A turbine

Abstract

The application provides a turbine, which comprises a guide vane and a moving vane arranged downstream of the guide vane, i.e. fluid flows to the moving vane under the guidance of the guide vane. The meridian streamline curvature radius r m satisfies the following condition: wherein r is a flow passage height, C m is a meridian streamline tangential velocity, δ is a flow passage expansion angle, C u is a circumferential velocity. By limiting the value of r m , centrifugal force generated by the meridian streamline can be counteracted by centrifugal force generated by the circumferential velocity of the fluid, and the counteracted reaction degree along the height of the guide vane is ensured to increase, the control of the incoming flow boundary layer at the moving vane inlet root and the transverse pressure gradient on the moving vane is realized, and then the generation of passage vortex is inhibited from the source, and the end area secondary flow loss is reduced.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and more specifically, to a turbine. Background Technology

[0002] Civilian high-bypass turbofan engines pursue high thrust-to-weight ratio, low fuel consumption, and long lifespan, placing higher demands on engine efficiency and lifespan. To reduce component weight, shorten engine axial dimensions, reduce the number of parts, and lower maintenance costs, turbine blades are typically designed for high loads. However, increased blade aerodynamic load leads to enhanced end-region secondary flow. End-region secondary flow is a significant source of turbine aerodynamic losses and a crucial factor determining impeller mechanical efficiency. End-region secondary flow refers to the lateral boundary layer flow within the end-region boundary layer under the influence of the lateral pressure gradient in the blade passage. The incoming boundary layer in the end region washes down near the leading edge, forming horseshoe vortices. Its pressure-side and suction-side branches converge at the blade suction surface, forming channel vortices. The formation of channel vortices originates from two sources: the incoming boundary layer flow at the leading edge and the further replenishment of low-energy fluid in the suction-side reverse pressure region by the end-region lateral flow within the channel.

[0003] Existing technology provides a composite sweep design that can effectively control secondary flow losses in the end region. However, for rotor blades, considering strength constraints, this leads to the dispersion of the centrifugal center of gravity of each radial element level of the blade, increasing centrifugal bending moment. Furthermore, the airfoil-based loading method for controlling the secondary flow in the end region has a limited adjustment range. Increasing the number of moving blades to reduce the lateral pressure gradient and control the secondary flow in the end region results in a decrease in the cooling air volume of individual blades, while simultaneously increasing the disk load, severely impacting the lifespan of the high-vortex rotor. Summary of the Invention

[0004] The purpose of this invention is to provide a turbine that can control the blade root passage vortex of the moving blade, thereby helping to control the secondary flow loss in the end region of the moving blade.

[0005] The turbine provided by this invention is implemented in the following way:

[0006] A turbine includes guide vanes and a moving blade disposed downstream of the guide vanes, wherein the meridional streamline radius r at the blade root of the moving blade inlet is... m The following conditions must be met:

[0007]

[0008] In the formula: r is the channel height, C m Where δ is the tangential velocity of the meridional streamline, and C is the channel expansion angle. u This refers to the circumferential velocity.

[0009] Optionally, the isoflow line of the guide vane is concave at the vane root at the outlet of the guide vane.

[0010] Optionally, along the direction from the tip of the guide vane to the root of the guide vane, the variation curve of the effective exit angle of the guide vane includes a decreasing segment and an increasing segment; within the decreasing segment, the effective exit angle of the guide vane decreases along the direction from the tip of the guide vane to the root; within the increasing segment, the effective exit angle of the guide vane increases along the direction from the tip of the guide vane to the root.

[0011] The intersection of the decreasing effective exit angle segment and the increasing effective exit angle segment is located below 35% of the guide vane's blade height, and the effective exit angle at 0% of the guide vane's blade height is greater than the effective exit angle at 100% of the guide vane's blade height.

[0012] Optionally, the increasing segment of the effective exit angle has a first inflection point, and the second derivative of the portion of the increasing segment of the effective exit angle located above the first inflection point is less than the second derivative of the portion of the increasing segment of the effective exit angle located below the first inflection point.

[0013] Optionally, the first inflection point is located below 25% of the blade height of the guide vane.

[0014] Optionally, the first inflection point is located at 10% to 15% of the blade height of the guide vane.

[0015] Optionally, along the direction from the tip of the guide leaf to the root of the guide leaf, the throat width variation curve of the guide leaf includes a throat width decreasing segment and a throat width increasing segment; within the throat width decreasing segment, the throat width of the guide leaf decreases along the direction from the tip of the guide leaf to the root of the guide leaf; within the throat width increasing segment, the throat width of the guide leaf increases along the direction from the tip of the guide leaf to the root of the guide leaf.

[0016] The intersection of the decreasing throat width segment and the increasing throat width segment is located below 35% of the guide vane's leaf height, and the throat width at 0% of the guide vane's leaf height is greater than the throat width at 100% of the guide vane's leaf height.

[0017] Optionally, the increasing throat width segment has a second inflection point, and the second derivative of the portion of the increasing throat width segment located above the second inflection point is less than the second derivative of the portion of the increasing throat width segment located below the second inflection point.

[0018] Optionally, the second inflection point is located below 25% of the blade height of the guide vane.

[0019] Optionally, the moving blade has a non-axisymmetric end wall.

[0020] A turbine having a moving blade, wherein a portion of low-energy fluid at the blade root on the pressure surface of the moving blade is driven in a decreasing direction toward the blade of the moving blade, so that a portion of the low-energy fluid moves upward.

[0021] Optionally, the pressure surface of the moving blade root forms an acute angle with the end wall of the blade root.

[0022] The beneficial effects of the turbine provided by the embodiments of the present invention include:

[0023] Embodiments of the present invention provide a turbine comprising guide vanes and a moving blade disposed downstream of the guide vanes, wherein fluid flows toward the moving blade under the guidance of the guide vanes. The meridional streamline radius r at the blade root at the inlet of the moving blade is... m The following conditions must be met: In the formula: r is the channel height, C m Where δ is the tangential velocity of the meridional streamline, and C is the channel expansion angle. u The circumferential velocity is determined by r. m The value is limited so that the centrifugal force generated by the meridional streamline can cancel the centrifugal force generated by the circumferential velocity of the fluid, and ensure that the reaction force along the blade height on the guide vane increases after cancellation. This achieves control over the incoming flow boundary layer at the blade root of the moving blade inlet and the lateral pressure gradient on the moving blade, thereby suppressing the generation of channel vortices from the source and reducing secondary flow losses in the end region.

[0024] An embodiment of the present invention also provides a turbine having a moving blade, wherein the driving force of a portion of the low-energy fluid at the blade root of the pressure surface of the moving blade decreases in the direction of the blade center, thereby causing the low-energy fluid in this portion to move upward, thereby suppressing the movement of the low-energy fluid towards the end, thereby reducing the further replenishment of the low-energy fluid in the suction reverse pressure zone by the lateral flow, realizing the control of the channel vortex intensity, and reducing the secondary flow loss in the end region. Attached Figure Description

[0025] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0026] Figure 1 A comparison diagram of the isoflow line distribution of a turbine according to one aspect of the present invention and a conventional design is shown;

[0027] Figure 2 A schematic diagram of the effective exit angle of a turbine guide vane according to one aspect of the present invention is shown;

[0028] Figure 3 A graph comparing the effective exit angle of the turbine guide vanes provided according to one aspect of the present invention with that of a conventional design is shown.

[0029] Figure 4 The diagram shows the distribution of low-energy fluid driving force near the wall of the blade in a conventional design.

[0030] Figure 5 A diagram showing the low-energy fluid driving force distribution near the wall of a turbine blade according to one aspect of the present invention is provided.

[0031] Figure 6 A diagram showing a comparison of the total outlet pressure of a turbine guide vane provided according to one aspect of the invention with that of a conventionally designed guide vane is presented.

[0032] Figure 7 A schematic diagram of the three-dimensional flow field in the lower region of a conventionally designed moving blade is shown.

[0033] Figure 8 A three-dimensional flow field diagram of the lower end region of the moving blade of a turbine according to one aspect of the present invention is shown;

[0034] Figure 9 The diagram shows the total pressure loss at the outlet of a conventionally designed moving blade;

[0035] Figure 10 A diagram showing the total pressure loss at the outlet of the moving blades of a turbine according to one aspect of the present invention is provided.

[0036] Figure 11 The diagram shows the exit wake shape of a conventionally designed guide vane;

[0037] Figure 12 A diagram showing the shape of the exit wake of a turbine guide vane according to one aspect of the present invention is provided;

[0038] Figure 13 A comparison diagram of the total pressure loss at the blade root section of a turbine blade provided according to one aspect of the present invention and a conventionally designed blade blade is shown.

[0039] Figure 14 A comparison diagram of the radial distribution of the outlet blockage coefficient of a turbine blade provided according to one aspect of the present invention and a conventionally designed turbine blade is shown.

[0040] Figure 15 A graph showing the variation curves of the throat width of the guide vane of a turbine provided according to another aspect of the present invention with that of a conventionally designed throat width is shown. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0042] This invention provides a turbine comprising multi-stage guide vanes and moving blades, such as... Figure 1 As shown, Figure 1Each box marked with an "×" represents a blade, from left to right: first-stage guide vane, first-stage moving blade, second-stage guide vane, and second-stage moving blade. The turbine provided by the embodiments of the present invention will be further described below, while using a conventionally designed blade with the same throat area as the guide vane of the turbine provided by the present invention as a comparative example to illustrate the turbine's performance. It should be noted that the terms "guide vane" and "moving blade" mentioned in the following description refer to "first-stage guide vane" and "first-stage moving blade," respectively.

[0043] According to the complete radial equilibrium equation:

[0044]

[0045] In the formula: ρ is density, C u Let r be the circumferential velocity of the airflow, r be the channel height, and C be the circumferential velocity of the airflow. m r is the tangential velocity of the meridional streamline. m Let δ be the radius of curvature of the meridional streamline, δ be the channel expansion angle, m be the coordinates of the meridional streamline, and A be the circumferential velocity C. u The centrifugal force generated is directed outward along r. Option B represents the centrifugal force generated by the meridional streamline, and r m When the direction is the same as r, it is positive; when it is opposite, it is negative. Item C is the radial component of the inertial force, which is generated by the acceleration of the mainstream moving along the meridional streamline, and its direction is opposite to the acceleration.

[0046] The inventors discovered that by changing the r at the leaf root of the moving leaf inlet... m Value, such that r m Within the following range:

[0047]

[0048] In the formula: r is the channel height, C m Where δ is the tangential velocity of the meridional streamline, and C is the channel expansion angle. u This refers to the circumferential velocity.

[0049] At this point, the sign of option B is opposite to that of option A, meaning that option B and option A cancel each other out. This reduces the radial pressure gradient inside the flow channel, changes the boundary layer thickness at the blade root at the blade inlet, and ensures the stability of the flow field at the blade outlet. This weakens the vortex intensity in the blade channel from the source and reduces the end-area loss of the blade.

[0050] Furthermore, the inventors discovered that if some low-energy fluid can move upwards at the blade root on the pressure surface of the moving blade, it can suppress the movement of low-energy fluid towards the end wall. For example... Figure 4 and Figure 5As shown, in conventional design, the driving force 4 on the moving blade pressure surface causes the low-energy fluid to move downwards, thus promoting the movement of the low-energy fluid towards the endwall and increasing end-area losses. However, if the decreasing direction of the driving force 4′ on the moving blade pressure surface is directed towards the center of the blade, i.e. Figure 5 The arrows in the middle point upwards, and correspondingly, some low-energy fluid exhibits an upward-moving characteristic, thereby suppressing the movement of low-energy fluid towards the endwall. This reduces the further replenishment of low-energy fluid in the suction-side reverse pressure zone by lateral flow, thus controlling the intensity of the channel vortex and reducing root blockage (e.g., Figure 10 (As shown by the dashed line).

[0051] It should be noted that, Figure 4 and Figure 5 The streamlines in the image represent the low-energy fluid driving force on the blade surface, and the arrows point in the direction of decreasing pressure.

[0052] The inventors designed the upstream guide vane of the moving blade to allow the fluid at the guide vane outlet to move downwards, achieving a reverse curvature, thereby realizing the control of the flow rate at the root of the moving blade. m The range is adjusted, and at the same time, low-energy fluid shows the characteristic of upward submersion at the blade root of the pressure surface of the moving blade.

[0053] Specifically, the isoflow lines distribution of the turbine are as follows: Figure 1 As shown, Figure 1 The horizontal axis represents the axial dimension, and the vertical axis represents the radial dimension. The vertical line between two adjacent blades represents the line where the interface between adjacent fluid domains is located. Multiple lines extending roughly towards the horizontal axis are isoflow lines, and the flow rates between adjacent isoflow lines are equal. Meanwhile, the solid lines in the figure represent conventionally designed turbines, and the dashed lines represent the turbine provided by this invention.

[0054] according to Figure 1 As shown in the isoflow lines, the isoflow lines of the guide vane are concave at the vane root at the guide vane outlet, creating a... Figure 1 The dashed lines indicate the reverse curvature meridional streamlines ( Figure 1 (The position indicated by 1′ in the middle) At this time, the distance between the two isoflow lines on the bottom side decreases, which indicates that the flow rate at the blade root increases. In other words, the fluid at the guide vane outlet flows downward.

[0055] Furthermore, the effective outlet angle of the guide vane is adjusted by 100° to guide the fluid at the guide vane outlet downwards. For example... Figure 2 As shown, the effective exit angle 100° is the arcsine angle determined by the ratio of the throat width (hereinafter referred to as throat width) o to the gate pitch t.

[0056] Figure 3 The diagram shows the distribution of the effective exit angle of the guide vane provided by the present invention and the effective exit angle of the guide vane in a conventional design. Figure 3The horizontal axis represents the effective exit angle, and the vertical axis represents the blade height. The solid line represents the curve of the effective exit angle of the conventional design as a function of blade height, while the dashed line represents the curve of the effective exit angle of the guide vane provided by this invention as a function of blade height. The effective exit angle values ​​of the guide vane provided by this invention and those of the guide vane in the conventional design are shown in Table 1 below.

[0057] Table 1

[0058] 1.0 11.9 14.3 0.9 12.0 13.6 0.8 12.1 12.8 0.7 12.2 11.8 0.6 12.4 11.0 0.4 12.6 10.5 0.3 12.9 10.6 0.2 13.2 11.5 0.1 13.6 19.7 0.0 14.0 23.8

[0059] Reference Figure 3 According to Table 1, in the turbine provided by this invention, the variation curve of the effective exit angle of the guide vane along the direction from the blade tip to the blade root includes an effective exit angle decreasing segment 111 and an effective exit angle increasing segment 112. Within the effective exit angle increasing segment 111, the effective exit angle 100° decreases along the direction from the blade tip to the blade root; within the effective exit angle decreasing segment 112, the effective exit angle 100° increases along the direction from the blade tip to the blade root. The intersection of the effective exit angle decreasing segment 111 and the effective exit angle increasing segment 112, i.e., the peak value, is located below 35% of the guide vane height. That is, the guide vane height corresponding to the peak value is less than 35%, and the effective exit angle at 0% of the guide vane height is greater than the effective exit angle at 100% of the guide vane height.

[0060] By designing the effective exit angle variation curve of the guide vane, the minimum (i.e., peak) effective exit angle of the guide vane is located in the part of the guide vane near the root, and the effective exit angle at 0% of the guide vane height is greater than the effective exit angle at 100% of the guide vane height. In this way, while ensuring the smoothness of the guide vane surface, the effective exit angle at the root of the guide vane increases rapidly. Based on the characteristic that fluids tend to flow towards areas with larger flow, the fluid is guided to flow towards the root of the vane, forming a reverse curvature to balance the radial pressure gradient.

[0061] Furthermore, the effective angle increasing section 112 at the outlet also has a first inflection point 113. At the same time, the second derivative of the part of the effective angle increasing section 112 at the outlet above the first inflection point 113 is less than the second derivative of the part of the effective angle increasing section 112 at the outlet below the first inflection point 113. Thus, the effective angle at the outlet near the blade root end increases much faster than that near the middle of the blade, thereby further ensuring that the fluid flows along the blade root end.

[0062] Further, the first inflection point 113 is located below 25% of the guide vane's leaf height, that is, the first inflection point 113 is located between 25% and 0% of the guide vane's leaf height. In this embodiment, the first inflection point 113 is approximately located at 20% of the leaf height. Further, the first inflection point 113 is located at 10% to 15% of the guide vane's leaf height. Optionally, the first inflection point 113 can also be set to be located at 10%, 13%, or 15% of the guide vane's leaf height.

[0063] Simultaneously, due to the increased flow through the guide vane root, the axial velocity near the wall increases, and the total pressure increases, resulting in a thinner boundary layer thickness in the incoming flow to the moving blades. For example... Figure 6 This diagram shows a comparison of the total outlet pressure of the turbine guide vanes provided by this invention and conventionally designed guide vanes. Figure 6 As can be seen from the present invention, in the turbine provided by the present invention, the blade height corresponding to the first inflection point 5′ of the total pressure at the outlet of the guide vane root along the direction from the blade root to the blade tip is significantly smaller than the blade height in the conventional design. The blade height corresponding to the first inflection point of the total pressure at the outlet of the guide vane root represents the thickness of the boundary layer of the moving blade inflow.

[0064] Figure 7 The three-dimensional flow field at the lower end region of a conventionally designed blade is shown. Figure 8 The three-dimensional flow field in the lower end region of the turbine blades provided by this invention is shown, and Figure 7 and Figure 8 The diagram uses axial vorticity coloring for illustration. For example... Figure 7 and Figure 8 As shown, the incoming flow boundary layer stagnates at the leading edge of the moving blade, forming a horseshoe vortex. The horseshoe vortex forms pressure surface branches 7 and 7' and suction surface branches 6 and 6'. The pressure surface branches 7 and 7' flow towards the suction surface of the adjacent blade under the action of the lateral pressure gradient. Since the lateral flow of low-energy fluid is weakened in the turbine provided by this invention, and the incoming flow boundary layer is thin, the intersection area of ​​pressure surface branch 7' and suction surface branch 6' is moved backward, and the position of reaching the suction surface of the adjacent blade is delayed, so the size and intensity of the channel vortex are controlled. Figure 9 It shows Figure 7 A certain cross section (along...) Figure 7 The color contrast diagram at the surface intercepted by the horizontal lines extending to the left and right in the middle shows that each black blob represents a channel vortex, thus illustrating the total pressure loss at the outlet of the conventionally designed blade. Figure 10 It shows Figure 8 A certain cross section (along...) Figure 8 The color contrast diagram at the surface intercepted by the horizontal lines extending to the left and right in the middle shows that each black blob represents a channel vortex, thus illustrating the total pressure loss at the outlet of the conventionally designed blade. Figure 9 and Figure 10A comparison of the channel vortex 8 and the channel vortex 8′ shows that the channel vortex at the moving blade in the turbine provided by this invention is significantly controlled, thereby achieving a 22.9% reduction in the total pressure loss at the moving blade root (e.g., ...). Figure 13 (As shown). The turbine provided by this invention, by suppressing the vortex in the blade passage, can suppress the secondary flow loss in the end region of the blade, thereby helping to break the limitation of the end region secondary flow on the number of blades and reducing the number of blades. In this way, the cooling volume of a single blade can be increased under the condition of a fixed total cooling volume, which is of great significance for improving turbine life.

[0065] Furthermore, in the turbine provided by this invention, by setting the effective angle of the guide vane exit, the shape of the guide vane exit wake can be significantly improved, such as... Figure 12 As shown, in the turbine provided by this invention, the exit wake 9′ of the guide vane is C-shaped, thereby offsetting the guide vane wake and the leading edge geometry of the moving blade, reducing the excitation force of the wake on the moving blade. A conventionally designed exit wake 9′ is as follows: Figure 11 As shown in the image.

[0066] It should be noted that other methods can also be used to improve the flow of the guided fluid to the root of the guide vanes, achieving similar results. Figure 1 The inverse curvature shown.

[0067] As an example, Figure 15 A comparison diagram of the throat width variation curve of the turbine guide vane provided by another aspect of the present invention and the throat width variation curve of a conventional design is shown. By setting the throat width variation curve of the turbine guide vane, the fluid is guided to flow to the root of the guide vane. Figure 15 In the figure, the horizontal axis represents throat width and the vertical axis represents blade height. The solid line represents the throat width variation curve of a conventionally designed turbine with blade height, while the dashed line represents the throat width variation curve of the turbine provided by this invention with blade height.

[0068] Specifically, the throat widths at multiple blade heights of the turbine guide vane provided by the present invention and the throat widths at multiple blade heights of the guide vane in conventional designs are shown in Table 2:

[0069] Table 2

[0070] 1.0 13.380 16.102 0.9 13.254 15.069 0.8 13.139 13.935 0.7 13.043 12.599 0.6 12.971 11.566 0.4 12.931 10.791 0.3 12.928 10.618 0.2 12.967 11.357 0.1 13.037 18.742 0.0 13.076 21.919

[0071] Reference Figure 15According to Table 2, in another aspect of the present invention, the throat width variation curve of the guide vane along the direction from the tip to the root includes a throat width decreasing segment 211 and a throat width increasing segment 212. Within the throat width decreasing segment 211, the throat width of the guide vane decreases along the direction from the tip to the root; within the throat width increasing segment 212, the throat width of the guide vane increases along the direction from the tip to the root. The intersection of the throat width decreasing segment 211 and the throat width increasing segment 212, i.e., the peak value, is located below 35% of the guide vane's blade height; that is, the guide vane blade height corresponding to the peak value is less than 35%, and the throat width at 0% of the guide vane's blade height is greater than the throat width at 100% of the guide vane's blade height.

[0072] Furthermore, the throat width increasing segment 212 also has a second inflection point 213. At the same time, the second derivative of the portion of the throat width increasing segment 212 located above the second inflection point 213 is less than the second derivative of the portion of the throat width increasing segment 212 located below the second inflection point 213. Thus, the throat width increases significantly faster near the leaf root end than the portion near the middle of the leaf.

[0073] Furthermore, the second inflection point 213 is located below 25% of the guide vane's leaf height, that is, between 25% and 0% of the guide vane's leaf height. In this embodiment, the second inflection point 213 is approximately located at 20% of the leaf height. It is understood that the position of the second inflection point 213 can also be set at 25% or 15% of the leaf height, etc. Specifically, while ensuring the guide vane's leaf surface is smooth, the lower the leaf height at which the second inflection point 213 is located, the better. In other words, the greater the throat width variation rate near the leaf root end of the guide vane, the better.

[0074] In this embodiment, the moving blade adopts an asymmetric endwall. The asymmetric endwall is to adjust the concavity and convexity of the endwall surface. It has an upward convex feature near the pressure side and a downward concave feature near the suction side in order to control the lateral pressure gradient in the end region and delay the formation of the channel vortex. By combining the asymmetric endwall of the moving blade with the design of the guide vane, they can promote each other and further improve the control effect of the channel vortex.

[0075] In this embodiment, the pressure surface at the root of the moving blade forms an acute angle with the end wall of the root, thereby creating an upward pressure distribution and further suppressing the downward movement of low-energy fluid.

[0076] The turbine provided by this invention can effectively control the channel vortex of the moving blades, thereby suppressing the secondary flow loss in the end region of the moving blades and helping to break the limitation of the end region secondary flow on the number of moving blades.

Claims

1. A turbine, the turbine comprising guide vanes and a moving blade disposed downstream of the guide vanes, characterized in that, The radius of curvature r of the meridional streamline at the blade root of the inlet of the moving blade. m The following conditions must be met: In the formula: r is the channel height, Cm is the meridional streamline tangential velocity, δ is the channel expansion angle, and Cu is the circumferential velocity; Along the direction from the tip to the root of the guide vane, the curve of the effective exit angle of the guide vane includes a decreasing segment and an increasing segment. Within the decreasing segment, the effective exit angle decreases along the direction from the tip to the root. Within the increasing segment, the effective exit angle increases along the direction from the tip to the root. The intersection of the decreasing and increasing segments is located below 35% of the guide vane's leaf height. Along the direction from the tip of the guide leaflet to the root of the guide leaflet, the throat width variation curve of the guide leaflet includes a throat width decreasing segment and a throat width increasing segment; within the throat width decreasing segment, the throat width of the guide leaflet decreases along the direction from the tip of the guide leaflet to the root of the guide leaflet; within the throat width increasing segment, the throat width of the guide leaflet increases along the direction from the tip of the guide leaflet to the root of the guide leaflet; wherein, the intersection of the throat width decreasing segment and the throat width increasing segment is located below 35% of the leaf height of the guide leaflet.

2. The turbine according to claim 1, characterized in that, The isoflow line of the guide vane is concave at the vane root at the outlet of the guide vane.

3. The turbine according to claim 1, characterized in that, The effective exit angle at 0% blade height of the guide vane is greater than the effective exit angle at 100% blade height of the guide vane.

4. The turbine according to claim 3, characterized in that, The effective exit angle increasing segment has a first inflection point, and the second derivative of the portion of the effective exit angle increasing segment located above the first inflection point is less than the second derivative of the portion of the effective exit angle increasing segment located below the first inflection point.

5. The turbine according to claim 4, characterized in that, The first inflection point is located below 25% of the blade height of the guide vane.

6. The turbine according to claim 5, characterized in that, The first inflection point is located at 10% to 15% of the blade height of the guide vane.

7. The turbine according to claim 1, characterized in that, The throat width at 0% leaf height of the guide vane is greater than the throat width at 100% leaf height of the guide vane.

8. The turbine according to claim 7, characterized in that, The increasing throat width segment has a second inflection point, and the second derivative of the portion of the increasing throat width segment located above the second inflection point is less than the second derivative of the portion of the increasing throat width segment located below the second inflection point.

9. The turbine according to claim 8, characterized in that, The second inflection point is located below 25% of the blade height of the guide vane.

10. The turbine according to any one of claims 1-9, characterized in that, The moving blade has an asymmetric end wall.

11. A turbine having a moving blade and a guide vane disposed upstream of the moving blade, characterized in that, The driving force of the low-energy fluid at the root of the pressure surface of the moving blade decreases and points towards the middle of the moving blade, so that part of the low-energy fluid moves upward. The radius of curvature r of the meridional streamline at the blade root of the inlet of the moving blade. m The following conditions must be met: In the formula: r is the channel height, Cm is the meridional streamline tangential velocity, δ is the channel expansion angle, and Cu is the circumferential velocity; Along the direction from the tip to the root of the guide vane, the curve of the effective exit angle of the guide vane includes a decreasing segment and an increasing segment. Within the decreasing segment, the effective exit angle decreases along the direction from the tip to the root. Within the increasing segment, the effective exit angle increases along the direction from the tip to the root. The intersection of the decreasing and increasing segments is located below 35% of the guide vane's leaf height. Along the direction from the tip of the guide leaflet to the root of the guide leaflet, the throat width variation curve of the guide leaflet includes a throat width decreasing segment and a throat width increasing segment; within the throat width decreasing segment, the throat width of the guide leaflet decreases along the direction from the tip of the guide leaflet to the root of the guide leaflet; within the throat width increasing segment, the throat width of the guide leaflet increases along the direction from the tip of the guide leaflet to the root of the guide leaflet; wherein, the intersection of the throat width decreasing segment and the throat width increasing segment is located below 35% of the leaf height of the guide leaflet.

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