Movable guide vane for realizing balance between turbulent flow and kinetic energy

Abstract

The invention discloses a movable guide vane for realizing turbulent flow and kinetic energy balance, which belongs to the technical field of fluid mechanical equipment, is arranged between a fixed guide vane and a rotating wheel, and is characterized in that the movable guide vane is divided into a front section and a rear section in the horizontal direction, a pressure section is arranged on the upper contour line of the front section, and the rear section is arranged on the upper contour line of the rear section; the pressure section is a cubic polynomial, c3 in the pressure section is equal to 0.093 n, n is equal to 3, 6 and 9, c4 in the transition section is equal to 0.32 n, n is equal to 3, 6 and 9, and b4 is larger than or equal to 0 and smaller than or equal to 0.1. The movable guide vane is optimized and improved on the basis of an original guide vane airfoil, balance of turbulent flow and kinetic energy is well achieved, generation of flow channel vortexes is reduced, energy dissipation in the flowing process is reduced, the overflowing capacity of a rotating wheel domain is improved, and therefore the S characteristic of the pump turbine is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid mechanical equipment and relates to a movable guide vane for achieving turbulent flow and kinetic energy balance. Background Art

[0002] In the design of a pump-turbine, as one of the core components, the movable guide vane undertakes important functions such as guiding water flow, regulating flow rate, and achieving energy conversion. The curvature design of the movable guide vane directly affects the flow state of water, energy loss, and the overall efficiency of the turbine. Especially in achieving the balance between turbulent flow and kinetic energy, the curvature design of the movable guide vane is particularly crucial. This design process is extremely complex, and the curvature design of the movable guide vane needs to find the best balance point between reducing turbulent flow and maximizing kinetic energy transfer. The generation of turbulent flow will lead to energy loss and reduce the efficiency of the turbine, while the efficiency of kinetic energy transfer is directly related to the output power of the turbine. Designers need to make fine adjustments in aspects such as the curved surface shape, angle distribution, and installation position of the guide vane to ensure that the water flow can maintain a stable flow state when entering the runner and transfer kinetic energy to the maximum extent.

[0003] Due to the complexity and non-linear characteristics of water flow, it is often difficult to accurately predict the actual performance of the guide vane solely relying on theoretical calculations or numerical simulations. Therefore, when designing the curvature of the movable guide vane, it is necessary to optimize the design scheme through a large number of experimental verifications. During the experiment, different water flow conditions, guide vane openings, and rotational speed conditions need to be simulated to comprehensively evaluate the performance of the guide vane. The experimental verification not only includes hydraulic performance tests but also requires a comprehensive evaluation of the mechanical strength, fatigue life, and cavitation resistance performance of the guide vane. These experiments usually need to be carried out in a special hydraulic laboratory or test bench, involving complex test equipment and high-precision measuring instruments. The process of experimental verification requires a large investment of manpower, material resources, and financial resources.

[0004] Chinese Patent Publication No.: CN102287307B, Publication Date: July 18, 2012, discloses a patent named "Spatial Curved Surface Movable Guide Vane of Pump-Turbine", which mainly includes an upper end surface, a lower end surface, and a ruled surface composed of several straight lines between the upper and lower end surfaces. Connect a straight line OA from the connection point A between the water inlet edge of the guide vane and the upper end surface and the rotation center O of the guide vane on the upper end surface, and connect a straight line O'A' from the connection point A' between the water inlet edge of the guide vane and the lower end surface and the rotation center O' of the guide vane on the lower end surface. The straight line OA and the straight line O'A' are not parallel to each other and are not in the same plane. Although this patent can reduce the hydraulic loss of the double-row cascade and improve the efficiency of the turbine operating condition, problems such as excessive periodic pressure pulsation of the unit, vortex blocking the flow passage, and low "S" characteristic margin have not been improved. Summary of the Invention

[0005] The present invention provides a movable guide vane for achieving turbulent flow and kinetic energy balance. By improving the curvature and thickness of the L1 section of the movable guide vane, it improves the problems such as excessive pressure pulsation, obvious "S" characteristics, serious noise, wear and energy dissipation during the actual operation of the pump-turbine.

[0006] A further object of the present invention is to achieve a good balance between turbulent flow and kinetic energy by designing a pressure section.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A movable guide vane for achieving turbulent flow and kinetic energy balance, which is divided into a front section and a rear section in the horizontal direction. The front section and the rear section are the L1 section and the L2 section respectively, and the length ratio range of the front section to the rear section is 1.7 - 1.72. The ratio of the distance from the end point of the pressure section to the lower contour line of the movable guide vane to the length of the movable guide vane is 0.13 - 0.14. The leading end of the movable guide vane in the L1 section is fitted with an arc with a radius of Ra. The upper contour line of the movable guide vane is divided into an arc section, a transition section and a pressure section in the L1 section; taking the tangent of the leading end of the movable guide vane and the vertical line as the O point to establish an x-y coordinate axis, the transition section is a quadratic polynomial, and the pressure section is a cubic polynomial. In the pressure section, c3 = 0.093n, n = 3, 6, 9, and in the transition section, c4 = 0.32n, n = 3, 6, 9, 0 ≤ b4 ≤ 0.1. This movable guide vane is optimized and improved on the basis of the original guide vane airfoil, mainly reducing the curvature of the upper contour line corresponding to the L1 length of the movable guide vane and the guide vane thickness. The deflection of the upper contour line corresponding to the L1 length of the movable guide vane is reduced, the inlet angle of the guide vane is increased, the inflow resistance is correspondingly reduced, the generation of vortices in the flow passage is reduced, the energy dissipation during the flow process is reduced, the flow capacity of the runner domain is improved, and thus the "S" characteristics of the pump-turbine are improved.

[0008] Preferably, the o-x axis passes through the center of the arc with a radius of Ra. The o-y axis passes through the intersection point of the leading end of the L1 section of the movable guide vane and the vertical line. The o-x axis is located above the lower contour line of the movable guide vane. The lower contour line and the L2 section of this movable guide vane are the same as those of the original movable guide vane. By optimizing the setting of the coordinate axis, it ensures that the geometric design of the guide vane is more accurate, can better control the fluid flow in the flow passage, further reduces the pressure pulsation and energy dissipation, and at the same time maintains compatibility with the original guide vane, facilitating replacement and installation in actual applications.

[0009] Preferably, both the leading end of the L1 section and the leading end of the L2 section of the movable guide vane are fitted with arcs. The leading end of L1 is fitted with an arc with a radius of Ra, and the L2 section is fitted with an arc with a radius of Rb. By adopting the arc fitting method, the transition of the guide vane is made smoother, reducing the separation and vortex generation of the fluid at the leading and trailing ends of the guide vane, further optimizing the flow field characteristics, and improving the overall efficiency and operation stability of the pump-turbine.

[0010] Preferably, the arc segment is a fitting segment of the leading edge of the movable guide vane corresponding to the L1 segment and an arc with a radius of Ra. By defining the arc segment clearly, it is ensured that the streamline design at the leading edge of the guide vane is more reasonable, which can effectively guide the fluid into the guide vane, reduce the inflow resistance, and reduce the wear and energy loss caused by fluid impact.

[0011] Preferably, the arc segment is a semi - circle equation plus a constant term b. The starting point of the arc segment is point o, and the ending point is the tangent point with the arc of the O - A2 segment, namely A2. Introducing the design of the semi - circle equation and the constant term b can flexibly adjust the shape and position of the arc segment, further optimize the flow field characteristics at the leading edge of the guide vane, reduce the generation of local pressure pulsation and eddy currents, and improve the fatigue resistance of the guide vane.

[0012] Preferably, the starting point A2 of the transition segment is the tangent point with the arc of the O - A2 segment. Defining the starting position of the transition segment clearly ensures that the connection between the arc segment and the transition segment of the guide vane profile is smoother, avoiding fluid separation and energy loss caused by geometric mutations, and further improving the hydraulic performance of the guide vane.

[0013] Preferably, the ending point of the transition segment is the intersection point B2 of the extension line passing through the center of the arc with a radius of Ra and along the positive y - axis direction and the upper contour of the guide vane. By precisely defining the ending position of the transition segment, the length and shape of the transition segment can be better controlled, further optimizing the fluid flow characteristics in the flow channel, reducing eddy currents and pressure pulsation, and improving the operating efficiency of the pump - turbine.

[0014] Preferably, the constant term of the quadratic polynomial in the transition segment is d4, and d4 ∈ [1, 4]. By introducing the range limit of the constant term d4, the shape of the transition segment can be flexibly adjusted, further optimizing the flow field characteristics, reducing the generation of local pressure pulsation and eddy currents, and at the same time improving the fatigue resistance and service life of the guide vane.

[0015] Preferably, the starting point of the pressure segment is the ending point of the transition segment, and the ending point is the starting point of the L2 segment of the movable guide vane. Defining the starting and ending positions of the pressure segment clearly ensures that the connection between different segments of the guide vane profile is smoother, avoiding fluid separation and energy loss caused by geometric mutations, and further improving the overall hydraulic performance of the guide vane.

[0016] Preferably, in the cubic polynomial of the pressure segment, 0.001 ≤ b3 ≤ 0.007, and the constant term is d3, d3 ∈ [1, 4]. By restricting the parameter range of the cubic polynomial of the pressure segment, the shape and curvature change of the pressure segment can be precisely controlled, further optimizing the fluid flow characteristics in the flow channel, reducing energy dissipation and pressure pulsation, and improving the operating efficiency and stability of the pump - turbine.

[0017] Advantages of the present invention: The present invention provides a new type of movable guide vane airfoil, which is optimized and improved on the basis of the original guide vane airfoil. The main improvements are to reduce the curvature of the contour line of the movable guide vane corresponding to the length L1 and the guide vane thickness. The deflection of the contour line of the movable guide vane corresponding to the length L1 is reduced, the inlet angle of the guide vane is increased, the inflow resistance is correspondingly reduced, the generation of vortices in the flow passage is reduced, the energy dissipation during the flow process is reduced, the flow capacity of the runner domain is improved, and thus the "S" characteristic of the pump-turbine is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. is a schematic structural diagram of a movable guide vane structure for achieving the balance of turbulent flow and kinetic energy according to the present invention.

[0019] Figure 2 FIG. is a comparison diagram of the optimized profile lines of the movable guide vane airfoil for achieving the balance of turbulent flow and kinetic energy according to the present invention.

[0020] Figure 3 FIG. is an assembly drawing of a movable guide vane for achieving the balance of turbulent flow and kinetic energy according to the present invention on a water turbine.

[0021] Figure 4 FIG. is a comparison diagram of the "S" characteristic curves of a movable guide vane for achieving the balance of turbulent flow and kinetic energy according to the present invention at different opening degrees.

[0022] Reference numerals: 1. GV1 guide vane profile line, 2. movable guide vane, 3. fixed guide vane, 4. runner. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] The present invention provides a movable guide vane 2 for achieving the balance of turbulent flow and kinetic energy, which is characterized in that: it is optimized and improved on the basis of the original guide vane airfoil. The main improvements are to reduce the curvature of the contour line of the movable guide vane 2 corresponding to the length L1 and the guide vane thickness. The deflection of the contour line of the movable guide vane 2 corresponding to the length L1 is reduced, the inlet angle of the guide vane is increased, the inflow resistance is correspondingly reduced, the generation of vortices in the flow passage is reduced, the energy dissipation during the flow process is reduced, the flow capacity of the runner domain is improved, and thus the "S" characteristic of the pump-turbine is improved. The specific optimization parameters are as Figure 2 shown.

[0025] Under the turbine operating condition, the turbine operating surface (i.e., the pressure section) of the movable guide vane plays a crucial role. It not only guides the water flow smoothly into the runner but also precisely controls the magnitude and direction of the water flow by adjusting the angle of the guide vane, thereby effectively regulating the power output of the turbine. This process may seem simple, but in fact, it involves complex fluid mechanics principles, especially those related to turbulent flow and kinetic energy balance.

[0026] When the water flow passes through the movable guide vane, the shape and angle of the guide vane have a decisive impact on the flow state of the water flow. If the guide vane is properly designed, the water flow can form a relatively stable flow state before entering the runner, thus significantly reducing the generation of turbulent flow. Turbulent flow is a complex and disordered flow state, and the vortices and velocity fluctuations inside it will cause a large amount of energy loss. Therefore, reducing the generation of turbulent flow is one of the keys to improving the efficiency of the turbine.

[0027] At the same time, the movable guide vane also needs to efficiently transfer the kinetic energy of the water flow to the runner. The kinetic energy of the water flow is the basis for the turbine to convert into mechanical energy, and the role of the guide vane is to ensure that this kinetic energy can be maximally utilized by the runner. If the guide vane is not reasonably designed, such as improper guide vane angle or overly complex water flow conditions, turbulent flow phenomena such as trailing vortices may occur when the water flow passes through the guide vane. These trailing vortices will not only increase energy loss but also have a negative impact on the performance of the runner, reducing the overall efficiency of the turbine.

[0028] The pressure section of the present invention is the turbine operating surface. In order to achieve the balance of turbulent flow and kinetic energy, the design of the pressure section of the movable guide vane is particularly important. To achieve the ideal balance of turbulent flow and kinetic energy, the design of the pressure section is extremely difficult. This is because, on the one hand, it is necessary to ensure that the water flow can form a stable flow when passing through the guide vane, reducing the generation of turbulent flow; on the other hand, it is necessary to ensure that the kinetic energy of the water flow can be efficiently transferred to the runner. These two goals seem contradictory, but they need to be achieved simultaneously in the design of the guide vane.

[0029] To overcome this problem, through multiple experiments and in-depth research, the present invention finally obtained the curvature of the limited pressure section. The determination of this curvature is not easy, and it requires comprehensive consideration of multiple factors such as the velocity, pressure, direction of the water flow, and the geometric shape of the guide vane. Through the precise analysis and optimization of these factors, the present invention has successfully achieved the balance of turbulent flow and kinetic energy, thereby significantly improving the efficiency and performance of the turbine.

[0030] Such as Figure 1As shown, take the tangent of the leading end of the movable guide vane 2 and the vertical line as point O to establish the x-y coordinate axes. The o-x axis passes through the center of the arc with a radius of Ra and is located above the lower contour line of the movable guide vane 2; the o-y axis passes through the intersection point of the leading end of the L1 section of the movable guide vane 2 and the vertical line. This way of setting the coordinate axes plays an important role. It ensures that the geometric design of the guide vane is more accurate and can better control the fluid flow in the flow channel. During the actual operation of the pump-turbine, the accurate geometric design can make the fluid flow more smoothly in the guide vane, reducing unnecessary energy losses. At the same time, the lower contour line and the L2 section of the present movable guide vane 2 are the same as those of the original movable guide vane 2. Such a design maintains compatibility with the original guide vane, facilitating replacement and installation in practical applications, and reducing the cost and difficulty of equipment transformation.

[0031] As Figure 1 shown, the leading ends of both the L1 section and the L2 section of the movable guide vane 2 adopt the method of circular arc fitting. The leading end of the L1 section is fitted with an arc with a radius of Ra, and the L2 section is fitted with an arc with a radius of Rb. Circular arc fitting is of great significance in fluid mechanics. During the fluid flow process, a smooth transition can reduce the separation and vortex generation of the fluid at the leading and trailing ends of the guide vane. When the fluid flows through the leading end of the guide vane, if the shape of the leading end is irregular, it is easy to cause fluid separation and form vortices, which will increase energy losses and reduce the efficiency of the pump-turbine. After adopting circular arc fitting, the transition at the leading end of the guide vane is smoother, the fluid can enter the guide vane more smoothly, reducing the generation of vortices, further optimizing the flow field characteristics, and improving the overall efficiency and operation stability of the pump-turbine.

[0032] The arc section of the upper contour line of the movable guide vane 2 in the L1 section is the fitting section of the leading end of the corresponding L1 section of the movable guide vane 2 and the arc with a radius of Ra. The arc section is a semi-circle equation plus a constant term b. Its starting point is point O, and the ending point is the tangent point with the arc of the O-A2 section, that is, A2. This design can flexibly adjust the shape and position of the arc section. In practical applications, different operating conditions of the pump-turbine may require different shapes of the leading end of the guide vane to guide the fluid. By introducing the semi-circle equation and the constant term b, it can be adjusted according to the specific operating conditions, further optimizing the flow field characteristics at the leading end of the guide vane, reducing the generation of local pressure pulsations and vortices, and improving the anti-fatigue performance of the guide vane. Because the generation of local pressure pulsations and vortices will cause frequent impacts on the guide vane, which is easy to lead to fatigue damage of the guide vane, while the optimized flow field characteristics can effectively reduce such impacts and extend the service life of the guide vane.

[0033] The starting point A2 of the transition section is the tangent point with the arc of the O - A2 section, and the ending point is the intersection point B2 of the extension line passing through the center of the arc with a radius of Ra along the positive y - axis and the upper contour line of the guide vane. The transition section is a quadratic polynomial, and the constant term of the quadratic polynomial is d4, where d4 ∈ [1, 4]. Defining the starting and ending positions of the transition section ensures smoother connection between the arc section and the transition section of the guide vane profile. During the fluid flow process, if the connection between different sections of the guide vane profile is not smooth, it will lead to fluid separation and energy loss. By precisely defining the starting and ending positions of the transition section, this situation can be avoided. At the same time, introducing the range limit of the constant term d4 can flexibly adjust the shape of the transition section, further optimize the flow field characteristics, reduce the generation of local pressure pulsation and eddy currents, and improve the fatigue resistance and service life of the guide vane.

[0034] The starting point of the pressure section is the ending point of the transition section, and the ending point is the starting point of the 2L2 section of the movable guide vane. The pressure section is a cubic polynomial, where c3 = 0.093n, n = 3, 6, 9, 0.001 ≤ b3 ≤ 0.007, and the constant term is d3, d3 ∈ [1, 4]. Defining the starting and ending positions of the pressure section ensures smoother connection between different sections of the guide vane profile and avoids fluid separation and energy loss caused by geometric mutations. By restricting the parameter range of the cubic polynomial of the pressure section, the shape and curvature change of the pressure section can be precisely controlled. When the fluid flows through the pressure section, reasonable shape and curvature changes can make the velocity and pressure distribution of the fluid more uniform, reduce energy dissipation and pressure pulsation, and improve the operating efficiency and stability of the pump - turbine.

[0035] By improving the curvature and thickness of the 2L1 section of the movable guide vane, the deflection of the upper contour line of the movable guide vane 2 corresponding to the L1 length is reduced, the inlet angle of the guide vane is increased, and the inflow resistance is correspondingly reduced. During the actual operation of the pump - turbine, the reduction of the inflow resistance allows the fluid to enter the runner domain more smoothly and reduces the generation of flow path vortices. The reduction of flow path vortices is crucial for improving the "S" characteristic of the pump - turbine. In traditional pump - turbines, the obvious "S" characteristic will lead to unstable operation and reduced efficiency under certain working conditions. However, through the optimized design of the movable guide vane 2 of the present invention, the flow path vortices are reduced, enabling the pump - turbine to operate stably within a wider range of working conditions and effectively improving the "S" characteristic.

[0036] The energy dissipation during the flow process is mainly caused by factors such as fluid friction and eddies. This movable guide vane 2 reduces the generation of vortices in the flow passage by decreasing the curvature of the upper contour line and the guide vane thickness, thereby reducing the energy loss of the fluid during the flow process. In the actual operation of a pump-turbine, the reduction of energy dissipation means that more energy can be effectively utilized, improving the energy conversion efficiency of the pump-turbine. For example, in the renovation of a pump-turbine in a certain hydropower station, after adopting the movable guide vane 2 of the present invention, the energy conversion efficiency of the pump-turbine has increased by 2% - 5%, greatly reducing the power generation cost.

[0037] Pressure pulsation and noise are common problems during the operation of a pump-turbine. They not only affect the stability and service life of the equipment but also have an impact on the surrounding environment. This movable guide vane 2 reduces the generation of local pressure pulsation and eddies by optimizing the flow field characteristics. The reduction of pressure pulsation makes the operation of the pump-turbine more stable, reducing the vibration and noise of the equipment. In practical applications, when the pump-turbine with this movable guide vane 2 operates, the noise level is significantly reduced, improving the working environment and also reducing the impact on the surrounding residents.

[0038] During the operation of a pump-turbine, the high-speed flow and eddies of the fluid will cause wear on the guide vanes. This movable guide vane 2 reduces the impact and wear of the fluid on the guide vanes by optimizing the design, reducing the flow passage vortices and local pressure pulsation. In the pump-turbine of a certain water resources allocation project, after adopting the movable guide vane 2 of the present invention, the wear degree of the guide vanes is significantly reduced, extending the maintenance cycle and reducing the equipment maintenance cost.

[0039] such as Figure 2As described above, the GV1 guide vane profile line 1, 2. GV2 guide vane profile line, the GV1 guide vane profile line 1 corresponds to the original movable guide vane profile line, GV2 corresponds to the optimized movable guide vane profile line, that is, the present movable guide vane 2. The head and tail of the guide vane profile line are both fitted by arcs. The total length of the guide vane is defined as L. The curvature of the upper contour line of the GV2 guide vane corresponding to the length L1 is reduced, and the guide vane thickness is reduced. The profile line corresponding to the length L2 of the guide vane maintains the original size. The maximum distance between the upper contour line of the movable guide vane 2 and the O-x axis is defined as T. The upper contour line of the GV1 movable guide vane corresponding to the length L1 mainly includes an arc segment O-A1 with a head radius of Ra. The O-A1 segment is an arc segment, the starting point is the point A1 tangent to the O-A1 segment arc, and the ending point is the intersection point B1 of the extension line passing through the center of the arc with a radius of Ra along the positive y-axis direction and the upper contour line of the guide vane. The curve segment A1-B1 is a transition segment and the connected curve segment B1-C. The B1-C segment is a pressure segment, and the specific function is as shown in Equation (1). The upper contour line of the GV2 movable guide vane corresponding to the length L1 mainly includes an arc segment O-A2 with a head radius of Ra. The O-A2 segment is an arc segment, the starting point is the point A2 tangent to the O-A2 segment arc, and the ending point is the intersection point B2 of the extension line passing through the center of the arc with a radius of Ra along the positive y-axis direction and the upper contour line of the guide vane. The curve segment A2-B2 is a transition segment and the connected curve segment B2-C. The B2-C segment is a pressure segment, and the specific function is as shown in Equation (2).

[0040] Among them, in the interval ([x3, x4]), (y(x)) is a cubic polynomial; in the interval ([x2, x3]), (y(x)) is a quadratic polynomial; in the interval ([0, x2]), (y(x)) is a semi-circle equation plus a constant term. Usually, c1 = 0.1706n, n = 3, 6, 9; 0 ≤ b2 ≤ 0.05; c2 = 0.31n, n = 3, 6, 9.

[0041] Among them, in the interval ([x3, x4]), (y(x)) is a cubic polynomial; in the interval ([x1, x3]), (y(x)) is a quadratic polynomial; in the interval ([0, x1]), (y(x)) is a semi-circle equation plus a constant term. Usually, 0 ≤ a1, a3 ≤ 0.00002; 0.001 ≤ b1, b3 ≤ 0.007; c3 = 0.092n, n = 3, 6, 9; 0 ≤ b4 ≤ 0.1; c4 = 0.32n, n = 3, 6, 9; d1, d2, d3, d4 ∈ [1, 4].

[0042] In the formula, x1 is the projection value of point A2 on the O-x axis; x2 is the projection value of point A1 on the O-x axis; (a, b) are the coordinates of the center of the head arc with a radius of Ra; x3 is the projection value of points B1 and B2 on the O-x axis, which also corresponds to the abscissa value a of the center of the arc with a radius of Ra; x4 is the projection value of point C on the O-x axis.

[0043] As Figure 3 shown, the movable guide vane 2 of the present invention is arranged between the fixed guide vane 3 and the runner 4. Under the water turbine condition, the design of the pressure section of the movable guide vane (i.e., the surface used under the water turbine condition) is particularly crucial. It not only needs to guide the water flow smoothly into the runner, but also precisely control the size and direction of the water flow by adjusting the angle of the guide vane, so as to effectively regulate the power output of the water turbine. This process involves complex fluid mechanics principles, especially the balance problem of turbulent flow and kinetic energy.

[0044] When the water flow passes through the movable guide vane, the shape and angle of the guide vane have a decisive influence on the flow state of the water flow. If the guide vane is reasonably designed, the water flow can form a relatively stable flow state before entering the runner, thus significantly reducing the generation of turbulent flow. Turbulent flow is a complex and disordered flow state, and the vortices and velocity fluctuations inside it will cause a large amount of energy loss. Therefore, reducing the generation of turbulent flow is one of the keys to improving the efficiency of the water turbine.

[0045] At the same time, the movable guide vane also needs to efficiently transfer the kinetic energy of the water flow to the runner. The kinetic energy of the water flow is the basis for the water turbine to convert into mechanical energy, and the role of the guide vane is to ensure that this kinetic energy can be maximally utilized by the runner. If the guide vane is not reasonably designed, such as improper guide vane angle or overly complex water flow conditions, turbulent flow phenomena such as trailing vortices may occur when the water flow passes through the guide vane. These trailing vortices will not only increase energy loss, but also have a negative impact on the performance of the runner, reducing the overall efficiency of the water turbine.

[0046] In order to achieve the balance of turbulent flow and kinetic energy, the pressure section of the movable guide vane of the present invention adopts a unique design. Through multiple experiments and studies, the present invention has obtained the curvature that defines the pressure section. The determination of this curvature is not easy, and it needs to comprehensively consider multiple factors such as the velocity, pressure, direction of the water flow and the geometric shape of the guide vane. For example, under the optimal working condition, the pressure distribution in each guide vane interval decreases uniformly from the inlet of the fixed guide vane to the outlet of the movable guide vane, the velocity vector increases uniformly, the streamline is smooth, and there is basically no obvious flow separation and vortex generation at the inlet and outlet of the guide vane. This design ensures that the water flow can form a stable flow when passing through the guide vane, reduces the generation of turbulent flow, and at the same time efficiently transfers the kinetic energy of the water flow to the runner.

[0047] In addition, the present invention also considers the dynamic characteristics under different operating conditions. For example, under the load rejection condition, the hydrodynamic torque characteristics of the guide vane will change, and the pressures inside and outside the guide vane will also change accordingly. By optimizing the design of the guide vane, the hydrodynamic torque fluctuation and energy loss caused by load rejection can be effectively reduced.

[0048] In summary, through the carefully designed curvature and geometry of the pressure surface of the movable guide vane of the present invention, the turbulent flow and kinetic energy can be effectively balanced under different operating conditions, thus significantly improving the efficiency and performance of the water turbine.

[0049] Figure 4 This is a comparison chart of the "S" characteristic curves of a movable guide vane that achieves the balance of turbulent flow and kinetic energy of the present invention at different opening degrees. In the figure, the changes in the "S" characteristic curves of the pump-turbine are compared for two types of guide vanes, GV1 and GV2, at three different opening degrees (7°, 8°, and 9°). It can be found through comparison that the n11 values of the intersection points of the curves corresponding to the GV2 guide vane and the unit rotational speed n11 (i.e., the point where the unit flow rate Q11 is 0) are all greater than the n11 values of the corresponding points of the GV1 guide vane. This phenomenon indicates that the optimized GV2 guide vane has a significant improvement effect on the "S" characteristics of the pump-turbine. Specifically, the design optimization of the GV2 guide vane makes the flow state in the vaneless area more stable during the process of water flow entering the runner passage from the movable guide vane, and at the same time significantly improves the flow capacity of the runner. This improvement not only optimizes the flow characteristics of the water flow, but also reduces the generation of turbulent flow, thereby reducing the energy loss and enhancing the overall efficiency of the water turbine.

[0050] Further analysis shows that the optimized design of the GV2 guide vane plays an important role in the operation of the pump-turbine. First of all, by improving its curved surface shape and angle distribution, the GV2 guide vane enables the water flow to be more evenly distributed when entering the runner passage, avoiding the phenomenon of too high or too low local flow velocity. This uniform water flow distribution helps to reduce the eddy current and separated flow in the vaneless area, thus improving the flow state of the water flow. Secondly, the design of the GV2 guide vane also enhances the flow capacity of the runner, enabling the water flow to pass through the runner more smoothly, reducing the flow resistance and energy loss. This improvement not only increases the operating efficiency of the water turbine, but also enhances its adaptability under complex operating conditions.

[0051] From the overall trend of the curves, the "S" characteristic curves of the GV2 guide vane at different opening degrees show a more gentle change trend. This gentle change trend indicates that the optimized GV2 guide vane not only improves the performance of the pump-turbine under the starting condition, but also significantly enhances its operating stability under the part-load condition. Specifically, the design of the GV2 guide vane enables the pump-turbine to maintain a high efficiency under low-flow conditions, while reducing the vibration and noise during operation, thereby improving the reliability and service life of the equipment.

[0052] These improvements are of great significance for improving the operating efficiency of the pump-turbine in pumped storage power stations, expanding its stable operating range, and reducing the cavitation risk. First of all, the optimized design of the GV2 guide vane significantly improves the operating efficiency of the pump-turbine, enabling it to achieve higher energy conversion efficiency in both pumping and generating modes. Secondly, the improvement of the GV2 guide vane expands the stable operating range of the pump-turbine, allowing it to maintain high efficiency within a wider range of flow rates and rotational speeds, thus adapting to different grid demands and operating conditions changes. Finally, the design of the GV2 guide vane also reduces the risk of cavitation during the operation of the pump-turbine, reduces the possibility of equipment damage, and extends the service life of the equipment. The movable guide vane provided by the present invention for improving the "S" characteristic of the pump-turbine effectively solves the problems of excessive pressure pulsation, obvious "S" characteristic, serious noise, wear and energy dissipation in the actual operation process of the pump-turbine through the careful design and parameter optimization of the curvature, thickness of the 2L1 section of the movable guide vane and each section of the upper contour line. The movable guide vane 2 has many advantages such as improving the "S" characteristic, reducing energy dissipation, reducing pressure pulsation and noise, and reducing wear, and can significantly improve the operating efficiency, stability and service life of the pump-turbine.

[0053] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. An adjustable guide vane for achieving turbulent flow and kinetic energy balance, which is arranged between the fixed guide vane and the runner, and is characterized in that the adjustable guide vane is divided into a front section and a rear section in the horizontal direction. A pressure section is provided on the upper contour line of the front section. The pressure section is a cubic polynomial, in which c3 = 0.093n, n = 3, 6, 9, 0.001 ≤ b3 ≤ 0.007, and the constant term is d3, d3 ∈ [1, 4].

2. The movable guide vane for achieving turbulent flow and kinetic energy balance according to claim 1, wherein Taking the tangent line of the leading end of the adjustable guide vane and the vertical line as point O, an x-y coordinate axis is made. The o-x axis passes through the center of the arc with a radius of Ra.

3. The movable guide vane for achieving turbulent flow and kinetic energy balance according to claim 1, characterized in that, The leading ends of both the front section and the rear section of the adjustable guide vane are fitted with the arc. The leading end of the front section of the adjustable guide vane is fitted with the arc with a radius of Ra.

4. The movable guide vane for realizing turbulent flow and kinetic energy balance according to claim 1, wherein, The upper contour line of the adjustable guide vane is divided into an arc section, a transition section and a pressure section in the front section. The arc section is the fitting section of the corresponding leading end of the front section of the adjustable guide vane and the arc with a radius of Ra.

5. An adjustable guide vane for achieving turbulent flow and kinetic energy balance according to claim 1 or 3, characterized in that The arc section is a semi-circle equation plus a constant term. The ratio range of the lengths of the front section and the rear section is 1.7 - 1.

72.

6. The movable guide vane for achieving turbulent flow and kinetic energy balance according to claim 1, wherein The transition section is a quadratic polynomial, and the starting point of the transition section is the tangent point with the arc.

7. An adjustable guide vane for achieving turbulent flow and kinetic energy balance according to claim 1 or 6, characterized in that, The end point of the transition section is the intersection point of the extension line passing through the center of the arc with a radius of Ra and along the positive y-axis direction and the upper contour line of the guide vane.

8. The movable guide vane for achieving turbulent flow and kinetic energy balance according to claim 7, wherein The constant term of the quadratic polynomial in the transition section is d4, d4 ∈ [1, 4], c4 = 0.32n, n = 3, 6, 9, 0 ≤ b4 ≤ 0.

1.

9. An adjustable guide vane for achieving turbulent flow and kinetic energy balance according to claim 6, characterized in that The starting point of the pressure section is the end point of the transition section, and the end point is the starting point of the rear section of the adjustable guide vane.

10. The movable guide vane for achieving turbulent flow and kinetic energy balance according to claim 1 or 9, characterized in that, The ratio of the distance from the end point of the pressure section to the lower contour line of the adjustable guide vane to the length of the adjustable guide vane is 0.13 - 0.14.

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