Power turbine blade, power turbine, and gas turbine engine

Abstract

The application discloses a power turbine blade, which comprises a blade body, a blade crown and a tenon, the blade body is composed of a plurality of blade two-dimensional sections which are stacked along a radial stacking line, the blade two-dimensional section comprises a profile centroid F(x, y), a profile area A and a radial height H, the blade body comprises a preset shedding area, a ratio of the radial height of the preset shedding area to the radial height of the blade body is 0.05-0.5, the profile centroid F(x, y) of the blade two-dimensional section in the preset shedding area is distributed in a "<" shape along the radial height direction, the preset shedding area is provided with a blade body maximum section with the largest profile area A and a preset fly-off section for blade fracture, the radial height of the blade body maximum section is higher than that of the preset fly-off section, and a ratio of the radial length of the preset shedding area to the radial length of the blade body is 0.05-0.2. In addition, the application also discloses a power turbine. In addition, the application also discloses a gas turbine engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of turbine blades, in particular, the present application relates to a power turbine blade. In addition, the present application also relates to a power turbine comprising the above-mentioned power turbine blade. In addition, the present application also relates to a gas turbine engine comprising the above-mentioned power turbine. BACKGROUND

[0002] The mechanical overspeed protection function of preventing blade shedding from breaking the disc in an aero-engine or other gas turbine engine, that is, a fly-off section is designed on the power turbine blade, and once the engine loses load, the power turbine blade will be shed at the fly-off section when the turbine rotor overspeeds to a certain speed, so that the disc loses the power to continue to rise in speed, and the damage to the engine caused by the disc overspeed breaking is avoided.

[0003] Chinese invention patent CN 109977537 A proposes a "turbine blade and preparation method of turbine blade", which realizes that when the rotor overspeeds to a certain speed, the blade is broken at the mortise joint part section to fly off, so that the turbine rotor loses the ability to continue to accelerate, and then the disc speed continues to rise to the breaking speed, which leads to the disc breaking. However, in this scheme, the fly-off section of the turbine blade is selected at the blade mortise part, which makes the broken blade contain the complete blade body, the lower edge plate and part of the mortise, resulting in the large weight of the broken blade and high kinetic energy. In order to avoid the fly-off blade from penetrating the casing, the thickness of the casing must be increased to improve the casing containment. At the same time, the fly-off section is selected at the mortise part, so that the length of the mortise part of the blade needs to be appropriately increased to arrange the fly-off section when designing, which also leads to the increase of the weight of the blade itself. On the other hand, in order to maintain the speed margin between the shedding speed of the turbine blade and the breaking speed of the disc, this design also needs to widen and thicken the disc to increase the breaking speed of the disc, so as to realize that the breaking speed of the disc is higher than the breaking speed of the blade, which will lead to the increase of the weight and size of the disc, and the increase of the weight and processing cost of the power turbine.

[0004] Chinese invention patent CN110185498A proposes a "design method for anti-disk burst blades and their weak structures," which provides a method to prevent disk bursting by setting weak structures on the blade body of a power turbine, thereby ensuring that the blade breaks off and flies away before the disk. Compared with Chinese invention patent CN 109977537 A, this method can reduce the mass of the broken and flyaway blade, reduce the kinetic energy of the broken blade, and avoid the consequences of disk bursting that could damage the engine. However, this patent only proposes a design method for the weak structure of the flyaway blade from the perspective of structural strength, without mentioning the function of organizing fluid flow and realizing power extraction and output conversion that turbine blades should first achieve. Furthermore, since this patent ensures blade flyaway at the bursting speed by changing the distribution of blade weight along the blade height and changing the tensile stress, this method has a significant impact on the blade shape, increasing blade flow losses and reducing turbine performance. In addition, the flyaway design of the blade may also bring certain problems, especially for the first-stage working blades of a power turbine with low tensile stress, which may lead to failure of the flyaway design or excessive disk weight. Therefore, although the turbine blades designed using this method can meet the blade fly-off design requirements, the turbine performance is reduced because the blades are not designed in the most or best way, and the blade shape design does not meet the airflow organization requirements. This leads to performance and life problems in the engine, such as high fuel consumption, exhaust overheating, and blade erosion. Summary of the Invention

[0005] This invention provides a power turbine blade and its gas turbine engine to solve the technical problem that existing power turbine blades cannot accurately meet the requirements of structural strength and blade fly-off while minimizing or eliminating the impact on turbine aerodynamic performance.

[0006] According to one aspect of the present invention, a power turbine blade is provided, comprising a blade body, a blade crown, and a tenon. The blade body is composed of a plurality of blade two-dimensional cross-sections stacked along a radial stacking line. The blade two-dimensional cross-section includes a profile center F(x, y), a profile area A, and a radial height H. The blade body includes a predetermined detachment region. The ratio of the radial height of the predetermined detachment region to the radial height of the blade body is 0.05-0.5. The profile center F(x, y) of the blade two-dimensional cross-sections within the predetermined detachment region is distributed in a "<" shape along the radial height direction. The predetermined detachment region is provided with a maximum blade body cross-section with the largest profile area A and a predetermined fly-off cross-section for blade breakage. The radial height of the maximum blade body cross-section is higher than the radial height of the predetermined fly-off cross-section. The ratio of the radial length of the predetermined detachment region to the radial length of the blade body is 0.05-0.2.

[0007] As a further improvement to the above technical solution:

[0008] Furthermore, the ratio of the leaf root cross-sectional area to the leaf tip cross-sectional area is 1.5-1.8.

[0009] Furthermore, the ratio of the maximum cross-sectional area Amax of the blade to the cross-sectional area of ​​the blade root is 1.0-1.02.

[0010] Furthermore, the blade also includes a first region located between the lower edge section of the preset detachment area and the root section of the blade, and a second region located between the upper edge section of the preset detachment area and the tip section of the blade. The surface area A in the first region remains constant or decreases from the tip to the root. The surface area A in the preset detachment area first increases in area and then decreases or remains constant from the tip to the root. The surface area A in the second region gradually increases in area from the tip to the root.

[0011] Furthermore, the centroids of the lower and upper sections of the detachment area are located in the same position in the X direction, and the distance between the centroid of the detachment section and the centroids of the lower and upper sections of the detachment area in the X direction is ΔX, with ΔX ranging from 0.1 to 0.2.

[0012] Furthermore, the distance between the centroids of the two-dimensional cross sections and the centroids of the fly-off cross sections of each blade in the second region in the X direction is less than ΔX.

[0013] Furthermore, the centroids of the lower and upper sections of the detachment area are in the same position in the Y direction, and the distance between the centroid of the fly-off section and the centroids of the lower and upper sections of the detachment area in the Y direction is ΔY. The distance between the centroids of the two-dimensional sections of each blade and the centroids of the fly-off section in the Y direction in the second region is less than ΔY.

[0014] Furthermore, the ratio of the radial height of the tenon to the radial height of the power turbine blade is 0.08-0.13.

[0015] According to another aspect of the present invention, a power turbine is also provided, which includes the aforementioned plurality of power turbine blades uniformly arranged circumferentially.

[0016] According to another aspect of the invention, a gas turbine engine is also provided, which includes the aforementioned power turbine.

[0017] The present invention has the following beneficial effects:

[0018] The power turbine blade of this invention features a pre-defined detachment area positioned on the blade body, eliminating the need for an extension root area on the tenon. This effectively reduces the tenon size and the weight of the power turbine blade. Furthermore, a suitable value can be selected based on the impact of the kinetic energy of the detached blade on the casing's containment capacity and the ratio of the radial height of the remaining blade body to the radial height of the pre-defined detachment area (0.05-0.5), preventing the detached blade from penetrating the casing. The power turbine blade is first iteratively designed based on fluid simulation results in an aerodynamically optimal manner. Then, the centroid F(x, y) of the blade's two-dimensional cross-section within the pre-defined detachment area is adjusted to create a "<" shape along the radial height, increasing the bending stress of the detachment section. Since the ratio of the radial length of the pre-defined detachment area to the radial length of the blade body is only 0.05-0.2, the two-dimensional cross-section of the blade is locally adjusted. The profile center F(x, y) of the blade has a relatively small impact on the shape of the turbine blade, which helps to reduce blade loss and meets the airflow organization requirements of the turbine blade. The radial height of the maximum cross section of the blade is higher than the radial height of the preset fly-off section, so as to increase the blade weight above the fly-off section and reduce the tensile strength at the fly-off section. Combined with the precise adjustment of the profile center F(x, y) of the preset detachment area, the bending stress and tensile stress at the fly-off section are increased simultaneously, ensuring that the turbine blade breaks and flies off at the set speed. Moreover, it has fewer restrictions on the blade cross section design. Therefore, it can meet the design requirements of any turbine blade, especially the first-stage working blade of the turbine. Compared with the existing technology, it reduces blade loss, meets the airflow organization requirements of the turbine blade, and precisely meets the blade fly-off requirements. It is highly practical and suitable for widespread promotion and application.

[0019] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a schematic diagram of the structure of a power turbine blade in the prior art;

[0022] Figure 2 This is a schematic diagram of the structure of a power turbine blade according to a preferred embodiment of the present invention;

[0023] Figure 3 This is a diagram showing the distribution pattern of the two-dimensional cross-sectional area of ​​each blade within the blade body along the radial height direction, according to a preferred embodiment of the present invention.

[0024] Figure 4 This is a diagram showing the distribution pattern of the centroids of the two-dimensional cross sections of each blade within the blade body in the X direction along the radial height direction, according to a preferred embodiment of the present invention. Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0026] Figure 1 This is a schematic diagram of the structure of a power turbine blade in the prior art; Figure 2 This is a schematic diagram of the structure of a power turbine blade according to a preferred embodiment of the present invention; Figure 3 This is a diagram showing the distribution pattern of the two-dimensional cross-sectional area of ​​each blade within the blade body along the radial height direction, according to a preferred embodiment of the present invention. Figure 4 This is a diagram showing the distribution pattern of the centroids of the two-dimensional cross sections of each blade within the blade body in the X direction along the radial height direction, according to a preferred embodiment of the present invention.

[0027] like Figures 1-4As shown, the power turbine blade of this embodiment includes a blade body, a blade crown, and a tenon. The blade body is composed of multiple blade two-dimensional cross-sections stacked along a radial stacking line. The blade two-dimensional cross-section includes a profile center F(x, y), a profile area A, and a radial height H. The blade body includes a preset detachment area. The ratio of the radial height of the preset detachment area to the radial height of the blade body is 0.05-0.5. The profile center F(x, y) of the blade two-dimensional cross-sections in the preset detachment area is distributed in a "<" shape along the radial height direction. The preset detachment area has a maximum blade body cross-section with the largest profile area A and a preset fly-off cross-section for blade breakage. The radial height of the maximum blade body cross-section is higher than the radial height of the preset fly-off cross-section. The ratio of the radial length of the preset detachment area to the radial length of the blade body is 0.05-0.2. Specifically, in the power turbine blade of this invention, a pre-defined detachment area is arranged on the blade body, eliminating the need for an extension root area on the tenon, thereby effectively reducing the tenon size and the weight of the power turbine blade. Furthermore, a suitable value can be selected based on the influence of the kinetic energy of the detached power turbine blade on the casing's containment capacity and the ratio of the radial height of the remaining blade body to the radial height of the pre-defined detachment area (0.05-0.5), to prevent the detached power turbine blade from penetrating the casing. The power turbine blade can first be iteratively designed based on fluid simulation results in an aerodynamically optimal manner. Then, by adjusting the centroid F(x, y) of the blade's two-dimensional cross-section within the pre-defined detachment area, it is distributed in a "<" shape along the radial height direction to increase the bending stress of the detachment section. Since the ratio of the radial length of the pre-defined detachment area to the radial length of the blade body is only 0.05-0.2, local adjustments to the blade... The centroid F(x, y) of the two-dimensional cross-section has a relatively small impact on the shape of the turbine blade, which helps to reduce blade loss and meets the airflow organization requirements of the turbine blade. The radial height of the maximum cross-section of the blade body is higher than the radial height of the preset fly-off section to increase the blade weight above the fly-off section and reduce the tensile strength at the fly-off section. Combined with the precise adjustment of the centroid F(x, y) of the preset detachment area, the bending stress and tensile stress at the fly-off section are increased simultaneously, ensuring that the turbine blade breaks and flies off at the set speed. Moreover, it has fewer restrictions on the blade cross-section design. Therefore, it can meet the design requirements of any turbine blade, especially the first-stage working blade of the turbine. Compared with the existing technology, it reduces blade loss, meets the airflow organization requirements of the turbine blade, and precisely meets the blade fly-off requirements. It is highly practical and suitable for widespread promotion and application. It should be understood that the fracture speed of the fly-off section on the power turbine blade mainly depends on the equivalent stress σ of the blade body at that point. The equivalent stress σ = σ1 + σ2, where σ1 is the tensile stress. According to the formula σ1 = mrω2 / A, m is the mass of the turbine blade that flies off from the fracture section, r is the radius height of the fracture section, ω is the turbine rotor speed, and A is the area of ​​the fracture section.σ2 is the bending stress, which can be calculated by the bending moment on the blade using the finite element method. The bending moment on the blade is composed of the load on the blade multiplied by the deviation of the blade profile center in the X direction ΔX, plus the load on the blade multiplied by the deviation of the blade profile center in the Y direction ΔY. Therefore, by making the surface center F(x, y) of the blade's two-dimensional cross-section in the preset detachment area distributed in a "<" shape along the radial height direction, the bending stress σ2 on the blade at the detachment section can be increased. Since the maximum cross-sectional area of ​​the blade is located above the detachment section, the tensile stress σ1 on the blade at the detachment section also increases, thereby simultaneously increasing the tensile stress and bending stress at the detachment section. It should be understood that the radial height of the first-stage working blade of the power turbine is smaller than that of the blades in subsequent stages, resulting in a lower blade weight and relatively lower tensile stress above the flyoff section. This leads to a higher flyoff speed for the blades compared to the blades in subsequent stages. If existing power turbine blades are used, simply changing the geometry of the flyoff section to increase tensile stress may not meet the flyoff design requirements of this stage of turbine blades, or may cause flyoff failure, over-rotation and breakage of the turbine disk, endangering the safe operation of the turbine and engine. This embodiment, by combining the increase of tensile stress and bending stress, can effectively meet the flyoff requirements of the first-stage working blade of the power turbine at the fracture speed. It should be understood that the radial direction and the radial height direction of the blade are equivalent. It should be understood that the preset flyoff section refers to the section at which the blade breaks and flies off at a set speed.

[0028] In this embodiment, the ratio of the blade root cross-sectional area to the blade tip cross-sectional area is 1.5-1.8. Specifically, when the ratio is between 1.5 and 1.8, the blade root strength requirements are met while reducing airfoil losses, achieving optimized aerodynamic performance design. When the ratio is less than 1.5, the blade root area is too small, resulting in high root stress and difficulty in meeting blade strength and life requirements. When the ratio is greater than 1.8, the root area is too large, leading to heavy blade weight, significant airfoil losses, and an inability to achieve optimal aerodynamic performance design. It should be understood that a smaller blade cross-sectional area is beneficial for reducing airfoil losses, and since airfoil losses are the main source of flow losses in power turbines, a smaller blade cross-sectional area and a more suitable stacking pattern are more conducive to reducing two-dimensional airfoil losses and three-dimensional secondary flow losses, thereby improving turbine efficiency. It should be understood that, in order to simultaneously meet the requirements of structural strength and aerodynamic performance, the ratio of the root cross-sectional area to the tip cross-sectional area of ​​conventional power turbine blades is generally greater than 2.0.

[0029] In this embodiment, the ratio of the maximum cross-sectional area Amax of the blade to the cross-sectional area of ​​the blade root is 1.0-1.02. Specifically, by reducing the cross-sectional area, the blade strength reserve in the area below the maximum cross-sectional area Amax is reduced, thereby lowering the blade breakage speed. At the same time, controlling the cross-sectional area ratio below 1.02 ensures that the blade strength reserve does not decay too quickly, keeping the blade life within the required range.

[0030] In this embodiment, the blade also includes a first region located between the lower edge section of the preset detachment area and the leaf root section of the blade, and a second region located between the upper edge section of the preset detachment area and the leaf tip section of the blade. The surface area A in the first region remains constant or decreases from the leaf tip to the leaf root. The surface area A in the preset detachment area first increases in area and then decreases or remains constant from the leaf tip to the leaf root. The surface area A in the second region gradually increases in area from the leaf tip to the leaf root. Specifically, although the surface area A in the first region remains constant or decreases from the blade tip to the blade root, resulting in higher tensile stress at the blade root, the difference in tensile stress is not significant because the reduction in the blade cross-sectional area does not exceed 2%. Furthermore, since the centroid of the pre-set detachment area is arranged in a "<" shape, the eccentricity of the centroid of the two-dimensional cross-section of each blade in the first region gradually decreases, resulting in lower bending stress at the blade root. Thus, they work together to ensure that the equivalent stress borne by the two-dimensional cross-section of each blade in the first region is less than the equivalent stress of the detachment cross-section, meeting the detachment requirements and strength and life requirements of the power turbine blade. In the second region, the surface area A gradually increases from the blade tip to the blade root, resulting in greater strength of the blades in the second region along the blade tip to the blade root direction. The equivalent stress borne by the two-dimensional cross-section of each blade in the second region is less than that of the detachment cross-section, meeting the detachment requirements and strength and life requirements of the power turbine blade.

[0031] In this embodiment, the centroids of the lower and upper cross sections of the detachment area are located at the same position in the X direction. The distance between the centroid of the detachment cross section and the centroids of the lower and upper cross sections of the detachment area in the X direction is ΔX, where ΔX ranges from 0.1 to 0.2. Specifically, when ΔX is between 0.1 and 0.2, the maximum displacement of the two-dimensional cross sections of each blade within the preset detachment area is small, ensuring a smooth connection between the first region, the preset detachment area, and the second region of the blade body, preventing excessive distortion of the entire blade surface and thus affecting the aerodynamic performance of the blade.

[0032] In this embodiment, the distance in the X direction between the centroids of the two-dimensional cross sections and the centroids of the fly-off cross sections of each blade in the second region is less than ΔX. Specifically, because the distance in the X direction between the centroids of the two-dimensional cross sections and the centroids of the fly-off cross sections of each blade in the second region is less than ΔX, the centroid of the two-dimensional cross section of each blade in the second region deviates less from the centroid of the fly-off cross section, resulting in relatively smaller bending stress. Consequently, the equivalent stress borne by the two-dimensional cross sections of each blade in the second region is less than that of the fly-off cross section, thus meeting the fly-off requirements and strength and life requirements of the power turbine blade.

[0033] In this embodiment, the centroids of the lower and upper cross sections of the detachment area are at the same position in the Y direction. The distance between the centroid of the fly-off section and both the centroids of the lower and upper cross sections of the detachment area in the Y direction is ΔY. The distance between the centroids of the two-dimensional cross sections of each blade in the second region and the centroids of the fly-off section in the Y direction is less than ΔY. Specifically, because the distance between the centroids of the two-dimensional cross sections of each blade in the second region and the centroids of the fly-off section in the Y direction is less than ΔY, the centroid of the two-dimensional cross section of each blade in the second region deviates less from the blade centroid relative to the centroid of the fly-off section, resulting in relatively smaller bending stress. Consequently, the equivalent stress borne by the two-dimensional cross sections of each blade in the second region is less than that of the fly-off section, thus meeting the fly-off requirements and strength and life requirements of the power turbine blade.

[0034] In this embodiment, the ratio of the radial height of the tenon to the radial height of the turbine blade is 0.08-0.13. Specifically, when the ratio is between 0.08 and 0.13, the tenon is small, which helps reduce the weight of the turbine blade, while the tenon strength is appropriate. When the ratio is less than 0.08, the tenon strength is too low. When the ratio is greater than 0.13, the tenon is too large and cannot reduce the weight of the turbine blade.

[0035] It should be understood that, in this embodiment, the two-dimensional cross-section of the blade includes the upper edge cross-section of the preset detachment area, the lower edge cross-section of the preset detachment area, the detachment cross-section, the root cross-section of the blade body, and the tip cross-section of the blade body.

[0036] The power turbine in this embodiment includes multiple power turbine blades arranged circumferentially as described in any of the above embodiments. Specifically, while power transmission is achieved through multiple power turbine blades, the blade profile loss is small, meeting airflow organization requirements, resulting in high power turbine efficiency. Simultaneously, it precisely meets the fly-off requirements of the power turbine at a set speed, preventing engine disc over-rotation and breakage, and casing failure.

[0037] The gas turbine engine of this embodiment includes the power turbine of any of the above embodiments. Specifically, by using the above-mentioned power turbine for power transmission, the transmission efficiency is high and the engine safety is good.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A power turbine blade, comprising a blade body, a blade crown, and a tenon, wherein the blade body is composed of multiple blade two-dimensional cross-sections stacked along a radial stacking line, and the blade two-dimensional cross-section includes a profile centroid F(x, y), a profile area A, and a radial height H, characterized in that, The blade includes a pre-defined detachment area. The ratio of the radial height of the pre-defined detachment area to the radial height of the blade is 0.05-0.

5. The centroid F(x, y) of the two-dimensional cross-section of the blade within the pre-defined detachment area is distributed in a "<" shape along the radial height direction. The pre-defined detachment area has a maximum blade cross-section with the largest surface area A and a pre-defined fly-off cross-section for blade breakage. The radial height of the maximum blade cross-section is higher than the radial height of the pre-defined fly-off cross-section. The ratio of the radial length of the pre-defined detachment area to the radial length of the blade is 0.05-0.

2.

2. The power turbine blade according to claim 1, characterized in that, The ratio of the cross-sectional area of ​​the leaf root to the cross-sectional area of ​​the leaf tip is 1.5-1.

8.

3. The power turbine blade according to claim 1, characterized in that, Maximum cross section A of the blade max The ratio of the leaf root cross-sectional area to the leaf blade area is 1.0-1.

02.

4. The power turbine blade according to any one of claims 1-3, characterized in that, The blade also includes a first region located between the lower edge section of the preset detachment area and the leaf root section of the blade, and a second region located between the upper edge section of the preset detachment area and the leaf tip section of the blade. The surface area A in the first region remains constant or decreases from the leaf tip to the leaf root. The surface area A in the preset detachment area first increases in area and then decreases or remains constant from the leaf tip to the leaf root. The surface area A in the second region gradually increases in area from the leaf tip to the leaf root.

5. The power turbine blade according to any one of claims 1-3, characterized in that, The centroids of the lower and upper sections of the detachment area are in the same position in the X direction. The distance between the centroid of the detachment section and the centroids of the lower and upper sections of the detachment area in the X direction is ΔX, and the value of ΔX is 0.1-0.

2.

6. The power turbine blade according to claim 5, characterized in that, In the second region, the distance between the centroids of the two-dimensional cross sections and the centroids of the fly-off cross sections of each blade in the X direction is less than ΔX.

7. The power turbine blade according to any one of claims 1-3, characterized in that, The centroids of the lower and upper sections of the detachment area are in the same position in the Y direction. The distance between the centroid of the fly-off section and the centroids of the lower and upper sections of the detachment area in the Y direction is ΔY. The distance between the centroids of the two-dimensional sections of each blade and the centroids of the fly-off section in the Y direction in the second region is less than ΔY.

8. The power turbine blade according to any one of claims 1-3, characterized in that, The ratio of the radial height of the tenon to the radial height of the power turbine blade is 0.08-0.

13.

9. A power turbine, characterized in that, It includes a plurality of power turbine blades as described in any one of claims 1-8, which are evenly arranged circumferentially.

10. A gas turbine engine, characterized in that, Including the power turbine as described in claim 9.

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