CN103745030B - A kind of eccentric drum barrel aerodynamics evaluation method with labyrinth gas seals - Google Patents

Abstract

The invention discloses a kind of eccentric drum barrel aerodynamics evaluation method with labyrinth gas seals belonging to rotor dynamics technical field. The method is: 1) integrated fluid calculates and structural analysis, sets up the three-dimensional drum barrel geometrical calculation model with labyrinth gas seals and three-dimensional drum barrel structural model; 2) utilize the three-dimensional geometry computation model in step 1), calculate drum surface static pressure under different offset; 3) in step 2) basis on, calculate the drum surface with labyrinth gas seals radially aerodynamic force and tangential aerodynamic force; 4) utilize the three-valued structures model in step 1), in step 2) basis on, the impact on drum barrel characteristic of the calculated gas flow exciting. The present invention is by calculating with the eccentric drum surface aerodynamic force of labyrinth gas seals and aerodynamic force the change about static characteristic of the drum barrel structure, combine the simple Airflow Exciting-Vibration Force calculating certain rotor structure and research structure mechanical characteristic under dynamic excitation affects, be suitable for the calculating of the cartridge type rotor of concrete size and structure.

Description

A Calculation Method of Aerodynamic Force of Eccentric Drum with Grate Seal

technical field

The invention belongs to the technical field of rotor dynamics, in particular to an aerodynamic calculation method of an eccentric drum with a grate tooth seal.

Background technique

Turbomachinery (axial flow compressor, turbine engine and steam turbine) in large rotating machinery is an important equipment in the power industry and aerospace industry. However, there are still many problems in its design and manufacture, which lead to serious accidents in operation, resulting in heavy economic losses and even casualties.

The main cause of various vicious accidents is the vibration and instability of large rotating machinery, and the main factor causing vibration and instability is the various exciting forces of the system. Therefore, according to the research on the exciting force of the rotor, it can be known that the exciting force of the rotor mainly includes the oil film reaction force, the periodic air flow exciting force, and the sealing force. In addition, the excitation force caused by the eccentricity of the flexible rotor (Alford force for short) is also a common type of excitation force.

The drum is a common connection structure in the rotor system of the above rotating machinery, and the grate teeth on the drum also have a sealing effect, and its sealing performance affects the overall performance of the aero-engine. Due to problems in the manufacturing process or unbalanced forces, the rotor stator will produce relative eccentricity, making the circumferential clearance of the rotor stator uneven, and this uneven distribution changes with the rotation of the rotor. Therefore, the uneven spacing between the sealing grate teeth and the eccentricity of the rotor and stator will inevitably generate aerodynamic forces that are not equal at each position of the drum, and the complex airflow excitation will affect the dynamic characteristics of the drum structure. Whether the sealing model and reasonable calculation of the grate drum can be established determines whether the dynamic influence of aerodynamic force on the drum structure can be accurately analyzed and the aerodynamic boundary conditions can be determined.

Although many scholars at home and abroad have done a lot of research on the airflow excitation of the sealing structure, they mainly focus on the sealing mechanism of the disc grate, and carry out numerical simulation calculations on the sealing characteristics of the grate from the aspects of leakage and speed. Drum grates are under-calculated.

Contents of the invention

In order to overcome the vacancy in the above-mentioned prior art, the present invention proposes a method for calculating the aerodynamic force of an eccentric drum with a grate tooth seal, which is characterized in that the specific steps of the calculation method are:

1) Comprehensive fluid calculation and structural analysis, establish a three-dimensional drum geometric calculation model with a grate seal and a three-dimensional drum structure model with a grate seal;

2) Use the three-dimensional geometric calculation model in step 1) to calculate the surface static pressure value of the drum under different eccentricities;

3) On the basis of step 2), calculate the radial aerodynamic force and tangential aerodynamic force on the surface of the drum with grate tooth seal;

4) Using the three-dimensional structural model in step 1), on the basis of step 2), calculate the influence of airflow excitation on the characteristics of the drum.

The step 1) establishing a three-dimensional drum geometric calculation model with a grate seal specifically includes:

11) Simplify and omit geometric details that will not have a great impact on the flow field structure;

12) In order to accelerate the calculation convergence, the multi-grid technology is used to divide the grid;

The number of layers of the multigrid is determined by the number of grids, and the number of grids satisfies:

∑2 ⁿ +1(n≥2)

where n represents the number of grid layers;

The number of layers of the multigrid is: min(n)+1;

13) Calculate and set the grid width of the first layer of the channel wall:

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; wall</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 6</span>}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}}{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{<span\; class="notranslate">\; +</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>$

Among them, y _wall is the grid size of the first layer of the wall, the unit is m; V _ref is the reference velocity, the unit is m/s; L _ref is the reference length, the unit is m; v is the kinematic viscosity of the fluid, the unit is m ² / s; Y ₁ ⁺ is a dimensionless quantity, which corresponds to different turbulence models and has different value ranges.

The geometric details in step 11) refer to the tooth shape of the grate and the specific shape and size between the simulation blades in the set flow channel.

In step 1) to establish a three-dimensional drum structure model, it is necessary to divide grids corresponding to the grids of the three-dimensional drum geometric calculation model, mainly referring to the number of grids in the circumferential direction.

The step 2) is specifically:

21) Set the different eccentricity e of the drum grate and the stator, and select the appropriate inlet and outlet boundary conditions;

22) Calculate and extract multiple sets of static pressure values according to different vortex frequency ratios Ω/ω, where Ω is the eccentric drum vortex motion speed, ω is the drum rotor speed;

23) On the basis of calculating the static pressure value on the surface of the drum, obtain the relationship of the static pressure p on the surface of the drum with time, and the transformation relationship is as follows:

in, is the circumferential angle of the eccentric coordinate system, is the circumferential angle of the rotor coordinate system.

The inlet and outlet boundary conditions in the step 21) refer to the pressure and temperature at the inlet and outlet.

The whirl frequency ratio in the step 22) is 0, 0.2, -0.5, -1.0.

The step 3) is specifically:

31) On the basis of step 23), integrate the static pressure value of the drum surface under different eccentricities, and solve the radial aerodynamic force and tangential aerodynamic force. The formula is

Among them, F _r is the radial aerodynamic force, F _t is the tangential aerodynamic force, z is the axial coordinate of the drum, r is the radial radius, L is the axial length, is the circumferential angle of the eccentric coordinate system;

32) Neglecting the influence of additional mass and inertia, when a certain amount of eccentricity is obtained, the aerodynamic stiffness coefficient and aerodynamic damping coefficient are solved, the formula is

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; c\&Omega;</span>}\\ {\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C\&Omega;</span>}\end{array}\right.$

Among them, Ω is the rotational speed of eccentric drum whirling motion, e is the eccentricity, K and C are the main stiffness coefficient and main damping coefficient respectively, k and c are the cross-coupling stiffness coefficient and cross-coupling damping coefficient.

In the step 32), the eccentricity e=0.2mm.

The step 4) is specifically: according to the known surface aerodynamic force of the drum, load the static pressure value obtained in step 22) to the drum surface by linear interpolation loading method for loading calculation, and use finite element software to calculate the Structural deformation and stress changes.

Beneficial effects of the invention: the present invention combines the simple calculation of the air flow excitation of a certain rotor structure in the past by calculating the aerodynamic force on the surface of the eccentric drum with the grate tooth seal structure and the change of the aerodynamic force on the static characteristics of the drum structure. The vibration force and the simple study of the mechanical characteristics of the structure under the influence of external excitation are suitable for the calculation of the cylindrical rotor with specific size and structure.

Description of drawings

Fig. 1 is a flow chart of the aerodynamic calculation method for an eccentric drum with a grate tooth seal;

Fig. 2 is a simplified geometric model of the grate tooth sealing drum flow channel-the grate tooth cavity;

Figure 3 is the calculation model and grid division of the grate tooth sealing drum flow channel-grate tooth cavity mold;

Fig. 4 is a schematic diagram of the fan rotor structure of a certain type of aero-engine;

Fig. 5 is the three-dimensional structural model of the grate tooth sealing drum;

Figure 6 shows the precession movement of the eccentric rotor shaft;

Figure 7 shows the distribution of static pressure on the surface of the eccentric drum of the grate tooth seal.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

The specific dimensions of the second-stage drum structure in the fan rotor of a certain type of aero-engine are shown in Figure 2 below, where the height of the grate tooth H=5.5mm, the gap between the grate tooth and the stator C=2mm, and the width of the grate tooth top T=0.3mm, the distance between the first grate and the second grate B1=2.7mm, the distance between the second and the third grate B2=59.7mm, the tooth profile angle a= 5°, elastic modulus E=1.15×10 ¹¹ Pa, density ρ=4.48×10 ³ kg/m ³ , Poisson’s ratio μ=0.3, these data are used in the three-dimensional drum geometric calculation model and the three-dimensional drum The structural model is being built.

As shown in Fig. 1, it is a kind of eccentric drum aerodynamic calculation method flowchart with grate tooth seal of the present invention, then the concrete steps of the present invention's method are as follows:

1) Comprehensive fluid calculation and structural analysis, establish a three-dimensional drum geometric calculation model with a grate seal and a three-dimensional drum structure model with a grate seal;

Step 1) Establish a three-dimensional drum geometric calculation model with a grate seal, specifically including:

11) Simplify and omit geometric details that will not have a great impact on the flow field structure;

The flow structure in the grate cavity is complex. If the uneven flow caused by the upstream and downstream blade rows is further considered, the flow at the inlet and outlet boundaries of the grate cavity is an unsteady flow field that changes with time. To accurately simulate the flow in such a grate cavity, it is necessary to carry out unsteady numerical simulation including the upstream and downstream blade rows of the grate, and the calculation amount is quite huge. Therefore, some reasonable simplifications are required.

First of all, when analyzing the influence of grate aerodynamic force on drum vibration, it is not necessary to consider the flow field details in the blade channel, but only need to give the grate cavity inlet and outlet boundaries close to the actual flow state. Therefore, a simplified diagram of the three-dimensional drum geometric calculation model is established, as shown in Figure 3. The influence of adjacent blades can be reflected by the boundary of the inlet and outlet. Secondly, in the absence of large-scale intake distortion or stall disturbance, the circumferential flow field of the compressor takes the number of blades as a period, which is approximately cyclical. Therefore, in the calculation of the flow field, only a single blade sector is usually analyzed, and the assumption The flow field in the rest of the blade channels is the same as that of this sector. In this way, it can be simplified to a flow channel-grate cavity model with the circumferential span of a single blade channel as a sector.

As shown in Figure 4, the space between the first-stage rotor blade 1 and the first-stage stator blade 2, the second-stage rotor blade 3 and the second-stage stator blade 4, the third-stage rotor blade 5 and the subsequent third-stage stator blades is not a standard cuboid The shape is a space where the plane approximates a parallelogram, and here it is simplified to the shape of a standard cuboid for the convenience of calculation.

The so-called geometric details refer to the tooth shape of the grate teeth and the specific shape and size of the simulated blades in the set flow channel.

12) In order to accelerate the calculation convergence, the multi-grid technology is used to divide the grid;

The number of layers of the multigrid is determined by the number of grids, and the number of grids satisfies:

∑2 ⁿ +1(n≥2)

where n represents the number of grid layers;

The number of layers of the multigrid is: min(n)+1;

For example: 17=2 ⁴ +1, min(n)=4, that is to meet the 5-fold multi-grid;

61=2 ⁵ +2 ⁴ +2 ³ +2 ² +1, min(n)=2, that is, 3-fold multigrid is satisfied.

13) Calculate and set the grid width of the first layer of the channel wall:

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; wall</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 6</span>}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}}{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{<span\; class="notranslate">\; +</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>$

Among them, y _wall is the grid size of the first layer of the wall, the unit is m; V _ref is the reference velocity, the unit is m/s; L _ref is the reference length, the unit is m; v is the kinematic viscosity of the fluid, the unit is m ² / s; Y ₁ ⁺ is a dimensionless quantity, which corresponds to different turbulence models and has different value ranges.

When using NUMECA software to calculate, it is necessary to determine the grid width of the first layer according to the calculated model, and the software automatically generates the next grid width according to the width of the first layer. So it needs to be calculated to set the grid width of the first layer.

Step 1) Use finite element software to establish a structural model of a three-dimensional drum, see Figure 5. The circumferential grid of the outer surface of the drum corresponds to the grid division of the fluid channel model. Choose the 8-node three-dimensional solid unit solid45 to model the drum. The drum model includes a total of 7314 units and 10764 nodes.

2) Use the three-dimensional geometric calculation model in step 1) to calculate the surface static pressure value of the drum under different eccentricities.

Step 2) specifically:

21) Set the different eccentricity e of the drum grate and the stator, and select the appropriate inlet and outlet boundary conditions. This step qualitatively analyzes the influence of different eccentricity on the excitation force of the airflow.

Set the eccentricity e between the grate tooth surface of the drum and the stator, and refer to Figure 6 for the movement process of the eccentric drum. Considering the uneven distribution of air flow direction, velocity and total pressure in the flow process, the most commonly used Spalart-Allmaras turbulence model is used for the turbulence model, and the unsteady calculation uses the double time step central difference for aerodynamic calculation. During the calculation, the walls are all set as adiabatic boundaries, and the gas and the walls use no-slip boundary conditions. The given total temperature of the inlet is 393K, the total pressure of the two inlets is 287KPa, 280KPA in turn, and the static pressure of the two outlets is 220KPa, 240KPa in turn. Since the airflow at the inlet and outlet of the stator is not axial, on the inlet boundary, the corresponding axial velocity component of the airflow, that is, the pre-swirl angle, is given to be 56° and 30° respectively. Here, the eccentricity of 0mm, 0.2mm, 0.5mm, 1.0mm, and 1.9mm is mainly used to calculate the static pressure value of the drum surface, and the static pressure value of each position on the surface can be expanded to refer to Figure 7.

22) Calculate and extract multiple sets of static pressure values according to different whirl frequency ratios Ω/ω, where Ω is the rotational speed of the eccentric drum whirling motion, and ω is the rotational speed of the drum rotor. Here, the whirl frequency ratio is mainly 0, 0.2, -0.5, -1.0. In addition to the qualitative analysis of the whirl effect, the calculation of the whirl ratio in this step is also required for the calculation of stiffness and damping in step 3), because there are four unknowns, so multiple sets of solutions are required. The static pressure values on the surface of the drum are calculated by NUMECA software, and these static pressure values can be taken out, and then directly applied to step 4) to calculate the static characteristics of the drum.

23) On the basis of calculating the static pressure value on the surface of the drum, obtain the relationship of pressure with time, and the transformation relationship is as follows:

in, is the circumferential angle of the eccentric coordinate system, is the circumferential angle of the rotor coordinate system. This step is for the next step to calculate the radial force and tangential force for illustration. Because the calculated static pressure value is a numerical solution, the specific value is determined through each coordinate. However, these values cannot be substituted into the calculation formulas of radial force and tangential force, so they must be fitted into this transformation relation, so that calculations can be performed.

3) On the basis of step 2), calculate the radial aerodynamic force and tangential aerodynamic force on the surface of the drum with grate tooth seal;

Step 3) Specifically:

31) On the basis of step 23), integrate the static pressure value of the drum surface under different eccentricities, and solve the radial aerodynamic force and tangential aerodynamic force. The formula is

Among them, F _r is the radial aerodynamic force, F _t is the tangential aerodynamic force, z is the axial coordinate of the drum, r is the radial radius, L is the axial length, is the circumferential angle of the eccentric coordinate system;

32) Neglecting the influence of additional mass and inertia, when a certain amount of eccentricity is obtained, the aerodynamic stiffness coefficient and aerodynamic damping coefficient are solved, the formula is

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; c\&Omega;</span>}\\ {\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C\&Omega;</span>}\end{array}\right.$

Among them, Ω is the rotational speed of eccentric drum whirling motion, e is the eccentricity, K and C are the main stiffness coefficient and main damping coefficient respectively, k and c are the cross-coupling stiffness coefficient and cross-coupling damping coefficient. Among them, the main stiffness coefficient K reflects the influence of the airflow on the stiffness of the rotor system. The larger the value of K, the stronger the stiffness of the rotor and the better the stability. Conversely, the cross-coupling stiffness coefficient k is expressed as the magnitude of the tangential force. The larger the value, the greater the tangential force and the more unstable the rotor system.

Calculate the drum grate under the condition that the eccentricity e is 0.2mm. Analyzing the three-dimensional streamlines in the grate tooth cavity, it can be seen that the air flow enters the grate tooth cavity from the high pressure area at the rear end and leaks to the low pressure end with a certain circumferential speed. energy of. At different vortex speeds, the leakage remains unchanged at 0.48kg/s, which is about 0.58% of the total flow. However, the pressure is unevenly distributed along the circumferential direction, and when the whirl angular velocity changes, the amplitude and phase of pressure fluctuations are different. Also take the axial coordinate center position of the model, and compare and analyze the axial static pressure values of different whirl frequency ratios. After linear fitting, the relationship between radial force and whirl angular velocity can be obtained: F _r /e=-1.09×105-143.30Ω, and the relationship between tangential force and whirl angular velocity is: F _t /e=1.39× 105-462.77Ω. Available aerodynamic stiffness and aerodynamic damping coefficients: K=107000N/m, k=138000N/m, c=143.3Ns/m,=461.67Ns/m.

4) Using the three-dimensional structural model in step 1), on the basis of step 2), calculate the influence of airflow excitation on the characteristics of the drum.

According to the known aerodynamic forces on the surface of the drum, load the static pressure value obtained in step 22) to the surface of the drum by linear interpolation loading for loading calculation, and use finite element software to calculate the structural deformation and stress changes of the drum. This step is completed in ANSYS. In the software, a three-dimensional structural model is established, constraints are set, surface static pressure is loaded, and then the software is used to solve the problem by itself, and finally the solution result can be extracted.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (7)

1. A kind of eccentric drum aerodynamic calculation method with grate tooth sealing is characterized in that, the concrete steps of this calculation method are: 1) Comprehensive fluid calculation and structural analysis, establish a three-dimensional drum geometric calculation model with a grate seal and a three-dimensional drum structure model with a grate seal; the establishment of a three-dimensional drum structure model, the outer surface of the drum The circumferential grid corresponds to the grid division of the fluid channel model in the three-dimensional drum geometric calculation model; 2) Utilize the three-dimensional geometric calculation model in step 1) to calculate the drum surface static pressure value under different eccentricities; 3) On the basis of step 2), calculate the radial aerodynamic force and tangential aerodynamic force on the surface of the drum with the grate tooth seal; 4) Using the three-dimensional structural model in step 1), on the basis of step 2), calculate the influence of airflow excitation on the characteristics of the drum. 2. A kind of eccentric drum aerodynamic calculation method with grate tooth seal according to claim 1, is characterized in that, described step 1) establishes the three-dimensional drum geometric calculation model with grate tooth seal include: 11) Simplify the geometric details that will not have a great impact on the flow field structure; the geometric details refer to the tooth shape of the grate and the specific shape and size between the simulated blades in the set flow channel; 12) In order to accelerate the calculation convergence, the multi-grid technology is used to divide the grid; The number of layers of the multigrid is determined by the number of grids, and the number of grids satisfies: Σ ²ⁿ +1n≥2 where n represents the number of grid layers; The number of layers of the multigrid is: min(n)+1; 13) Calculate and set the grid width of the first layer of the channel wall: ${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 6</span>}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}}{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; +</span>}<span\; class="notranslate">\; ...</span>$ Among them, y _wall is the grid size of the first layer of the wall, the unit is m; V _ref is the reference velocity, the unit is m/s; L _ref is the reference length, the unit is m; v is the kinematic viscosity of the fluid, the unit is m ² / s; is a dimensionless quantity, which corresponds to different turbulence models and has different value ranges. 3. A method for calculating the aerodynamic force of an eccentric drum with a grate seal according to claim 1, wherein said step 2) is specifically: 21) Different eccentricities e of drum grate teeth and stator are set, and suitable inlet and outlet boundary conditions are selected; said inlet and outlet boundary conditions refer to pressure and temperature at the inlet and outlet; 22) Calculate and extract multiple sets of static pressure values according to different vortex frequency ratios Ω/ω, where Ω is the rotational speed of the eccentric drum’s whirling motion, and ω is the rotational speed of the drum rotor; 23) On the basis of calculating the static pressure value on the surface of the drum, obtain the relationship of the static pressure p on the surface of the drum with time, and the transformation relationship is as follows: in, is the circumferential angle of the eccentric coordinate system, is the circumferential angle of the rotor coordinate system. 4. A method for calculating the aerodynamic force of an eccentric drum with a grate tooth seal according to claim 3, wherein the frequency ratio of whirl in said step 22) is 0, 0.2, -0.5, -1.0 . 5. A method for calculating the aerodynamic force of an eccentric drum with a grate tooth seal according to claim 3, wherein said step 3) is specifically: 31) On the basis of step 23), the static pressure value on the surface of the drum under different eccentricities is integrated, and the radial aerodynamic force and tangential aerodynamic force are obtained. The formula is Among them, F _r is the radial aerodynamic force, F _t is the tangential aerodynamic force, z is the axial coordinate of the drum, r is the radial radius, L is the axial length, is the circumferential angle of the eccentric coordinate system; 32) Neglecting the influence of additional mass and inertia, when a certain amount of eccentricity is obtained, the aerodynamic stiffness coefficient and aerodynamic damping coefficient are solved, the formula is $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; \&Omega;</span>}\\ {\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; \&Omega;</span>}\end{array}\right.$ Among them, Ω is the rotational speed of eccentric drum whirling motion, e is the eccentricity, K and C are the main stiffness coefficient and main damping coefficient respectively, k and c are the cross-coupling stiffness coefficient and cross-coupling damping coefficient. 6 . The method for calculating the aerodynamic force of an eccentric drum with a grate seal according to claim 5 , wherein the eccentricity e=0.2 mm in the step 32). 7. A method for calculating the aerodynamic force of an eccentric drum with a grate tooth seal according to claim 3, wherein said step 4) is specifically: according to known drum surface aerodynamic force, using linear The static pressure value obtained in step 22) is loaded to the surface of the drum by interpolation loading for loading calculation, and the structural deformation and stress change of the drum are calculated by using finite element software.