High-temperature spray gun performance test design method based on scale model

Abstract

The invention discloses a high-temperature spray gun performance test design method based on a scaling model. The method specifically comprises the steps that the structure length, the structure outer diameter, the structure inner diameter, the in-pipe gas pressure and the flow speed of a spray gun pipeline test structure after scaling are obtained; obtaining a similarity criterion of related physical parameters of the test model and the prototype; acquiring a gas inlet velocity and external temperature similarity criterion of the test model and the prototype under the condition of similar temperature; and obtaining a final scaling model after scaling. The final scale model designed by the method can reflect temperature distribution, stress and displacement distribution in proportion to a prototype structure, meanwhile, the space needed by a test is reduced, the test influence quantity such as the external temperature and the pipeline air inlet flow speed and temperature can be changed at will, scale model design scheme guidance is provided for test design of the high-temperature spray gun, and the method is suitable for large-scale test design of the high-temperature spray gun. The device has the advantages of easy adjustment of test conditions, high safety and good economic efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of structure / strength test of a high-temperature environment gas spray gun, and in particular to a high-temperature spray gun performance test design method based on a scaled model. Background Art

[0002] The combustion device is one of the important equipment in the current waste treatment process. It has a complex structural design, strong sealing performance, and can operate at a relatively high operating temperature. Its safety will directly affect the reliability of the entire equipment. The combustion-supporting gas nozzle inside the equipment is directly in the high-temperature range. Strength reliability is an important factor affecting the operating state and service life of the combustion chamber. In order to ensure the stability and efficiency of the combustion system, the nozzle needs to have a reasonable structural design. While achieving a stable air intake, its structural deformation should be as small as possible. In the high-temperature working range, the burner spray gun is prone to large creep deformation, and finally to failure and fracture. Conducting multi-physical field coupling tests on the spray gun device is of great significance to the structural design of the burner.

[0003] The verification methods of equipment strength under high temperature mainly include numerical calculation and physical simulation test. Numerical simulation alone cannot accurately simulate all the loads on the spray gun; and the physical simulation test can be divided into prototype simulation test and similar model simulation test.

[0004] Due to the high difficulty of processing the prototype device, the long time consumption and the large test equipment, it is difficult to build the experimental environment, and it is difficult to conduct a real-scale simulation test of large equipment. Relatively speaking, similar model tests are often used in various types of tests because of their excellent economy and test flexibility. They use indirect methods to obtain the performance data of the prototype structure under actual working conditions. The temperature distribution law and stress-strain distribution law of the similar model test spray gun under high temperature working conditions have great engineering application value for the structural optimization design of the nozzle.

[0005] In view of the above technical problems, the present invention designs a high-temperature spray gun performance test design method based on a scaled model. Summary of the invention

[0006] The purpose of the present invention is to provide a high-temperature spray gun performance test design method based on a scaled model. The method takes into account the coupling relationship between the temperature-structure multi-physical fields and has the advantages of high test accuracy and test efficiency. By determining the proportional dimensions of the prototype and the model in terms of geometric dimensions, based on the dimensional analysis method, dimensional analysis is performed on the physical parameters concerned in the test, the proportional relationship of each physical property is obtained, and a complete scaled model test method is designed.

[0007] The present invention adopts the following technical solution:

[0008] A high-temperature spray gun performance test design method based on a scaled model, the specific steps are as follows:

[0009] Step 1: Determine the physical phenomena and required physical parameters that need to be analyzed for the prototype. The specific required physical phenomena are the changes that can be described by physical parameters during the test process, thereby determining the physical parameters required in the design of the scaled model test plan for the spray gun pipeline;

[0010] Step 2: Determine the geometric similarity ratio between the scaled model and the prototype, and stipulate that the geometric scaling coefficients of the structural parameters in different directions are consistent;

[0011] Step 3: Determine the material used to make the scale model;

[0012] Step 4: Determine the similarity ratio and similarity criterion between the physical parameters of the scaled model and the prototype, wherein the similarity ratio is the ratio of the same parameter of the prototype and the scaled model, and the similarity criterion is a criterion used to ensure that the scaled model can accurately reflect the physical characteristics of the prototype object in the test, and the similarity criterion includes the load boundary similarity criterion, the convection heat transfer similarity criterion and the temperature boundary similarity criterion;

[0013] Step 5: Determine the load boundary similarity criterion between the physical parameters of the scaled model and the prototype based on the structural stress equation;

[0014] Step 6: Determine the convective heat transfer similarity criteria between the physical parameters of the scaled model and the prototype based on the convective heat transfer boundary conditions;

[0015] Step 7: Determine the temperature boundary similarity criterion between the physical parameters of the scaled model and the prototype based on the structural temperature equation;

[0016] Step 8: Combining various similarity criteria, perform temperature-structure coupling simulation, specifically perform structure-heat coupling direct coupling simulation on the high-temperature spray gun, that is, consider the changes in temperature field and stress field at the same time during the calculation, and compare with the simulation results of the prototype model; compare the numerical calculation results of different scaled models and prototypes. Since the scaling of gravity acceleration is more difficult, gravity acceleration will affect the calculation results of the scaled model. If the difference between the calculation results of the two is less than or equal to 5%, confirm that the current scaled model is the final spray gun pipeline scaled model; if the comparison result is greater than 5%, it can be considered that the current scaling ratio is not suitable for the scaling analysis of the model, and the scaled model with the largest scale but meeting the test accuracy can be obtained according to this evaluation method.

[0017] According to the above steps, the further design is as follows:

[0018] In step 1, the required physical parameters include structural parameters, material properties, constraint boundaries, applied loads and other physical parameters;

[0019] The structural parameters include: pipeline length l, pipeline length at high temperature, pipeline width w, pipeline thickness h, pipeline outer diameter, and pipeline inner diameter; for spray guns with complex structures, they are simplified into pipeline structures, and the size of the spray gun pipeline nozzle is used as the pipe diameter;

[0020] The material properties include: material density ρ, material elastic modulus E, material Poisson's ratio ν, material specific heat capacity C, material thermal conductivity λ, and material thermal expansion coefficient α;

[0021] The load parameters include: force F, moment M, pressure p, and gravitational acceleration g;

[0022] The other physical parameters include: displacement D, stress σ, strain ε, mass M0, convection heat transfer coefficient of outer wall of pipe inside the heat chamber h0, convection heat transfer coefficient of inner wall of pipe h1, heat chamber temperature T0, pipe nozzle inlet temperature T1, nozzle inlet velocity v.

[0023] In step 2, the geometric scaling coefficients of the specified structural parameters in different directions are consistent, and are specifically defined as:

[0024]

[0025] in,

[0026] S l Indicates the length scaling factor when the pipe nozzle is geometrically scaled;

[0027] S w Indicates the width scaling factor when the pipe nozzle is geometrically scaled;

[0028] S b Indicates the thickness scaling factor when the pipe nozzle is geometrically scaled;

[0029] p means prototype, m means scaled model;

[0030] l p 、w p 、h p Respectively represent the length, width and thickness of the prototype, l m 、w m 、h m Represent the length, width and thickness of the scaled model respectively.

[0031] In step 3, the same material parameters as those of the prototype may be used, or a material different from that of the prototype may be used; in the present invention, it is particularly necessary to verify the strength of the current material at high temperatures, so the material used in the scaled model test is the same as that of the prototype.

[0032] In step 4, the material selection of the scaled model is the same as that of the prototype, and the physical property parameters of the scaled model material are also the same as those of the prototype, specifically:

[0033]

[0034] in:

[0035] α p , α m Respectively represent the thermal expansion coefficient of the materials of the prototype and the scaled model, S α is the thermal expansion coefficient proportionality factor;

[0036] E p 、E m Represents the elastic modulus of the material of the prototype and the scaled model, S E is the elastic modulus proportional factor;

[0037] v p 、v m Represent the Poisson's ratio of the material of the prototype and the scaled model, S υ is the Poisson's ratio scaling factor;

[0038] ρ p , m Represents the density of the material of the prototype and the scaled model, S ρ is the density scaling factor;

[0039] C p , C m Represent the specific heat capacity of the materials of the prototype and the scaled model, S C is the specific heat capacity proportionality factor;

[0040] λ p , m Respectively represent the thermal conductivity of the materials of the prototype and the scaled model; S λ is the thermal conductivity scaling factor.

[0041] The step 4 uses the dimensional similarity criterion and the Π theorem to deduce the proportional relationship between the experimental physical parameters, and determines that the physical parameters that need to be observed during the scaled model test are consistent with those corresponding to the prototype. The physical parameters that need to be observed include: displacement D, force F, torque M, pressure p, stress σ, strain ε, mass M0, gravitational acceleration g, convection heat transfer coefficient of the outer wall of the pipeline h0, convection heat transfer coefficient of the inner wall of the pipeline h1, hot chamber temperature T, pipeline nozzle inlet temperature T0, nozzle inlet velocity v; when the dimensions of the physical parameters are the same, the scale of the scaled model and the prototype are the same.

[0042] The specific implementation of step 5 includes the following:

[0043] 5.1 Determine the proportional factors of each physical parameter during the test: displacement proportional factor Force Scale Factor Torque scaling factor Pressure scaling factor Stress Scale Factor Strain scale factor Mass scale factor Gravity acceleration scale factor Convective heat transfer coefficient proportionality factor of pipe outer wall Convective heat transfer coefficient proportionality factor of pipe inner wall Heat chamber temperature scaling factor Pipe inlet gas temperature proportionality factor Flow rate scaling factor of fluid in pipe

[0044] in,

[0045] D p 、F p 、M p , P p , σ p , ε p , , g p , 、T p , 、v p They represent the displacement, force, moment, pressure, stress, strain, mass, gravitational acceleration, convection heat transfer coefficient of the outer wall of the pipeline, convection heat transfer coefficient of the inner wall of the pipeline, temperature of the hot chamber, gas temperature at the pipeline inlet, and flow rate of the fluid in the pipeline respectively;

[0046] D m 、F m 、M m , P m , σ m , ε m , , g m , 、h 1m 、T m 、T 0m 、v m They represent the displacement, force, moment, pressure, stress, strain, mass, gravitational acceleration, convection heat transfer coefficient of the outer wall of the pipeline, convection heat transfer coefficient of the inner wall of the pipeline, temperature of the hot chamber, gas temperature at the pipeline inlet, and flow rate of the fluid in the pipeline respectively;

[0047] 5.2 Based on the dimensional analysis method, the relationship between the proportional factors of the physical parameters of the scaled model and the prototype is obtained. The load boundary similarity criterion is specifically as follows:

[0048] S ε =S σ =1, the strain proportional factor and stress factor are both 1;

[0049] S F =(S l ) 2 , the force scale factor is the square of the length scale factor;

[0050] S M =(S l ) 3 , the moment scale factor is the cube of the length scale factor;

[0051] S P =1, pressure proportional factor 1;

[0052] S M =(S l ) 3 , the mass scale factor is the cube of the length scale factor;

[0053] The convective heat transfer coefficient scaling factor is the inverse of the length scaling factor;

[0054] S T =1, the temperature proportional factor is 1;

[0055] S D =S l , the displacement scale factor and the length scale factor are equal;

[0056] The relationship between the proportionality factors expressed above is not limited to a specific physical quantity. As long as the dimensions are equal, the proportionality factors satisfy the above relationship. For example, the relationship of the proportionality factor of the convective heat transfer coefficient is applicable to both the convective heat transfer coefficient of the inner wall of the pipe and the convective heat transfer coefficient of the outer wall of the pipe. The elastic modulus proportionality factor is the same as the stress proportionality factor.

[0057] In step 6, the convection heat transfer coefficient of the inner wall of the pipe is related to the flow velocity and the flow state of the medium in the pipe; specifically, the critical Reynolds number Re is usually taken as 2300 in engineering applications. When Re<2300, the flow is laminar; when Re>2300, the flow is considered to be turbulent;

[0058]

[0059] When the medium flowing in the pipeline is laminar flow, the local flow velocity distribution in the pipeline is relatively uniform. At this time, the pipeline convection heat transfer coefficient h is calculated by Lloyd's equation:

[0060]

[0061] Among them, h represents the convection heat transfer coefficient of the pipe, d represents the inner diameter of the pipe, k represents the thermal conductivity coefficient of the fluid, ρ represents the density of the liquid, and v represents the average flow velocity of the liquid.

[0062] When the medium flow state in the pipeline is only turbulent, the pipeline convection heat transfer coefficient h is calculated using the Fouch equation:

[0063] Nu=0.023*Re 0.8 *Pr 0.33

[0064]

[0065] Nu stands for Nusselt number, Re stands for Reynolds number, and Pr stands for Prandtl number.

[0066] Therefore, the convective heat transfer coefficient in the tube can be changed by adjusting the flow rate in the tube.

[0067] In step 7, the influence of the gas flow rate of the hot chamber outside the test piece is ignored. The test piece is located in a constant temperature environment, and the medium in the pipeline will not change its properties or phase change inside the test device.

[0068] The temperature boundary similarity criterion includes the similarity of temperature in time and space. Geometric similarity is manifested in that the temperatures of corresponding points are proportional to each other, that is, the temperature values ​​of each corresponding point in space are proportional; temporal similarity is manifested in that the temperature values ​​at corresponding moments are proportional to each other, that is, at different time points, the temperature values ​​of each corresponding point are proportional.

[0069] In step 8, different geometric scale factors are considered to satisfy the scaled model, that is, multiple scaled models are considered, and different geometric scaled factors are set respectively. A scaled model that satisfies both the maximum scaled scale and the minimum error between the result and the prototype is obtained through a numerical simulation method, the flow rate of the medium in the pipeline is adjusted, and the numerical simulation values ​​under different scaled sizes are obtained through a structure-temperature coupling calculation method, and the scaled size of the final scaled model is determined based on the processing feasibility of the test device.

[0070] The beneficial effects of the present invention are as follows:

[0071] This method uses the similarity criteria between the test model and the prototype to obtain a final scaled model that can reflect the temperature distribution, stress, and displacement distribution that are proportional to the prototype structure. Through this design method, not only can the space required for the test be reduced, but also the test influencing quantities such as the external temperature, pipeline inlet air velocity and temperature can be arbitrarily changed to meet the test design of the high-temperature spray gun. The scaled model can provide a prediction of the stress characteristics of the prototype structure, which can significantly reduce the complexity of the test device and improve the test efficiency. The overall design scheme has the advantages of easy adjustment of the test conditions, high safety, and good economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a design flow chart of the present invention.

[0073] Figure 2 is the finite element model of high temperature spray gun.

[0074] FIG. 3 is a simulation result of the prototype structure of the present invention.

[0075] FIG. 4 is a calculation result of a scaled model with a scale factor of 0.5 in the embodiment. DETAILED DESCRIPTION

[0076] The technical solutions in the embodiments of the present invention will be fully described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0077] The scaled model test method based on similarity theory and dimensional analysis method specifically includes: the design of structural scaled model, the design of flow field scaled model, the design of temperature field scaled model, the scaled design of boundary constraints and the scaled design of external loads.

[0078] in:

[0079] The design of the structural similarity model is used to determine the geometric dimensions and structural physical parameters of the spray gun pipeline and derive the similarity ratio of the scaled model of the structural physical phenomenon;

[0080] The design of the flow field similarity model is used to determine the flow field velocity and temperature of the gas inlet of the spray gun pipeline and to perform the convection heat transfer similarity criterion of the flow field;

[0081] The similarity criterion of the boundary constraint is used to determine the fixing method and fixing position of the test model;

[0082] The scaled design of the external load is used to determine the size and application position of the external load;

[0083] The design of the temperature field similarity model is used to determine the temperature distribution of the device and perform numerical simulation calculations on the prototype structure.

[0084] Based on the above design principles, this embodiment provides a high-temperature spray gun performance test design method based on a scaled model, and its design process is as follows: Figure 1 The steps shown specifically include:

[0085] Based on similarity theory and dimensional analysis, the proportional relationship between the test model structural parameters, the test model physical property parameters and the original model is derived, and based on dimensional analysis, the relationship expression between the test model physical property parameters and the physical quantity parameter proportional factor is obtained;

[0086] Specifically, the test process is designed to couple the temperature-structure multi-physics field. The strength of the high-temperature nozzle is related to its own material properties, structural parameters and external loads. The material properties include: material density ρ, material elastic modulus E, material Poisson's ratio ν, material specific heat capacity C, material thermal conductivity λ, material thermal expansion coefficient α. The structural parameters specifically include: length l, width w, and thickness h of the structure. External load parameters include: force F, moment M, pressure p, and gravitational acceleration g. In addition, it is necessary to obtain the physical relationships required in the test process, including: displacement D, stress σ, strain ε, mass M0, convection heat transfer coefficient of the outer wall of the pipe in the hot chamber h0, convection heat transfer coefficient of the inner wall of the pipe h1, hot chamber temperature T0, pipe nozzle inlet temperature T1, and nozzle inlet velocity v.

[0087] Among the external load parameters, the value of gravity acceleration has little influence on the calculation results, so it is ignored.

[0088] For the scaled model design, the scaling coefficients of the structural parameters and physical parameters reflect the relationship between the test model and the original model. Specifically, in this embodiment, the scaling coefficient of each parameter is defined as: the ratio of the characteristic parameter of the scaled model to the corresponding characteristic parameter of the prototype.

[0089] In particular, the geometric scaling factor in this embodiment remains uniform in space, that is, the size scaling factor in all directions in space remains consistent. Specifically:

[0090]

[0091] Where: S l Indicates the length scaling factor when the pipe nozzle is geometrically scaled;

[0092] S w Indicates the width scaling factor when the pipe nozzle is geometrically scaled;

[0093] S b Indicates the thickness scaling factor when the pipe nozzle is geometrically scaled;

[0094] p means prototype, m means scaled model; l p 、w p 、h p Respectively represent the length, width and thickness of the prototype, l m 、w m 、h m Represent the length, width and thickness of the scaled model respectively.

[0095] Select the material used to make the scaled model, and deduce the medium similarity ratio between the scaled model and the prototype based on the material properties of the test model;

[0096] Based on the geometric scaled model of the high-temperature spray gun, the relationship between the heat transfer coefficient of the heat transfer convection in the tube and the flow rate of the fluid in the tube is obtained to obtain the flow rate in the tube under the current model;

[0097] A finite element geometric model is established based on the scaled model and the original size model. The material is 304 stainless steel, the fluid in the tube is air, fixed boundary conditions are added to simulate the actual working conditions, and meshing is performed. The mesh is calculated as follows: Figure 2 As shown in the figure, from left to right, the number of grids is 7000. The scaled model prediction simulation analysis was carried out to obtain the stress and strain distribution results.

[0098] The results of numerical simulation calculations are compared in Figures 3 and 4, where Figures 3(a), 3(b), and 3(c) are the stress, temperature, and displacement cloud maps of the full-size model; Figures 4(a), 4(b), and 4(c) are the stress, temperature, and displacement cloud maps of the scaled model.

[0099] Comparative analysis of the results of Figure 3 and Figure 4 shows that this design method can accurately reflect the stress characteristics of the original structure. Therefore, it can effectively improve the existing high-temperature nozzle test constraints of large size and high cost. By predicting the stress characteristics of the prototype structure with a miniaturized model, it can reduce the complexity of the test device and improve the test efficiency.

Claims

1. A high-temperature spray gun performance test design method based on a scaled model as claimed in claim 1, characterized in that: Here are the steps: Step 1: Determine the physical phenomena and required physical parameters that need to be analyzed for the prototype. The specific required physical phenomena are the changes described by physical parameters during the test process, thereby determining the physical parameters required in the design of the scaled model test plan for the spray gun pipeline; Step 2: Determine the geometric similarity ratio between the scaled model and the prototype, and stipulate that the geometric scaling coefficients of the structural parameters in different directions are consistent; Step 3: Determine the material used to make the scale model; Step 4: Determine the similarity ratio and similarity criterion between the physical parameters of the scaled model and the prototype, wherein the similarity ratio is the ratio of the same parameter of the prototype and the scaled model, and the similarity criterion is a criterion used to ensure that the scaled model can accurately reflect the physical characteristics of the prototype object in the test, and the similarity criterion includes the load boundary similarity criterion, the convection heat transfer similarity criterion and the temperature boundary similarity criterion; Step 5: Determine the load boundary similarity criterion between the physical parameters of the scaled model and the prototype based on the structural stress equation; Step 6: Determine the convective heat transfer similarity criteria between the physical parameters of the scaled model and the prototype based on the convective heat transfer boundary conditions; Step 7: Determine the temperature boundary similarity criterion between the physical parameters of the scaled model and the prototype based on the structural temperature equation; Step 8: Based on various similarity criteria, perform structural-thermal direct coupling simulation on the high-temperature spray gun. The changes in temperature field and stress field must be considered at the same time, and compared with the simulation results of the prototype model; compare the numerical calculation results of different scaled models and prototypes: if the difference between the calculation results of the two is less than or equal to 5%, confirm that the current scaled model is the final high-temperature spray gun pipeline scaled model; if the difference between the calculation results of the two is greater than 5%, confirm that the current scaling ratio is not suitable for the scaling analysis of the model, and then re-evaluate to obtain the scaled model with the largest scale but meeting the test accuracy.

2. A high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: In step 1, the required physical parameters include structural parameters, material properties, constraint boundaries, applied loads and other physical parameters; The structural parameters include: the structural parameters include: pipeline length l, pipeline length at high temperature, pipeline width w, pipeline thickness h, pipeline outer diameter, pipeline inner diameter; for spray guns with complex structures, they are simplified to pipeline structure forms, and the nozzle size of the spray gun pipeline is used as the pipe diameter; The material properties include: material density ρ, material elastic modulus E, material Poisson's ratio ν, material specific heat capacity C, material thermal conductivity λ, material thermal expansion coefficient α The load parameters include: force F, moment M, pressure p, and gravitational acceleration g; The other physical parameters include: displacement D, stress σ, strain ε, mass M0, convection heat transfer coefficient of outer wall of pipe inside the heat chamber h0, convection heat transfer coefficient of inner wall of pipe h1, heat chamber temperature T0, pipe nozzle inlet temperature T1, nozzle inlet velocity v.

3. The high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: In step 2, it is stipulated that the geometric scaling coefficients of the structural parameters in different directions are consistent, which are specifically defined as: in, S l Indicates the length scaling factor when the pipe nozzle is geometrically scaled; S w Indicates the width scaling factor when the pipe nozzle is geometrically scaled; S b Indicates the thickness scaling factor when the pipe nozzle is geometrically scaled; p means prototype, m means scaled model; l p 、w p 、h p Respectively represent the length, width and thickness of the prototype, l m 、w m 、h m Represent the length, width and thickness of the scaled model respectively.

4. The high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: In step 3, the material that is the same as or different from the prototype is selected based on the matching strength of the material and temperature.

5. A high temperature spray gun performance test design method based on a scaled model according to claim 1 or 4, characterized in that: In step 4, the material selection of the scaled model is the same as that of the prototype, and the physical property parameters of the scaled model material are also the same as those of the prototype, specifically: in: α p , α m Respectively represent the thermal expansion coefficient of the materials of the prototype and the scaled model, S α is the thermal expansion coefficient proportionality factor; E p 、E m Represents the elastic modulus of the material of the prototype and the scaled model, S E is the elastic modulus proportional factor; υ p 、v m Represent the Poisson's ratio of the material of the prototype and the scaled model, S υ is the Poisson's ratio scaling factor; ρ p , m Represents the density of the material of the prototype and the scaled model, S ρ is the density scaling factor; C p , C m Represent the specific heat capacity of the materials of the prototype and the scaled model, S C is the specific heat capacity proportionality factor; λ p , m Respectively represent the thermal conductivity of the materials of the prototype and the scaled model; S λ is the thermal conductivity scaling factor.

6. A high temperature spray gun performance test design method based on a scaled model according to claim 5, characterized in that: In step 4, the dimensional similarity criterion and the Π theorem are used to deduce the proportional relationship between the experimental physical parameters to determine whether the physical parameters that need to be observed during the scaled model test are consistent with those corresponding to the prototype. The physical parameters that need to be observed include: displacement D, force F, torque M, pressure p, stress σ, strain ε, mass M0, gravitational acceleration g, convection heat transfer coefficient of the outer wall of the pipeline h0, convection heat transfer coefficient of the inner wall of the pipeline h1, hot chamber temperature T, pipeline nozzle inlet temperature T0, nozzle inlet velocity v; when the dimensions of the physical parameters are the same, the scale of the scaled model and the prototype is the same.

7. The high-temperature spray gun performance test design method based on a scaled model according to claim 5, characterized in that: The specific implementation of step 5 includes the following: 5.1 Determine the proportional factors of each physical parameter during the test: displacement proportional factor Force scale factor Torque scaling factor Pressure scaling factor Stress Scale Factor Strain scale factor Mass scale factor Gravity acceleration scale factor Convective heat transfer coefficient proportionality factor of pipe outer wall Convective heat transfer coefficient proportionality factor of pipe inner wall Heat chamber temperature scaling factor Pipe inlet gas temperature proportionality factor Flow rate scaling factor of fluid in pipe in, D p 、F p 、M p , P p , σ p , ε p , g p , T p , v p They represent the displacement, force, moment, pressure, stress, strain, mass, gravitational acceleration, convection heat transfer coefficient of the outer wall of the pipeline, convection heat transfer coefficient of the inner wall of the pipeline, temperature of the hot chamber, gas temperature at the pipeline inlet, and flow rate of the fluid in the pipeline respectively; D m 、F m 、M m , P m , σ m , ε m , g m , h 1m , T m , T 0m 、v m They represent the displacement, force, moment, pressure, stress, strain, mass, gravitational acceleration, convection heat transfer coefficient of the outer wall of the pipeline, convection heat transfer coefficient of the inner wall of the pipeline, temperature of the hot chamber, gas temperature at the pipeline inlet, and flow rate of the fluid in the pipeline respectively; 5.2 Based on the dimensional analysis method, the relationship between the proportional factors of the physical parameters of the scaled model and the prototype is obtained. The load boundary similarity criterion is specifically: S ε =S σ =1, the strain proportional factor and stress factor are both 1; S F =(S l ) 2 , the force scale factor is the square of the length scale factor; S M =(S l ) 3 , the moment scale factor is the cube of the length scale factor; S P =1, pressure proportional factor 1; S M =(S l ) 3 , the mass scale factor is the cube of the length scale factor; The convective heat transfer coefficient scaling factor is the inverse of the length scaling factor; S T =1, the temperature proportional factor is 1; S D =S l , the displacement scale factor and the length scale factor are equal; For the relationship between the proportional factors expressed above, when the dimensions are equal, the proportional factors satisfy the above relationship.

8. A high temperature spray gun performance test design method based on a scaled model according to claim 7, characterized in that: The boundary conditions refer to the displacement boundary. The test model is consistent with the prototype, and the spray gun is a fixed support, that is, S D =1; For temperature boundary conditions, there are first-class temperature boundaries and second-class temperature boundaries. The first-class boundary conditions stipulate the surface temperature of the pipeline in the high-temperature zone, and the third-class boundary conditions stipulate the surface convection heat transfer coefficient between the pipeline and the surrounding fluid, that is, S T =1, 9. The high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: In step 6, the convection heat transfer coefficient of the inner wall of the pipe is related to the flow velocity and the flow state of the medium in the pipe; specifically, the value of the critical Reynolds number Re is: In engineering applications, Re is taken as 2300; When Re < 2300, the flow is laminar; When Re>2300, the flow is considered turbulent; When the medium flowing in the pipeline is laminar flow, the local flow velocity distribution in the pipeline is relatively uniform. At this time, the pipeline convection heat transfer coefficient h is calculated by Lloyd's equation: Among them, h represents the convection heat transfer coefficient of the pipeline, d represents the inner diameter of the pipeline, k represents the thermal conductivity of the fluid, ρ represents the density of the liquid, and v represents the average flow velocity of the liquid; When the medium flow state in the pipeline is only turbulent, the pipeline convection heat transfer coefficient h is calculated using the Fouch equation: No=0.023*Re 0.8 *Pr 0.33 Nu stands for Nusselt number, Re stands for Reynolds number, and Pr stands for Prandtl number; Therefore, the convective heat transfer coefficient in the tube can be changed by adjusting the flow rate in the tube.

10. The high temperature spray gun performance test design method based on a scaled model according to claim 2, characterized in that: In step 7, the temperature boundary similarity criterion includes the similarity of temperature in time and space. Geometric similarity is manifested as the temperatures of corresponding points being proportional to each other, that is, the temperature values ​​of each corresponding point in space are proportional; temporal similarity is manifested as the temperature values ​​at corresponding moments being proportional to each other, that is, the temperature values ​​of each corresponding point at different time points are proportional.

11. The high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: In step 8, different geometric scale factors are considered to satisfy the scaled model, that is, multiple scaled models are considered, and different geometric scaled factors are set respectively. A scaled model that satisfies both the maximum scaled scale and the minimum error between the result and the prototype is obtained through a numerical simulation method, the flow rate of the medium in the pipeline is adjusted, and the numerical simulation values ​​under different scaled sizes are obtained through a structure-temperature coupling calculation method, and the scaled size of the final scaled model is determined based on the processing feasibility of the test device.

12. The high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: The medium flowing in the scaled model of the high-temperature spray gun is the same as that in the prototype.

13. The high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: The temperature of the working fluid at the pipeline inlet of the high-temperature spray gun remains unchanged; the various physical parameters of the working fluid remain unchanged, the working fluid will not undergo phase change in the pipeline, and the gas inside the pipeline has a certain constant pressure.

14. The high temperature spray gun performance test design method based on a scaled model according to claim 1, characterized in that: The scaled-down model of the high-temperature spray gun is in a certain proportional relationship with the flow rate of the medium flowing in the prototype, and the flow rate of the medium should make the scaled-down factor of the convection coefficient of the flow in the tube meet the design requirements of the scaled-down model.

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