Turbine guide vane design method and turbine

Abstract

The invention provides a turbine guide vane design method used for adjusting temperature distribution of high-temperature fuel gas incoming flow in the blade height direction. The method comprises the following steps that a plurality of blade profiles are selected in a blade root area, a blade middle area and a blade tip area of a turbine guide vane respectively; and the outlet effective angle of each blade profile is adjusted, and then the throat width of the blade height where the blade profile is located is adjusted, so that the throat width of the blade tip area is larger than that of the blade middle area. According to the method, the temperature distribution of the high-temperature fuel gas incoming flow in the blade height direction can be adjusted, and particularly the temperature of the high-temperature fuel gas incoming flow at the blade root can be reduced. A turbine is also provided.

Description

Technical Field

[0001] The present invention relates to the field of aero engines, and in particular to the field of turbines. Background Art

[0002] With the development of aero-engine technology, the temperature at the combustion chamber outlet is constantly increasing to achieve higher engine performance. The high-temperature, high-pressure gas discharged from the combustion chamber enters the high-pressure turbine, and after being turned and accelerated by the guide vanes, it impacts the rotor blades, causing them to rotate and output power. The working characteristics of high temperature, high pressure, and high speed put forward higher requirements for turbine design. The high-pressure turbine rotor blades are simultaneously subjected to high-temperature gas ablation and centrifugal tensile forces caused by high speed, and the tensile stress is the largest in the root area of ​​the blades. Therefore, the root area of ​​the blades becomes a key position that restricts the improvement of the service life of the rotor blades.

[0003] The strength and service life of turbine rotor blades mainly depend on two aspects: one is the temperature of the upstream incoming gas, and the other is the cooling scheme of the rotor blades themselves. In order to improve the service life of rotor blades, the main solution in current engineering is to improve the cooling scheme of rotor blades, reduce the metal temperature of blades, improve temperature gradient and thermal stress by increasing the cooling air flow, optimizing the internal cooling channel, optimizing the shape and arrangement of air film holes, etc. However, increasing the cooling air flow of rotor blades will reduce the performance of aircraft engines and increase fuel consumption. As the temperature before the turbine continues to increase, the life improvement brought by the optimization of the cooling scheme of the rotor blades itself is becoming more and more limited. Therefore, under the condition of a certain combustion chamber outlet temperature, reducing the temperature of the incoming gas in the root area of ​​the rotor blades by optimizing the guide vanes can be used as another effective measure to improve the service life of rotor blades.

[0004] However, the existing turbine guide vane distribution structure is generally set in the upper and lower end wall areas of the flow channel with high aerodynamic losses to reduce the flow rate, and is set in the mid-diameter area of ​​the flow channel with low aerodynamic losses to increase the flow rate, thereby reducing the aerodynamic losses of the blades. However, such a structure ignores the migration path of the high-temperature combustion gas in the combustion chamber in the guide vanes, which can easily lead to a further increase in the temperature of the flow in the root area of ​​the downstream rotor blades, thereby affecting the service life of the blades. Summary of the invention

[0005] An object of the present invention is to provide a turbine guide vane design method capable of adjusting the temperature distribution of high-temperature combustion gas inflow along the blade height direction, especially reducing the temperature of high-temperature combustion gas inflow at the blade root.

[0006] A turbine guide vane design method for achieving the above-mentioned purpose is used to adjust the temperature distribution of the high-temperature combustion gas flow along the blade height direction, comprising the following steps: selecting a plurality of blade profiles in the blade root area, the blade mid-area and the blade tip area of ​​the turbine guide vane respectively; adjusting the outlet effective angle of each blade profile, and then adjusting the throat width at the blade height where the blade profile is located, so that the throat width in the blade tip area is greater than the throat width in the blade mid-area, wherein the narrowest throat width at the blade height where the blade profile is located has a first intersection point and a second intersection point with two circumferentially adjacent turbine guide vanes, the first intersection point is the leading edge of one of the turbine guide vanes, the second intersection point is located at the blade body of the other turbine guide vane, and the angle between the line connecting the second intersection point and the leading edge point of the other turbine guide vane and the turbine guide vane forehead line is the outlet effective angle.

[0007] In one or more embodiments, the throat width of the blade tip region is made 15-25% greater than the throat width of the blade mid-region.

[0008] In one or more embodiments, the method further includes the following steps: determining the flow channel position of the peak value of the high-temperature fuel gas flow; and making the minimum throat width be located below the flow channel position of the peak value.

[0009] In one or more embodiments, the throat width of the blade root region is made greater than the throat width of the blade mid-region.

[0010] In one or more embodiments, the blade root region is a region of 0% to 33% of the blade height, the blade mid-region is a region of 33% to 66% of the blade height, and the blade tip region is a region of 66% to 100% of the blade height.

[0011] In one or more embodiments, stacked line design is adopted for each blade profile to obtain a three-dimensional profile of the designed guide vane.

[0012] In one or more embodiments, the form of controlling the radial stacking curve includes one or more of a Bezier curve, a polynomial curve or a spline curve.

[0013] In one or more embodiments, the outlet effective angle is set in a range of 5° to 10°.

[0014] Another object of the present invention is to provide a turbine, comprising turbine guide vanes, wherein the throat width between adjacent circumferential guide vanes is configured to be smaller in the middle and larger at both ends along the blade height direction.

[0015] In one or more embodiments, the radial height at which the narrowest throat is located is lower than the radial height at which the high temperature combustion gas peak is located.

[0016] The above-mentioned turbine guide vane design method uses the calculated relationship between the outlet effective angle of the blade shape and the throat width to adjust the width of the throat, and uses the width of the throat to adjust the flow direction of the high-temperature airflow in the combustion chamber, thereby changing the temperature distribution of the high-temperature airflow in the radial direction, reducing the incoming flow temperature of the airflow in the root area of ​​the rotor blade, thereby increasing the service life of the blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0018] Figure 1 It is a schematic diagram of the structure of turbine guide vanes and throat;

[0019] Figure 2A is a schematic diagram of the two-dimensional blade profile of a turbine guide vane;

[0020] Figure 2B is a schematic diagram of the effective outlet angle;

[0021] Figure 3 is the radial distribution of the blade throat width along the flow channel height direction

[0022] Figure 4 is the radial distribution of the blade geometry outlet angle along the flow channel height direction;

[0023] Figure 5 is the radial distribution diagram of the blade installation angle along the flow channel height direction;

[0024] Figure 6 is the radial distribution of the gas temperature at the inlet and outlet of the guide vane along the height direction of the flow channel;

[0025] Figure 7 It is a flow chart of the turbine guide vane design method. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0027] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual scope of protection required by the present invention.

[0028] An aircraft engine mainly consists of a compressor, a combustion chamber and a turbine. The high-temperature and high-pressure combustion gas discharged from the combustion chamber changes direction, expands and accelerates through the high-pressure turbine guide vanes, and impacts the turbine blades at a certain angle, causing them to rotate and thus output power.

[0029] In the center of the combustion chamber flame tube, the fuel combustion produces a high temperature core. In the area near the flame tube wall, the gas temperature is relatively low due to the distance from the combustion core and the cooling effect of the wall. Therefore, the temperature field of the high-temperature gas at the combustion chamber outlet is non-uniform, showing a distribution feature of high center and low surrounding. Usually, the peak temperature of the high-temperature gas is located near 50% of the flow channel height.

[0030] The high-pressure turbine guide vanes are connected to the combustion chamber. The distribution of the combustion chamber outlet temperature will change when passing through the guide vanes: on the one hand, the cooling air of the turbine guide vanes will reduce the local gas temperature, and on the other hand, the guiding effect of the guide vanes will change the airflow migration path.

[0031] The turbine guide blades consist of several blades in the circumferential direction, such as Figure 1 As shown, the first guide blade 1 and the second guide blade 2 are two guide blades adjacent to each other in the circumferential direction along the Y direction, and have a pressure surface 7 (blade basin) and a suction surface 6 (blade back). The minimum distance position between the first guide blade 1 and the second guide blade 2 cooperates with the lower edge plate 3 and the upper edge plate 4 to form the throat 5 of the guide blade. The throat width determines the size of the airflow, so the radial distribution of the throat width along the Z direction determines the radial migration direction of the high-temperature combustion gas flow from the leading edge to the trailing edge of the guide blade.

[0032] However, the current radial flow distribution of turbine guide vanes mainly considers reducing aerodynamic losses. Usually, the flow is reduced in the upper and lower end wall areas of the flow channel with high aerodynamic losses, or the flow is increased in the mid-diameter area of ​​the flow channel with low losses to reduce the aerodynamic losses of the blades. This can easily lead to a further increase in the temperature of the incoming flow in the root area of ​​the downstream rotor blades, while ignoring the influence of the radial migration of the guide vanes on the gas temperature distribution and the strength and service life of the downstream rotor blades. The high-pressure turbine rotor blades are simultaneously subjected to high-temperature gas ablation and centrifugal tensile forces caused by high speed. The tensile stress is the largest in the root area of ​​the blades. The blade strength reserve in this area is low, and it is difficult to meet the engine life requirements. It is a key position that restricts the improvement of the service life of the rotor blades.

[0033] To solve the above problems, the turbine guide vane disclosed in the present invention controls the guide vane throat width according to the exhaust temperature distribution characteristics of the combustion chamber, thereby controlling the radial distribution of the high-temperature combustion gas flow rate, guiding the high-temperature core area of ​​the combustion chamber away from the lower end area, and reducing the temperature of the incoming combustion gas at the root of the rotor blade, thereby increasing the service life of the blade and taking into account the aerodynamic performance of the guide vane and the downstream rotor blade.

[0034] The turbine guide vane design method disclosed in the present invention comprises the following steps: selecting a plurality of blade profiles in the blade root region, the blade middle region and the blade tip region of the turbine guide vane, which are the blade root, blade middle and blade tip shaping sections respectively; adjusting the outlet effective angle of each blade profile, and then adjusting the throat width at the blade height where the blade profile is located, so that the throat width of the blade tip region is greater than the throat width of the blade middle region

[0035] Specifically, if Figure 2A The blade profile diagram shown in the figure shows that the two-dimensional cross section consists of the blade back and the blade basin. The entire profile is smooth and continuous to ensure excellent aerodynamic performance. The circumferential blade is also called a cascade. The minimum distance o between two adjacent guide blades defines the width of the throat at this blade height. It can be understood that the minimum distance is defined between each layer of adjacent blade profiles in the blade height direction, forming a throat distribution along the blade height direction.

[0036] The blade profile has parameters: throat width o, blade pitch t, ​​blade installation angle s, outlet effective angle α, and chord length c.

[0037] The straight line connecting the leading edge points of the blade in the plane cascade is called the frontal line E. The blade installation angle s is defined as the angle between the blade chord line X and the frontal line E, which indicates the degree of inclination of the blade in the cascade.

[0038] Continue to refer to Figure 2B As shown, the throat width o at the narrowest point has a second intersection point M and a first intersection point N with the first guide blade 1 and the second guide blade 2, respectively. It can be understood that the first intersection point N is the leading edge point of the second guide blade 2. The line formed by the second intersection point M and the leading edge P of the first guide blade 1 where it is located is called the first line Q, and the outlet effective angle α is defined as the angle between the first line Q and the front line E. The first line Q forms a triangle together with the sides where the throat width o and the grid pitch t are located, and the angle β of the triangle is approximately equal to 90°. Since β is approximately equal to 90°, the throat width o can be approximately considered to be equal to t*sin(α), and the difference is negligible.

[0039] Therefore, for the two-dimensional blade section of the blade, when the pitch t is constant, the throat width o can be adjusted by changing the outlet effective angle α.

[0040] It should be noted that, in this embodiment, the blade root region is generally located at 0% to 33% of the blade height, the blade mid-region is generally located at 33% to 66% of the blade height, and the blade tip region is generally located at 66% to 100% of the blade height. However, those skilled in the art will appreciate that the blade root region, blade mid-region, and blade tip region include but are not limited to the above ranges.

[0041] Along the radial direction of the guide blade, a stacking line design is adopted in the form of a spline curve, and a three-dimensional profile is formed by stacking through a stacking axis. The form of the radial stacking curve is not limited to a Bezier curve, a polynomial curve or a combination of several spline curves. The desired throat width radial distribution curve along the blade height is constructed as follows: Figure 3 In this embodiment, the stacking axis of the guide vanes is the center of the leading edge diameter of the guide vanes.

[0042] Multiple two-dimensional blade profiles can be used in the blade root area, the blade middle area and the blade tip area at the blade height to achieve a higher degree of freedom in the control of the radial distribution of the throat width. Since the throat width can guide the flow direction of the high-temperature gas, the throat width of the blade tip area is made larger than the throat width of the blade middle area, such as making the throat width of the blade tip area larger than the throat width of the blade middle area by 15-25%. In this way, the highest temperature high-temperature gas located near 50% of the flow channel height flows toward the blade tip under the guidance of the increased area of ​​the throat width of the blade tip area, thereby guiding the high-temperature core area of ​​the combustion chamber outlet gas to move upward and reduce the incoming flow temperature of the rotor blade root area.

[0043] Preferably, the peak position of the high-temperature gas in the blade height direction is determined; the outlet effective angle of the blade profile located in the middle area of ​​the blade is adjusted so that the minimum throat width is located below the blade height position where the gas has the highest temperature. This design can ensure that most of the high-temperature gas flow discharged from the combustion chamber can be guided by the throat width design and flow toward the blade tip.

[0044] like Figure 3 and Figure 4 As shown in the figure, when the peak temperature position of the high-temperature gas in the combustion chamber is at the 50% flow channel height position, below the 50% flow channel height position, such as above the 45% flow channel height, the outlet effective angle of the blade profile of the guide blade along the blade height direction is gradually increased, so that the throat width is gradually increased along the blade height direction. The trend of the throat width increasing along the blade height direction is a smooth curve, and its slope gradually increases, so that the throat width of the blade tip shaping section is preferably 15% to 25% larger than the blade middle shaping section.

[0045] Therefore, under the guidance of the guide vanes, the gas migrates from the radial height with a small throat width to the radial height with a large throat width. Therefore, the high-temperature core area of ​​the gas discharged from the combustion chamber gradually migrates upward in the process of moving from the leading edge to the trailing edge of the guide vanes, and the radial position of the peak temperature moves to more than 50%. Therefore, the gas temperature in the area below 50% blade height decreases, such as Figure 6 The dotted line represents the gas temperature at the inlet of the guide vane, and the solid line represents the gas temperature at the outlet of the guide vane. It can be seen that after the turbine guide vane is adjusted according to the above design, the temperature distribution curve of the high-temperature gas is significantly moved upward, thereby reducing the incoming flow temperature at the blade root.

[0046] Continue back Figure 3 and Figure 4 As shown, below 50% of the blade height where the highest temperature high-temperature combustion gas is located, such as below 45% of the blade height, the outlet effective angle of the blade profile surface in the blade root area is made greater than the outlet effective angle of the blade profile surface in the blade middle area, so as to increase the throat width of the blade root shaping section, increase the flow rate in the blade root area, and increase the axial velocity of the airflow. The high flow capacity of the lower end area can reduce the aerodynamic loss at the root of the downstream rotor blade, thereby delaying the development of the vortex in the end wall channel of the downstream rotor blade and reducing the aerodynamic loss at the root of the rotor blade, thereby improving the turbine efficiency.

[0047] like Figure 4 and Figure 5 As shown, the radial distribution characteristics of the guide vane installation angle s and the outlet effective angle α are kept consistent, so that the blade profile characteristics of the blade root, blade middle and blade tip regions in the radial direction are similar.

[0048] The guide vane installation angle in the tip area is greater than that in the middle area, and the guide vane installation angle in the root area is greater than that in the middle area. The deviation of the effective outlet angle α of each blade profile in the radial direction is 5° to 10°, and the deviation of the guide vane installation angle s at different radial positions is 3° to 7°.

[0049] The specific value of the guide vane installation angle of the two-dimensional blade and the design of the blade profile profile should take into account the aerodynamic performance of the guide vane and the distribution law of the blade thickness. Along the blade height direction, the blade thickness in the leading edge area of ​​each two-dimensional blade is the same in the radial direction, and the blade thickness in the trailing edge area gradually decreases from bottom to bottom, so as to facilitate the design and installation of the impingement cooling sleeve inside the hollow guide vane.

[0050] The turbine guide vanes that meet the above-mentioned radial distribution of throat width have excellent aerodynamic performance, and can guide the high-temperature core area of ​​the combustion chamber outlet gas to move upward, thereby reducing the incoming flow temperature in the root area of ​​the rotor blades. This area is subjected to high temperature and high centrifugal force at the same time. Reducing the incoming flow temperature of the high-temperature gas at this critical position can increase the strength reserve and service life of the rotor blade roots. At the same time, increasing the flow capacity of the lower end area can reduce the aerodynamic losses at the roots of the downstream rotor blades, thereby taking into account the aerodynamic performance and strength and service life of the rotor blades, and improving the reliability of the blades.

[0051] The height position, number of profile sections and peak position of combustion chamber outlet temperature of the above-mentioned two-dimensional blade profile are only examples and need to be adjusted according to the actual peak position of combustion chamber outlet temperature.

[0052] Combined with the introduction of the above-mentioned turbine guide vane design method, it can also be understood that a turbine, by adjusting the radial position of the two-dimensional modeling section, increasing the number of modeling sections, and the stacking rule along the blade height direction, makes the throat width between adjacent circumferential guide vanes of the turbine present a distribution characteristic of small in the middle and large at both ends along the blade height, the radial height of the smallest throat width is lower than the radial height of the peak temperature of the combustion chamber outlet gas, the throat width of the blade tip area is 15% to 25% greater than the throat width of the blade middle area, and the increase in the throat width of the blade profile surface in the blade tip area relative to the throat width of the blade profile surface in the blade middle area is determined according to the demand for reducing the incoming flow temperature in the root area of ​​the rotor blade. It can be understood that the greater the increase in the throat width of the blade tip area compared to the throat width of the blade middle area, the lower the incoming flow temperature in the root area of ​​the rotor blade.

[0053] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0054] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A turbine guide vane design method for adjusting the temperature distribution of high-temperature combustion gas flow along the blade height direction, characterized in that: The steps include: Selecting a plurality of blade profiles in a blade root region, a blade mid region, and a blade tip region of a turbine guide vane; The effective outlet angle of each blade profile is adjusted, and then the throat width at the blade height where the blade profile is located is adjusted, so that the throat width of the blade tip area is greater than the throat width of the blade mid-area. Among them, the narrowest throat width at the blade height where the blade profile is located has a first intersection and a second intersection with two circumferentially adjacent turbine guide vanes, the first intersection is the leading edge of one of the turbine guide vanes, the second intersection is located at the blade body of the other turbine guide vane, and the angle between the line connecting the second intersection and the leading edge point of the other turbine guide vane and the turbine guide vane forehead line is the outlet effective angle.

2. The turbine guide vane design method according to claim 1, characterized in that: The throat width of the blade tip region is made 15-25% greater than the throat width of the blade mid-region.

3. The turbine guide vane design method according to claim 1, characterized in that: The method further comprises the steps of: Determining the flow channel position of the peak value of the high-temperature fuel gas flow; The minimum throat width is located below the flow channel position of the peak.

4. The turbine guide vane design method according to claim 3, characterized in that: Make the throat width in the blade root area larger than the throat width in the blade mid-section.

5. The turbine guide vane design method according to claim 1, characterized in that: The blade root area is a region of 0% to 33% of the blade height, the blade middle area is a region of 33% to 66% of the blade height, and the blade tip area is a region of 66% to 100% of the blade height.

6. The turbine guide vane design method according to claim 1, characterized in that: The stacked line design is adopted for each blade profile to obtain the three-dimensional profile of the designed guide vane.

7. The turbine guide vane design method according to claim 6, characterized in that: The form of controlling the radial stacking curve includes one or more of Bezier curve, polynomial curve or spline curve.

8. The turbine guide vane design method according to claim 1, characterized in that: The setting range of the outlet effective angle is 5° to 10°.

9. A turbine, comprising turbine guide vanes, characterized in that The throat width between adjacent circumferential guide vanes is configured to be smaller in the middle and larger at both ends along the blade height direction.

10. The turbine according to claim 9, characterized in that The radial height at which the narrowest throat is located is lower than the radial height at which the high-temperature combustion gas peak is located.

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