Power turbine rotor and blade active falling design method thereof

Abstract

The invention discloses a power turbine rotor and a blade active falling-off design method thereof, and relates to the technical field of aero-engines, and the power turbine rotor comprises a turbine disc with a rim cavity formed in the circumferential direction; each blade is provided with a margin plate and a stretching root, the stretching root is located below the margin plate, the stretching root is provided with a weak section, and the blades are connected to a rim cavity of the turbine disc through the stretching root; the air blocking piece is connected to the lower portion of a margin plate of the blade and located on the air inlet side of a rim cavity of the turbine disc, the turbine disc is provided with a first installation part, the margin plate of the blade is provided with a second installation part, and the air blocking piece is connected between the first installation part and the second installation part in a clamped mode. According to the power turbine rotor, the gas blocking piece is additionally arranged on the gas inlet side of the turbine rotor, the situation that fuel gas runs out of the rim cavity is relieved through the gas blocking piece, stability of aerodynamic performance of an engine is ensured by preventing the fuel gas from overflowing, and improvement of the aerodynamic performance of the engine is facilitated.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to a design method for the active shedding of a power turbine rotor and its blades. Background Technology

[0002] During aircraft engine operation, if the power shaft unfortunately breaks, the turbine rotor will continue to spin without load, and its speed will steadily increase. Once the speed exceeds the turbine disk's bursting speed, the turbine disk will explode. The resulting fragments possess enormous kinetic energy, and these fragments could potentially penetrate the engine casing, posing a serious threat to the lives of the passengers. Moreover, the instant the turbine disk explodes, it will cause extremely severe damage to various engine components, and in extreme cases, could even lead to a tragic crash with loss of life.

[0003] Given this critical situation, it is essential to incorporate over-speed protection design for the turbine blades. Once the turbine blades reach a certain speed, a specific design will cause them to detach actively. This will deprive the turbine disk of the power to continue increasing its speed, effectively preventing the more serious accident of turbine disk rupture and maximizing aviation safety.

[0004] For example, Chinese patent document CN103790640B discloses a blade designed to prevent wheel disc from bursting. This blade has a weak section near the outer rim of the wheel disc. When the wheel disc approaches its bursting speed, the blade breaks first at the weak section. The breakage of a single blade will subsequently break other connected blades. After the blade breaks, the wheel disc loses some power, the broken blades hinder the wheel disc's rotation, and the wheel disc vibrates violently due to the broken blades, colliding with stationary engine components. Through these multiple actions, the wheel disc's speed is rapidly reduced, fundamentally preventing the wheel disc from bursting and improving the aircraft's operational safety.

[0005] In existing technologies, turbine rotors are typically assembled and fixed using a locking plate structure. However, due to the presence of assembly gaps, the aerodynamic performance of the turbine is reduced, which in turn adversely affects the thrust-to-weight ratio of the engine. Summary of the Invention

[0006] In view of this, the present invention provides a design method for the active shedding of a power turbine rotor and its blades to solve the problem of reduced turbine aerodynamic performance caused by assembly clearance.

[0007] This invention provides a power turbine rotor, comprising:

[0008] The turbine disk has a circumferentially formed rim cavity; The blade has a rim plate and an extension root, the extension root being located below the rim plate and having a weak section thereon, the blade being connected to the turbine disk circumferentially via the extension root; An air baffle is connected below the rim plate of the blade and located on the air intake side of the rim cavity of the turbine disk. The turbine disk has a first mounting portion, and the rim plate of the blade has a second mounting portion. The air baffle is engaged between the first mounting portion and the second mounting portion.

[0009] The power turbine rotor provided by this invention adds a baffle plate to the intake side of the turbine rotor. The baffle plate alleviates the situation where the gas escapes from the gap between the blade edge plate and the turbine disk. By preventing the gas from overflowing, the stability of the engine's aerodynamic performance is ensured, which is very beneficial to improving the engine's aerodynamic performance.

[0010] After the power turbine rotor reaches a certain speed, the blades can break off actively, thus avoiding the devastating disaster of turbine disk explosion caused by the turbine rotor speed continuously increasing after the engine load shaft breaks. This ensures the safety of the engine and aircraft personnel, while also reducing the difficulty and weight of the casing's impact resistance design, which is conducive to improving the engine's thrust-to-weight ratio and reducing fuel consumption.

[0011] Optionally, the turbine disk has a mounting groove in its circumference, and the mounting groove has a mounting notch.

[0012] Optionally, a locking groove is provided at the mounting notch.

[0013] Optionally, the first mounting part is a first hook with the opening facing the blade, the second mounting part is a second hook with the opening facing the turbine disk, and the baffle plate is engaged between the first hook and the second hook.

[0014] Optionally, the groove cross-section of the second hook has a straight segment of the retaining edge, a first transition arc segment, a connecting straight segment and a second transition arc segment connected in sequence, and the second transition arc segment is connected to the root of the blade.

[0015] The first transition arc segment needs to be designed according to the maximum speed of the turbine rotor and the blade shedding speed of the overspeed protection. According to the speed, the radius of the first transition arc segment is designed to be 0.4-0.8mm. The second transition arc segment is mainly used to reduce the stress concentration at the connection between the first hook and the extension root caused by the centrifugal force of the baffle plate acting directly on the first hook when the turbine rotor rotates at high speed. The larger the second transition arc segment, the smaller the stress concentration at this point. In order to balance the stress concentration and the installation of the baffle plate, the radius of the second transition arc segment in this invention is 0.8-1.2mm.

[0016] Optionally, the second hook is formed below the rim plate of the blade.

[0017] The thickness of the rim plate at the first hook is directly related to whether the blade can withstand the centrifugal load of the baffle at high speeds. Therefore, its thickness needs to be designed according to the blade's detachment speed so that it can withstand the centrifugal load of the baffle without causing excessive bending and tensile stress to the dangerous section of the root extension due to the increase in thickness. Taking all factors into consideration, this patent sets the rim plate thickness at the first hook to be between 2 and 2.4 mm.

[0018] Optionally, the air deflector has multiple sections.

[0019] Optionally, the plurality of air deflectors includes several small air deflectors and at least one large air deflector, wherein the arc length of the large air deflector is greater than the arc length of the small air deflectors, and the large air deflector has a locking strip extending radially.

[0020] Optionally, a shock absorber is connected between the roots of two adjacent blades, and the shock absorber is hidden below the edge plates of the two adjacent blades.

[0021] The present invention places a shock absorber between two blades to reduce the vibration caused by the large gap between the two blades at the root during operation, and at the same time facilitates the positioning of the blades during assembly.

[0022] The present invention also provides a design method for active blade shedding of a power turbine rotor according to any one of the above-mentioned schemes, comprising the following steps:

[0023] The blade fracture speed was calculated using simulation software, and the baffle was applied to the blade hook position in the form of a mass point. Through formula To determine whether the blade has broken; In the above formula, Indicates rotational speed. Indicates the rotational speed Maximum strain of the lower blade This represents the maximum strain at any infinitesimal speed increment; If the above formula is not met, it means that the blade has not broken. In this case, the calculated rotational speed needs to be increased, and the process should be repeated until the formula is met. When the above formula is satisfied, it means that the strain growth rate of the blade is greater than 15% under any small speed increment. At this time, the blade is judged to have failed, and the speed at this time is the blade's fracture speed.

[0024] To prevent turbine rotor over-spinning from causing disk rupture and resulting in serious damage, implementing an active blade shedding design is essential. When the rotor rotates at high speed, the centrifugal load on the baffles is transmitted to the blades, increasing the stress at the blade root and affecting the blade breakage speed. Therefore, the influence of the baffle structure must be considered during the design process.

[0025] The centrifugal force generated by the high-speed rotation of the air deflector acts directly on the blade, causing uneven stress distribution in the weakest section of the blade, which increases the difficulty of designing active blade shedding for overspeed protection. Currently, most existing blade shedding technologies focus on the blade root and blade root section, without considering the influence of the air deflector structure in the design.

[0026] In designing the active blade shedding mechanism, this invention fully considers the influence of the baffle structure, aiming to improve engine aerodynamic performance while enhancing engine safety. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 A front view of a specific embodiment of a power turbine rotor provided in this invention; Figure 2 for Figure 1 The side sectional view of the power turbine rotor shown; Figure 3 for Figure 1 Enlarged side view of the middle blade; Figure 4 for Figure 1 A partially enlarged perspective view of the power turbine rotor shown; Figure 5 for Figure 4 The front view of the small baffle in the power turbine rotor shown; Figure 6 for Figure 4 The front view of the large baffle plate in the power turbine rotor shown; Figure 7 for Figure 6 A three-dimensional view of the large air baffle shown; Figure 8 for Figure 3 A magnified side view of the second hook in the blade shown; Figure 9 for Figure 3A simplified 3D view of the blade structure shown; Figure 10 for Figure 9 The blade shown is in a bottom view; Figure 11 for Figure 2 A perspective view of the shock absorber shown; Figure 12 for Figure 3 A close-up front view of the blade shown; Figure 13 for Figure 12 A magnified view of a portion of region A in the middle.

[0029] Explanation of reference numerals in the attached figures 1. Turbine disk; 101. First hook; 102. Mounting slot; 1021. Mounting notch; 1022. Locking slot; 2. Leaves; 201. Root extension; 2011. First circular arc segment; 2012. Transition straight line segment; 2013. Second circular arc segment; 202. Second hook; 2021. Straight section of the edge guard; 2022. First transition arc section; 2023. Connecting straight section; 2024. Second transition arc section; 203. Edge plate; 3. Air baffle; 301, large air deflector; 3011, locking strip; 302. Small air baffle; 4. Shock-absorbing components. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] In related technologies, the blade 2 and the turbine disk 1 are connected by a tenon and mortise joint. Specifically, the blade 2 has a tenon, and the turbine disk 1 has a mortise. During installation, the tenon is inserted into the mortise.

[0035] However, there is a gap in the fit between the tenon and the mortise. When in use, when the gas escapes from the gap between the blade 2 edge plate 203 and the turbine disk 1, it will cause the aerodynamic performance of the turbine to decrease, thereby affecting the thrust-to-weight ratio of the engine.

[0036] like Figure 1 As shown, this embodiment provides a power turbine rotor, including: a turbine disk 1, blades 2, and baffles 3. The blades 2 have multiple blades, which are respectively connected to the circumference of the turbine disk 1.

[0037] like Figure 2As shown, the air baffle 3 is connected below the rim plate 203 of the blade 2 and is located on the intake side of the rim cavity formed above the turbine disk 1. The turbine disk 1 has a first mounting portion, and the blade 2 has a second mounting portion. The air baffle 3 is snapped between the first mounting portion and the second mounting portion. Specifically, in this embodiment, the first mounting portion is a first hook 101, with its opening facing the blade 2. The second mounting portion is a second hook 202, with its opening facing the turbine disk 1. The air baffle 3 is snapped between the first hook 101 and the second hook 202. Of course, the above description is not limiting. In some alternative embodiments, the first mounting portion and the second mounting portion can be other structures, such as protruding structures. Correspondingly, the air baffle 3 has a groove structure. During installation, the protruding structure is inserted into the groove structure to achieve a snap-fit ​​connection, etc.

[0038] like Figure 3 As shown, the blade 2 has an extension root 201, and the extension root 201 has a weak section. The weak section is designed to facilitate breakage when the speed exceeds the limit.

[0039] The power turbine rotor provided in this embodiment mitigates the situation where gas escapes from the gap between the blade 2 edge plate 203 and the turbine disk 1 through the baffle plate 3. By preventing gas overflow, the stability of the engine's aerodynamic performance is ensured, which is very beneficial to improving the engine's aerodynamic performance.

[0040] After the power turbine rotor reaches a certain speed, the blade 2 can break off actively, thus avoiding the devastating disaster of the turbine disk 1 bursting due to the continuous increase in turbine rotor speed after the load shaft breaks. This ensures the safety of the engine and aircraft personnel, while also reducing the impact resistance design difficulty and weight of the casing, which is conducive to improving the engine thrust-to-weight ratio and reducing fuel consumption.

[0041] like Figure 1 , Figure 4 As shown, the air baffle 3 has multiple pieces, and the turbine disk 1 has a mounting groove 102 in its circumference, with a mounting notch 1021 on the mounting groove 102. During installation, the multiple air baffles 3 are sequentially installed into the mounting groove 102 through the mounting notch 1021.

[0042] like Figure 5 , Figure 6As shown, the multiple air baffles 3 include several small air baffles 302 and one large air baffle 301, with the arc length of the large air baffle 301 being greater than that of the small air baffles 302. A small air baffle 302 can pass through the mounting notch 1021 on the turbine disk 1. During installation, the small air baffle 302 directly passes through the mounting notch 1021 into the mounting groove 102. Finally, the large air baffle 301 is installed; it needs to be elastically deformed before it can pass through the mounting notch 1021 into the mounting groove 102. Specifically, in this embodiment, both types of air baffles 3 have a fan-shaped structure with rounded inner and outer edges. The rounded edges are chamfered, ensuring line contact with the blades 2 during operation. This results in uniform contact, prevents stress concentration, and facilitates movement during installation.

[0043] like Figure 5 , Figure 6 As shown, in this embodiment, both the inner and outer circles of the two types of air baffles 3 are bent. The bending radius is determined according to the width of the mounting groove 102 and the hook groove of the blade 2, which is usually 0.4-0.8mm. The fan-shaped area of ​​the large air baffle 301 is twice the fan-shaped area of ​​the small air baffle 302. The number of small air baffles 302 is set according to the number of blades 2, usually two blades 2 correspond to one small air baffle 302.

[0044] like Figure 4 , Figure 7 As shown, a locking groove 1022 is provided at the installation notch 1021, and a locking strip 3011 extending radially is provided on the large air baffle 301. The large air baffle 301 has a locking strip 3011 pre-reserved on its inner circle. After the large air baffle 301 is installed, the locking strip 3011 can be bent into the locking groove 1022 of the installation notch 1021 to complete the installation of the air baffle 3. This is convenient, quick, and secure.

[0045] like Figure 3 , Figure 8 As shown, the groove cross-section of the second hook 202 has a straight edge segment 2021, a first transition arc segment 2022, a connecting straight segment 2023, and a second transition arc segment 2024 connected in sequence. The second transition arc segment 2024 is connected to the root 201 of the blade 2. The height of the straight edge segment 2021 is 0.3-0.8 mm, the radius of the first transition arc segment 2022 is 0.4-0.8 mm, and the radius of the second transition arc segment 2024 is 0.8-1.2 mm.

[0046] like Figure 9As shown, the second hook 202 is formed below the rim plate 203 of the blade 2. The thickness of the rim plate 203 at the second hook 202 is directly related to whether the blade 2 can withstand the centrifugal load of the baffle plate 3 at high speeds. In this embodiment, the thickness of the second hook 202 is 2-2.4 mm. During the design, the weight and center of mass of the blade 2 above the root 201 section, and the position of the centroid of the root 201 section, are controlled by adjusting the thickness of the rim plate 203, the size of the protrusion, and the hook length of the blade 2.

[0047] like Figure 2 , Figure 10 and Figure 11 As shown, a shock absorber 4 is connected between the roots of two adjacent blades 2, and the shock absorber 4 is hidden below the edge plates 203 of the two adjacent blades 2.

[0048] like Figure 12 , Figure 13 As shown, in this embodiment, the active detachment of blade 2 is designed based on the cross-section of the root 201. The root 201 of blade 2 has two arc segments and one straight segment, specifically including: a first arc segment 2011, a transition straight segment 2012, and a second arc segment 2013. The straight segment is very short, mainly to facilitate casting and machining of blade 2 during manufacturing. The arc segments are used to control the speed of blade 2 by adjusting the cross-sectional area of ​​the root 201 when designing the fracture speed. Specifically, by adjusting the radii of the two arc segments, the position of the straight segment tangent to them is controlled, thereby adjusting the cross-sectional area of ​​the root 201. By adjusting the size of the arc segments of the root 201 and lengthening the straight segment, the stress concentration at the root 201 can be reduced.

[0049] The fracture section designed in this embodiment is the root section 201 of the blade 2. For the turbine rotor blade 2 with the baffle 3, the area of ​​the root section 201, the mass of the part of the blade 2 above the root section 201, and the bending stress brought to the blade 2 by the centrifugal force of the baffle 3 directly acting on the hook groove of the blade 2 during high-speed rotation are all the main factors affecting the fracture speed of the blade 2.

[0050] The power turbine rotor provided in this embodiment is simple to manufacture, easy to process, and convenient to install, which can effectively improve the aerodynamic performance of the engine and increase its safety.

[0051] To avoid the more dangerous accident of turbine disk 1 bursting due to over-revving, the turbine blades 2 need to be designed to actively detach. When the turbine reaches a certain speed, the blades 2 will actively detach, cutting off the power source for the turbine disk 1 to continue to increase its speed, thus protecting the engine and passengers.

[0052] Embodiments of the present invention also provide a method for designing active blade shedding of a power turbine rotor, comprising the following steps: First, the fracture speed of turbine disk 1 and the design speed of turbine rotor are obtained, and the active shedding speed range of turbine blade 2 is initially designed.

[0053] Then, data such as the mechanical properties and stress-strain curves of the turbine blade 2 are obtained, the stress distribution of the blade 2 under the engine design load is calculated, and the strength of key parts such as the hook structure, blade body, extension root 201 and tenon of the blade 2 is checked. Based on the check results, the blade 2 is initially improved as appropriate.

[0054] Then, using the initially improved blade 2 initial model, the initial fracture speed and fracture cross section were calculated and obtained.

[0055] Then, based on the difference between the initial rotational speed and the rotational speed range for active detachment of blade 2, the radii of the first arc segment 2011 and the second arc segment 2013 in blade 2 are adjusted to control the cross-sectional area of ​​the root extension 201. The length of the transition straight segment 2012 remains unchanged. When the area of ​​the arc segment is increased, the cross-sectional area of ​​the root extension 201 is smaller, and the fracture rotational speed decreases until the fracture rotational speed of blade 2 falls within the range of the initially designed active detachment. This method can reduce control parameters, increase design speed, and accelerate the design process when designing the root extension 201 of blade 2.

[0056] To further control the fracture speed range of blade 2, the manufacturing tolerance of blade 2 and the ultimate strength of blade 2 material need to be considered. Therefore, in this embodiment, the upper limit of the fracture speed of blade 2 is determined by considering the upper limit of the manufacturing tolerance of blade 2 and the upper limit of the ultimate strength of the material. The lower limit of the fracture speed of blade 2 is determined by the lower limit of the tolerance of blade 2 and the lower limit of the ultimate strength of the material. When the upper limit speed exceeds the designed speed range, the ultimate strength of the material needs to be controlled to meet the design range.

[0057] like Figure 9 As shown, to simplify the calculation, the tenon teeth of the turbine blade 2 can be simplified, and the blade 3 can be divided into equal parts according to the distribution of the baffles 3, and its weight and center of mass can be measured. The fracture speed of blade 2 was calculated using ANSYS Workbench. The elastic-plastic mechanical properties of the blade 2 material were considered during the calculation. In ANSYS Workbench, the air baffle 3 was applied as a mass point to the hook position of blade 2.

[0058] After constraint simplification, the displacements of the bottom surface of blade 2 in the X, Y, and Z directions are calculated. Material data and rotational speed are applied. The elastic-plastic effect of the material is considered during the calculation. The fracture speed of blade 2 is then calculated. Specifically, through the formula Determine whether blade 2 has broken; In the above formula, Indicates rotational speed. Indicates the rotational speed The maximum strain of the lower blade 2 This represents the maximum strain at any infinitesimal speed increment; If the above formula is not met, it means that blade 2 has not broken. In this case, the calculated rotational speed needs to be increased, and the process should be repeated until the formula is met. When the above formula is satisfied, it means that the strain growth rate of blade 2 is greater than 15% under any small speed increment. At this time, blade 2 is judged to have failed, and the speed at this time is the fracture speed of blade 2.

[0059] The active blade shedding design method for the power turbine rotor provided in this embodiment, compared with other active blade shedding design methods, considers the influence of the baffle plate 3 structure and the centrifugal load of the baffle plate 3 on the fracture speed of the turbine blade 2. It can accurately and effectively design the active shedding speed range of the turbine rotor. Through the measurement of the fracture speed of multiple batches and multiple blades 2, the fracture speed measurement results all fall within the designed active shedding speed range of the rotor, and the design is accurate.

[0060] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A power turbine rotor, characterized in that, include: The turbine disk (1) has a circumferentially formed rim cavity; The blade (2) has a rim plate (203) and an extension root (201), the extension root (201) being located below the rim plate (203), the extension root (201) having a weak section, and the blade (2) being connected to the rim cavity of the turbine disk (1) via the extension root (201); A baffle plate (3) is connected below the rim plate (203) of the blade (2) and located on the air intake side of the rim cavity of the turbine disk (1). The turbine disk (1) has a first mounting part, and the rim plate (203) of the blade (2) has a second mounting part. The baffle plate (3) is snapped between the first mounting part and the second mounting part.

2. The power turbine rotor according to claim 1, characterized in that, The turbine disk (1) has a mounting groove (102) in the circumferential direction, and the mounting groove (102) has a mounting notch (1021).

3. The power turbine rotor according to claim 2, characterized in that, A locking groove (1022) is provided at the installation notch (1021).

4. The power turbine rotor according to claim 1, characterized in that, The first mounting part is a first hook (101), the opening of the first hook (101) faces the blade (2), the second mounting part is a second hook (202), the opening of the second hook (202) faces the turbine disk (1), and the air baffle (3) is engaged between the first hook (101) and the second hook (202).

5. The power turbine rotor according to claim 4, characterized in that, The groove section of the second hook (202) has a straight edge segment (2021), a first transition arc segment (2022), a connecting straight segment (2023) and a second transition arc segment (2024) connected in sequence. The second transition arc segment (2024) is connected to the root (201) of the blade (2).

6. The power turbine rotor according to claim 5, characterized in that, The second hook (202) is formed below the edge plate (203) of the blade (2).

7. The power turbine rotor according to any one of claims 1-6, characterized in that, The air baffle (3) has multiple pieces.

8. The power turbine rotor according to claim 7, characterized in that, The plurality of air deflectors (3) include a plurality of small air deflectors (302) and at least one large air deflector (301), wherein the arc length of the large air deflector (301) is greater than the arc length of the small air deflectors (302), and the large air deflector (301) has a locking strip (3011) extending radially.

9. The power turbine rotor according to any one of claims 1-6, characterized in that, A shock absorber (4) is connected between the roots of two adjacent blades (2), and the shock absorber (4) is hidden below the edge plate (203) of the two adjacent blades (2).

10. A method for designing the active blade shedding of a power turbine rotor according to any one of claims 1-9, characterized in that, Includes the following steps: The fracture speed of the blade (2) was calculated using simulation software, and the baffle plate (3) was applied to the hook position of the blade (2) in the form of a mass point. Through formula Determine whether the blade (2) has broken; In the above formula, Indicates rotational speed. Indicates the rotational speed The maximum strain of the lower blade (2) This represents the maximum strain at any infinitesimal speed increment; If the above formula is not met, it means that the blade (2) has not broken. In this case, the calculated rotational speed needs to be increased. Through continuous attempts, the formula is not met. When the above formula is satisfied, it means that the strain growth rate of the blade (2) is greater than 15% under any small speed increment. At this time, the blade (2) is judged to be in failure, and the speed at this time is the fracture speed of the blade (2).

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