CN111241609A - Prediction method for blade tip clearance of rotor and stator assembly of aircraft engine - Google Patents

Abstract

The invention discloses a method for predicting the clearance of an aero-engine rotor and stator assembly blade tip, comprising the following steps: S1, establishing a rotor blade tip calculation model; S2, establishing a support structure calculation model; S3, establishing a casing inner flow channel surface calculation model ; S4, establish a rotor-stator blade tip clearance calculation model, and then input the deviation data and size data of the rotor system, the supporting frame, the casing and the stator assembly into the model calculation; the model outputs the different rotor phases according to the input data. The predicted value of the gap between the rotor and the stator tip, the corresponding gap distribution curve is given, and the maximum, minimum and average gaps of the rotor and stator at all levels predicted by the model are obtained; the predicted results are compared with the gap requirements of the process standard to determine the rotor and stator. Whether the assembled blade tip clearance index is qualified, or the out-of-tolerance part is given according to the predicted value, that is, the prediction of the blade tip clearance of the aero-engine rotor and stator assembly is completed. It solves the problem of difficulty in predicting the tip clearance of the rotor and stator assembly of the existing aero-engine.

Description

A prediction method for tip clearance of aero-engine rotor-stator assembly

【Technical field】

The invention belongs to the technical field of aero-engine assembly, and in particular relates to a method for predicting a blade tip clearance of an aero-engine rotor-stator assembly.

【Background technique】

Aero-engine rotor-stator blade tip clearance is an important indicator that affects the safety and performance of aero-engines. The uneven circumferential distribution of rotor-stator blade tip clearance and the friction between the rotor and the inner flow surface are a problem that plagues major airlines and military enterprises in the world. big problem. There are a lot of errors in the manufacturing and assembly process of aero-engines. The accumulation and transmission of multiple errors lead to the inability to accurately predict the blade tip clearance of the aero-engine rotor and stator assembly. Repeated assembly and adjustment are required to meet the requirements, resulting in low assembly efficiency and poor quality consistency. . At present, there are few publications related to the prediction method of aero-engine rotor blade tip clearance in China.

[Content of the invention]

The purpose of the present invention is to provide a method for predicting the tip clearance of aero-engine rotor and stator assembly, so as to solve the problem of difficulty in predicting the tip clearance of the existing aero-engine rotor and stator assembly.

The present invention adopts the following technical solutions: a method for predicting the tip clearance of an aero-engine rotor and stator assembly. The aero-engine includes a rotor system, a support frame, a casing and a stator assembly, and the tip clearance refers to the flow between the rotor blade tip and the casing. The radial clearance of the road surface, and the radial clearance of the stator blade tip and the rotor hub, the prediction method includes the following steps:

S1. Establish a rotor blade tip calculation model;

S2, establish a support structure calculation model;

S3. Establish a calculation model of the flow channel surface in the casing;

S4, in the absolute coordinate system, use the homogeneous coordinate transformation matrix to integrate the three calculation models obtained in the steps 1 to 3 into the rotor-stator blade tip clearance calculation model, and carry out the calculation of the blade tip clearance under different rotor phase angles. predict.

Further, in step 1, a space coordinate system is established with the centroid of the first-level rotor or the axial reference plane of the front journal as the origin; the part detects the coordinate points of the rear end face of the first-level rotor, and uses the coordinate points to establish a space plane equation, and sequentially Calculate the plane equation of the rear end face of each rotor between the front and rear supports; calculate the unit normal vector of the rear end face of each rotor from the plane equation, that is, complete the geometric modeling of the runout deviation of the end face; the coordinates of the outer web surface of the front and rear end faces of the rotor are detected by the parts. Point, establish the circle equation in the section plane, estimate the parameters of the equation by the least square method, and obtain the centroid coordinates, that is, complete the geometric modeling of radial eccentricity deviation; calculate the centroid direction vector inside the single-stage rotor from the centroid coordinates of the front and rear faces; Calculate the tip height and initial phase angle of each blade, thereby calculating the actual coordinates of each blade tip point, that is, to complete the rotor tip calculation model.

Further, the specific calculation process of step 1 is as follows:

The coordinate system is established with the rotor datum plane as the assembly global reference, the origin is the centroid of the rotor datum plane, the axial stacking direction is the positive x direction, the section plane is the yOz plane, and the vertical direction is the z-axis direction;

A plane equation is established according to the contour data points of the rear face of the i-th rotor obtained by the testing instrument, and the parameters of the plane equation are fitted by the least squares method to obtain the equation expression:

A _pla,i x+B _pla,i y+C _pla,i z+D _pla,i =0 (1),

In the formula, A _pla , B _pla , C _pla , and D _pla are all calibration plane parameter coefficients. The plane normal vector obtained from formula (1) is normalized to obtain the unit normal vector of the rear face of the i-th rotor:

The outer ring profile of the cross-section plane of the outer web of the front end face of the single-stage rotor at the axial direction x is obtained by the turntable testing instrument. According to the least squares method, the outer circle equation of the front end face is fitted as:

A _cir,f,i y ² +B _cir,f,i z ² +C _cir,f,i y+D _cir,f,i z+E _cir,f,i =0 (3),

In the above formula, A _cir,f,i ,B _cir,f,i ,C _cir,f,i ,D _cir,f,i ,E _cir,f,i are the front ends of the i-th rotors calibrated by the least square method The circular characteristic parameters of the surface are approximated by the sectional plane circle equation to estimate the position vector of the centroid of the front end surface of the i-th stage rotor as:

为前i-1级转子轴向尺寸累积坐标由式(3)和式(4)同理可得后端面近似形心位置矢量(x_cir,l,y_cir,l,z_cir,l)，分量n_x,i由下式给出，第i级转子形心轴的单位方向向量为：In the formula,

For the accumulated coordinates of the axial dimension of the front i-1 stage rotor, the approximate centroid position vector (x _cir,l , y _cir,l , z _cir,l ) of the rear face can be obtained in the same way as equations (3) and (4), The components n _x,i are given by the following equation, the unit direction vector of the rotor centroid axis of the i-th stage is:

为第i级转子内部形心轴矢的模长；In the formula,

is the modulo length of the inner centroid axicon of the i-th rotor;

Assume that the axial positioning dimension of the rotor blade tip of the i-th stage is l _i , the design dimension of the radial height is R _i , and the total number of rotor blades of the i-th stage is N _i , then the circumferential angle of the adjacent blades is

In the yOz plane, the positive z-axis is used as the initial edge of the phase angle, and the circumferential blades are numbered incrementally from 1 along the positive direction of the rotation angle as j, 0<j≤N _i , where the phase angle of the No. 1 blade is φ _{i, 1} , the phase angle of the j blade is φ _i,j =φ _i,1 +(j-1)φ _i,Δ ;

其满足空间相互垂直条件：Set the unit direction vector from the centroid to the zero-phase point of the blade tip in the section plane where the blade tip of the i-th stage is located as

It satisfies the condition that the spaces are perpendicular to each other:

旋转得到

满足公式：Then the unit direction vector corresponding to the blade tip of the blade j of the i-th rotor is from the section axis to the zero-phase point, and the direction vector revolves around the centroid axis

rotate to get

Satisfy the formula:

The radial runout of the blade tip of the rotor j of the i-th stage relative to the design height R _i is δ _j ; therefore, the actual height of the corresponding blade is R _i,j , so the absolute coordinates of the blade tip of the rotor j of the i-th stage are:

Further, in step 2, a coordinate system is established with the centroid of the left end face of the inner ring of the front bearing matched with the rotor as the origin, and the line connecting the centroid of the adjacent end faces of the inner ring of the front and rear bearings is the axis of rotation of the rotor; the unit vector of the axis of rotation of the rotor is calculated, That is, the modeling of the rotor rotary axis is completed; the deformation coordinate component of the elastic support and the bearing clearance value of the simulation are substituted, and the centroid offset vector of the casing datum plane under the bearing clearance deviation is calculated, and the modeling of the supporting frame is completed.

Further, the specific calculation process of step 2 is as follows: two bearings are installed before and after the rotor structure, the bearings have radial clearance and axial clearance deviation, the left end face of the bearing inner ring is the yOz plane, and the centroid of the end face is the coordinate origin O , the vertical direction is the z-axis direction, the direction of the centroid to the internal normal vector is the x-direction; the bearing axial clearance is Δx _cle , (x _cle,min ≤Δx _cle ≤x _cle,max ), the bearing radial clearance is Δr _cle ,(r _cle,min ≤Δr _cle ≤r _cle,max );

Set in the global coordinate system established by the rotor datum plane, measure the arc profiles of the rear end surfaces of the inner and outer rings of the front bearing respectively, and calculate the centroid coordinates as (x _f,in,cle ,y _f,in,cle ,z _{f, in, cle} ) and (x _{f, out, cle} , y _{f, out, cle} , z _{f, out, cle} ); similarly, measure the circular arc profiles of the front end faces of the inner and outer rings of the rear bearing respectively, and the calculated centroid coordinates are, (x _l,in,cle ,y _l,in,cle ,z _l,in,cle ) and (x _l,out,cle ,y _l,out,cle ,z _l,out,cle ), then the bearing inner ring The axis unit direction vector is:

根据弹性支座结构仿真结果，得前弹性支座和后弹性支座变形分别造成机匣基准面偏移位置矢量为，(δx_sup,f,δy_sup,f,δz_sup,f)和(δx_sup,l,δy_sup,l,δz_sup,l)。Similarly, the unit direction vector of the outer ring axis can be obtained

According to the simulation results of the elastic support structure, the displacement position vectors of the casing datum plane caused by the deformation of the front elastic support and the rear elastic support are, respectively, (δx _sup,f ,δy _sup,f ,δz _sup,f ) and (δx _sup,l , δy _sup,l , δz _sup,l ).

Further, in step 3, a coordinate system is established with the centroid of the left end face of the casing as the origin, the contour points at the joints between the inner flow channel and the rotor blade tips are measured, and the axial position and the coordinates of the contour points are recorded as model input; the contour ellipse equation is established. , use the contour coordinates to calibrate the parameters with the least squares method, extract the center of the ellipse equation, the phases of the long, short semi-axis and long axis; calculate the interpolated centroid, and substitute the flow channel surface contour runout values of different phases into the ellipse equation to establish the inner flow channel The surface contour equation is completed, that is, the calculation model of the casing is completed.

Further, the specific establishment process of the casing calculation model is as follows:

Establish the ellipse equation of the inner flow channel surface of the single-segment casing, take the centroid of the base end face of the casing as the coordinate origin, the axial direction is the x direction, its positive direction is the same as the rotor stacking direction, the cross-section plane is the yOz plane to set the coordinate system, and the vertical direction is the yOz plane. The straight direction is the z-axis direction, then the ellipse equation of the inner flow channel surface matched with the i-th stage rotor is,

y ² +A _cas,i yz+B _cas,i z ² +C _cas,i y+D _cas,i z+E _cas,i =0 (10),

In the formula, A _cas,i ,B _cas,i ,C _cas,i ,D _cas,i ,E _cas,i are the parameters of the ellipse equation calibrated by the least squares method. After fitting the ellipse by the least squares method, the cross section of the flow channel is obtained. The centroid coordinates (x _cas,i ,y _cas,i ,z _cas,i ), the non-negative minimum phase angle of the semimajor axis of the ellipse equation is θ _cas,i , and the following conditions are met:

结合支承变形造成的机匣位置偏差，可得机匣前端基准面形心坐标为(x_cas,ben,y_cas,ben,z_cas,ben)；When the casing assembly structure is placed horizontally, in the global coordinate system of the rotor datum, the relative sinking amount of the casing is

Combined with the position deviation of the casing caused by the deformation of the support, the centroid coordinates of the base plane of the front end of the casing can be obtained as (x _cas,ben ,y _cas,ben ,z _cas,ben );

According to the design shape of the flow channel surface in the casing, the variation equation of the radius of the cross-sectional profile of the flow channel surface in the casing along the axial direction is R _ca =R(x); then calculate the centroid curve.

Further, when the receiver is a split-half receiver, the calculation method of its centroid curve is:

The cubic spline interpolation function of the coordinate components y and z with respect to x is established for the centroid of the flow channel surface in the half casing. The interpolation node matrix formula is:

为插值节点向量，f[x_i-1,x_i,x_i+1]为三阶差分，约束条件m₀,m_n可分别由零件的左端面和右端面的端面姿态向量的分量y，z关于轴向x的向量夹角计算得到，则插值函数为：In the formula, _hi is the node step size,

is the interpolation node vector, f[x _i-1 , x _i , x _i+1 ] is the third-order difference, the constraints m ₀ , m _n can be determined by the component y of the end face attitude vector of the left and right end faces of the part, respectively, The vector angle of z with respect to the axial x is calculated, and the interpolation function is:

In the formula, s(x) refers to y _cas,c (x) or z _cas,c (x), and (x _cas,c ,y _cas,c ,z _cas,c ) is calculated.

Further, when the receiver is an integral thin-walled annular receiver, the calculation method of its centroid curve is:

For the integral thin-walled annular casing, the elliptical contour equations of the inner runners of the front and rear faces of the i-th casing are given by Equation (10). Inner ellipse center coordinates and major axis declination y _cas,f,i ,z _cas,f,i ,θ _cas,f,i and ellipse center coordinates and major axis declination y _cas,l,i , z _cas,l,i ,θ _cas,l,i , then the contour equation of the flow channel in the front end of the casing of the i-th section, the coordinates of any centroid point inside the casing are:

After the multi-segment casings are stacked, in the same way as formula (4), the centroid coordinates of the front end face of the i-th casing are calculated as:

为第i段机匣后端面单位法向量，由式(1)和式(2)计算得出，E_cas,f,i为第i段机匣前端面椭圆截面参数，由最小二乘法标定；In the formula,

is the unit normal vector of the rear face of the casing of the i-th section, calculated from equations (1) and (2), and E _cas,f,i is the ellipse section parameter of the front-end face of the i-th section of the casing, which is calibrated by the least squares method;

Then the centroid coordinates of any point inside the i-th casing are determined by the centroid coordinates of the front and rear surfaces of the single-section casing (x _{cas, f, i} , y _{cas, f, i} , z _{cas, f, i} ) and (x _{cas, l ) ,i} ,y _cas,l,i ,z _cas,l,i ) into formula (5), the calculation can be obtained (x _cas,c ,y _cas,c ,z _cas,c );

测量数据可得流道面待测点相对于设计尺寸的跳动δ_i,j,cas，每个数据可用轴向位置x_i,cas和相位角φ_i,j,cas＝j·Δφ_i,cas唯一表示；则机匣轴向任意位置和相位角所对应的内流道面坐标为：The total number of collection points for measuring the radius value of the flow channel section matched with the i-th rotor blade tip is Ni,cas , and the angle between the collection points is N _i,cas .

The measured data can be used to obtain the runout δ _i,j,cas of the point to be measured on the flow channel surface relative to the design size, and the axial position x _i,cas and the phase angle φ _i,j,cas =j·Δφ _i,cas can be used for each data The only representation; then the coordinates of the inner runner surface corresponding to any position and phase angle of the axial direction of the casing are:

[g]为取整函数，即不超过g值的最大整数。In the formula,

[g] is the rounding function, that is, the largest integer that does not exceed the value of g.

Further, the specific calculation process of step 4 is as follows:

In the absolute coordinate system, when there is no phase deflection of the rotor, the cross-section of the flow channel matched with the tip of the blade j of the i-th rotor satisfies the relational expression:

Substitute the conditions satisfied by Equation (17) into Equation (16), and calculate the coordinates of the runner points that match with it; then the assembly of the i-th stage rotor and the j-th blade tip around the rotation axis is 0° without rotation The tip clearance cle _i,j is expressed as:

旋转后的叶尖位置矢量

和叶片方向向量

分别满足下式：When the rotor rotation axis is deflected by the phase angle θ _rot , set the initial tip position vector of the rotor j of the i-th stage rotor

Rotated tip position vector

and the leaf direction vector

respectively satisfy the following formulas:

Then under the condition of the current phase angle θ _rot , the corresponding point of the flow channel surface matched with the blade j of the i-th rotor satisfies the relationship:

表达为：Substitute the conditional expression of Equation (20) into Equation (16) to calculate the coordinates of the corresponding point of the flow channel surface matched with the blade j of the i-th rotor, then the blade tip clearance

Expressed as:

Then the maximum clearance cle _m,max and the minimum clearance cle _m,min of the m-th stage rotor are:

其中，k为转角编号，则第m级转子的平均间隙cle_m,mean为：Assuming that the number of measurements for the i-th rotor to make one revolution at a certain angle is N _rot,i , the phase angle of a single rotation is

Among them, k is the angle number, then the average clearance cle _m,mean of the m-th rotor is:

The beneficial effects of the invention are: according to the structural characteristics of the rotor and the stator and the actual assembly process, the blade tip clearance prediction model based on error transmission is composed of three parts: the rotor blade tip, the supporting frame and the stator casing. In order to facilitate the data collection and simplify the calculation, the local error transfer model is established for the three parts according to the assembly process. The tip clearance at the rotor phase angle is predicted. The method of the invention correlates the deviation data of each part, establishes a mathematical model through the assembly relationship of the rotor and stator, provides a solution for the current situation of difficult assembly prediction of the rotor and stator blade tip clearance, helps the assembly engineer to analyze the accurate distribution of the rotor stator blade tip clearance, and provides It provides a basis for the optimization of the assembly process for the rotor and stator tip clearance.

【Description of drawings】

Figure 1. Overall frame diagram of the rotor-stator blade tip clearance calculation model;

Figure 2 is a schematic diagram of the formation mechanism of the rotor-stator tip clearance;

Figure 3. The coordinate diagram of the rotor blade tip and the corresponding flow channel surface in the casing;

Figure 4. Boxplots of the calculation results of different phase gaps at rotor tips of all stages.

【Detailed ways】

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention provides a method for predicting the blade tip clearance of aero-engine rotor-stator assembly. The assembly structure affecting the aero-engine rotor-stator assembly blade tip clearance includes three parts: rotor system, support frame and casing and stator assembly. The blade tip clearance in the present invention refers to the radial clearance between the rotor blade tip and the flow channel surface in the casing and the radial clearance between the stator blade tip and the rotor hub. Include the following steps:

S1. Establish a rotor blade tip calculation model:

The space coordinate system is established with the centroid of the front end face of the first-stage rotor as the origin; the coordinate points of the rear face contour are detected by the part, and the space plane equation is established by using the coordinate points, and the plane equation of the rear end face of the rotor at all levels between the front and rear supports is calculated in turn; calculated by the plane equation The unit normal vector of the rear face of the rotor at all levels, that is, the geometric modeling of the runout deviation of the end face is completed; the coordinate points of the outer web surface of the front and rear faces of the rotor are detected by the parts, and the ellipse equation in the section plane is established, and the parameters of the equation are estimated by the least square method. , the centroid coordinates are obtained, that is, the geometric modeling of radial eccentricity deviation is completed; the centroid direction vector inside the single-stage rotor is calculated from the centroid coordinates of the front and rear faces; the tip height and initial phase angle of each blade are calculated, so as to calculate each blade tip The actual coordinates of the point, that is, the calculation model of the rotor tip is completed;

The specific calculation process is as follows:

The coordinate system is established with the rotor datum plane as the assembly global reference, the origin is the centroid of the rotor datum plane, the axial stacking direction is the positive x direction, the section plane is the yOz plane, and the vertical direction is the z-axis direction;

A plane equation is established according to the contour data points of the rear face of the i-th rotor obtained by the testing instrument, and the parameters of the plane equation are fitted by the least squares method to obtain the equation expression:

A _pla,i x+B _pla,i y+C _pla,i z+D _pla,i =0 (24),

In the formula, A _pla , B _pla , C _pla , and D _pla are all calibration plane parameter coefficients. The plane normal vector obtained from formula (1) is normalized to obtain the unit normal vector of the rear face of the i-th rotor:

The outer ring profile of the cross-section plane of the outer web of the front end face of the single-stage rotor at the axial direction x is obtained by the turntable testing instrument. According to the least squares method, the outer circle equation of the front end face is fitted as:

A _cir,f,i y ² +B _cir,f,i z ² +C _cir,f,i y+D _cir,f,i z+E _cir,f,i =0 (26),

In the above formula, A _cir,f,i ,B _cir,f,i ,C _cir,f,i ,D _cir,f,i ,E _cir,f,i are the front ends of the i-th rotors calibrated by the least square method The circular characteristic parameters of the surface are approximated by the sectional plane circle equation to estimate the position vector of the centroid of the front end surface of the i-th stage rotor as:

为前i-1级转子轴向尺寸累积坐标由式(3)和式(4)同理可得后端面近似形心位置矢量(x_cir,l,y_cir,l,z_cir,l)，分量n_x,i由下式给出，第i级转子形心轴的单位方向向量为：In the formula,

For the accumulated coordinates of the axial dimension of the front i-1 stage rotor, the approximate centroid position vector (x _cir,l , y _cir,l , z _cir,l ) of the rear face can be obtained in the same way as equations (3) and (4), The components n _x,i are given by the following equation, the unit direction vector of the rotor centroid axis of the i-th stage is:

为第i级转子内部形心轴矢的模长；In the formula,

is the modulo length of the inner centroid axicon of the i-th rotor;

Assume that the axial positioning dimension of the rotor blade tip of the i-th stage is l _i , the design dimension of the radial height is R _i , and the total number of rotor blades of the i-th stage is N _i , then the circumferential angle of the adjacent blades is

In the yOz plane, the positive z-axis is used as the initial edge of the phase angle, and the circumferential blades are numbered incrementally from 1 along the positive direction of the rotation angle as j, 0<j≤N _i , where the phase angle of the No. 1 blade is φ _{i, 1} , the phase angle of the j blade is φ _i,j =φ _i,1 +(j-1)φ _i,Δ ;

其满足空间相互垂直条件：Set the unit direction vector from the centroid to the zero-phase point of the blade tip in the section plane where the blade tip of the i-th stage is located as

It satisfies the condition that the spaces are perpendicular to each other:

旋转得到

满足公式：Then the unit direction vector corresponding to the blade tip of the blade j of the i-th rotor is from the section axis to the zero-phase point, and the direction vector revolves around the centroid axis

rotate to get

Satisfy the formula:

The radial runout of the blade tip of the rotor j of the i-th stage relative to the design height R _i is δ _j ; therefore, the actual height of the corresponding blade is R _i,j , so the absolute coordinates of the blade tip of the rotor j of the i-th stage are:

S2. Establish the calculation model of the support structure:

The coordinate system is established with the centroid of the left end face of the inner ring of the front bearing matched with the rotor as the origin, and the line connecting the centroid of the adjacent end faces of the inner ring of the front and rear bearings is the axis of rotation of the rotor; the unit vector of the axis of rotation of the rotor is calculated, and the modeling of the axis of rotation of the rotor is completed ; Substitute the deformation coordinate component of the elastic support and the bearing clearance value into the simulation, calculate the centroid offset vector of the casing datum plane under the bearing clearance deviation, and complete the modeling of the support frame.

The specific calculation process is as follows: There are two bearings installed before and after the rotor structure. The bearings have radial clearance and axial clearance deviation. The left end face of the bearing inner ring is the yOz plane, the centroid of the end face is the coordinate origin O, and the vertical direction is z Axial direction, the direction of the centroid to the internal normal vector is the x direction; the axial clearance of the bearing is Δx _cle , (x _cle,min ≤Δx _cle ≤x _cle,max ), and the radial clearance of the bearing is Δr _cle ,(r _{cle ,min} ≤Δr _cle ≤r _cle,max );

Set in the global coordinate system established by the rotor datum plane, measure the arc profiles of the rear end surfaces of the inner and outer rings of the front bearing respectively, and calculate the centroid coordinates as (x _f,in,cle ,y _f,in,cle ,z _{f, in, cle} ) and (x _{f, out, cle} , y _{f, out, cle} , z _{f, out, cle} ); similarly, measure the circular arc profiles of the front end faces of the inner and outer rings of the rear bearing respectively, and the calculated centroid coordinates are, (x _l,in,cle ,y _l,in,cle ,z _l,in,cle ) and (x _l,out,cle ,y _l,out,cle ,z _l,out,cle ), then the bearing inner ring The axis unit direction vector is:

根据弹性支座结构仿真结果，得前弹性支座和后弹性支座变形分别造成机匣基准面偏移位置矢量为，(δx_sup,f,δy_sup,f,δz_sup,f)和(δx_sup,l,δy_sup,l,δz_sup,l)。Similarly, the unit direction vector of the outer ring axis can be obtained

According to the simulation results of the elastic support structure, the displacement position vectors of the casing datum plane caused by the deformation of the front elastic support and the rear elastic support are, respectively, (δx _sup,f ,δy _sup,f ,δz _sup,f ) and (δx _sup,l , δy _sup,l , δz _sup,l ).

S3. Establish the calculation model of the flow channel surface in the casing:

Take the centroid of the left end face of the casing as the origin to establish a coordinate system, measure the contour points where the inner flow channel and the rotor blade tip cooperate, record the axial position and the coordinates of the contour points as the model input; establish the contour ellipse equation, use the contour coordinates with the least two Multiply the calibration parameters, extract the center of the ellipse equation, the phases of the long and short semi-axes and the long axis; calculate the interpolated centroid, and substitute the runout values of the runner surface contour of different phases into the ellipse equation to establish the inner runner surface contour equation, that is, to complete the machine. Box calculation model.

The specific calculation process is as follows:

Establish the ellipse equation of the inner flow channel surface of the single-segment casing, take the centroid of the base end face of the casing as the coordinate origin, the axial direction is the x direction, its positive direction is the same as the rotor stacking direction, the cross-section plane is the yOz plane to set the coordinate system, and the vertical direction is the yOz plane. The straight direction is the z-axis direction, then the ellipse equation of the inner flow channel surface matched with the i-th stage rotor is,

y ² +A _cas,i yz+B _cas,i z ² +C _cas,i y+D _cas,i z+E _cas,i =0 (33),

In the formula, A _cas,i ,B _cas,i ,C _cas,i ,D _cas,i ,E _cas,i are the parameters of the ellipse equation calibrated by the least squares method. After fitting the ellipse by the least squares method, the cross section of the flow channel is obtained. The centroid coordinates (x _cas,i ,y _cas,i ,z _cas,i ), the non-negative minimum phase angle of the semimajor axis of the ellipse equation is θ _cas,i , and the following conditions are met:

结合支承变形造成的机匣位置偏差，可得机匣前端基准面形心坐标为(x_cas,ben,y_cas,ben,z_cas,ben)。When the casing assembly structure is placed horizontally, in the global coordinate system of the rotor datum, the relative sinking amount of the casing is

Combined with the positional deviation of the casing caused by the deformation of the support, the centroid coordinates of the base plane of the front end of the casing can be obtained as (x _cas,ben ,y _cas,ben ,z _cas,ben ).

According to the design shape of the flow channel surface in the casing, the variation equation of the sectional contour radius of the flow channel surface in the casing along the axial direction is R _ca =R(x). According to the different structural characteristics of the casing, different centroid curve calculation methods are adopted for the split-half casing and the integral thin-walled annular casing.

(1) When the receiver is a split-half receiver, the calculation method of its centroid curve is:

The cubic spline interpolation function of the coordinate components y and z with respect to x is established for the centroid of the flow channel surface in the half casing. The interpolation node matrix formula is:

为插值节点向量，f[x_i-1,x_i,x_i+1]为三阶差分，约束条件m₀,m_n可分别由零件的左端面和右端面的端面姿态向量的分量y，z关于轴向x的向量夹角计算得到，则插值函数为：In the formula, _hi is the node step size,

is the interpolation node vector, f[x _i-1 , x _i , x _i+1 ] is the third-order difference, the constraints m ₀ , m _n can be determined by the component y of the end face attitude vector of the left and right end faces of the part, respectively, The vector angle of z with respect to the axial x is calculated, and the interpolation function is:

In the formula, s(x) refers to y _cas,c (x) or z _cas,c (x), and (x _cas,c ,y _cas,c ,z _cas,c ) is calculated.

(2) When the receiver is an integral thin-walled annular receiver, the calculation method of its centroid curve is:

For the integral thin-walled annular casing, the elliptical contour equations of the inner runners of the front and rear faces of the i-th casing are given by Equation (10). Inner ellipse center coordinates and major axis declination y _cas,f,i ,z _cas,f,i ,θ _cas,f,i and ellipse center coordinates and major axis declination y _cas,l,i , z _cas,l,i ,θ _cas,l,i , then the contour equation of the flow channel in the front end of the casing of the i-th section, the coordinates of any centroid point inside the casing are:

After the multi-segment casings are stacked, in the same way as formula (4), the centroid coordinates of the front end face of the i-th casing are calculated as:

为第i段机匣后端面单位法向量，由式(1)和式(2)计算得出，E_cas,f,i为第i段机匣前端面椭圆截面参数，由最小二乘法标定；In the formula,

is the unit normal vector of the rear face of the casing of the i-th section, calculated from equations (1) and (2), and E _cas,f,i is the ellipse section parameter of the front-end face of the i-th section of the casing, which is calibrated by the least squares method;

Then the centroid coordinates of any point inside the i-th casing are determined by the centroid coordinates of the front and rear surfaces of the single-section casing (x _{cas, f, i} , y _{cas, f, i} , z _{cas, f, i} ) and (x _{cas, l ) ,i} ,y _cas,l,i ,z _cas,l,i ) into formula (5), the calculation can be obtained (x _cas,c ,y _cas,c ,z _cas,c );

测量数据可得流道面待测点相对于设计尺寸的跳动δ_i,j,cas，每个数据可用轴向位置x_i,cas和相位角φ_i,j,cas＝j·Δφ_i,cas唯一表示；则机匣轴向任意位置和相位角所对应的内流道面坐标为：The total number of collection points for measuring the radius value of the flow channel section matched with the i-th rotor blade tip is Ni,cas , and the angle between the collection points is N _i,cas .

The measured data can be used to obtain the runout δ _i,j,cas of the point to be measured on the flow channel surface relative to the design size, and the axial position x _i,cas and the phase angle φ _i,j,cas =j·Δφ _i,cas can be used for each data The only representation; then the coordinates of the inner runner surface corresponding to any position and phase angle of the axial direction of the casing are:

[g]为取整函数，即不超过g值的最大整数。In the formula,

[g] is the rounding function, that is, the largest integer that does not exceed the value of g.

S4. Establish an absolute coordinate system with the assembly reference centroid of the front end face of the first-level rotor as the global reference, the reference centroid as the origin, the reference normal direction as the x-axis direction, and the reference plane as the yOz plane; calculate the blade tip coordinates under the absolute coordinate system; Calculate the inner flow channel surface equation in the absolute coordinate system, and substitute the blade tip coordinates into the equation to calculate the absolute coordinates of the flow channel matching point; calculate the initial tip clearance of each rotor; input the deflection phase angle, calculate the tip clearance of different rotor phases, and record Numerical value, that is, all modeling is completed; after the modeling is completed, the deviation data and dimension data required by the rotor, support and stator casing models are input into the model calculation; the model outputs the rotors and stators at all levels under different rotor phases according to the input data. The predicted value of the clearance of the blade tip, the corresponding clearance distribution curve is given, and the maximum, minimum and average clearances of the rotor and stator at all levels predicted by the model are obtained; the predicted results are compared with the clearance requirements of the process standard to determine the rotor and stator assembly Whether the tip clearance index is qualified or not, or the out-of-tolerance part is given according to the predicted value, to provide a basis for reprocessing, that is, to complete the prediction of the tip clearance of the aero-engine rotor and stator assembly.

The method of the present invention predicts the blade tip clearance after the assembly is completed according to the measurement data of the parts during the assembly process, because the blade tip clearance is invisible after the assembly is completed. The measurement data of different features of the part fit the deviation feature according to the model method. The model uses the centroid and unit direction vector to represent the deviation feature, and then establishes the dimension chain transfer model of the deviation feature, and finally calculates the tip clearance. In the method of the present invention, the prediction result of the blade tip clearance can be obtained by importing the measurement deviation data of the parts and the dimension data.

The specific calculation process is as follows:

Combining the above three parts of the calculation model, the core model of the rotor-stator blade tip clearance, the core part is the process of changing the relative position relationship of the three axis curves and one height vector as shown in Figure 2 with the change of the rotor tip phase angle. In the absolute coordinate system, when there is no phase deflection of the rotor, the cross-section of the flow channel matched with the tip of the blade j of the i-th rotor satisfies the relational expression:

Substitute the conditions satisfied by Equation (17) into Equation (16), and calculate the coordinates of the runner points that match with it; then the assembly of the i-th stage rotor and the j-th blade tip around the rotation axis is 0° without rotation The tip clearance cle _i,j is expressed as:

旋转后的叶尖位置矢量

和叶片方向向量

分别满足下式：When the rotor rotation axis is deflected by the phase angle θ _rot , set the initial tip position vector of the rotor j of the i-th stage rotor

Rotated tip position vector

and the leaf direction vector

respectively satisfy the following formulas:

Then under the condition of the current phase angle θ _rot , the corresponding point of the flow channel surface matched with the blade j of the i-th rotor satisfies the relationship:

表达为：Substitute the conditional expression of Equation (20) into Equation (16) to calculate the coordinates of the corresponding point of the flow channel surface matched with the blade j of the i-th rotor, then the blade tip clearance

Expressed as:

Then the maximum clearance cle _m,max and the minimum clearance cle _m,min of the m-th stage rotor are:

其中，k为转角编号，则第m级转子的平均间隙cle_m,mean为：Assuming that the number of measurements for the i-th rotor to make one revolution at a certain angle is N _rot,i , the phase angle of a single rotation is

Among them, k is the angle number, then the average clearance cle _m,mean of the m-th rotor is:

The invention provides a method for predicting the blade tip clearance of an aero-engine rotor and stator assembly, which collects the coordinates of the contour feature points on the front and rear surfaces of the rotors at all levels, the coordinates of the circular contour points on the contour plate surface of the outer ring of the end face, and the tip jump as input; For the assembly structure, enter the rotor axial dimension, radial dimension, blade tip height dimension, number of blades and the circumferential phase angle of the No. 1 blade; the coordinate points of the deviation data are fitted by features to express the fitting features with deviation; The plane equation is expressed, the real centroid and the surface contour of the web are expressed by the space circle equation, and the rotor centroid axial curve is expressed in the form of a vector. mark to clarify the circumferential phase angle when the blisk is installed. In order to facilitate the calculation of the actual height of each blade tip in the circumferential direction, it is a personal definition to denote the first blade in the zero-phase forward direction as the No. 1 blade. After each step of the assembly process is completed, the size data and deviation data of the rotor being assembled are substituted into the calculation model to complete a deviation transfer. At the same time, the initial phase blades of all the tip points of the rotor of this stage in the circumferential direction are also generated in the model. Point coordinates; rotor assembly is a process of stacking parts. Each time the next rotor is assembled, the end face of the previous one is the reference assembly. The dimensional deviation is transmitted between the stages by affecting the centroid pose data of the mating surface, and finally mapped to the rotor blades of each stage. The coordinates of the cusp.

The data obtained from the detection of the bearing radial clearance parts are used as the rigidity deviation, the elastic support deformation obtained by the finite element simulation of the structure is used as the flexible deviation, and the two parts of the deviation data are used as the input of the support structure calculation model; the center line of the front and rear bearings is is the axis of rotation of the rotor, and the rotor rotates around the axis of rotation at a low speed for one cycle, then it is calculated that the tip clearance presents different distribution characteristics under different phase angles.

During the actual assembly and inspection process of the casing structure, measure the contour of a circle around the circumference of the axial specified position of the inner runner surface of the casing, and obtain the contour coordinate point data of the inner runner section under the axial constant coordinates; establish a multi-section inner The ellipse equation of the flow channel surface, according to the rotor series and the axial dimension matched with the casing, determine the number and axial position of the ellipse section equation of the inner flow channel surface; the input deviation data of the casing calculation model include: the elliptical deformation deviation of the casing , end face runout deviation, inner flow channel face runout deviation, stator blade tip runout deviation; for the casing, different casing centroid estimation equations are established according to different structural types. Among them, the axial direction of the casing is a continuum, and the cubic spline interpolation method is used to calculate the centroid of the casing at any position in the axial direction; for the overall thin-walled annular casing, it is a multi-segment stacking assembly method. Error propagation is the same as the rotor stacking principle.

For two different casing structures, different centroid evaluation schemes are adopted: for the split-half type casing, cubic spline interpolation is used to establish an interpolation function for calculating the centroid at any axial position; for the integral thin-walled ring machine box, calculate the plane equation of the rear face of the single-segment casing, and complete the modeling of the runout deviation of the end face; take the detection data of the inner runner profile of the front and rear faces of the casing as the input, calculate the centroid; connect the centroid of the front and rear faces to establish a single-segment vector The calculation function of the centroid coordinates of any position in the axial direction inside the casing.

The calculation of the above three steps respectively simulates the deviation transfer law affecting the three plate assembly process of the rotor system, the stator system and the support structure. The transfer of the size and deviation chain in the model is developed along two paths respectively, and finally the coordinates of the matching point between the tip and the corresponding flow channel surface are calculated, and the tip clearance value is calculated from the coordinate difference; because the rotor centroid is not concentric with the center of the rotating shaft , the gap between the rotor blade tip and the flow channel surface is different in different phases; the rotation declination value is set in the calculation model, and all the rotor features rotate the declination value around the rotation axis from the initial phase. After the circumferential direction is completed for one week, the mean, maximum and minimum value of the tip clearances are obtained for all the tip clearances of the rotors at all levels.

Example

The method for predicting the blade tip clearance of aero-engine rotor-stator assembly of the present invention is formed into a calculation program, and the rotor end face beating, radial eccentricity, blade tip beating, the end face beating and elliptical deformation of the casing detected during the assembly process are used. The bearing clearance and the deformation of the elastic support are input, and a mathematical calculation model is constructed to output the coordinates of the rotor blade tip, the section equation of the flow passage surface in the casing, the maximum clearance, minimum clearance and average clearance of the rotor at all levels.

From input to output, the data flow goes through four stages of feature computation, volume module construction, global assembly, and gap computation, and inherits properties in the form of classes in the first two stages. The following takes the rotor blade tip clearance of a certain engine as the research object, and takes the key parameters of the assembly of specific rotor and casing-related aero-engine components as an example to illustrate the method of the present invention. The key structural characteristic parameters are shown in the following table:

Table 1 Key characteristic parameters of rotor and casing structure (unit: mm)

Rotor radial height Radial height of casing runner section tip clearance Number of leaves Axial coordinates first stage rotor 110 110.8 0.8 20 25 Secondary rotor 102.5 103.2 0.7 20 75 three-stage rotor 95 95.6 0.6 20 125 four-stage rotor 87.5 88 0.5 20 175 five-stage rotor 80 80.4 0.4 20 225

The global error transmission path includes three parts: rotor, support frame and stator casing. The specific transmission path is shown in Figure 1. It is expanded by the global benchmark and transmitted in two paths, and finally the tip clearance is formed.

Step 1, rotor tip coordinate calculation:

In the example, there is a five-stage rotor blisk, and its structural data refer to the table, and because the amount of error detection data is too large, it is explained with the fitted characteristic data, and the detailed fitting error characteristic data is referred to the table.

Table 2 Rotor deviation data after fitting and processing of partial data

backside runout Maximum beat phase angle Radial maximum eccentricity Eccentric phase angle Maximum tip runout first stage rotor 0.019mm 97° 0.003mm 135° 0.031mm Secondary rotor 0.030mm 167° 0.005mm 247° 0.026mm three-stage rotor 0.025mm 295° 0.002mm 67° 0.021mm four-stage rotor 0.011mm 206° 0.003mm 94° 0.022mm five-stage rotor 0.018mm 341° 0.002mm 301° 0.018mm

Table 2 is calculated by substituting the data in the table into equations (1)-(8) for the rotor deviation data after fitting and processing of some data, and finally the absolute coordinates of each tip point of the rotor are given by equation (8).

Step 2, support structure calculation:

According to the actual measurement parameters of the bearing structure, the maximum radial clearance of the front bearing structure is 0.005mm, the axial clearance is 0.008mm, the maximum radial clearance of the rear bearing is 0.006mm, and the axial clearance is 0.007mm. ) to get the rotor rotation axis vector. According to the design of the elastic support and the deformation simulation analysis results, the deformation of the highest point in the z-axis direction of the front support is δ _supf ,=(-0.001mm,0,0.0), and the deformation of the highest point in the z-axis direction of the rear support is δ _sup,l =( 0.001mm, 0, 0.002mm).

Step 3. Calculation of the flow channel surface in the casing:

Taking the split-half casing as an example, the calculation of the deviation of the inner flow channel surface is explained. The characteristic data obtained after processing the initial point cloud data of the inner flow channel surface deviation are shown in the table. The axial coordinates in the table are the x-axis coordinates in the casing coordinate system in step 3.

Table 3 Partial data fitting and processing of casing deviation data

Substitute the processed case deviation characteristic data into equations (10)-(13) respectively, and calculate the ellipse characteristic equation of each section and the cubic spline interpolation function of the centroid. The matching point of the flow channel surface in the casing is calculated by substituting the feature relationship in step 4.

Step 4, rotor tip clearance calculation:

The core of the rotor-stator assembly tip clearance calculation model is the introduction of the rotation deflection angle θ _rot , so that the rotor's centroid axis rotates around the rotation axis in space at different phase angles as shown in Figure 2, which is consistent with the shape of the stator casing. The mandrel presents different changing laws in space.

Substituting the above deviation into the model calculation, the coordinates of the rotor blade tip in a single section shown in Figure 3 and the spatial coordinate diagram of the corresponding flow channel section in the casing can be obtained. Substitute the coordinates of the rotor tip point into equation (16) to calculate the coordinates of the corresponding blade tip point, according to the transformation relationship of equations (17)-(20). The rotor tip rotates around the axis of rotation, and the tip clearance value of each rotor tip at any phase is calculated by equation (21), and the program gives the boxplot shown in Figure 4 according to the calculation result. In the figure, a unit represents the fluctuation of 20 blade tips of a single-stage rotor with a total of 400 tip clearance values in 20 phases in the circumferential direction. The red line represents the median value of the tip clearance, and the upper and lower ends of the dotted line represent the maximum value respectively. and minimum values, while the red "+" indicates outliers that are too biased. At the same time, the maximum clearance, minimum clearance and average clearance of the blade tip are calculated by formula (22) and formula (23) respectively, and the calculation results are shown in Table 4.

Table 4 Calculation results of rotor tip clearance (unit: mm)

From the results shown in Table 4 and FIG. 4 , the method shown in the present invention can more accurately evaluate the blade tip clearance of the aero-engine rotor and stator assembly. Through a total of 400 tip clearance values of 20 tips of a single-stage rotor under 20 different phases, the maximum and minimum clearances and average clearances of rotors at all levels can be evaluated. The fluctuation range of the predicted results of rotors at all levels is within ±0.15mm. Meets empirical expectations and tolerances.

If the result of the assembly tip clearance value exceeds the assembly process requirements of the relevant blade, the assembly engineer can predict the result according to the method, locate the out-of-tolerance part, and provide parameters according to the out-of-tolerance value, so that the engineer can reprocess the corresponding part, such as: grinding the blade tip , Turn the runner surface or adjust the process parameters.

The conventional aero-engine assembly process only tests each part to meet the tolerance requirements of each part, and does not associate the deviation data of each part and establish a dimensional error transfer model for the rotor-stator assembly tip clearance. For the tip clearance, the traditional process only detects the part with good openness, and most of the tip clearance with poor openness cannot be detected, and other technical means are needed to evaluate and assemble the tip clearance. With the continuous improvement of aero-engine performance requirements, the assembly process needs to be transformed into precision and digitalization, and traditional technical means can no longer meet the demand. The invention proposes a method for predicting the clearance of the rotor and stator assembly blade tip of an aero-engine, correlates the deviation data of each part, and establishes a mathematical model through the assembly relationship of the rotor and stator, which can provide a solution for the current situation that the rotor and stator blade tip clearance is difficult to predict. , which helps the assembly engineer analyze the accurate distribution of the rotor-stator tip clearance, and provides a basis for the assembly process optimization for the rotor-stator tip clearance.

Claims (10)

1. a prediction method of aero-engine rotating stator assembly tip clearance, it is characterized in that, described aero-engine comprises rotor system, support frame, casing and stator assembly, and described blade tip clearance refers to the rotor blade tip and the inside of the casing. The radial clearance of the flow passage surface, and the radial clearance of the stator blade tip and the rotor hub, the prediction method includes the following steps: Step 1. Establish a rotor blade tip calculation model; Step 2. Establish a calculation model of the support structure; Step 3. Establish a calculation model of the flow channel surface in the casing; Step 4. In the absolute coordinate system, use the homogeneous coordinate transformation matrix to integrate the three calculation models obtained in the steps 1 to 3 into the rotor-stator tip clearance calculation model, and analyze the tip clearance under different rotor phase angles. Make predictions. 2. The method for predicting aero-engine rotor-stator assembly tip clearance as claimed in claim 1, wherein in the step 1, the centroid of the first-stage rotor or the axial reference plane of the front journal is taken as the origin The space coordinate system is established; the contour coordinate points of the rear end face of the first-level rotor are detected by the part, and the space plane equation is established by using the coordinate points, and the plane equation of the rear end face of each rotor between the front and rear supports is calculated in turn; the unit method of the rear end face of the rotor at each level is calculated by the plane equation vector, that is, to complete the geometric modeling of the runout deviation of the end face; the part detects the coordinate points of the outer web surface of the front and rear faces of the rotor, establishes the circle equation in the section plane, and estimates the parameters of the equation by the least square method to obtain the centroid coordinates, namely Complete the geometric modeling of radial eccentricity deviation; calculate the centroid direction vector inside the single-stage rotor from the centroid coordinates of the front and rear faces; calculate the tip height and initial phase angle of each blade, so as to calculate the actual coordinates of each blade tip point, that is, complete Rotor tip calculation model. 3. the prediction method of a kind of aero-engine rotor-stator assembly tip clearance as claimed in claim 2, is characterized in that, the concrete calculation process of described step 1 is as follows: The coordinate system is established with the rotor datum plane as the assembly global reference, the origin is the centroid of the rotor datum plane, the axial stacking direction is the positive x direction, the section plane is the yOz plane, and the vertical direction is the z-axis direction; A plane equation is established according to the contour data points of the rear face of the i-th rotor obtained by the testing instrument, and the parameters of the plane equation are fitted by the least squares method to obtain the equation expression: A _pla,i x+B _pla,i y+C _pla,i z+D _pla,i =0 (1), In the formula, A _pla , B _pla , C _pla , and D _pla are all calibration plane parameter coefficients. The plane normal vector obtained from formula (1) is normalized to obtain the unit normal vector of the rear face of the i-th rotor:

The outer ring profile of the cross-section plane of the outer web of the front end face of the single-stage rotor at the axial direction x is obtained by the turntable testing instrument. According to the least squares method, the outer circle equation of the front end face is fitted as: A _cir,f,i y ² +B _cir,f,i z ² +C _cir,f,i y+D _cir,f,i z+E _cir,f,i =0 (3), In the above formula, A _cir,f,i ,B _cir,f,i ,C _cir,f,i ,D _cir,f,i ,E _cir,f,i are the front ends of the i-th rotors calibrated by the least square method The circular characteristic parameters of the surface are approximated by the sectional plane circle equation to estimate the position vector of the centroid of the front end surface of the i-th stage rotor as:

In the formula,

For the accumulated coordinates of the axial dimension of the front i-1 stage rotor, the approximate centroid position vector (x _cir,l , y _cir,l , z _cir,l ) of the rear face can be obtained in the same way as equations (3) and (4), The components n _x,i are given by the following equation, the unit direction vector of the rotor centroid axis of the i-th stage is:

In the formula,

is the modulo length of the inner centroid axicon of the i-th rotor; Assume that the axial positioning dimension of the rotor blade tip of the i-th stage is l _i , the design dimension of the radial height is R _i , and the total number of rotor blades of the i-th stage is N _i , then the circumferential angle of the adjacent blades is

In the yOz plane, the positive z-axis is used as the initial edge of the phase angle, and the circumferential blades are numbered incrementally from 1 along the positive direction of the rotation angle as j, 0<j≤N _i , where the phase angle of the No. 1 blade is φ _{i, 1} , the phase angle of the j blade is φ _i,j =φ _i,1 +(j-1)φ _i,Δ ; Set the unit direction vector from the centroid to the zero-phase point of the blade tip in the section plane where the blade tip of the i-th stage is located as

It satisfies the condition that the spaces are perpendicular to each other:

Then the unit direction vector corresponding to the blade tip of the blade j of the i-th rotor is from the section axis to the zero-phase point, and the direction vector revolves around the centroid axis

rotate to get

Satisfy the formula:

The radial runout of the blade tip of the rotor j of the i-th stage relative to the design height R _i is δ _j ; therefore, the actual height of the corresponding blade is R _i,j , so the absolute coordinates of the blade tip of the rotor j of the i-th stage are:

4. The method for predicting the clearance of aero-engine rotor and stator assembly blade tip clearance according to claim 1 or 2, wherein in the step 2, the centroid of the left end face of the inner ring of the front bearing matched with the rotor is taken as the origin A coordinate system is established, and the centroid of the adjacent end faces of the inner ring of the front and rear bearings is the rotor rotation axis; the unit vector of the rotor rotation axis is calculated, and the modeling of the rotor rotation axis is completed; the deformation coordinate component of the elastic support and the bearing clearance value are substituted into the simulation , calculate the centroid offset vector of the casing datum plane under the bearing clearance deviation, that is, complete the modeling of the support frame. 5. the prediction method of a kind of aero-engine rotor-stator assembly blade tip clearance as claimed in claim 4, is characterized in that, the concrete calculation process of described step 2 is as follows: rotor structure is installed with two bearings before and after, and the bearing has radial Clearance and axial clearance deviation, take the left end face of the bearing inner ring as the yOz plane, the centroid of the end face as the coordinate origin O, the vertical direction as the z-axis direction, and the centroid to the internal normal vector direction as the x direction; The clearance is Δx _cle ,(x _cle,min ≤Δx _cle ≤x _cle,max ), and the bearing radial clearance is Δr _cle ,(r _cle,min ≤Δr _cle ≤r _cle,max ); Set in the global coordinate system established by the rotor datum plane, measure the arc profiles of the rear end surfaces of the inner and outer rings of the front bearing respectively, and calculate the centroid coordinates as (x _{f, in, cle} , y _{f, in, cle} , z _{f, in, cle} ) and (x _{f, out, cle} , y _{f, out, cle} , z _{f, out, cle} ); similarly, measure the circular arc profiles of the front end faces of the inner and outer rings of the rear bearing respectively, and the calculated centroid coordinates are, (x _l,in,cle ,y _l,in,cle ,z _l,in,cle ) and (x _l,out,cle ,y _l,out,cle ,z _l,out,cle ), then the bearing inner ring The axis unit direction vector is:

Similarly, the unit direction vector of the outer ring axis can be obtained

According to the simulation results of the elastic support structure, the displacement position vectors of the casing datum plane caused by the deformation of the front elastic support and the rear elastic support are, respectively, (δx _sup,f ,δy _sup,f ,δz _sup,f ) and (δx _sup,l , δy _sup,l , δz _sup,l ). 6. a kind of prediction method of aero-engine rotor-stator assembly blade tip clearance as claimed in claim 1 or 2, it is characterized in that, in described step 3, take the centroid of the left end face of the casing as the origin to establish the coordinate system, measure the inner The contour point at the joint of the flow channel and the rotor tip, record the axial position and the coordinates of the contour point as the model input; establish the contour ellipse equation, use the contour coordinates to calibrate the parameters with the least squares method, extract the center of the ellipse equation, the long and short semi-axis and Long-axis phase; calculate the interpolated centroid, and substitute the runout value of the runner surface profile of different phases into the ellipse equation to establish the inner runner surface profile equation, that is, to complete the casing calculation model. 7. the prediction method of a kind of aero-engine rotor-stator assembly blade tip clearance as claimed in claim 6, is characterized in that, the concrete establishment process of described casing calculation model is as follows: Establish the ellipse equation of the inner flow channel surface of the single-segment casing, take the centroid of the base end face of the casing as the coordinate origin, the axial direction is the x direction, its positive direction is the same as the rotor stacking direction, the cross-section plane is the yOz plane to set the coordinate system, and the vertical direction is the yOz plane. The straight direction is the z-axis direction, then the ellipse equation of the inner flow channel surface matched with the i-th stage rotor is, y ² +A _cas,i yz+B _cas,i z ² +C _cas,i y+D _cas,i z+E _cas,i =0 (10), In the formula, A _cas,i ,B _cas,i ,C _cas,i ,D _cas,i ,E _cas,i are the parameters of the ellipse equation calibrated by the least squares method. After fitting the ellipse by the least squares method, the runner cross section is obtained. The centroid coordinates (x _cas,i ,y _cas,i ,z _cas,i ), the non-negative minimum phase angle of the semimajor axis of the ellipse equation is θ _cas,i , and the following conditions are met:

When the casing assembly structure is placed horizontally, in the global coordinate system of the rotor datum, the relative sinking amount of the casing is

Combined with the position deviation of the casing caused by the deformation of the support, the centroid coordinates of the base plane of the front end of the casing can be obtained as (x _cas,ben ,y _cas,ben ,z _cas,ben ); According to the design shape of the flow channel surface in the casing, the variation equation of the radius of the cross-sectional profile of the flow channel surface in the casing along the axial direction is R _ca =R(x); then calculate the centroid curve. 8. the prediction method of a kind of aero-engine rotor-stator assembly blade tip clearance as claimed in claim 7, is characterized in that, when the casing is a split-half casing, its centroid curve calculation method is: The cubic spline interpolation function of the coordinate components y and z with respect to x is established for the centroid of the flow channel surface in the half casing. The interpolation node matrix formula is:

In the formula, _hi is the node step size,

is the interpolation node vector, f[x _i-1 , x _i , x _i+1 ] is the third-order difference, the constraints m ₀ , m _n can be determined by the component y of the end face attitude vector of the left end face and the right end face of the part, respectively, The vector angle of z with respect to the axial x is calculated, and the interpolation function is:

In the formula, s(x) refers to y _cas,c (x) or z _cas,c (x), and (x _cas,c ,y _cas,c ,z _cas,c ) is calculated. 9. the prediction method of a kind of aero-engine rotor-stator assembly blade tip clearance as claimed in claim 7, is characterized in that, when the casing is the integral thin-walled annular casing, its centroid curve calculation method is: For the integral thin-walled annular casing, the ellipse contour equations of the inner runners on the front and rear faces of the i-th casing are given by equation (10). Inner ellipse center coordinates and major axis declination y _cas,f,i ,z _cas,f,i ,θ _cas,f,i and ellipse center coordinates and major axis declination y _cas,l,i , z _cas,l,i ,θ _cas,l,i , then the contour equation of the flow channel in the front end of the casing of the i-th section, the coordinates of any centroid point inside the casing are:

After the multi-segment casings are stacked, in the same way as formula (4), the centroid coordinates of the front end face of the i-th casing are calculated as:

In the formula,

is the unit normal vector of the rear face of the casing of the i-th section, calculated from equations (1) and (2), and E _cas,f,i is the ellipse section parameter of the front-end face of the i-th section of the casing, which is calibrated by the least squares method; Then the centroid coordinates of any point inside the i-th casing are determined by the centroid coordinates of the front and rear surfaces of the single-section casing (x _{cas, f, i} , y _{cas, f, i} , z _{cas, f, i} ) and (x _{cas, l ) ,i} ,y _cas,l,i ,z _cas,l,i ) into formula (5), the calculation can be obtained (x _cas,c ,y _cas,c ,z _cas,c ); The total number of collection points for measuring the radius value of the flow channel section matched with the i-th rotor blade tip is Ni,cas , and the angle between the collection points is N _i,cas .

The measured data can be used to obtain the runout δ _i,j,cas of the point to be measured on the flow channel surface relative to the design size, and the axial position x _i,cas and the phase angle φ _i,j,cas =j·Δφ _i,cas can be used for each data The only representation; then the coordinates of the inner runner surface corresponding to any position and phase angle of the axial direction of the casing are:

In the formula,

[g] is the rounding function, that is, the largest integer that does not exceed the value of g. 10. a kind of prediction method of aero-engine rotor stator assembly tip clearance as claimed in claim 1 or 2, is characterized in that, the concrete calculation process of described step 4 is as follows: In the absolute coordinate system, when there is no phase deflection of the rotor, the cross-section of the flow channel matched with the tip of the blade j of the i-th rotor satisfies the relational expression:

Substitute the conditions satisfied by Equation (17) into Equation (16), and calculate the coordinates of the runner points; then the rotor of the i-th stage, the assembly of the blade tip of the j-th blade around the rotation axis is 0° without rotation The tip clearance cle _i,j is expressed as:

When the rotor rotation axis is deflected by the phase angle θ _rot , set the initial tip position vector of the rotor j of the i-th stage rotor

Rotated tip position vector

and the leaf direction vector

respectively satisfy the following formulas:

Then under the condition of the current phase angle θ _rot , the corresponding point of the flow channel surface matched with the blade j of the i-th rotor satisfies the relationship:

Substitute the conditional expression of Equation (20) into Equation (16) to calculate the coordinates of the corresponding point of the flow channel surface matched with the blade j of the i-th rotor, then the blade tip clearance

Expressed as:

Then the maximum clearance cle _m,max and the minimum clearance cle _m,min of the m-th stage rotor are:

Assuming that the number of measurements for the i-th rotor to make one revolution at a certain angle is N _rot,i , the phase angle of a single rotation is

Among them, k is the angle number, then the average clearance cle _m,mean of the m-th rotor is:

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