Rotor blade disc deformation efficient prediction method considering centrifugal temperature coupling effect

Abstract

The invention discloses a rotor blade disc deformation efficient prediction method considering a centrifugal temperature coupling effect, and belongs to the technical field of aero-engines, and the method comprises the following steps: S1, building a blade analysis model, and inputting blade parameters to solve centrifugal and temperature loads, and blade deformation and blade centrifugal load under the centrifugal and temperature coupling effect; s2, applying a centrifugal load generated by the blade to a wheel flange node of the wheel disc plane model in a discrete form along an axial distribution function; s3, establishing an axial symmetry finite element model, and solving the disc edge deformation condition; and S4, blade body deformation obtained through the blade analysis method and disc edge deformation obtained through the axisymmetric wheel disc finite element method are combined, blade tip deformation of the blisk structure under the corresponding working condition is obtained, and deformation caused by tenon connection is corrected. According to the rotor blade disc deformation efficient prediction method considering the centrifugal temperature coupling effect, rapid calculation of blade deformation and loads thereof is achieved, and rapid calculation of rim deformation is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aeroengines, and in particular to an efficient prediction method for rotor blade deformation taking into account centrifugal temperature coupling. Background Art

[0002] The size of the rotor-static clearance is an important factor affecting the aerodynamic and thermal efficiency and safety of the entire aircraft engine. The rotor deformation induced by complex working loads and its incoordination and asynchrony with the stator deformation are the main reasons for the change in the rotor-static clearance. Therefore, efficient and accurate calculation of rotor deformation in the design stage is one of the important prerequisites for achieving clearance prediction. The working loads of aircraft engines are extremely complex, including inertial loads, temperature loads, rotating centrifugal loads, aerodynamic loads and various vibration loads generated by maneuvering overloads. Among them, the load factors that affect the deformation of the engine rotor are mainly rotating centrifugal loads, temperature loads and maneuvering overload inertial loads. Rotating centrifugal loads and temperature loads mainly cause the deformation of the blade disk components, which is related to the structural characteristic parameters of the components; while the deformation caused by the maneuvering overload inertial load is closely related to the rotor stiffness distribution. This research report focuses on the deformation prediction and model establishment of blade disk components under rotating centrifugal loads and temperature loads.

[0003] At present, the main means of calculating rotor static deformation and clearance changes at home and abroad include analytical methods and finite element methods. Since analytical methods usually require a significant simplification of the structure, although the calculation efficiency is high, the prediction accuracy is extremely limited. At present, the finite element analysis method is the mainstream method for predicting rotor deformation and rotor-static clearance in engineering. Most of them use three-dimensional high-fidelity modeling, and on this basis, a certain dimensionality reduction is performed through periodic symmetry characteristics. Although this method is relatively reliable, it has a large amount of calculation, a long calculation time, and a high calculation cost. It is not suitable for rapid iterative optimization in the design stage. In addition, an analysis method based on a two-dimensional axisymmetric model has also been derived. This method can quickly calculate the structural deformation and stress. However, it must ignore the blade's own structure, simplify the tenon and mortise structure, and simplify the periodic symmetry to axisymmetry, which usually produces large errors when calculating the tip deformation. Summary of the invention

[0004] The purpose of the present invention is to provide an efficient prediction method for rotor blade deformation taking into account the centrifugal temperature coupling effect. On the basis of the parameterization of the blade disk structure, an analytical method is used to establish the explicit relationship between the blade body elongation / root centrifugal load and the blade structure parameters and load parameters, so as to realize the rapid calculation of blade deformation and its load; the axisymmetric finite element method is used for the wheel disk, and an axisymmetric finite element model based on the APDL language and the automatic equivalent application technology of loads are established to realize the rapid calculation of wheel rim deformation.

[0005] To achieve the above object, the present invention provides an efficient prediction method for rotor blade deformation considering centrifugal temperature coupling, comprising the following steps:

[0006] S1. Establish a blade analytical model, input blade geometric characteristic parameters, material parameters and load parameters to solve the centrifugal load, temperature load and the deformation of the blade under the coupling of the two, as well as the centrifugal load of the blade;

[0007] S2, the centrifugal load generated by the blade is applied to the rim nodes of the disk plane model in a discrete form along the axial distribution function;

[0008] S3, establish an axisymmetric finite element model, input the wheel disc geometric characteristic parameters, material parameters and load parameters, apply temperature load and centrifugal load to solve the wheel disc edge deformation;

[0009] S4. The blade deformation obtained by the blade analytical method and the disk edge deformation obtained by the axisymmetric disk finite element method are combined to obtain the tip deformation of the overall blade disk structure under corresponding working conditions, and the deformation caused by the tenon connection is corrected.

[0010] Preferably, the centrifugal load in S1 includes the centrifugal tensile stress F in the blade height Z direction. blade And the centrifugal bending moment M Y1 ;

[0011] Centrifugal tensile stress F blade The calculation formula is as follows:

[0012]

[0013] Where ρ is the density, ω is the rotation speed, A(Z) is the variation law of the cross-sectional area of ​​the blade along the blade height direction, and F crown The centrifugal force generated by the leaf crown;

[0014] For a turbine rotor blade with a shroud, the centrifugal force generated by the shroud is F crown , the calculation formula is as follows:

[0015] F crown =ρω 2 V crown Z crown ;

[0016] Among them, V crown is the canopy volume, Z crown is the leaf crown height directional coordinate;

[0017] Centrifugal bending moment M Y1 The calculation formula is as follows:

[0018]

[0019] Among them, Z bt and Z br are the blade height coordinates of the blade tip and blade root respectively, and X(Z) is the functional relationship between the blade height Z and the axial X coordinate of the cross-section centroid.

[0020] Preferably, the cross section A(Z) is subjected to the centrifugal force above the interface:

[0021]

[0022] The deformation Δl1 of the blade due to centrifugal tensile stress is shown as follows:

[0023]

[0024] Where, E is the elastic modulus;

[0025] The temperature of the blade is the same on the cross section, and the temperature in the Z direction changes with the blade height. Let the temperature of any thin section A(Z) be T(Z), then the radial deformation of the entire blade due to the temperature increase is Δl T , the calculation formula is as follows:

[0026]

[0027] Where α(Z) is the linear expansion coefficient of the blade material, and T0 is the reference temperature;

[0028] Due to the influence of temperature, the elastic modulus E of the blade material is no longer a constant. With the blade height Z direction, the elastic modulus of the blade is E(Z), then the comprehensive deformation Δl of the blade under centrifugal and temperature loads Z&T for:

[0029]

[0030] Preferably, in S2, the centrifugal load generated by the blade acts on the wheel in the form of a distributed force. Due to the complexity of the blade structural characteristics, the distributed force is not ideally evenly distributed. The function of the centrifugal load density of the blade along the axial direction is f(x), and it is necessary to satisfy that the resultant force and resultant moment corresponding to the load distribution are equal to the resultant force F and resultant moment M generated by the blade. Z :

[0031]

[0032] Choose a distribution function to program and solve the resultant force F and resultant moment M Z The solution is applied to the rim nodes of the wheel plane model in a discrete form. When the grid is dense enough, it can be considered that the nodes are equidistantly distributed in the axial direction. The total number of nodes is n, and the corresponding axial coordinate is x i(i=1,2,…,n), then the load value F on each node can be obtained i for:

[0033]

[0034] Preferably, when calculating the radial deformation of the wheel under the centrifugal load in S3, the angular velocity of rotation is applied to the wheel, and the centrifugal load generated by the blades is applied to each node of the rim; when calculating the radial deformation of the wheel under the temperature load, the temperature load is applied to the wheel rim and the center assembly of the wheel respectively; when calculating the radial deformation of the wheel under the combined action of the centrifugal load and the temperature, the centrifugal load and the temperature load are applied jointly.

[0035] Preferably, in S4, the actual tenon connection structure is taken as the object, and its deformation is calculated by establishing a three-dimensional solid finite element model considering the tenon connection interface contact; on the other hand, the influence of the tenon connection contact interface is ignored and the gap of the tenon and mortise structure is filled, and it is treated as an integral blade disk structure to calculate its deformation; by comparing the deformation results of the two models, the influence of the tenon connection structure on the blade tip deformation is analyzed; and the average radial deformation Δl of the blade tip of the integral blade disk and the tenon connection blade disk is obtained. tenon and Δl blisk , and finally the range of the correction coefficient K2 is obtained as follows:

[0036] Δl tenon =K2Δl blisk .

[0037] Therefore, the present invention adopts the above-mentioned efficient prediction method for rotor blade deformation considering the centrifugal temperature coupling effect. On the basis of the parameterization of the blade disk structure, an analytical method is used to establish the explicit relationship between the blade body elongation / root centrifugal load and the blade structure parameters and load parameters, so as to realize the rapid calculation of blade deformation and its load; the axisymmetric finite element method is used for the wheel disk, and an axisymmetric finite element model based on the APDL language and the automatic equivalent application technology of load are established to realize the rapid calculation of the wheel rim deformation.

[0038] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of a method for efficiently predicting rotor blade deformation taking into account centrifugal temperature coupling effect of the present invention;

[0040] Figure 2 It is a schematic diagram of a blade analytical model of a rotor blade disk deformation efficient prediction method considering centrifugal temperature coupling effect of the present invention;

[0041] Figure 3Schematic diagram of a wheel disc plane model drawing of a rotor blade disc deformation efficient prediction method considering centrifugal temperature coupling effect of the present invention, wherein Figure 3 a in the figure is the three-dimensional model of the roulette wheel. Figure 3 b in the figure is the plane model of the roulette wheel;

[0042] Figure 4 It is a schematic diagram of load application of a disk plane finite element model of an efficient prediction method for rotor blade deformation considering centrifugal temperature coupling effect of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0044] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0045] Embodiment 1

[0046] like Figure 1 As shown, the present invention provides an efficient prediction method for rotor blade deformation considering centrifugal temperature coupling, comprising the following steps:

[0047] S1. Establish a blade analytical model, input blade geometric characteristic parameters, material parameters and load parameters to solve the centrifugal load, temperature load and the deformation of the blade under the coupling of the two, as well as the centrifugal load of the blade;

[0048] The required geometric characteristic parameters of the blade are as follows: Figure 2 As shown, Z is the blade radial direction, Y is the engine axial direction, X is perpendicular to the two, and the radial positions of the blade tip and blade root sections are Z and bt and Z br The curve formed by the superposition of the centroids of each section of the blade is called the blade superposition line, which is described by X(Z) and Y(Z). It determines the swept form of the blade. A(Z) describes the variation law of the blade cross-sectional area. Z crown 、V crownrepresents the radial position and volume of the centroid of the blade crown, and ω represents the angular velocity of rotation. The centrifugal load includes the centrifugal tensile stress F in the Z direction of the blade height. blade And the centrifugal bending moment M Y1 ;

[0049] Centrifugal tensile stress F blade The calculation formula is as follows:

[0050]

[0051] Where ρ is the density, ω is the rotation speed, A(Z) is the variation law of the cross-sectional area of ​​the blade along the blade height direction, and F crown The centrifugal force generated by the leaf crown;

[0052] For a turbine rotor blade with a shroud, the centrifugal force generated by the shroud is F crown , the calculation formula is as follows:

[0053] F crown =ρω 2 V crown Z crown ;

[0054] Among them, V crown is the canopy volume, Z crown is the leaf crown height directional coordinate;

[0055] Centrifugal bending moment The calculation formula is as follows:

[0056]

[0057] Among them, Z bt and Z br are the blade height coordinates of the blade tip and blade root respectively, and X(Z) is the function relationship between the blade height Z and the axial X coordinate of the cross-section centroid.

[0058] The cross section A(Z) is subject to the centrifugal force above the interface:

[0059]

[0060] The deformation Δl1 of the blade due to centrifugal tensile stress is shown as follows:

[0061]

[0062] Where E is the elastic modulus.

[0063] The temperature of the blade is the same on the cross section, and the temperature in the Z direction changes with the blade height. Let the temperature of any thin section A(Z) be T(Z), then the radial deformation of the entire blade due to the temperature increase is Δl T, the calculation formula is as follows:

[0064]

[0065] Where α(Z) is the linear expansion coefficient of the blade material, and T0 is the reference temperature;

[0066] Due to the influence of temperature, the elastic modulus E of the blade material is no longer a constant. With the blade height Z direction, the elastic modulus of the blade is E(Z), then the comprehensive deformation Δl of the blade under centrifugal and temperature loads Z&T for:

[0067]

[0068] S2, the centrifugal load generated by the blade is applied to the rim nodes of the disk plane model in a discrete form along the axial distribution function;

[0069] The centrifugal load generated by the blade acts on the impeller in the form of distributed force. Due to the complexity of the blade structure, the distributed force is not ideally evenly distributed. The function of the centrifugal load density distribution along the axial direction of the blade (referred to as the centrifugal load density distribution function) is f(x), which needs to satisfy the resultant force and moment corresponding to the load distribution equal to the resultant force F and moment M generated by the blade. Z :

[0070]

[0071] Select a distribution function (uniform equal value distribution, linear non-uniform distribution and quadratic function distribution) to program and solve the above equation. Apply the solution result in discrete form to the rim nodes of the wheel plane model. If the grid is dense enough, it can be considered that the nodes are equidistantly distributed in the axial direction. The total number of nodes is n, and the corresponding axial coordinate is x i (i=1,2,…,n), then the load value F on each node can be obtained i for:

[0072]

[0073] S3, establish an axisymmetric finite element model, input the wheel disc geometric characteristic parameters, material parameters and load parameters, apply temperature load and centrifugal load to solve the wheel disc edge deformation;

[0074] Draw a plane model of the meridian section of the wheel in the drawing software, such as Figure 3 As shown, Figure 3 a in the figure is the three-dimensional model of the roulette wheel. Figure 3b in the figure is the plane model of the wheel. An axisymmetric finite element model based on the ANSYS APDL command flow language and the automatic equivalent application of loads are established to achieve rapid calculation of wheel rim deformation. Through the command flow, ANSYS automatically imports the wheel model file, sets the unit type to plane axisymmetric, assigns the material, identifies the centroid coordinates of each side of the wheel, and defines the edge with the largest radial coordinate as the wheel edge, and the edge with the smallest radial coordinate as the wheel center. The wheel is meshed, and the number of nodes at the wheel edge is n.

[0075] When calculating the radial deformation of the disk under centrifugal load, the angular velocity of rotation is applied to the disk, and the centrifugal load generated by the blade is applied to each node of the disk rim; when calculating the radial deformation of the disk under temperature load, the temperature load is applied to the disk rim and disk core components respectively; when calculating the radial deformation of the disk under the combined action of centrifugal load and temperature, the above two types of loads are applied together. The specific load and constraint application conditions are shown in the figure. Figure 4 As shown in the figure, different combinations of temperature and speed are used as a working condition, and the radial deformation of the wheel disc is solved by using the command flow cycle. The radial deformation of all nodes of the disc rim assembly is extracted to solve the deformation of the disc rim.

[0076] S4, combining the blade deformation obtained by the blade analytical method and the disk edge deformation obtained by the axisymmetric disk finite element method to obtain the tip deformation of the overall blade disk structure under corresponding working conditions, and correcting the deformation caused by the tenon connection;

[0077] Taking the actual tenon connection structure as the object, a three-dimensional solid finite element model considering the tenon connection interface contact is established to calculate its deformation; on the other hand, the influence of the tenon connection contact interface is ignored and the gap of the tenon and mortise structure is filled, and it is treated as an integral blade disk structure to calculate its deformation; by comparing the deformation results of the two models, the influence of the tenon connection structure on the blade tip deformation is analyzed; the average radial deformation Δl of the blade tip of the integral blade disk and the tenon connection blade disk is obtained. tenon and Δl blisk , and finally the range of the correction coefficient K2 is obtained as follows:

[0078] Δl tenon =K2Δl blisk .

[0079] Therefore, the present invention adopts the above-mentioned efficient prediction method for rotor blade deformation considering the centrifugal temperature coupling effect. On the basis of the parameterization of the blade disk structure, an analytical method is used to establish the explicit relationship between the blade body elongation / root centrifugal load and the blade structure parameters and load parameters, so as to realize the rapid calculation of blade deformation and its load; the axisymmetric finite element method is used for the wheel disk, and an axisymmetric finite element model based on the APDL language and the automatic equivalent application technology of load are established to realize the rapid calculation of the wheel rim deformation.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. An efficient prediction method for rotor blade deformation considering centrifugal temperature coupling, characterized by: The following steps are involved: S1. Establish a blade analytical model, input blade geometric characteristic parameters, material parameters and load parameters to solve the centrifugal load, temperature load and the deformation of the blade under the coupling of the two, as well as the centrifugal load of the blade; S2, the centrifugal load generated by the blade is applied to the rim nodes of the disk plane model in a discrete form along the axial distribution function; S3, establish an axisymmetric finite element model, input the wheel disc geometric characteristic parameters, material parameters and load parameters, apply temperature load and centrifugal load to solve the wheel disc edge deformation; S4. The blade deformation obtained by the blade analytical method and the disk edge deformation obtained by the axisymmetric disk finite element method are combined to obtain the tip deformation of the overall blade disk structure under the corresponding working conditions, and the deformation caused by the tenon connection is corrected.

2. The efficient prediction method for rotor blade deformation considering centrifugal temperature coupling according to claim 1 is characterized in that: The centrifugal load in S1 includes the centrifugal tensile stress F in the Z direction of the blade height. blade And the centrifugal bending moment M Y1 ; Centrifugal tensile stress F blade The calculation formula is as follows: Where ρ is the density, ω is the rotation speed, A(Z) is the variation law of the cross-sectional area of ​​the blade along the blade height direction, and F crown The centrifugal force generated by the leaf crown; For a turbine rotor blade with a shroud, the centrifugal force generated by the shroud is F crown , the calculation formula is as follows: F crown =ρω 2 V crown Z crown ; Among them, V crown is the canopy volume, Z crown is the leaf crown height directional coordinate; Centrifugal bending moment The calculation formula is as follows: Among them, Z bt and Z br are the blade height coordinates of the blade tip and blade root respectively, and X(Z) is the functional relationship between the blade height Z and the axial X coordinate of the cross-section centroid.

3. The efficient prediction method for rotor blade deformation considering centrifugal temperature coupling according to claim 2 is characterized in that: The cross section A(Z) is subject to the centrifugal force above the interface: The deformation Δl1 of the blade due to centrifugal tensile stress is shown as follows: Where, E is the elastic modulus; The temperature of the blade is the same on the cross section, and the temperature in the Z direction changes with the blade height. Let the temperature of any thin section A(Z) be T(Z), then the radial deformation of the entire blade due to the temperature increase is Δl T , the calculation formula is as follows: Where α(Z) is the linear expansion coefficient of the blade material, and T0 is the reference temperature; Due to the influence of temperature, the elastic modulus E of the blade material is no longer a constant. With the blade height Z direction, the elastic modulus of the blade is E(Z), then the comprehensive deformation Δl of the blade under centrifugal and temperature loads Z&T for:

4. The efficient prediction method for rotor blade deformation considering centrifugal temperature coupling according to claim 1 is characterized in that: In S2, the centrifugal load generated by the blade acts on the impeller in the form of distributed force. Due to the complexity of the blade structure characteristics, the distributed force is not ideally evenly distributed. The function of the centrifugal load density of the blade along the axial direction is f(x). It is necessary to satisfy that the resultant force and moment corresponding to the load distribution are equal to the resultant force F and moment M generated by the blade. Z : Choose a distribution function to program and solve the resultant force F and resultant moment M Z The solution is applied to the rim nodes of the wheel plane model in a discrete form. When the grid is dense enough, it can be considered that the nodes are equidistantly distributed in the axial direction. The total number of nodes is n, and the corresponding axial coordinate is x i (i=1,2,…,n), then the load value F on each node can be obtained i for:

5. The efficient prediction method for rotor blade deformation considering centrifugal temperature coupling according to claim 1 is characterized in that: When calculating the radial deformation of the disk under centrifugal load in S3, the rotational angular velocity is applied to the disk, and the centrifugal load generated by the blades is applied to each node of the disk rim; when calculating the radial deformation of the disk under temperature load, the temperature load is applied to the disk rim and disk core components respectively; When the radial deformation of the wheel is calculated under the combined effect of centrifugal load and temperature, the centrifugal load and temperature load are applied together.

6. The efficient prediction method for rotor blade deformation considering centrifugal temperature coupling according to claim 1 is characterized in that: In S4, the actual tenon connection structure is taken as the object, and its deformation is calculated by establishing a three-dimensional solid finite element model considering the tenon connection interface contact; on the other hand, the tenon connection contact interface is ignored and the gap of the tenon and mortise structure is filled, and it is treated as an integral blade disk structure to calculate its deformation; By comparing the deformation results of the two models, the influence of the tenon connection structure on the blade tip deformation is analyzed. Calculate the average radial deformation Δl of the blade tip of the integral blade and the tenon-connected blade tenon and Δl blisk , and finally the range of the correction coefficient K2 is obtained as follows: Δl tenon =K2Δl blisk 。

Images