] The maximum thickness of the lower gradual change section 5 is greater than the maximum thickness of the middle gradual change section 4. In the spanwise direction, the maximum thickness of the middle gradual change section 4 is less than the maximum thickness of the lower gradual change section 5, which can avoid disturbing the uniformity of the incoming flow and reduce the pressure pulsation in the bladeless area.

[0115] The maximum thickness distribution of the blade airfoil head in different spanwise directions is defined, which is suitable for runner design of different water head sections and different optimal unit parameter levels, and has better applicability.

[0116] Embodiment 5

[0117] Referring to FIGS. 1-7, a preparation method of a double-curved mixed-flow runner blade includes the following steps:

[0118] S1, obtaining unit operation parameters and blade inlet geometric parameters;

[0119] S2, calculating and determining the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil;

[0120] S3, processing a gradually changing blade head 1 according to the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil and the maximum thickness of the blade head airfoil section, and integrally forming a blade tail 2 with the gradually changing blade head 1.

[0121] The embodiment is another preferred embodiment. Compared with the current old power station water turbine runner design scheme, under the condition of the same parameters of the runner, the gradually changing blade head 1 maximum thickness distribution is adopted, the airfoil thickness at the upper crown 6 and the lower ring 7 is increased, the overall rigidity level and fatigue damage resistance of the runner are improved, and the risk of runner cracks is effectively reduced.

[0122] Embodiment 6

[0123] Referring to FIGS. 1-7, a preparation method of a double-curved mixed-flow runner blade includes the following steps:

[0124] S1, obtaining unit operation parameters and blade inlet geometric parameters;

[0125] S2, calculating and determining the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil;

[0126] S3, according to the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil and the maximum thickness of the blade head airfoil section, a gradually changing blade head 1 is processed, and then the blade tail 2 is integrally formed with the gradually changing blade head 1.

[0127] In the S1, the unit speed includes a minimum unit speed, an optimal unit speed and a maximum unit speed, and the unit flow includes a rated unit flow and an optimal unit flow.

[0128] The relative guide vane height is a ratio of a guide vane height to a runner throat diameter.

[0129] The unit flow includes a rated unit flow and an optimal unit flow.

[0130] The embodiment is another preferred embodiment, which has good adaptability to the inlet flow of the movable guide vane at any guide vane height, can reduce the large pressure gradient change in the runner caused by the separation of the blade inlet back surface, and can make the initial generation of the blade passage vortex and the development of the blade passage vortex far away from the long-term stable operation area, thereby ensuring the stability of the runner operation.

[0131] Embodiment 7

[0132] Referring to FIGS. 1-7, a preparation method of a double-curved mixed-flow runner blade includes the following steps:

[0133] S1, obtaining unit operation parameters and blade inlet geometric parameters;

[0134] S2, calculating and determining the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil;

[0135] S3, according to the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil and the maximum thickness of the blade head airfoil section, a gradually changing blade head 1 is processed, and then the blade tail 2 is integrally formed with the gradually changing blade head 1.

[0136] In the S1, the unit speed includes a minimum unit speed, an optimal unit speed and a maximum unit speed, and the unit flow includes a rated unit flow and an optimal unit flow.

[0137] The relative guide vane height is a ratio of a guide vane height to a runner throat diameter.

[0138] The unit flow includes a rated unit flow and an optimal unit flow.

[0139] The blade inlet geometry parameters in the S1 include a guide vane height, an inlet radius of a blade head airfoil section, a blade inlet wrap angle, and a blade inlet setting angle.

[0140] The distribution ratio in the S2 refers to a ratio of a length of each airfoil section of the blade along a flow direction of the blade airfoil to a length of the blade airfoil.

[0141] The distribution ratio in the S2 includes a distribution ratio of a maximum thickness of a front airfoil section along the blade airfoil and a distribution ratio of a maximum thickness of a back airfoil section along the blade airfoil.

[0142] The distribution ratio of the maximum thickness of the front airfoil section along the blade airfoil refers to a ratio of a length of the maximum thickness of the front airfoil section of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

[0143] The distribution ratio of the maximum thickness of the back airfoil section along the blade airfoil refers to a ratio of a length of the maximum thickness of the back airfoil section of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

[0144] In the embodiment, the maximum thickness distribution law of the gradually changing blade head 1 is used, so that the back flow separation line of the water turbine is farther away from the normal operation range, and the operation reliability of the runner is ensured.

[0145] Embodiment 8

[0146] Referring to FIGS. 1-7, a preparation method of a double-curved mixed-flow runner blade includes the following steps:

[0147] S1, obtaining unit operation parameters and blade inlet geometry parameters;

[0148] S2, calculating and determining a distribution ratio of a maximum thickness of a blade head airfoil section along a blade airfoil;

[0149] S3, processing a gradually changing blade head 1 according to the distribution ratio of the maximum thickness of the blade head airfoil section along the blade airfoil, and integrally forming a blade tail 2 with the gradually changing blade head 1.

[0150] The unit operation parameters in the S1 include a water head amplitude, a relative guide vane height, a unit speed, and a unit flow rate, the unit speed includes a minimum unit speed, an optimal unit speed, and a maximum unit speed, and the unit flow rate includes a rated unit flow rate and an optimal unit flow rate.

[0151] The relative guide vane height is a ratio of the guide vane height to a runner throat diameter.

[0152] The unit flow ratio of the rated unit flow to the optimal unit flow.

[0153] In the S1, the blade inlet geometric parameters include the guide vane height, the inlet radius of the blade head airfoil section, the blade inlet wrap angle, and the blade inlet setting angle.

[0154] In the S2, the distribution ratio refers to the ratio of the length of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

[0155] In the S2, the distribution ratio includes the distribution ratio of the maximum thickness of the front airfoil section along the blade airfoil and the distribution ratio of the maximum thickness of the back airfoil section along the blade airfoil.

[0156] The distribution ratio of the maximum thickness of the front airfoil section along the blade airfoil refers to the ratio of the length of the maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

[0157] The distribution ratio of the maximum thickness of the back airfoil section along the blade airfoil refers to the ratio of the length of the maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

[0158] The distribution ratio of the maximum thickness of the front airfoil section along the blade airfoil is calculated by formula 4;

[0159] Formula 4;

[0160] wherein, is the length of the maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil, is the length of the blade airfoil, is the spanwise direction, i.e., the position of each blade head airfoil section relative to the upper crown 6, is a coefficient, and the value is , is the guide vane height, is the runner throat diameter, is the blade inlet setting angle, is the maximum water head, is the minimum water head, is the rated unit flow, is the optimal unit flow.

[0161] This embodiment is another preferred embodiment, because the airfoil thickness at the upper crown 6 and the lower ring 7 is further relatively increased, the strength level of the runner is greatly improved, and the risk of runner cracking can be further reduced.

[0162] Embodiment 9

[0163] Referring to FIGS. 1-7, a method for manufacturing a double-curved mixed-flow runner blade comprises the following steps:

[0164] S1, obtaining unit operation parameters and blade inlet geometric parameters;

[0165] S2, calculating and determining a distribution ratio of a maximum thickness of a blade head airfoil section along a blade airfoil;

[0166] S3, processing a gradually-changing blade head 1 according to the distribution ratio of the maximum thickness of the blade head airfoil section along the blade airfoil and the maximum thickness of the blade head airfoil section, and integrally forming a blade tail 2 with the gradually-changing blade head 1.

[0167] In the S1, the unit operation parameters include a water head amplitude, a relative guide vane height, a unit rotational speed, and a unit flow rate, the unit rotational speed includes a minimum unit rotational speed, an optimal unit rotational speed, and a maximum unit rotational speed, and the unit flow rate includes a rated unit flow rate and an optimal unit flow rate.

[0168] The relative guide vane height is a ratio of a guide vane height to a runner throat diameter.

[0169] The unit operation parameters further include a ratio of the rated unit flow rate to the optimal unit flow rate.

[0170] In the S1, the blade inlet geometric parameters include a guide vane height, an inlet radius of a blade head airfoil section, a blade inlet wrap angle, and a blade inlet setting angle.

[0171] In the S2, the distribution ratio refers to a ratio of a length of each airfoil section of the blade along a flow direction of the blade airfoil to a length of the blade airfoil.

[0172] In the S2, the distribution ratio includes a distribution ratio of a maximum thickness of a front airfoil section along the blade airfoil and a distribution ratio of a maximum thickness of a back airfoil section along the blade airfoil.

[0173] The distribution ratio of the maximum thickness of the front airfoil section along the blade airfoil refers to a ratio of a length of a maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

[0174] The distribution ratio of the maximum thickness of the back airfoil section along the blade airfoil refers to a ratio of a length of a maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

[0175] The distribution ratio of the maximum thickness of the front airfoil section along the blade airfoil is calculated by Formula 4;

[0176] Formula 4;

[0177] wherein, a length of the maximum thickness of the front surface of each airfoil section of the blade along the flow direction of the blade airfoil, a length of the blade airfoil, a position of each head airfoil section of the blade in the spanwise direction relative to the upper crown 6, a coefficient, taking a value of , a guide vane height, a runner throat diameter, a blade inlet setting angle, a maximum water head, a minimum water head, a rated unit flow rate, an optimal unit flow rate.

[0178] The distribution ratio of the maximum thickness of the back surface airfoil section along the blade airfoil is calculated by formula 5;

[0179] Formula 5;

[0180] wherein, a length of the maximum thickness of the back surface of each airfoil section of the blade along the flow direction of the blade airfoil, a coefficient, taking a value of .

[0181] The unit flow rate is calculated by formula 6;

[0182] Formula 6;

[0183] wherein, a unit flow rate, a flow rate.

[0184] The embodiment is still another preferred embodiment, which fully considers the design boundary limitations of the water turbine in different water head sections, different operating ranges and optimal unit parameter levels, further enhances the adaptability to the incoming flow, reduces the unstable flow in the non-optimal operating condition region, and thus can meet the operating requirements of the current wide water head amplitude and wide load of the hydropower station, and improves the flexibility of the station peak shaving and frequency modulation.

[0185] Embodiment 10

[0186] Referring to FIGS. 1-7, a Francis runner includes an upper crown 6 and a lower ring 7, and a plurality of hyperbolic Francis runner blades are arranged between the upper crown 6 and the lower ring 7.

[0187] The hyperbolic Francis runner blades are 15 in number and are uniformly distributed in a spiral shape on the upper crown 6.

[0188] The present embodiment is the best mode of embodiment, since the lower the water head is, the higher the guide vane height is, the greater the flow difference of water flow from the outlet of the movable guide vane to the inlet of the runner in the spanwise direction is, therefore the runner blade head 1 is specially designed, which can effectively increase the adaptability to the incoming flow.

[0189] The basic principle of the present application is as follows:

[0190] The flow pattern at the runner inlet is affected by the operating parameters of the unit and the geometric parameters of the runner. Generally speaking, the higher the guide vane height is, the lower the operating water head is, and the greater the difference of the flow pattern at the runner inlet in the spanwise direction is. Therefore, the conventional blade airfoil head maximum thickness design method with the equal thickness distribution and the linear change rule cannot adapt to the strong angle of attack change of the incoming flow caused by the large flow range and the large water head range, and a large pressure gradient change occurs at the runner inlet, which affects the downstream flow state and causes a series of unstable flow phenomena such as blade inlet flow separation, runner secondary flow, blade inlet cavitation and blade passage vortex, thereby affecting the operating stability of the water turbine.

[0191] The present application adopts the gradual change type blade head 1 maximum thickness distribution rule to design the change of the maximum thickness of the front and back surfaces of the blade airfoil head of different sections of the runner, and through the gradual transition change rule of thick-thin-thick in the upper crown 6-middle ring 7, the adaptability design of the water turbine with different water head sections, different operating ranges and optimal unit parameter level is realized, which can better adapt to the different difference incoming flow in the spanwise direction, weaken the intensity of blade inlet flow separation under the partial operating condition, reduce the possibility of blade inlet cavitation, and reduce the unstable flow phenomenon of blade passage vortex.

Claims

1. A double-curved mixed-flow runner blade comprising a blade head (1) and a blade tail (2), characterized in that: The blade head (1) and the blade tail (2) are integrally formed, the blade head (1) is of a gradually changing type, the blade head (1) comprises an upper gradually changing section (3), a middle gradually changing section (4) and a lower gradually changing section (5), and the upper gradually changing section (3), the middle gradually changing section (4) and the lower gradually changing section (5) are integrally formed in sequence.

2. A double-curved mixed flow runner blade according to claim 1, characterized in that: The blade head (1) gradually changes in space, specifically, the blade head airfoil section of the upper gradually changing section (3) is thick, the blade head airfoil section of the lower gradually changing section (5) is thick, and the blade head airfoil section of the middle gradually changing section (4) is thin.

3. A double-curved mixed flow runner blade according to claim 1, characterized in that: The gradual change refers to that the maximum thickness of the blade head airfoil section is distributed in the spanwise direction and presents upper and lower thickness and middle thinness.

4. A double-curved mixed-flow runner blade according to claim 3, characterized in that: The maximum thickness refers to the maximum value of the distance between the front profile of the blade head airfoil section and the blade skeleton or the maximum value of the distance between the back profile of the blade head airfoil section and the blade skeleton.

5. A double-curved mixed-flow runner blade according to claim 3, characterized in that: The spanwise direction refers to the height direction of the blade.

6. A double-curved mixed-flow runner blade according to claim 3, characterized in that: The upper gradual transition section (3) is specifically a blade head wing section axial plane projection position in the spanwise direction 0≤ <0.35, the middle gradual transition section (4) is located between the upper gradual transition section (3) and the lower gradual transition section (5), and the middle gradual transition section (4) is specifically a blade head wing section axial plane projection position in the spanwise direction 0.35≤ ≤0.75, and the lower gradual transition section is specifically a blade head wing section axial plane projection position in the spanwise direction 0.75< ≤1.

7. A double-curved mixed-flow runner blade according to claim 3, characterized in that: The maximum thickness of the blade head airfoil section includes the maximum thickness of the front airfoil section and the maximum thickness of the back airfoil section.

8. A double-curved mixed-flow runner blade according to claim 7, characterized in that: The maximum thickness of the front airfoil section refers to the maximum value of the distance between the front profile of each airfoil section of the blade and the blade skeleton.

9. A double-curved mixed-flow runner blade according to claim 7, characterized in that: The maximum thickness of the back airfoil section refers to the maximum value of the distance between the back profile of each airfoil section of the blade and the blade skeleton.

10. A double-curved mixed-flow runner blade according to claim 7, characterized in that: The maximum thickness of the front airfoil section is calculated by formula 1. Formula 1 wherein for the maximum thickness of the profile section in the front view, for the spanwise direction, i.e. the position of each blade head airfoil section relative to the upper crown (6), for maximum head, For minimum water head, the length of the maximum thickness of the front face of each airfoil section of the blade in the flow direction of the blade airfoil, for the blade inlet setting angle, to angle the blade inlet, for the inlet radius of the airfoil section of the blade head, for the optimum unit speed, is the maximum unit speed.

11. A double-curved mixed-flow runner blade according to claim 10, characterized in that: The maximum thickness of the back airfoil section is calculated by formula 2. Formula 2 wherein for the maximum thickness of the cross section of the back wing, the length of the maximum thickness of the back surface of each airfoil section along the flow direction of the airfoil of the blade, is the minimum unit speed.

12. A double-curved mixed-flow runner blade according to claim 10, characterized in that: The unit speed is calculated by formula 3. Formula 3 wherein for unit rotational speed, for the rotational speed, for the nominal diameter of the runner inlet, is the water head.

13. A double-curved mixed-flow runner blade according to claim 1, characterized in that: The connection between the upper gradually changing section (3) and the middle gradually changing section (4) is a smooth transition.

14. A double-curved mixed-flow runner blade according to claim 1, characterized in that: The connection between the middle gradually changing section (4) and the lower gradually changing section (5) is a smooth transition.

15. A double-curved mixed-flow runner blade according to claim 1, characterized in that: The maximum thickness of the upper gradually changing section (3) is greater than that of the lower gradually changing section (5).

16. A double-curved mixed-flow runner blade according to claim 1, characterized in that: The maximum thickness of the lower gradually changing section (5) is greater than that of the middle gradually changing section (4).

17. A method of manufacturing a double-curved mixed-flow runner blade as claimed in claim 1, characterized in that: The method comprises the following steps: S1, obtaining unit operation parameters and blade inlet geometric parameters; S2, calculating the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil; S3, processing the gradually changing blade head (1) according to the distribution proportion of the maximum thickness of the blade head airfoil section along the blade airfoil and the maximum thickness of the blade head airfoil section, and then integrally forming the blade tail (2) and the gradually changing blade head (1).

18. A method of manufacturing a double-curved mixed-flow runner blade according to claim 17, characterized in that: In the S1, the unit operation parameters include a water head amplitude, a relative guide vane height, a unit speed and a unit flow, the unit speed includes a minimum unit speed, an optimal unit speed and a maximum unit speed, and the unit flow includes a rated unit flow and an optimal unit flow.

19. A method of manufacturing a double-curved mixed-flow runner blade according to claim 18, characterized in that: The relative guide vane height is the ratio of the guide vane height to the runner throat diameter.

20. A method of making a double-curved mixed-flow runner blade according to claim 17, characterized in that: The unit operation parameters further include a ratio of the rated unit flow to the optimal unit flow.

21. A method of making a double-curved mixed-flow runner blade according to claim 17, wherein: In the S1, the blade inlet geometric parameters include a guide vane height, an inlet radius of the blade head airfoil section, a blade inlet wrap angle and a blade inlet setting angle.

22. A method of making a double-curved mixed-flow runner blade according to claim 17, characterized in that: In the S2, the distribution proportion refers to the ratio of the length of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

23. A method of making a double-curved mixed-flow runner blade according to claim 17, characterized in that: The distribution proportion in S2 includes the distribution proportion of the maximum thickness of the front airfoil section along the blade airfoil and the distribution proportion of the maximum thickness of the back airfoil section along the blade airfoil.

24. A method of manufacturing a double-curved mixed-flow runner blade according to claim 23, characterized in that: The distribution proportion of the maximum thickness of the front airfoil section along the blade airfoil refers to the ratio of the length of the maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

25. A method of making a double-curved mixed-flow runner blade according to claim 23, wherein: The distribution proportion of the maximum thickness of the back airfoil section along the blade airfoil refers to the ratio of the length of the maximum thickness of each airfoil section of the blade along the flow direction of the blade airfoil to the length of the blade airfoil.

26. A method of making a double-curved mixed-flow runner blade according to claim 23, wherein: The distribution proportion of the maximum thickness of the front airfoil section along the blade airfoil is calculated by formula 4. Formula 4; wherein the length of the maximum thickness of the front face of each airfoil section of the blade in the flow direction of the blade airfoil, for the length of the blade airfoil, for the spanwise direction, i.e. the position of each blade head airfoil section relative to the upper crown (6), for the coefficients, taking values ， For the height of the guide vanes, for the runner throat diameter, for the blade inlet setting angle, for maximum head, For minimum water head, for a rated unit flow, The optimal unit flow.

27. A method of making a double-curved mixed-flow runner blade according to claim 23, wherein: The distribution proportion of the maximum thickness of the back airfoil section along the blade airfoil is calculated by formula 5. Formula 5; wherein the length of the maximum thickness of the back surface of each airfoil section along the flow direction of the airfoil of the blade, wherein the coefficients are taken as 。 28. A method of making a double-curved mixed-flow runner blade according to claim 26, wherein: The unit flow is calculated by formula 6. Formula 6; wherein for unit flow rate, The flow.

29. A mixed flow runner comprising the double curved mixed flow runner blade of claim 1, characterized by: Further comprising an upper crown (6) and a lower ring (7), a plurality of hyperbolic mixed-flow runner blades are arranged between the upper crown (6) and the lower ring (7).

30. The mixed flow runner of claim 29, wherein: The hyperbolic mixed-flow runner blades are 13-17, and the hyperbolic mixed-flow runner blades are uniformly distributed in a spiral shape on the upper crown (6).

Images