A method for designing a water outlet edge of a runner blade, a runner and application

Abstract

The application discloses a runner blade water outlet edge design method, a runner and application, belongs to the technical field of water turbines, and relates to a runner blade water outlet edge design method, which comprises the following steps: S1, determining a thickened section of a blade water outlet edge close to an upper crown and a lower ring; S2, calculating and determining the thickness distribution of the water outlet edge in different sections of the blade water outlet edge; and S3, smoothly transitioning the lines between different sections of the blade water outlet edge. The application can effectively reduce the stress level of the runner blade at the connection between the upper crown and the lower ring, greatly reduces the risk of cracks at the welding seam between the blade water outlet edge and the upper crown and the lower ring, and can significantly expand the stable operation range of the water turbine unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic turbine, and particularly relates to a runner blade outflow edge design method, a runner and application. BACKGROUND

[0002] The conventional Francis turbine is the main force of power grid peak regulation and frequency regulation. After participating in automatic generation control, even if the measures of adding reinforcing triangular blocks at the outflow edges of the upper crown and the lower ring are taken, cracks often occur at the welding seams between the runner blade outflow edges and the upper crown and the lower ring. The power station needs frequent maintenance to repair the cracks of the runner, which also affects the safe and stable operation of the unit.

[0003] There are many reasons for the cracks of the runner blade, including external factors and internal factors, but the problems mainly concentrate on the aspects of material selection, design, process, operation and crack repair. For example, the unit often runs at partial load conditions, and the load changes frequently. The runner will bear a large alternating dynamic stress caused by pressure pulsation and load change process or the influence of high-frequency flow separation of the Karman vortex and resonance with the blade; casting defects, welding stress and imperfect post-welding heat treatment are the source of inducing cracks; the unreasonable selection and structural design make the runner poor in stability and lack of sufficient rigidity and strength margin. When long-term operation in the vibration zone, the material fatigue stress will cause cracks at the stress concentration position of the blade.

[0004] The basic reason for the occurrence of the runner cracks is that the runner blade cannot bear the dynamic load. In order to pursue higher efficiency, the thickness of the runner outflow edge of the current old power station is very small and basically consistent, which leads to a high stress level at the welding seam area of the upper crown and the lower ring, and obvious stress concentration phenomenon. Moreover, at the design stage, it is also impossible to quantify the relationship between the thickness variation of the runner blade outflow edge and the water head section, water head amplitude and flow amplitude under specific development conditions, so as to optimize the design of the runner outflow edge.

[0005] The Chinese patent document with the publication number CN102562415A and the publication date of 2012.07.11 discloses a water outlet edge of a Francis turbine runner blade, the blade comprising a blade body, a stress-reducing triangular block at an upper crown, and a stress-reducing triangular block at a lower ring, and the blade has an additional triangular shape near the upper crown and the lower ring; the spatial distance between P1 and P2 is D1 / 40-D1 / 20 and is not less than 75 mm; D1 is the nominal diameter of the Francis runner inlet; the spatial distance between P1 and P3 is D1 / 30-D1 / 15 and is not less than 100 mm; the spatial distance between P4 and P5 is 1 / 2 of the spatial distance between P1 and P2; the spatial distance between P4 and P6 is 1 / 2 of the spatial distance between P1 and P3; the thickness of the stress-reducing triangular block at the upper crown is selected to be 0.007-0.008 times D1, and the thickness of the stress-reducing triangular block at the lower ring is selected to be 0.005-0.006 times D1; the part between P3 and P6 of the blade water outlet edge adopts a shape for preventing the trapping of a vortex, the thickness of the blade water outlet edge is H, the rounding angle of the water outlet edge is 45°, and the rounding radius R of the water outlet edge is 3-4 times H; during the manufacturing process of the blade, the shape of the water outlet edge at the positions corresponding to P2 and P5 is square, and after the completion of the welding of the runner, the water outlet edges between P3 and P2 and between P6 and P5 should be polished to smoothly transition from the anti-vortex water outlet edge to the semicircular water outlet edge.

[0006] The water outlet edge of the Francis turbine runner blade disclosed in the patent document,

[0007] The stress-reducing triangular blocks are added at the upper crown and the lower ring of the blade, and the water outlet edge shape is adopted to prevent the trapping of a vortex, the thickness and the rounding angle of the water outlet edge are adjusted, the structural strength and the shape of the blade are optimized through finite element analysis, and the stress and the flow energy are reduced. Although the structural strength of the water outlet edge of the blade is improved, cracks are still prone to occur at the welding seams of the water outlet edge of the blade and the upper crown and the lower ring, which affects the stable operation range of the unit. SUMMARY

[0008] The present application can effectively reduce the stress level of the runner blade at the connection between the upper crown and the lower ring, greatly reduce the risk of cracks at the welding seams of the water outlet edge of the blade and the upper crown and the lower ring, and thus can significantly expand the stable operation range of the turbine unit.

[0009] The present application is realized by the following technical scheme:

[0010] A design method for a water outlet edge of a runner blade, comprising the following steps:

[0011] S1, determining a thickened section of the water outlet edge of the blade near the upper crown and the lower ring;

[0012] S2, calculating and determining the thickness distribution of the water outlet edge in different sections of the water outlet edge of the blade.

[0013] S3, the profile lines between different sections of the blade exit water edge are smoothly transitioned.

[0014] In S1, the thickened section of the blade exit water edge includes an upper crown thickened exit water edge interval arc segment and a lower ring thickened exit water edge interval arc segment.

[0015] The arc length of the upper crown thickened exit water edge interval arc segment is calculated by formula 1;

[0016] Formula 1;

[0017] Wherein, is the arc length of the upper crown thickened exit water edge interval arc segment, is the exit water edge arc length, is the diameter of the blade entry water edge at the lower ring, is the diameter of the blade exit water edge.

[0018] The arc length of the lower ring thickened exit water edge interval arc segment is calculated by formula 2;

[0019] Formula 2;

[0020] Wherein, is the arc length of the lower ring thickened exit water edge interval arc segment, is the exit water edge arc length, is the diameter of the blade entry water edge at the lower ring, is the diameter of the blade exit water edge.

[0021] In S2, the different sections of the blade exit water edge include a blade exit water edge near the upper crown section, a blade exit water edge middle section, and a blade exit water edge near the lower ring section.

[0022] In S2, the thickness distribution of the different sections of the blade exit water edge is that the thickness of the blade exit water edge near the upper crown section is thick, the thickness of the blade exit water edge middle section is thin, and the thickness of the blade exit water edge near the lower ring section is thick.

[0023] The thickness of the blade exit water edge near the upper crown section is calculated by formula 3;

[0024] Formula 3;

[0025] Wherein, is the thickness of the blade exit water edge near the upper crown section, is the diameter of the blade exit water edge, is the diameter of the blade exit water edge at the upper crown, is the maximum water head, is the ratio of the arc length at the upper crown position to the total arc length of the blade exit water edge, , is the arc length of the thickened waterside section along the upper crown, The arc length of the water side.

[0026] The thickness of the middle section of the blade outlet edge is calculated by formula 4;

[0027]

[0028] Formula 4;

[0029] in, is the thickness of the middle section of the blade at the water outlet, is the rated unit flow rate, is the optimal unit flow rate, is the maximum unit speed, is the minimum unit speed, is the maximum water head, is the high pressure side diameter of the model runner, for According to the real machine high pressure side diameter converted from the scale, is the ratio of the arc length relative to the crown position to the total arc length of the blade out of the water, , is the arc length of the thickened waterside section along the upper crown, is the arc length of the water side, It is the arc length of the water outlet section along the thickened lower ring.

[0030] The unit speed is calculated by formula 5;

[0031] Formula 5;

[0032] in, is the unit speed, is the rotation speed, is the water head, is the diameter of the blade at the water inlet edge at the lower ring.

[0033] The unit flow rate is calculated by formula 6;

[0034] Formula 6;

[0035] in, is the unit flow rate, For traffic, is the diameter of the blade water inlet side at the lower ring, For the water head.

[0036] The thickness of the blade outlet edge near the lower ring section is calculated by formula 7;

[0037] Formula 7;

[0038] wherein, is the thickness of the blade water exit edge close to the lower ring section, is the diameter of the blade water exit edge, is the diameter of the blade water exit edge at the upper crown, is the proportion of the arc length at the upper crown position to the total arc length of the blade water exit edge, , is the arc length of the water exit edge, is the arc length of the water exit edge section along the lower ring thickening, is the maximum water head.

[0039] A runner comprises an upper crown and a lower ring, and a plurality of runner blades are arranged between the upper crown and the lower ring.

[0040] The runner blade comprises a blade body, a blade water inlet edge and a blade water exit edge, and the blade water inlet edge, the blade body and the blade water exit edge are integrally formed.

[0041] The blade water exit edge comprises a blade water exit edge close to the upper crown section, a blade water exit edge middle section and a blade water exit edge close to the lower ring section, and the blade water exit edge close to the upper crown section, the blade water exit edge middle section and the blade water exit edge close to the lower ring section are integrally formed.

[0042] The thicknesses of the blade water exit edge close to the upper crown section and the blade water exit edge close to the lower ring section are both greater than the thickness of the blade water exit edge middle section.

[0043] The application of a runner blade water exit edge is suitable for a runner blade of a water turbine.

[0044] The application of a runner is suitable for a Francis turbine in a 50-500m water head section.

[0045] The beneficial effects of the present application mainly lie in the following aspects:

[0046] 1. Compared with the prior art, the present application can effectively reduce the stress level of the runner blade at the connection between the upper crown and the lower ring, greatly reduces the risk of cracks at the welding seam between the blade water exit edge and the upper crown and the lower ring, and can significantly expand the stable operation range of the water turbine unit.

[0047] 2. Compared with the conventional runner with an equal-thickness blade water exit edge, the present application effectively reduces the stress level of the runner blade at the connection between the upper crown and the lower ring by using specific section thickening of the blade water exit edge. The calculation results show that the maximum reduction of the static stress value and the dynamic stress amplitude in the typical working condition within the full load range is 42% and 61% respectively, as shown in Table 1.

[0048] 3. In the present invention, the thickened section of the water outlet edge of the blade includes an arc section of the water outlet edge thickened along the upper crown and an arc section of the water outlet edge thickened along the lower ring. The thickening is performed on the high stress areas of the water outlet edge of the blade close to the upper crown and the lower ring, which significantly improves the stiffness and fatigue resistance and cavitation damage resistance of the blade at these key positions, and enhances the overall structural reliability of the blade.

[0049] 4. The present invention effectively guides the water flow by precisely controlling the thickness distribution and smooth profile transition of the blade outlet edge, reduces the wake vortex, secondary flow and flow separation phenomena at the blade outlet edge, optimizes the hydraulic performance, reduces hydraulic loss and improves operating efficiency.

[0050] 5. The present invention comprehensively considers the geometric parameters of the runner and the operating parameters of the turbine unit, which are important parameters that actually affect the wide-load operating capability of the turbine unit, and then adopts segmented thickening of the water outlet edge of the runner blades, so that the geometric parameters of the runner and the operating parameters of the turbine unit are well optimized and matched, which is beneficial to reducing the dynamic stress level under partial load.

[0051] 6. The present invention effectively enhances the structural strength and fatigue resistance of the blade edge and improves the operational reliability of the runner by optimizing the thickness distribution of the blade outlet edge and achieving a smooth transition.

[0052] 7. In the present invention, the rigidity level of the runner at the connection between the upper crown and the lower ring is enhanced, which reduces or even avoids the risk of runner cracks caused by fatigue damage to the runner when the turbine unit is running at low load, and effectively improves the operating stability of the unit.

[0053] 8. In the present invention, the water outlet edge of the blade includes a section close to the upper crown of the blade, a middle section of the water outlet edge of the blade, and a section close to the lower ring of the blade. The section close to the upper crown of the blade, the middle section of the water outlet edge of the blade, and the section close to the lower ring of the blade are integrally formed, which not only enhances the fatigue resistance and cavitation resistance of the high stress area to extend the life of the blade, but also effectively suppresses flow separation and vortex through smooth lines, reduces hydraulic loss, and ultimately achieves coordinated optimization of reliability and energy conversion efficiency.

[0054] 9. In the present invention, the thickness of the blade outlet edge near the upper crown section and the blade outlet edge near the lower ring section are both greater than the thickness of the middle section of the blade outlet edge. By thickening the high stress area to enhance fatigue resistance and cavitation resistance, and thinning the middle section of the blade outlet edge to optimize the streamline shape, the hydraulic loss is significantly reduced while ensuring the reliability of the blade structure. This not only suppresses the risk of cracks caused by stress concentration at the end, but also reduces the wake vortex and flow separation at the blade outlet edge, thereby improving the energy conversion efficiency of the runner, and achieving a dual optimization effect of strength and flow state.

[0055] 10. The present application is suitable for Francis turbine in the range of 50-500m water head. By designing the blade outlet edge in different sections, the thickened blade outlet edge near the upper crown section and the blade outlet edge near the lower ring section can effectively resist high stress and cavitation damage in the range of 50-500m water head, ensuring structural reliability, and the thinned blade outlet edge middle section can optimize the water flow pattern and reduce hydraulic loss, achieving wide load efficient and stable operation. BRIEF DESCRIPTION OF DRAWINGS

[0056] The present application will be further described below in conjunction with the drawings and specific embodiments:

[0057] Figure 1 The structure of the runner of the present application is shown in the figure;

[0058] Figure 2 The structure of the runner blade of the present application is shown in the figure;

[0059] Figure 3 The thickness distribution of the blade outlet edge of the present application is shown in the figure;

[0060] Marked in the figure: 1, upper crown, 2, lower ring, 3, blade outlet edge, 4, blade inlet edge, 5, blade outlet edge near the upper crown section, 6, blade outlet edge middle section, 7, blade outlet edge near the lower ring section, 8, runner blade, 9, blade body;

[0061] The thickness of the blade outlet edge near the upper crown section, The arc length of the outlet edge section along the upper crown thickening, The thickness of the blade outlet edge middle section, The arc length of the outlet edge section along the lower ring thickening, The thickness of the blade outlet edge near the lower ring section. DETAILED DESCRIPTION

[0062] Example 1

[0063] Referring to Figure 1 A runner blade outlet edge design method, comprising the following steps:

[0064] S1, determining the thickened section of the blade outlet edge 3 near the upper crown 1 and the lower ring 2;

[0065] S2, calculating the thickness distribution of the blade outlet edge 3 in different sections;

[0066] S3, smoothing the transition of the profile line between different sections of the blade outlet edge 3.

[0067] The embodiment is the most basic implementation, which can effectively reduce the stress level of the runner blade 8 at the connection between the upper crown 1 and the lower ring 2, greatly reduce the risk of cracks at the welding seam between the blade water outlet edge 3 and the upper crown 1 and the lower ring 2, and further significantly expand the stable operation range of the water turbine unit.

[0068] Embodiment 2

[0069] Referring to Figures 1-3 A runner blade water outlet edge design method, comprising the following steps:

[0070] S1, determining the thickened section of the blade water outlet edge 3 close to the upper crown 1 and the lower ring 2;

[0071] S2, calculating the thickness distribution of the water outlet edge in different sections of the blade water outlet edge 3;

[0072] S3, smoothing the transition lines between different sections of the blade water outlet edge 3.

[0073] In the S1, the thickened section of the blade water outlet edge 3 includes an outlet edge interval arc segment thickened along the upper crown 1 and an outlet edge interval arc segment thickened along the lower ring 2.

[0074] The arc length of the outlet edge interval arc segment thickened along the upper crown 1 is calculated by formula 1;

[0075] Formula 1;

[0076] Wherein, is the arc length of the outlet edge interval arc segment thickened along the upper crown, is the outlet edge arc length, is the diameter of the blade water inlet edge at the lower ring, is the diameter of the blade water outlet edge.

[0077] The arc length of the outlet edge interval arc segment thickened along the lower ring 2 is calculated by formula 2;

[0078] Formula 2;

[0079] Wherein, is the arc length of the outlet edge interval arc segment thickened along the lower ring, is the outlet edge arc length, is the diameter of the blade water inlet edge at the lower ring, is the diameter of the blade water outlet edge.

[0080] The embodiment is a preferred embodiment. By using specific partitioned thickening on the blade water outlet edge 3, compared with the conventional blade water outlet edge 3 of the same thickness, the stress level of the runner blade 8 at the connection between the upper crown 1 and the lower ring 2 is effectively reduced. The calculation results show that the maximum reduction of the static stress value and the dynamic stress amplitude in the typical working condition within the full load range is 42% and 61%, respectively.

[0081] Embodiment 3

[0082] Referring to Figures 1-3 A design method of a runner blade water outlet edge, comprising the following steps:

[0083] S1, determining the thickening section of the blade water outlet edge 3 close to the upper crown 1 and the lower ring 2;

[0084] S2, calculating the thickness distribution of the water outlet edge in different sections of the blade water outlet edge 3;

[0085] S3, smoothing the transition of the profile line between different sections of the blade water outlet edge 3.

[0086] In the S1, the thickening section of the blade water outlet edge 3 includes the water outlet edge interval arc segment thickened along the upper crown 1 and the water outlet edge interval arc segment thickened along the lower ring 2.

[0087] The arc length of the water outlet edge interval arc segment thickened along the upper crown 1 is calculated by formula 1;

[0088] Formula 1;

[0089] Wherein, L1 is the arc length of the water outlet edge interval arc segment thickened along the upper crown, L is the arc length of the water outlet edge, Din is the diameter of the blade inlet edge at the lower ring, Dout is the diameter of the blade water outlet edge.

[0090] The arc length of the water outlet edge interval arc segment thickened along the lower ring 2 is calculated by formula 2;

[0091] Formula 2;

[0092] Wherein, L2 is the arc length of the water outlet edge interval arc segment thickened along the lower ring, L is the arc length of the water outlet edge, Din is the diameter of the blade inlet edge at the lower ring, Dout is the diameter of the blade water outlet edge.

[0093] In the S2, the different sections of the blade water outlet edge 3 include the blade water outlet edge close to the upper crown section 5, the blade water outlet edge middle section 6 and the blade water outlet edge close to the lower ring section 7.

[0094] The thickness of the blade outlet edge near the upper crown section 5 is calculated by formula 3.

[0095] The thickness of the blade outlet edge near the upper crown section 5 is calculated by formula 3.

[0096] Formula 3;

[0097] wherein, is the thickness of the blade outlet edge near the upper crown section, is the diameter of the blade outlet edge, is the diameter of the blade outlet edge at the upper crown, is the maximum water head, is the ratio of the arc length at the upper crown position to the total arc length of the blade outlet edge, , is the arc length of the outlet edge interval arc segment along the upper crown thickening, is the arc length of the outlet edge.

[0098] The thickness of the blade outlet edge near the upper crown section 5 is calculated by formula 3.

[0099]

[0100] Formula 4;

[0101] wherein, is the thickness of the blade outlet edge near the upper crown section, is the rated unit flow, is the optimal unit flow, is the maximum unit rotational speed, is the minimum unit rotational speed, is the maximum water head, is the high-pressure side diameter of the model runner, is the high-pressure side diameter of the model runner, is the high-pressure side diameter of the real machine according to the scale conversion, is the ratio of the arc length at the upper crown position to the total arc length of the blade outlet edge, , is the arc length of the outlet edge interval arc segment along the upper crown thickening, is the arc length of the outlet edge, is the arc length of the outlet edge interval arc segment along the lower ring thickening.

[0102] The embodiment is another preferred embodiment, the thickened section of the blade water outlet edge 3 includes the water outlet edge interval arc segment thickened along the upper crown 1 and the water outlet edge interval arc segment thickened along the lower ring 2, the high stress areas of the blade water outlet edge 3 close to the upper crown 1 and the lower ring 2 are thickened, the rigidity and the fatigue and cavitation erosion resistance of the blade water outlet edge 3 at these key positions are significantly improved, and the overall structural reliability of the blade is enhanced.

[0103] Embodiment 4

[0104] Referring to Figures 1-3 A design method of a runner blade water outlet edge, comprising the following steps:

[0105] S1, determining the thickened section of the blade water outlet edge 3 close to the upper crown 1 and the lower ring 2;

[0106] S2, calculating the thickness distribution of the water outlet edge in different sections of the blade water outlet edge 3;

[0107] S3, smoothing the transition of the profile between different sections of the blade water outlet edge 3.

[0108] In the S1, the thickened section of the blade water outlet edge 3 includes the water outlet edge interval arc segment thickened along the upper crown 1 and the water outlet edge interval arc segment thickened along the lower ring 2.

[0109] The arc length of the water outlet edge interval arc segment thickened along the upper crown 1 is calculated by formula 1;

[0110] Formula 1;

[0111] Wherein, L1 is the arc length of the water outlet edge interval arc segment thickened along the upper crown, L is the arc length of the water outlet edge, D1 is the diameter of the blade water inlet edge at the lower ring, D is the diameter of the blade water outlet edge.

[0112] The arc length of the water outlet edge interval arc segment thickened along the lower ring 2 is calculated by formula 2;

[0113] Formula 2;

[0114] Wherein, L2 is the arc length of the water outlet edge interval arc segment thickened along the lower ring, L is the arc length of the water outlet edge, D1 is the diameter of the blade water inlet edge at the lower ring, D is the diameter of the blade water outlet edge.

[0115] In the S2, the different sections of the blade water outlet edge 3 include the blade water outlet edge close to the upper crown section 5, the blade water outlet edge middle section 6 and the blade water outlet edge close to the lower ring section 7.

[0116] In S2, the thickness distribution of the blade outlet edge in different sections of the blade outlet edge 3 is that the thickness of the blade outlet edge near the upper crown section 5 is thick, the thickness of the blade outlet edge in the middle section 6 is thin, and the thickness of the blade outlet edge near the lower ring section 7 is thick.

[0117] The thickness of the blade outlet edge near the upper crown section 5 is calculated by formula 3;

[0118] Formula 3;

[0119] Wherein, t is the thickness of the blade outlet edge near the upper crown section, D is the diameter of the blade outlet edge, Dc is the diameter of the blade outlet edge at the upper crown, H is the maximum water head, is the ratio of the arc length at the upper crown position to the total arc length of the blade outlet edge, , is the arc length of the outlet edge interval arc segment along the upper crown thickening, is the arc length of the outlet edge.

[0120] The thickness of the blade outlet edge in the middle section 6 is calculated by formula 4;

[0121]

[0122] Formula 4;

[0123] Wherein, t is the thickness of the blade outlet edge in the middle section, Q is the rated unit flow, Qopt is the optimal unit flow, Nmax is the maximum unit rotational speed, Nmin is the minimum unit rotational speed, H is the maximum water head, Dh is the high-pressure side diameter of the model runner, Dh is the high-pressure side diameter of the model runner, Dh is the high-pressure side diameter of the model runner, is the ratio of the arc length at the upper crown position to the total arc length of the blade outlet edge, , is the arc length of the outlet edge interval arc segment along the upper crown thickening, is the arc length of the outlet edge, is the arc length of the outlet edge interval arc segment along the lower ring thickening.

[0124] The unit rotational speed is calculated by formula 5;

[0125] Formula 5;

[0126] Wherein, is the unit rotational speed, is the rotational speed, is the water head, is the diameter of the blade inlet edge at the lower ring.

[0127] The unit flow rate is calculated by formula 6;

[0128] Formula 6;

[0129] wherein, is the unit flow rate, is the flow rate, is the diameter of the blade inlet edge at the lower ring, is the water head.

[0130] The thickness of the blade outlet edge close to the lower ring section 7 is calculated by formula 7;

[0131] Formula 7;

[0132] wherein, is the thickness of the blade outlet edge close to the lower ring section, is the diameter of the blade outlet edge, is the diameter of the blade outlet edge at the upper crown, is the proportion of the arc length at the upper crown position to the total arc length of the blade outlet edge, is the outlet edge arc length, is the arc length of the outlet edge section arc segment along the lower ring thickening, is the maximum water head.

[0133] The embodiment is still another preferred embodiment, which effectively guides the water flow by precisely controlling the thickness distribution and smooth transition of the blade outlet edge 3, reduces the blade outlet edge 3 wake vortex, secondary flow and flow separation phenomenon, optimizes the hydraulic performance, reduces the hydraulic loss, and improves the operation efficiency.

[0134] By comprehensively considering the geometric parameters of the runner and the operating parameters of the turbine unit, which are important parameters that actually affect the wide load operation capacity of the turbine unit, and then adopting sectional thickening for the blade outlet edge 3 of the runner blade 8, the geometric parameters of the runner and the operating parameters of the turbine unit are well optimized and matched, which is beneficial to reduce the dynamic stress level under partial load.

[0135] Embodiment 5

[0136] Referring to Figure 1 and Figure 2 , a runner includes an upper crown 1 and a lower ring 2, and a plurality of runner blades 8 are arranged between the upper crown 1 and the lower ring 2.

[0137] ​The embodiment is another preferable implementation. By optimizing the thickness distribution of the blade water outlet edge 3 and achieving smooth transition, the structural strength and fatigue resistance of the blade edge are effectively enhanced, and the operation reliability of the runner is improved.

[0138] Embodiment 6

[0139] Referring to Figure 1 and Figure 2 A runner includes an upper crown 1 and a lower ring 2, and a plurality of runner blades 8 are arranged between the upper crown 1 and the lower ring 2.

[0140] The runner blade 8 includes a blade body 9, a blade water inlet edge 4, and a blade water outlet edge 3, and the blade water inlet edge 4, the blade body 9, and the blade water outlet edge 3 are integrally formed.

[0141] The blade water outlet edge 3 includes a blade water outlet edge near the upper crown section 5, a blade water outlet edge middle section 6, and a blade water outlet edge near the lower ring section 7, and the blade water outlet edge near the upper crown section 5, the blade water outlet edge middle section 6, and the blade water outlet edge near the lower ring section 7 are integrally formed.

[0142] The embodiment is another preferable implementation. The rigidity level of the runner at the connection between the upper crown 1 and the lower ring 2 is enhanced, the risk of runner cracks caused by fatigue damage of the runner caused by the water turbine unit in small load operation is reduced or even avoided, and the operation stability of the unit is effectively improved.

[0143] The blade water outlet edge 3 includes a blade water outlet edge near the upper crown section 5, a blade water outlet edge middle section 6, and a blade water outlet edge near the lower ring section 7, and the blade water outlet edge near the upper crown section 5, the blade water outlet edge middle section 6, and the blade water outlet edge near the lower ring section 7 are integrally formed. Both the fatigue resistance and the cavitation resistance of the high stress area are enhanced to prolong the service life of the blade, and the flow separation and vortex are effectively suppressed through the smooth profile, the hydraulic loss is reduced, and finally the reliability and energy conversion efficiency are synergistically optimized.

[0144] Embodiment 7

[0145] Referring to Figures 1-3 A runner includes an upper crown 1 and a lower ring 2, and a plurality of runner blades 8 are arranged between the upper crown 1 and the lower ring 2.

[0146] The runner blade 8 includes a blade body 9, a blade water inlet edge 4, and a blade water outlet edge 3, and the blade water inlet edge 4, the blade body 9, and the blade water outlet edge 3 are integrally formed.

[0147] The blade outlet edge 3 includes a blade outlet edge close to the upper crown section 5, a blade outlet edge middle section 6 and a blade outlet edge close to the lower ring section 7. The blade outlet edge close to the upper crown section 5, the blade outlet edge middle section 6 and the blade outlet edge close to the lower ring section 7 are integrally formed.

[0148] The thickness of the blade outlet edge close to the upper crown section 5 and the blade outlet edge close to the lower ring section 7 are both greater than the thickness of the blade outlet edge middle section 6.

[0149] This embodiment is another preferred implementation method. The thickness of the blade outlet edge near the upper crown section 5 and the blade outlet edge near the lower ring section 7 are both greater than the thickness of the middle section 6 of the blade outlet edge. By thickening the high stress area to enhance fatigue resistance and cavitation resistance, and thinning the middle section 6 of the blade outlet edge to optimize the streamline shape, the hydraulic loss is significantly reduced while ensuring the reliability of the blade structure. This not only suppresses the risk of cracks caused by end stress concentration, but also reduces the wake vortex and flow separation of the blade outlet edge 3, thereby improving the energy conversion efficiency of the runner and achieving a dual optimization effect of strength and flow state.

[0150] Table 1 shows the comparison of the static stress value and dynamic stress amplitude of the runner blade 8 before and after the thickness of the blade outlet edge 3 of the runner blade 8 is improved, with the unit being MPa; wherein: Pr is the rated output of the turbine, 10% of the rated head Pr means that the turbine output is 10% of the rated output under the rated head, 45% of the rated head Pr means that the turbine output is 45% of the rated output under the rated head, and 100% of the rated head Pr means that the turbine output is 100% of the rated output under the rated head.

[0151] Table 1

[0152]

[0153] The basic principles of the present invention are as follows:

[0154] For the high-stress and corrosion-prone areas at the welds between the blade outlet edge 3 and the upper crown 1 and lower ring 2, the blade outlet edge 3 is thickened and strengthened in sections to improve structural reliability; the thinnest allowable thickness in the medium and low stress areas is calculated, and the thickness distribution is optimized to reduce wake vortexes and hydraulic losses, thereby optimizing hydraulic performance; and the flow separation caused by sudden thickness changes is eliminated through smooth transition of the profile line to maintain water flow adhesion.

[0155] By seeking the optimal balance between mechanical reliability and hydraulic efficiency, the blade outlet edge is structurally thickened to resist damage, streamlined thinning is used to guide flow, and smooth transition continuous lines are used to stabilize the flow state. Ultimately, while ensuring the blade's anti-fatigue and anti-cavitation capabilities, hydraulic losses are significantly reduced, achieving a synergistic improvement in the runner's strength and efficiency, and improving the runner's overall performance.

Claims

1. A method for designing the water-outlet edge of a runner blade, characterized in that: The following steps are involved: S1. Determine the thickened section of the water outlet edge (3) of the blade near the upper crown (1) and the lower ring (2); S2, calculating and determining the thickness distribution of the water outlet edge of the blade (3) in different sections; S3, smoothly transitioning the profiles between different sections of the water outlet edge (3) of the blade; In said S1, the thickened section of the water outlet edge (3) of the blade includes an arc section of the water outlet edge interval thickened along the upper crown (1) and an arc section of the water outlet edge interval thickened along the lower ring (2); The arc length of the thickened water outlet arc segment along the upper crown (1) is calculated by formula 1; Formula 1; in, is the arc length of the thickened waterside section along the upper crown, is the arc length of the water side, is the diameter of the blade water inlet side at the lower ring, is the diameter of the blade at the water outlet; The arc length of the thickened water outlet arc along the lower ring (2) is calculated by formula 2; Formula 2; in, is the arc length of the thickened water outlet section along the lower ring, is the arc length of the water side, is the diameter of the blade water inlet side at the lower ring, is the diameter of the blade at the water outlet; In the aforementioned S2, the different sections of the blade outlet edge (3) include a blade outlet edge section close to the upper crown section (5), a blade outlet edge middle section (6), and a blade outlet edge section close to the lower ring section (7).

2. The method for designing the water outlet edge of a runner blade according to claim 1, characterized in that: In the above-mentioned S2, the thickness distribution of the water outlet edge of the blade (3) in different sections is as follows: the thickness of the water outlet edge of the blade close to the upper crown section (5) is thick, the thickness of the middle section (6) of the water outlet edge of the blade is thin, and the thickness of the water outlet edge of the blade close to the lower ring section (7) is thick.

3. The method for designing the water outlet edge of a runner blade according to claim 1, characterized in that: The thickness of the blade outlet edge near the upper crown section (5) is calculated by formula 3; Formula 3; in, is the thickness of the blade near the upper crown at the water outlet edge, is the diameter of the blade at the water outlet, is the diameter of the blade at the upper crown, is the maximum water head, is the ratio of the arc length relative to the crown position to the total arc length of the blade out of the water, , is the arc length of the thickened waterside section along the upper crown, The arc length of the water side.

4. The method for designing the water outlet edge of a runner blade according to claim 1, characterized in that: The thickness of the middle section (6) of the blade outlet edge is calculated by formula 4; Formula 4; in, is the thickness of the middle section of the blade at the water outlet, is the rated unit flow rate, is the optimal unit flow rate, is the maximum unit speed, is the minimum unit speed, is the maximum water head, is the high pressure side diameter of the model runner, for According to the real machine high pressure side diameter converted from the scale, is the ratio of the arc length relative to the crown position to the total arc length of the blade out of the water, , is the arc length of the thickened waterside section along the upper crown, is the arc length of the water side, It is the arc length of the water outlet section along the thickened lower ring.

5. The method for designing the water outlet edge of a runner blade according to claim 4, characterized in that: The unit speed is calculated by formula 5; Formula 5; in, is the unit speed, is the rotation speed, is the water head, is the diameter of the blade at the water inlet edge at the lower ring.

6. The method for designing the water outlet edge of a runner blade according to claim 4, characterized in that: The unit flow rate is calculated by formula 6; Formula 6; in, is the unit flow rate, For traffic, is the diameter of the blade water inlet side at the lower ring, For the water head.

7. The method for designing the water outlet edge of a runner blade according to claim 1, characterized in that: The thickness of the blade outlet edge close to the lower ring section (7) is calculated by formula 7; Formula 7; in, is the thickness of the blade near the lower ring section at the water outlet, is the diameter of the blade at the water outlet, is the diameter of the blade at the upper crown, is the ratio of the arc length relative to the crown position to the total arc length of the blade out of the water, , is the arc length of the water side, is the arc length of the thickened water outlet section along the lower ring, is the maximum water head.

8. A rotating wheel comprising an upper crown (1) and a lower ring (2), characterized in that: It also comprises the runner blade outlet edge as claimed in claim 1, wherein a plurality of runner blades (8) are arranged between the upper crown (1) and the lower ring (2).

9. The rotating wheel according to claim 8, characterized in that: The runner blade (8) comprises a blade body (9), a blade water inlet edge (4) and a blade water outlet edge (3), wherein the blade water inlet edge (4), the blade body (9) and the blade water outlet edge (3) are integrally formed.

10. The rotating wheel according to claim 9, characterized in that: The blade water outlet edge (3) comprises a blade water outlet edge close to an upper crown section (5), a blade water outlet edge middle section (6) and a blade water outlet edge close to a lower ring section (7); the blade water outlet edge close to the upper crown section (5), the blade water outlet edge middle section (6) and the blade water outlet edge close to the lower ring section (7) are integrally formed.

11. The rotating wheel according to claim 10, characterized in that: The thickness of the blade outlet edge close to the upper crown section (5) and the blade outlet edge close to the lower ring section (7) are both greater than the thickness of the blade outlet edge middle section (6).

12. An application of a runner blade at the water outlet, characterized by: The runner blade outlet edge as claimed in claim 1 is suitable for the runner blade (8) of a water turbine.

13. An application of a rotating wheel, characterized in that: The runner as claimed in claim 8 is suitable for Francis turbines with a head range of 50-500m.

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