Method for determining weakest bird strike part of aero-engine fan rotor blade

Abstract

The invention discloses a method for determining the weakest bird strike part of a fan rotor blade of an aero-engine. The method comprises the following steps: acquiring blade parameters, setting the axial relative speed of a bird body and the radial rotation radius of a strike position, establishing a fan blade bird strike mathematical model, and outputting the relative strike speed between the bird body and the blade; setting bird body parameters, constructing a cylindrical bird body model, and calculating the maximum bird body impact mass; calculating impact kinetic energy in combination with the relative impact speed; constructing bird strike equivalent stress, obtaining standard bird strike equivalent stress, and drawing a standard equivalent stress C-R distribution curve; and in the C-R distribution curve, the position of the radial rotation radius corresponding to the maximum equivalent stress on the blade is determined as the weakest bird impact part. According to the method, quick and quantitative identification of the weak bird impact area of the fan blade under various flight conditions is realized, the design of a bird impact resistant structure and the formulation of a whole machine bird swallowing test scheme can be effectively guided, and the method is high in engineering practicability, high in analysis efficiency and wide in adaptability.

Description

Technical Field

[0001] This invention relates to the field of bird strike testing technology for aero-engines, and specifically to a method for determining the weakest point of an aero-engine fan rotor blade during a bird strike. Background Technology

[0002] Aircraft engines may encounter bird strikes during flight, which seriously threaten the flight safety and structural integrity of the aircraft. When a bird enters the engine intake, it first collides violently with the high-speed rotating fan rotor blades, generating transient high-energy impact loads. This can easily cause localized plastic deformation, crack propagation, or even fracture of the blades, leading to a sudden drop in engine thrust, excessive vibration, and in extreme cases, in-flight engine failure or other major flight accidents. Therefore, military and civil aviation airworthiness regulations in various countries have imposed stringent whole-engine bird strike tests on aircraft engines to verify their structural integrity and functional continuity under typical bird strike conditions. As modern aero-engine propulsion systems evolve towards higher thrust-to-weight ratios and higher bypass ratios, fan rotor blades commonly employ advanced aerodynamic designs such as thinner walls, higher aspect ratios, and larger twist angles to improve aerodynamic efficiency and thrust-to-weight ratio. However, while these structures enhance performance, they also reduce overall blade stiffness and increase dynamic response sensitivity, posing greater challenges to bird strike resistance. Furthermore, the continuous improvement of the ecological environment in recent years has led to an expansion of bird habitats around airports and a significant increase in bird populations, further increasing the probability of bird strikes during aircraft takeoff and landing. These factors have collectively driven the rapid development of aero-engine bird strike resistance analysis technology. To ensure the effectiveness of testing, relevant airworthiness regulations explicitly require that birds be thrown at the "critical parts" or "weakest points" of engine or fan rotor blades. For example, the "General Specifications for Aircraft Turbojet and Turbofan Engines (GJB 241A-2010)" stipulates that "birds weighing over 1000g should be aimed at critical areas on the front of the engine"; the "Requirements for Bird Ingestion Tests of Aircraft Engines (GJB3727-1999)" states that "medium and large birds should be aimed at the weakest point of the engine subjected to bird strikes under the test conditions"; and the Chinese Civil Aviation Regulations (CCAR-33-R2 Airworthiness Regulations for Aircraft Engines) also require that in large and medium bird ingestion tests, the bird should be thrown at the "most critical exposure location" of the first-stage rotor blades, emphasizing the need to consider "any critical strike location." However, while the aforementioned airworthiness regulations provide qualitative guidance on the strike area for bird strike tests, they do not provide a clear definition of "critical area" or "weakest point," nor do they offer an operational technical path for determining this location. This technical gap leads to the fact that in practical engineering applications, the selection of the test strike point often relies on design experience, geometric symmetry assumptions, or repeated nonlinear transient simulation calculations, lacking scientific basis and affecting the validity and repeatability of the test results.

[0003] Existing technologies typically employ the following methods when analyzing the weakest points of fan blades during bird strikes: (1) making empirical judgments based on blade geometry (such as leading edge curvature and chord length distribution); (2) determining stress concentration areas based on static strength analysis results; and (3) simulating the degree of local damage under a single working condition using finite element simulation. However, these methods have significant limitations: First, they only consider single structural parameters or static load conditions, failing to comprehensively reflect the coupling effects of multiple key factors such as bird mass, aircraft flight speed, engine speed, impact phase, and local blade thickness; second, they do not establish a quantitative correlation model between energy input and structural impact resistance, making it difficult to compare the degree of damage under different working conditions; and third, traditional simulation methods are computationally expensive and time-consuming, making it difficult to support rapid evaluation of multiple scenarios. In particular, research shows that the engine fan speed and aircraft flight speed differ significantly at different flight stages (such as takeoff, cruise, and glide), causing changes in the distribution of impact loads on the blades, which in turn causes a shift in the spatial position of the weakest point. If a fixed impact position is still used for testing, the actual danger zone may not be covered, seriously affecting the adequacy of airworthiness verification.

[0004] In summary, there is currently a lack of a multi-factor coupled model that can comprehensively consider flight conditions, engine operating parameters, bird characteristics, and blade structural features to quickly, accurately, and quantitatively identify the weakest points of aero-engine fan rotor blades under different operating conditions caused by bird strikes. Therefore, there is an urgent need to propose a scientific, systematic, and engineering-implementable technical solution for determining the weakest points of blades under bird strikes, providing theoretical basis and technical support for bird strike resistant structural optimization design and the development of whole-aircraft bird ingestion test schemes. Summary of the Invention

[0005] To address the shortcomings of existing technologies in determining the weakest point of a fan blade during a bird strike, which lack comprehensive consideration of flight conditions, engine operating parameters, bird characteristics, and blade structural features, leading to inaccurate identification of the weakest point and failure to cover the actual danger zone, thus seriously affecting the adequacy of airworthiness verification, this invention provides a method for determining the weakest point of an aero-engine fan rotor blade during a bird strike, comprising the following steps: Obtain blade parameters and set the axial relative velocity of the bird entering the fan rotor intake under the current operating conditions. and the radial rotation radius at the impact location A mathematical model of bird strikes on fan blades is established, which is used to output the relative impact velocity between the bird and the blade. The blade parameters include the blade angular velocity. Number of leaves Leading edge structural angle of blade and the leading edge thickness Q; By setting the bird's body parameters and constructing a cylindrical bird model using 3D modeling software, and combining the blade parameters and axial relative velocity... Calculate the maximum bird impact mass that a single blade may strike under the current operating conditions. The bird's body parameters include its mass. and density ; Based on the relative impact velocity and the largest bird impact mass Calculate the impact kinetic energy of the bird on the blade at a specified radial position under the current operating conditions. ; Based on the blade parameters and impact kinetic energy Constructing bird strike equivalent stress Then, the equivalent stress of a standard bird strike was obtained. Combined with the radial rotation radius Plot the standard equivalent stress CR distribution curve under the current working condition; Based on the CR distribution curve, the weakest point of the bird strike under the current operating condition is determined; the weakest point of the bird strike is the equivalent stress of the standard bird strike in the CR distribution curve under the current operating condition. The radial rotation radius corresponding to the maximum point Position on the leaf.

[0006] Furthermore, the process of constructing the mathematical model for bird strikes on the fan blades includes: According to the blade angular velocity and radial rotation radius Obtain the blade linear velocity at the impact location. ; Combined with the construction angle of the blade leading edge Construct a mathematical model of bird strike on the fan blades and output the relative impact velocity between the bird and the blades. The mathematical model for the bird strike on the fan blades is expressed as follows: .

[0007] Furthermore, the method for constructing the cylindrical bird model includes: Based on the bird's body mass and bird body density Determine the length of the cylindrical bird model. ; By setting the aspect ratio, the diameter of the cylindrical bird model is determined. The aspect ratio is the length. With diameter The proportion; According to the length and diameter The cylindrical bird model was constructed using 3D modeling software.

[0008] Furthermore, the maximum bird impact mass that the single blade may strike. The calculation expression is: .

[0009] Furthermore, the impact kinetic energy The calculation expression is: .

[0010] Furthermore, the bird strike equivalent force The calculation expression is: .

[0011] Furthermore, the standard bird strike equivalent force The calculation expression is: ; Among them, the standard bird strike equivalent force The value is between 0 and 1, with a maximum value of 1; This indicates that, under the same flight phase and the same blade material conditions, all calculated positions are within the same range. The peak value.

[0012] Furthermore, the standard bird strike equivalent stress is present in all operating conditions. When 1 is reached, the radial rotation radius corresponding to the CR distribution curve is... The locations on the leaves were all the weakest points affected by the bird strike.

[0013] The beneficial effects of this invention are as follows: This invention comprehensively considers flight conditions, engine operating parameters, bird characteristics, and blade structural features. By establishing a mathematical model of bird strike involving fan blades and a cylindrical bird model, it obtains the relative impact velocity and the maximum bird impact mass, calculates the impact kinetic energy, and constructs a standard bird strike equivalent stress. Based on this, it plots the standard equivalent stress CR distribution curve under the current operating conditions. By analyzing the CR distribution curve, it determines that the radial rotation radius on the blade corresponding to the point of maximum equivalent stress on the CR curve is the weakest point in the bird strike. This enables rapid and quantitative identification of weak areas of fan blades under various flight conditions, effectively guiding the design of anti-bird strike structures and the formulation of whole-aircraft bird ingestion test schemes. It has the advantages of strong engineering practicality, high analytical efficiency, and wide adaptability. Attached Figure Description

[0014] Figure 1 This is a flowchart of the method for determining the weakest point of an aero-engine fan rotor blade in a bird strike, provided by the present invention. Figure 2This is a right view of the theoretical analysis of the impact between the blade and the bird provided by this invention; Figure 3 This is a top view of the theoretical analysis of the impact between the blade and the bird provided by this invention; Figure 4 This is a schematic diagram showing the relative impact velocity between the bird and the fan blades provided by the present invention; Figure 5 This is a schematic diagram of the frontal structure of the bird's body and the leaf during impact, provided by the present invention. Figure 6 The bird's body and the leaf, as provided by this invention, during impact A top view of the structure at any given moment; Figure 7 The bird's body and the leaf, as provided by this invention, during impact A top view of the structure at any given moment; Figure 8 These are the four typical flight conditions provided by this invention. Distribution curve. Detailed Implementation

[0015] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0016] This invention provides a method for determining the weakest point of aero-engine fan rotor blades in the event of a bird strike, such as... Figure 1 As shown, it includes the following steps: Step S100: Obtain blade parameters and set the axial relative velocity of the bird entering the fan rotor intake under the current operating conditions. and the radial rotation radius at the impact location A mathematical model of bird strikes on fan blades is established, which is used to output the relative impact velocity between the bird and the blade. The blade parameters include the blade angular velocity. Number of leaves Leading edge structural angle of blade and the leading edge thickness Q; The process of constructing the mathematical model for bird strikes on the fan blades includes: According to the blade angular velocity and radial rotation radius Obtain the blade linear velocity at the impact location. ; Combined with the construction angle of the blade leading edge Construct a mathematical model of bird strike on the fan blades and output the relative impact velocity between the bird and the blades. The mathematical model for the bird strike on the fan blades is expressed as follows: (1) Specifically, based on the angular velocity of the fan blades The motion state of the bird rotating around the engine axis, setting the relative speed of the bird's body along the axial direction relative to the aircraft. The air entered the intake manifold, and the impact point was located at a radius of [missing information - likely a distance from the pivot point]. The radial point where the angle between the mid-curve of the blade's leading edge and the engine axis is the blade's leading edge configuration angle. (i.e., the complementary angle of the blade's geometric inlet angle). Relative impact velocity. Take the axial relative velocity of the bird's body With blade linear velocity ( The projection interpolation in the leaf basin normal direction, since the impact is mainly dominated by the transfer of normal momentum, yields the relative impact velocity between the bird and the leaf through equation (1). The aforementioned mathematical model of bird strike on fan blades comprehensively reflects the influence of aircraft flight speed, engine speed, impact radial position, and blade profile on impact intensity.

[0017] Step S200: Set the bird body parameters, construct a cylindrical bird body model using 3D modeling software, and combine the blade parameters and axial relative velocity. Calculate the maximum bird impact mass that a single blade may strike under the current operating conditions. The bird's body parameters include its mass. and density ; The method for constructing the cylindrical bird model includes: Based on the bird's body mass and bird body density Determine the length of the cylindrical bird model. ; By setting the aspect ratio, the diameter of the cylindrical bird model is determined. The aspect ratio is the length. With diameter The proportion; According to the length and diameter The cylindrical bird model was constructed using 3D modeling software.

[0018] The maximum bird impact mass that a single blade could potentially strike. The calculation expression is: (2) Specifically, based on the parameters of the cylindrical bird model, the blade parameters, and the axial relative velocity... The spatial shielding effect during the bird's passage through the blade array was analyzed, and the maximum bird impact mass that a single blade might strike under the current operating conditions was determined by equation (2). .

[0019] The cylindrical bird model is based on the worst-case phase assumption, which states that when the front of the bird just misses the first blade, its rear section overlaps with the second blade to obtain the maximum possible impact mass. This breaks through the simplistic assumption of directly using the entire bird's mass as input, and more realistically reflects the distribution of actual impact energy.

[0020] Step S300, based on the relative impact velocity and the largest bird impact mass Calculate the impact kinetic energy of the bird on the blade at a specified radial position under the current operating conditions. ; The impact kinetic energy The calculation expression is: (3) The impact kinetic energy The leading edge structural angle of the blade was comprehensively correlated. Axial relative velocity Radial rotation radius angular velocity Number of leaves bird body mass and the length of the cylindrical bird model It includes multiple key physical factors, which can accurately characterize the impact load level under different working conditions.

[0021] Step S400: Based on the blade parameters and the impact kinetic energy... Constructing bird strike equivalent stress Then, the equivalent stress of a standard bird strike was obtained. Combined with the radial rotation radius Plot the standard equivalent stress CR distribution curve under the current working condition; The vertical axis of the standard equivalent stress CR distribution curve represents the standard bird strike equivalent stress. The horizontal axis represents the corresponding radial radius of rotation. The standard equivalent stress (CR) distribution curve on the blade, representing the equivalent stress of a bird strike at different blade heights under the current operating conditions, is used to illustrate the equivalent stress of a bird strike at different blade heights under the current operating conditions. Size; the standard bird strike equivalent force The larger the value, the more severe the damage to the corresponding location on the blade during a bird strike, thus identifying the weakest point in the bird strike.

[0022] The bird strike equivalent force The calculation expression is: (4) The standard bird strike equivalent force The calculation expression is: (5) Among them, the standard bird strike equivalent force The value is between 0 and 1, with a maximum value of 1; This indicates that, under the same flight phase and the same blade material conditions, all calculated positions are within the same range. The peak value.

[0023] Specifically, due to the thickness of the leading edge of the blade It is a key structural parameter affecting its impact resistance, and its bending stiffness is approximately the same as... Proportional, introducing the "bird strike equivalent force" "As a damage quantification index, the damage quantification index realizes the correlation between input energy and structural impact resistance by analogy with the concept of stress through dimensional analysis. It can be used to compare the degree of damage between different locations, different materials, and different design schemes."

[0024] To eliminate the influence of absolute numerical differences under different flight stages or material systems, the radial positions of each... Value divided by the maximum value under the current operating conditions The normalized standard bird strike equivalent force was obtained. .

[0025] Step S500: Based on the CR distribution curve, determine the weakest point of the bird strike under the current working condition; the weakest point of the bird strike is the equivalent stress of the standard bird strike in the CR distribution curve under the current working condition. The radial rotation radius corresponding to the maximum point The location on the blade. This can be used to guide the setting of the bird strike point in whole-aircraft bird-swallowing tests, ensuring coverage of the actual danger zone.

[0026] The standard bird strike equivalent stress under all operating conditions When 1 is reached, the radial rotation radius corresponding to the CR distribution curve is... The locations on the leaves were all the weakest points affected by the bird strike.

[0027] Specific examples are as follows: Taking small-to-medium bypass ratio turbofan engines as the application object, and combining the typical bird strike conditions specified in airworthiness regulations GJB 241A-2010 and GJB 3727-1999, the specific implementation process of the present invention is described in detail, and the method is systematically verified through LS-DYNA impact dynamics simulation, component-level bird strike test and whole-engine bird swallowing test.

[0028] Step 1: Construct a mathematical model of bird impact on fan blades and output the relative impact velocity between the bird and the blade. .

[0029] Fan blades at angular velocity Around the engine's central axis The axis rotates. Since the flight speed of birds is much slower than that of airplanes, the bird's speed is usually ignored, and the airplane's speed is taken as the relative speed between the bird and the airplane during the impact. Therefore, the bird's speed is relative to the airplane's speed. Being drawn in along the engine axis (i.e., relative axial velocity) The impact occurred with the fan blades, and the impact point was located within the radius of rotation along the engine axis. At the radial direction, the linear velocity of the blade at that position is ( In this invention, the angle between the mid-arc line of the blade leading edge and the engine axis is called the blade leading edge construction angle. (i.e., the complementary angle of the blade's geometric inlet angle), the leading edge thickness at each position is obtained through blade profile parameters of the characteristic section of the blade or through actual measurement. and blade leading edge construction angle Interpolation yields blade parameters at different radial heights. Theoretical analysis of impact between the blade and the bird is as follows: Figure 2 and Figure 3 As shown, Figure 2 and Figure 3 In this context, "Blade" represents a leaf and "Object" represents the bird's body. Figure 2 The right view is a theoretical analysis of the impact between the blade and the bird. Figure 3 This is a top view of the theoretical analysis of the impact between the blade and the bird.

[0030] Set the number of fan rotor blades Leaf tip radius leaf root radius Four typical flight conditions were selected, as shown in Table 1, corresponding to different axial relative velocities. With fan angular velocity : Table 1 Engine fan speed and aircraft speed under various conditions

[0031] like Figure 4 The diagram shows a breakdown of the relative impact velocity between the bird and the fan blades, representing the bird's velocity relative to the aircraft's flight speed. (i.e., axial relative velocity) ) and the blade linear velocity at the impact location Decompose the normal n and tangential τ of the leaf basin surface at this position, as follows: Figure 4 As shown in (a); the coordinate system has the point of impact as the origin ( (Relative coordinate system), the difference in velocity components decomposed to the normal direction of the leaf blade is the relative impact velocity between the bird and the leaf, such as Figure 4As shown in (b); multiple impact locations ranging from 0% to 100% of the blade height are selected radially along the blade, with a step size of 1% of the blade height. For each location... Based on the local leading edge structural angle of its blade The relative impact velocity between the bird and the leaf can be obtained according to formula (1). .

[0032] Step 2: Construct a cylindrical bird model and calculate the maximum impact mass. .

[0033] like Figure 5 The diagram shows the frontal structure of a bird colliding with a fan blade. Due to variations in blade angular velocity, bird size, and the number and density of blades, the maximum possible mass of the bird colliding with the fan blades also differs. (Based on the bird's mass...) Establish a cylindrical bird model with a length-to-diameter ratio of 2:1. The length of the cylindrical bird model is... The number of leaves is β is the leaf spacing angle, β = 2π / N. For example... Figure 6 The image shows the bird's body colliding with the leaf. A top view of the structure at a given moment. At any given moment, the maximum possible impact mass in a bird strike event is when the bird enters the fan's rotating region, at which point the bird just brushes past the leading edge of blade number 1 on its back. D is the diameter of the cylindrical bird model, and L is its length. The bird continues to fly along the engine axis, as... Figure 7 The image shows the bird's body colliding with the leaf. A top view of the structure at a given moment. At what moment, the maximum impact mass corresponding to the collision between blade #2 and the bird is the length of the bird entering the fan's rotating region. The mass of this part is defined as the maximum bird impact mass. .

[0034] Set bird body mass ,density A cylindrical model with a length-to-diameter ratio of 2:1 is constructed, and the length is calculated using formula (6). .

[0035] (6) Based on formula (2), calculate the maximum bird impact mass that may act on a single blade under each working condition. For example, in operational condition D (low-altitude penetration), due to the high flight speed and high rotation speed, Maximum In operating condition C (decline), Significantly reduced to .

[0036] Step 3: Calculate the impact kinetic energy of the bird on the blade at different radial positions. .

[0037] Based on formula (3), the impact kinetic energy at different radial positions is obtained. Distribution.

[0038] Step 4: Define the equivalent stress of a bird strike. And normalize.

[0039] The equivalent stress of bird strike at different radial positions is calculated based on formula (4). For example, the blade profile parameter of the 0-0 blade section is the radial radius of rotation. The blade is 379.7 mm (100% leaf height) with a leading edge construction angle of [missing information]. Leading edge thickness of the blade According to formula (4), the equivalent stress of bird strike at 100% blade height is 1563.9 GPa for condition A (climbing), 8.0 GPa for condition B (cruising), 1365.7 GPa for condition C (glide), and 1365.7 GPa for condition D (penetration). 1-1 Blade section air profile parameters are radial rotation radius The blade is 374.7 mm (98% of leaf height) with a leading edge structural angle of [missing information]. Leading edge thickness of the blade According to formula (4), the equivalent stress of bird strike in condition A (climbing) at 98% leaf height is 2020 GPa, the equivalent stress of bird strike in condition B (cruising) is 73.2 GPa, the equivalent stress of bird strike in condition C (glide) is 1699.5 GPa, and the equivalent stress of bird strike in condition D (penetration) is 6886 GPa. The blade profile parameters at 99% blade height were obtained by interpolating the blade section parameters at 0-0 and 1-1, and the radial rotation radius at 99% blade height was also obtained. The blade leading edge construction angle is 377.4 mm. Leading edge thickness of the blade According to formula (4), the equivalent stress of bird strike at 99% blade height is calculated as follows: Condition A (climbing) is 1789 GPa, Condition B (cruising) is 33 GPa, Condition C (glide) is 1531.1 GPa, and Condition D (penetration) is 7455.2 GPa. Using the same method, the equivalent stress of bird strike at 0% to 100% of other blade cross-sections and airfoil parameters can be obtained. .

[0040] All positions Value divided by the maximum value under the current operating conditions The standard bird strike equivalent force was obtained. ,draw Distribution curve, such as Figure 8 As shown, the vertical axis represents the equivalent stress of a standard bird strike. The horizontal axis represents the corresponding radial radius of rotation. The position on the leaf, that is, the corresponding leaf height position.

[0041] Step 5: Identify the weakest point.

[0042] Analysis of the above The extreme points of the distribution curve are shown below: Condition A (climbing): The weakest point is located at approximately 81% of the blade height; Operating condition B (cruise): The weakest point is located at 75% blade height; Condition C (sliding): The weakest point is located at 81% blade height; Operating condition D (breakthrough): The weakest part is concentrated in the blade tip area (>95% of blade height).

[0043] The results indicate that the weakest point shifts with changes in flight status, and traditional methods of fixing the strike position are insufficient to cover all dangerous situations.

[0044] To verify the accuracy and engineering applicability of the method of this invention, this invention provides a three-level verification method and conclusions: 1) LS-DYNA impact dynamics simulation verification: A finite element model of the impact dynamics between a fan blade and a bird was established using LS-DYNA. The bird was modeled using SPH (Smoothed Particle Hydrodynamics), and the blades were modeled using hexahedral solid elements. The material constitutive model included strain rate effects. Bird impact responses at different radial positions were simulated under the same operating conditions, and the root bending moment, leading-edge plastic strain, maximum impact force, and element failure energy were extracted. Simulation results show that the simulation results for the weakest point of the fan rotor blade under the same operating conditions, obtained from bird impact simulation, do not deviate from the calculated results of this invention within 5% of the blade height.

[0045] 2) Component-level bird strike test verification: Bird strike tests were conducted on a single-stage fan rotor on an aero-engine component test bench. The test results showed good agreement with the simulation results, demonstrating the effectiveness of the simulation analysis method. The location of the rotor structure most severely damaged by the bird strike during the test coincided with the weakest point of the bird strike obtained by the method of this invention.

[0046] 3) Verification through whole-machine bird-swallowing test: A bird ingestion test plan for the entire engine was developed based on this method and has been reviewed and approved by industry experts.

[0047] The above-disclosed embodiments are merely specific examples of the present invention. However, the present invention is not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for determining the weakest point of aero-engine fan rotor blades in the event of a bird strike, characterized in that, Includes the following steps: Obtain blade parameters and set the axial relative velocity of the bird entering the fan rotor intake under the current operating conditions. and the radial rotation radius at the impact location A mathematical model of bird strikes on fan blades is established, which is used to output the relative impact velocity between the bird and the blade. The blade parameters include the blade angular velocity. Number of leaves Leading edge structural angle of blade and the leading edge thickness Q; By setting the bird's body parameters and constructing a cylindrical bird model using 3D modeling software, and combining the blade parameters and axial relative velocity... Calculate the maximum bird impact mass that a single blade may strike under the current operating conditions. The bird's body parameters include its mass. and density ; Based on the relative impact velocity and the largest bird impact mass Calculate the impact kinetic energy of the bird on the blade at a specified radial position under the current operating conditions. ; Based on the blade parameters and impact kinetic energy Constructing bird strike equivalent stress Then, the equivalent stress of a standard bird strike was obtained. Combined with the radial rotation radius Plot the standard equivalent stress CR distribution curve under the current working condition; Based on the CR distribution curve, the weakest point of the bird strike under the current operating condition is determined; the weakest point of the bird strike is the equivalent stress of the standard bird strike in the CR distribution curve under the current operating condition. The radial rotation radius corresponding to the maximum point Position on the leaf.

2. The method for determining the weakest point of an aero-engine fan rotor blade in a bird strike, as described in claim 1, is characterized in that... The process of constructing the mathematical model for bird strikes on the fan blades includes: According to the blade angular velocity and radial rotation radius Obtain the blade linear velocity at the impact location. ; Combined with the construction angle of the blade leading edge Construct a mathematical model of bird strike on the fan blades and output the relative impact velocity between the bird and the blades. The mathematical model for the bird strike on the fan blades is expressed as follows: 。 3. The method for determining the weakest point of an aero-engine fan rotor blade in a bird strike, as described in claim 1, is characterized in that... The method for constructing the cylindrical bird model includes: Based on the bird's body mass and bird body density Determine the length of the cylindrical bird model. ; By setting the aspect ratio, the diameter of the cylindrical bird model is determined. The aspect ratio is the length. With diameter The proportion; According to the length and diameter The cylindrical bird model was constructed using 3D modeling software.

4. The method for determining the weakest point of an aero-engine fan rotor blade in a bird strike, as described in claim 3, is characterized in that... The maximum bird impact mass that a single blade could potentially strike. The calculation expression is: .

5. The method for determining the weakest point of an aero-engine fan rotor blade in a bird strike, as described in claim 1, is characterized in that... The impact kinetic energy The calculation expression is: .

6. The method for determining the weakest point of an aero-engine fan rotor blade in a bird strike, as described in claim 1, is characterized in that... The bird strike equivalent force The calculation expression is: .

7. The method for determining the weakest point of an aero-engine fan rotor blade in a bird strike as described in claim 6, characterized in that, The standard bird strike equivalent force The calculation expression is: ; Among them, the standard bird strike equivalent force The value is between 0 and 1, with a maximum value of 1; This indicates that, under the same flight phase and the same blade material conditions, all calculated positions are within the same range. The peak value.

8. The method for determining the weakest point of an aero-engine fan rotor blade in a bird strike, as described in claim 7, is characterized in that... The standard bird strike equivalent stress under all operating conditions When 1 is reached, the radial rotation radius corresponding to the CR distribution curve is... The locations on the leaves were all the weakest points affected by the bird strike.

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