A wide-output pump-turbine runner

Abstract

The present invention relates to a runner of a pump-turbine with a wide output range, which comprises three parts: a crown, a band and runner blades. The axial projection curves of the crown and the band of the runner are respectively determined by a five-point fourth-order Bezier curve, and the axial projection of the low-pressure side of the runner blade is determined by a certain quadratic equation of one variable. Moreover, the high-pressure sides of the runner blades are not on the same axial plane, that is, their axial projections form a fixed angle β with the rotation axis. Both ends of the blade are smoothly transitioned by 1 / 2 elliptical arcs, so as to improve the efficiency of the runner under off-design conditions and the operation stability of the unit, and at the same time reduce the inlet impact loss during two-way flow. The present invention takes into account the conventional performance indicators of the runner of the pump-turbine, and at the same time greatly improves the efficiency performance under deep partial load conditions, reduces the pressure pulsation intensity in the bladeless area, thereby effectively suppressing problems such as unit vibration, effectively broadening the high-efficiency and safe operation range of the pump-turbine, and improving the quality of the combined operation of wind power, photovoltaics and energy storage.

Description

Technical Field

[0001] The present application relates to the technical field of fluid machinery and engineering equipment, and particularly to a wide-output pump-turbine runner. Background Art

[0002] The decarbonization of electric power energy is an important part of achieving the goal of carbon neutrality. In this context, wind power and photovoltaic power will develop into the dominant energy sources of the power grid. However, wind and light are uncontrollable, with large fluctuations in seasons and within a day, making it difficult for the power grid to absorb. Therefore, large-scale energy storage facilities are needed. Pumped storage is currently recognized as the only commercially proven large-scale energy storage technology for the power grid. Currently, the installed capacity of pumped storage is 160 GW, and the energy storage capacity is 9000 GWh, accounting for more than 90% of the world's power grid-level energy storage applications, and this proportion will continue to increase as China, the country with the largest pumped storage scale in the world, accelerates its planning and construction. According to the "Medium- and Long-Term Development Plan for Pumped Storage (2021-2035)" of the China National Energy Administration, by 2025, the total installed capacity of pumped storage put into operation will be more than 62 GW; by 2030, the total installed capacity put into operation will be around 120 GW.

[0003] In a modern energy system dominated by new energy, pumped storage is increasingly being used for flexible regulation of random new energy. In order to cooperate with volatile new energy, the start-stop of the unit and operation under partial load or deep partial load are more frequent. Under off-design operating conditions, the flow pattern inside the turbine deteriorates, the efficiency is low, the pressure pulsation is intense, and the vibration of the unit is prominent, resulting in frequent power station safety accidents. Conventional pump-turbine runners only consider the efficiency and stability within a small range near the design condition during the design process, and the high-efficiency and stable operation area is relatively narrow, making it difficult to meet this new working requirement. Therefore, there is an urgent need to develop a wide-output pump-turbine runner with high efficiency and stable operation.

[0004] The design of a pump-turbine runner needs to take into account the efficiency, cavitation, and pressure pulsation performance of the runner, and these performances of the runner often restrict each other and cannot reach the optimal simultaneously. Therefore, how to design a runner with good comprehensive performance has always been a difficult point in the industry research work. On the basis of the performance targets of a conventional runner, a wide-output operating runner requires the turbine to operate efficiently and stably within a range of 40% - 100% output or a wider range, further increasing the design challenge. Summary of the Invention

[0005] In view of this, the present application provides a wide-output pump-turbine runner to solve the problem that the high-efficiency and safe operation area of the existing conventional pump-turbine is relatively narrow and it is difficult to support the flexible regulation work requirements of new energy.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A wide-output pump-turbine runner, the pump-turbine runner comprising a crown, a lower ring and runner blades welded between the two. The runner blades comprise a front face and a back face, where the front face is the pressure surface and the back face is the suction surface. It is characterized in that: both the front and back faces of the runner blades are three-dimensional space curves and convex towards the rotation direction of the pump operating condition. The axial projection curve of the runner crown and the axial projection curve of the runner lower ring are respectively determined by a five-point fourth-order Bezier curve. The axial projection of the low-pressure side of the runner blade is determined by a certain quadratic equation in one variable, and the high-pressure sides of the runner blades are not on the same axial plane, and its axial projection forms a fixed angle β with the rotation axis.

[0008] Further, taking the rotation axis of the turbine runner as the Z-axis and the R-axis perpendicular to the Z-axis, a (Z, R) coordinate system is established on the plane. The diameter of the high-pressure side of the runner blade is D1, the height of the high-pressure side blade is b, and the diameter of the intersection point of the low-side and the crown flow surface is D 2h , and the diameter of the intersection point of the low-pressure side and the lower ring flow surface is D 2s , where the D1 parameter is much larger than D 2s , making the blades as a whole present as long and narrow centrifugal blades. The hub diameter is D h , and the runner diameter is D r .

[0009] Further, the axial projection curve of the runner crown is determined by a five-point fourth-order Bezier curve, and its expression is as follows:

[0010]

[0011] Among them, H0, H1, H2, H3, H4 are control points, and their coordinates are (-145.94f, 9.64f), (-43.20f, 0.47f), (45.91f, 5.72f), (17.75f, 187.52f), (17.65f, 250f) respectively. f is a scaling factor, and f = D h / 10.

[0012] Further, the axial projection curve of the runner lower ring is determined by a five-point fourth-order Bezier curve, and its expression is as follows:

[0013]

[0014] Among them, S0, S1, S2, S3, S4 are control points, and their coordinates are (-145.944f, 116.51f), (-95.49f, 116.35f), (-11.24f, 106.03f), (-17.35f, 205.51f), (-17.65f, 250f) respectively. f is a scaling factor, and f = Dh / 10

[0015] Furthermore, the axial projection of the low-pressure side of the runner blade is determined by a certain quadratic equation of one variable, and its mathematical expression is:

[0016] Z = 0.0037R 2 - 0.2139R + 74.628

[0017] Furthermore, the control equation of the camber line of the middle section of the runner blade is:

[0018] Z = 3×10 -11 R 5 - 7×10 -8 R 4 + 2×10 -5 R 3 - 0.0036R 2 + 0.3454R + 102.85

[0019] According to the camber line equation of the blade, symmetric thickening can be carried out to obtain the whole blade.

[0020] Furthermore, both ends of the front and back sides of the runner blade are connected by a 1 / 2 ellipse. The vertex of the ellipse on the high-pressure side of the blade is determined by the outer diameter D1 of the runner, and the vertex of the ellipse on the low-pressure side is determined by the diameter D r of the runner. The minor axis of the ellipse is the corresponding blade thickness, and the major axis of the ellipse is four times the blade thickness.

[0021] Furthermore, the diameter D1 on the high-pressure side of the runner blade, the diameter D at the intersection of the low-pressure side and the lower circulation surface 2s and the height b of the high-pressure side of the blade are respectively determined by the following formulas:

[0022]

[0023] U2 is the circumferential speed of the high-pressure side of the runner, n is the rotational speed, Q is the design flow rate, k b is the correction coefficient, and k b can be obtained by looking up the table.

[0024] Furthermore, the included angle β between the axial projection of the high-pressure side of the blade and the rotation axis satisfies 0° < β < 10°.

[0025] Furthermore, the number of runner blades is multiple, generally 7 blades or 9 blades.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) The present invention designs the runner flow path and blades anew, while ensuring the conventional performance indicators, broadens the high-efficiency operation range of conventional pump-turbines, and particularly significantly improves the efficiency performance of the runner under deep partial load. Since the single-unit capacity of pumped storage power stations is generally large, the current mainstream single-unit capacity is 350,000 kW, and a 1% increase in efficiency also brings a very considerable increase in power generation. The runner blades of the present invention can increase the efficiency under deep partial load by about 9%, as Figure 7 shown.

[0028] 2) Under the deep partial load condition of the runner, the flow separation on the high-pressure side of the blade is very serious, resulting in a decrease in efficiency and vibration problems of the unit. The present invention increases the blade wrap angle and camber through hydrodynamic optimization, which can effectively inhibit the further development of flow separation on the high-pressure side in the flow path, and thus achieve the purpose of improving the efficiency under deep partial load.

[0029] 3) The present invention optimizes the inclination angle of the high-pressure edge of the runner blade, inhibits the pressure pulsation intensity in the vaneless area, as Figure 8 shown. It improves the operation stability of the unit in the whole operating condition range and effectively alleviates the vibration problem of the unit under partial load condition. Its technical principle is that the negative inclination angle of the high-pressure edge inhibits the flow separation on the crown side, thereby reducing the pressure pulsation.

[0030] 4) Due to the improvement of the efficiency performance and stability performance in the wide output range of the runner, the present invention significantly improves the ability of pumped storage power stations to flexibly regulate and store random new energy, and at the same time improves the economy and safety of the power stations. Brief Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 is the runner of the wide-output pump-turbine provided by the embodiment of the present application;

[0033] Figure 2 is the schematic diagram of a single runner blade and the schematic diagram of the inclination angle of the high-pressure edge provided by the embodiment of the present application;

[0034] Figure 3 is the axial projection diagram of the runner provided by the embodiment of the present application;

[0035] Figure 4 is the schematic diagram of the mid-section and the camber line of the blade provided by the embodiment of the present application;

[0036] Figure 5 is the schematic diagram of 7 blades provided by the embodiment of the present application;

[0037] Figure 6 Schematic diagram of 9 blades provided by the embodiment of the present application;

[0038] Figure 7 Schematic diagram of the improvement of the runner efficiency provided by the embodiment of the present application;

[0039] Figure 8 Schematic diagram of the reduction of the runner pressure pulsation intensity provided by the embodiment of the present application.

[0040] Among them, the component identifications in the figure are as follows:

[0041] 1 - Axial projection curve of the connection side between the upper crown of the runner and the blade, 2 - Runner blade, 3 - Axial projection curve of the connection side between the lower ring of the runner and the blade, 4 - Middle section, 5 - High-pressure side of the blade, 6 - Low-pressure side of the blade, 7 - Blade camber line. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0043] In the description of the present application, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0044] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection, an electrical connection or a communication with each other; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0045] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0046] The model runner of an embodiment proposed by the present invention is as Figure 1 , and the wide-output pump-turbine runner includes a crown, runner blades 2, and a lower ring. The runner blades include a front and a back, where the front is the pressure surface and the back is the suction surface. The front and back of the said runner blades 2 are three-dimensional space curves and bulge towards the rotation direction of the pump condition. The axial projection curves of the runner crown and the runner lower ring are respectively determined by a five-point fourth-order Bezier curve. The axial projection of the low-pressure side of the runner blades 2 is determined by a certain quadratic equation of one variable, and the high-pressure sides of the runner blades 2 are not on the same axial plane, and its axial projection forms a fixed angle β with the rotation axis.

[0047] A (Z, R) coordinate system is established on the plane, with the Z-axis as the rotation axis and the R-axis perpendicular to the Z-axis. Where the diameter of the high-pressure side of the runner blade is D1, the height of the high-pressure side blade is b, and the diameter of the intersection point of the low-side and the crown flow surface is D 2h , and the diameter of the intersection point of the low-pressure side and the lower ring flow surface is D 2s , where the parameter D1 is much larger than D 2s , making the overall blade present as a long and narrow centrifugal blade. The hub diameter is D h , and the runner diameter is D r , in this embodiment, the hub diameter D h = 10 mm, so the scaling factor f = 1.

[0048] Determine that β of the high-pressure side 5 of the blade is 4°, as Figure 2 shown. By formula calculation, determine that the diameter parameter D1 of the high-pressure side of the runner is 0.5 m, the blade height b = 0.03565 m, the intersection point of the low-pressure side and the lower ring flow surface is controlled by the parameter D 2s = 0.236 m, and the intersection point of the low-side and the crown flow surface is controlled by the parameter D 2h = 0.145 m, as Figure 3 shown.

[0049] Figure 3 The axial projection curve 1 of the connection side between the runner crown and the blade in

[0050]

[0051] Among them, The coordinates of H0, H1, H2, H3, and H4 are (-145.94, 9.64), (-43.20, 0.47), (45.91, 5.72), (17.75, 187.52), and (17.65, 250) respectively. The above control point coordinates are determined by Figure 3 The center O of the center, and the R axis passes through the center of the runner outlet.

[0052] Figure 3 Among them, the axial projection curve 3 on the side where the lower ring of the runner is connected to the blade is determined by a five-point fourth-order Bezier curve, and its expression is as follows:

[0053]

[0054] Among them, The coordinates of S0, S1, S2, S3, and S4 are (-145.944, 116.51), (-95.49, 116.35), (-11.24, 106.03), (-17.35, 205.51), and (-17.65, 250) respectively.

[0055] The axial projection of the low-pressure side 6 of the runner blade is calculated by the following equation:

[0056] Z = 0.0037R 2 -0.2139R + 74.628

[0057] The middle section camber line of the runner blade is calculated by the following formula:

[0058] Z = 3×10 -11 R 5 -7×10 -8 R 4 +2×10 -5 R 3 -0.0036R 2 +0.3454R + 102.85

[0059] Taking the blade camber line 7 as the center, symmetrically thickening by 30 mm to obtain the front and back sides of the blade. The two ends of the blade are connected by a 1 / 2 ellipse, the short axis of the ellipse is 30 mm, and the long axis is 120 mm, as Figure 4 shown.

[0060] After obtaining the shape of the middle section 4 of the blade, extending it uniformly in the directions of the upper crown and the lower ring, a single blade entity can be obtained, as Figure 5 shown.

[0061] Taking the above single blade as the center of rotation and arranging 7 copies of it, the runner blades of the 7-blade pump-turbine can be actuated, as shown in Figure 5 . Arranging 9 copies of it can also actuate the runner blades of the 9-blade pump-turbine, as shown in Figure 6 .

[0062] As shown in Figure 7 , the efficiency of the runner blades of this example is significantly higher than that of the conventional pump-turbine runner; as shown in Figure 8 , the pressure pulsation intensity of the runner provided by the embodiment of this application is significantly lower than that of the conventional pump-turbine runner.

[0063] The above are the specific embodiments of the technical solution of the present invention and the technical principles applied. Any modification, supplement, or equivalent replacement made by those skilled in the art to which the present invention pertains on the basis of this embodiment is within the scope protected by the claims of the present invention.

Claims

1. A wide-output pump-turbine runner, the pump-turbine runner comprising a crown, a lower ring and runner blades welded between the crown and the lower ring, the runner blades comprising a front face and a back face, wherein the front face is a pressure surface and the back face is a suction surface, characterized in that: The front and back surfaces of the runner blades are both three-dimensional space curves, and they bulge in the rotation direction of the pump operating condition. The axial projection curves of the runner crown and the runner lower ring are respectively determined by a five-point fourth-order Bezier curve. The axial projection of the low-pressure side of the runner blade is determined by a certain quadratic equation of one variable, and the high-pressure sides of the runner blades are not on the same axial plane, and the axial projection of the high-pressure side of the runner blade forms a fixed angle β with the rotation axis; the angle β between the axial projection of the high-pressure side of the runner blade and the rotation axis satisfies 0° < β < 10°; Taking the rotation axis of the water turbine runner as the Z-axis and the R-axis perpendicular to the Z-axis, a (Z, R) coordinate system is established on the plane. The diameter of the high-pressure side of the runner blade is D1, the height of the blade on the high-pressure side is b, the diameter of the intersection point of the low-side and the upper crown flow surface is D 2h , and the diameter of the intersection point of the low-pressure side and the lower circulation surface is D 2s , where the D1 parameter is much larger than D 2s , making the overall flow passage present a long and narrow centrifugal flow passage. The hub diameter is D h , and the runner diameter is D r ; The axial projection of the low-pressure side of the runner blade is determined by a certain quadratic equation of one variable, and its mathematical expression is: Z = 0.0037R 2 -0.2139R + 74.628; The control equation of the median section camber line of the runner blade is: Z = 3×10 -11 R 5 - 7×10 -8 R 4 + 2×10 -5 R 3 - 0.0036R 2 + 0.3454R + 102.85 According to the camber line equation of the blade, symmetric thickening can be carried out to obtain the entire blade.

2. The runner of a wide-output pump-turbine according to claim 1, characterized in that: The axial projection curve of the runner crown is determined by a five-point fourth-order Bezier curve, and its expression is as follows: Among them, H0, H1, H2, H3, H4 are control points, and their coordinates are (-145.94f, 9.64f), (-43.20f, 0.47f), (45.91f, 5.72f), (17.75f, 187.52f), (17.65f, 250f) respectively, where f is a scaling factor and f = D h / 10.

3. A runner of a wide-output pump-turbine according to claim 1, characterized in that: The axial projection curve of the runner lower ring is determined by a five-point fourth-order Bezier curve, and its expression is as follows: Among them, S0, S1, S2, S3, S4 are control points, and their coordinates are (-145.944f, 116.51f), (-95.49f, 116.35f), (-11.24f, 106.03f), (-17.35f, 205.51f), (-17.65f, 250f) respectively, where f is a scaling factor and f = D h / 10.

4. A runner of a wide-output pump-turbine according to claim 1, characterized in that: Both the front and back ends of the runner blade are connected by a 1 / 2 ellipse. The elliptical vertex on the high-pressure side of the blade is determined by the outer diameter of the runner, and the elliptical vertex on the low-pressure side is determined by the runner diameter D r The minor axis of the ellipse is the corresponding blade thickness, and the major axis of the ellipse is four times the blade thickness.

5. A runner of a wide-output pump-turbine according to claim 1, characterized in that: The diameter D1 of the high-pressure side of the runner blade, the diameter D at the intersection of the low-pressure side and the lower circulation surface 2s and the blade height b on the high-pressure side are determined respectively by the following formulas: U2 is the circumferential velocity of the high-pressure side of the runner, n is the rotational speed, Q is the design flow rate, and k b is the correction coefficient, and k b can be obtained by looking up the table.

6. A runner of a wide-output pump-turbine according to claim 1, characterized in that: The number of the runner blades is multiple, being 7 blades or 9 blades.

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