Total temperature sensor performance analysis method

Abstract

The invention provides a total temperature sensor performance analysis method, which comprises the following steps of: establishing a structural model of a sensor, and establishing a finite element mesh model according to the structural model; on the basis of a finite element mesh model, according to boundary conditions, a turbulence model, a radiation model, material physical parameters of structures of all parts of the sensor and working conditions of the sensor, through CFD fluid simulation, iteratively calculating the temperature of a thermal node of a thermocouple wire, and stopping iteration until convergence; obtaining values of fluid parameters in the stagnation cavity, the temperature of the inner wall surface of the stagnation cavity and the temperature of the root of the thermocouple wire; calculating a speed error, a radiation error and a conduction error of the total temperature measured by the sensor; and calculating the comprehensive error of the total temperature measured by the sensor according to the speed error, the radiation error and the conduction error. According to the technical scheme, the technical problem that in the prior art, the temperature measurement performance of the total temperature sensor used in the high-temperature environment cannot be accurately analyzed in the design stage, and consequently the development period is long is solved.

Description

Technical Field

[0001] The invention relates to the technical field of total temperature sensing, and in particular to a total temperature sensor performance analysis method. Background Art

[0002] As a flow field stagnation parameter, total temperature is a key parameter supporting the research and development of supersonic vehicle engine control, flight control, structural thermal protection, etc., especially in the control of air-breathing ramjet engines. High-precision real-time measurement of total temperature parameters is a prerequisite for ensuring safe, stable and efficient flight of the aircraft. However, under high temperature conditions, due to the influence of radiation, conduction, stagnation and other factors, radiation errors, conduction errors and velocity errors will occur. The main influencing factors are the stagnation cavity wall temperature, air properties, flow velocity, filament root temperature, etc.

[0003] However, the above factors cannot be obtained through theoretical calculations and experimental means, so it is impossible to accurately evaluate the performance of the sensor in the early stage of design, resulting in the inability to quickly optimize the design. Therefore, it is urgent to propose a temperature measurement performance analysis method for total temperature sensors under high temperature conditions to support the design of total temperature sensors, achieve efficient iterative design, and significantly shorten the development cycle. Summary of the invention

[0004] The present invention provides a total temperature sensor performance analysis method, which can solve the technical problem in the prior art that the temperature measurement performance of the total temperature sensor used in a high temperature environment cannot be accurately analyzed in the design stage, resulting in a long development cycle.

[0005] According to one aspect of the present invention, a method for analyzing the performance of a total temperature sensor is provided. The sensor includes a stagnation structure, a thermocouple wire and a thermocouple wire support. The stagnation structure has a stagnation cavity. The thermocouple wire is arranged in the stagnation cavity through the thermocouple wire support. The method includes:

[0006] Establish a structural model of the sensor, and establish a finite element mesh model based on the structural model;

[0007] Based on the finite element mesh model, the thermal node temperature T of the thermocouple wire is iteratively calculated according to the boundary conditions, turbulence model, radiation model, material properties of each part of the sensor structure and the sensor working conditions through CFD fluid simulation. g , when the calculated hot node temperature T g The iteration is stopped when convergence occurs, and the fluid parameters in the stagnation cavity and the wall temperature T in the stagnation cavity are obtained according to the final result of the iteration. W and the root temperature of the thermocouple wire T b The value of

[0008] According to the material properties of each part of the structure, the fluid parameters in the stagnation cavity, the wall temperature T W and the root temperature of the thermocouple wire Tb The velocity error ΔT of the sensor measuring the total temperature is obtained by numerical calculation V , Radiation error ΔT r and conduction error ΔT c ;

[0009] According to the speed error ΔT V , Radiation error ΔT r and conduction error ΔT c The comprehensive error ΔT of the total temperature measured by the sensor is calculated.

[0010] Furthermore, the material properties of each partial structure include material density, material specific heat, material thermal conductivity and material surface emissivity.

[0011] Furthermore, the fluid parameters in the stagnation chamber include the qualitative temperature of the airflow T f , air velocity V, air flow Mach number M, air flow static pressure P s , airflow density ρ, airflow specific heat ratio k, airflow specific heat C p , airflow dynamic viscosity μ, airflow thermal conductivity λ and Prandtl number P r .

[0012] Furthermore, according to the material properties of each part of the structure, the fluid parameters in the stagnation cavity, the wall temperature T W and the root temperature of the thermocouple wire T b The velocity error ΔT of the sensor measuring the total temperature is obtained by numerical calculation V , Radiation error ΔT r and conduction error ΔT c include:

[0013] According to the Prandtl number P r , airflow specific heat ratio k and airflow Mach number M or according to Prandtl number P r , air velocity V and air specific heat C p Calculate the speed error ΔT of the sensor measuring the total temperature V ;

[0014] According to the airflow density ρ, airflow velocity V, airflow dynamic viscosity μ, Prandtl number P r The convective heat transfer coefficient h is calculated by the airflow thermal conductivity λ;

[0015] According to the surface emissivity ε of the hot node of the thermocouple wire and the hot node temperature T g , convection heat transfer coefficient h and stagnation cavity wall temperature T W The radiation error ΔT of the total temperature measured by the sensor is calculated r ;

[0016] According to the hot node temperature T of the thermocouple wireg , Thermocouple wire root temperature T b , convection heat transfer coefficient h, thermal conductivity λ0 of thermocouple wire, and calculate the conduction error ΔT of the total temperature measured by the sensor c .

[0017] Further, according to the Prandtl number P, the following formula is used r , airflow specific heat ratio k and airflow Mach number M to calculate the velocity error ΔT of the total temperature measured by the sensor V :

[0018]

[0019] In the above formula, γ o The recovery coefficient of the bare thermocouple wire, T t Indicates the theoretical calculated value of total temperature.

[0020] Further, according to the Prandtl number P, the following formula is used r , air velocity V and air specific heat C p Calculate the speed error ΔT of the sensor measuring the total temperature V :

[0021]

[0022] Furthermore, the following formula is used according to the hot node surface emissivity ε of the thermocouple wire and the hot node temperature T of the thermocouple wire: g , convection heat transfer coefficient h and stagnation cavity wall temperature T W The radiation error ΔT of the total temperature measured by the sensor is calculated r :

[0023]

[0024] In the above formula, σ represents the blackbody radiation constant.

[0025] Further, according to the hot node temperature T of the thermocouple wire, the following formula is used g , Thermocouple wire root temperature T b , convection heat transfer coefficient h, thermal conductivity λ0 of thermocouple wire, and calculate the conduction error ΔT of the total temperature measured by the sensor c :

[0026]

[0027] In the above formula, L represents the length of the thermocouple wire extending from the supporting end face, S represents the circumference of the thermocouple wire end face, and A represents the cross-sectional area of ​​the thermocouple wire.

[0028] Further, according to the speed error ΔT, the following formula is used V , Radiation error ΔTr and conduction error ΔT c The comprehensive error ΔT of the total temperature measured by the sensor is calculated:

[0029] ΔT=ΔT V +ΔT r +ΔT c .

[0030] Furthermore, the values ​​of the fluid parameters in the stagnation chamber are all average values.

[0031] By applying the technical solution of the present invention, a total temperature sensor performance analysis method is provided. The method establishes a structural model for the sensor structure that is preliminarily determined, and establishes a finite element mesh model based on the structural model. With the help of CFD simulation analysis, the values ​​of the key parameters that affect the temperature measurement performance, such as the fluid parameters in the stagnation cavity, the wall temperature in the stagnation cavity, and the root temperature of the thermocouple wire, are obtained. Then, combined with the heat transfer theory, the radiation error, conduction error, and velocity error are calculated respectively, and then the comprehensive error is obtained. The method comprehensively considers the influencing factors of multiple dimensions, and through the technical means of CFD simulation grading and theoretical calculation, it realizes the accurate evaluation of the temperature measurement performance of the high-temperature total temperature sensor. It is simple and practical, easy to implement and effective, and has strong feasibility. It can provide necessary support for the performance analysis of the high-temperature total pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic diagram of the structure of a sensor provided according to a specific embodiment of the present invention is shown;

[0034] Figure 2 The temperature measurement principle of the hypersonic total temperature sensor provided in the specific embodiment of the present invention is shown;

[0035] Figure 3 A schematic diagram showing a process of fluid stagnation when a sensor provided by a specific embodiment of the present invention is working is shown;

[0036] Figure 4 A schematic diagram of the design process of a total temperature sensor provided according to a specific embodiment of the present invention is shown;

[0037] Figure 5 A velocity distribution cloud diagram in a stagnation cavity provided according to a specific embodiment of the present invention is shown;

[0038] Figure 6 A cloud diagram of pressure distribution in a stagnation cavity provided according to a specific embodiment of the present invention is shown;

[0039] Figure 7 It shows a static temperature distribution cloud diagram in a stagnation cavity provided according to a specific embodiment of the present invention;

[0040] Figure 8 A cloud diagram of density distribution in a stagnation cavity provided according to a specific embodiment of the present invention is shown.

[0041] The above drawings include the following reference numerals:

[0042] 10. Stagnation structure; 11. Stagnation cavity; 20. Thermocouple wire; 21. Thermal node of thermocouple; 30. Thermocouple wire support. DETAILED DESCRIPTION

[0043] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0046] like Figure 1 As shown, according to a specific embodiment of the present invention, a total temperature sensor performance analysis method is provided, the sensor includes a stagnation structure 10, a thermocouple wire 20 and a thermocouple wire support 30, the stagnation structure 10 has a stagnation cavity 11, the thermocouple wire 20 is arranged in the stagnation cavity 11 through the thermocouple wire support 30, and the method includes:

[0047] Establish a structural model of the sensor, and establish a finite element mesh model based on the structural model;

[0048] Based on the finite element mesh model, the thermal node temperature T of the thermocouple wire is iteratively calculated according to the boundary conditions, turbulence model, radiation model, material properties of each part of the sensor structure and the sensor working conditions through CFD fluid simulation. g , when the calculated hot node temperature T g The iteration is stopped when convergence occurs, and the fluid parameters in the stagnation cavity and the wall temperature T in the stagnation cavity are obtained according to the final result of the iteration. W and the root temperature of the thermocouple wire T b For the value of Figure 1 , 21 is the hot node of the thermocouple, also called the hot end of the thermocouple wire;

[0049] According to the material properties of each part of the structure, the fluid parameters in the stagnation cavity, the wall temperature T W and the root temperature of the thermocouple wire T b The velocity error ΔT of the sensor measuring the total temperature is obtained by numerical calculation V , Radiation error ΔT r and conduction error ΔT c ;

[0050] According to the speed error ΔT V , Radiation error ΔT r and conduction error ΔT cThe comprehensive error ΔT of the total temperature measured by the sensor is calculated.

[0051] Specifically, in the embodiment of the present invention, the material property parameters of each part of the structure include material density, material specific heat, material thermal conductivity and material surface emissivity. For example, the density, specific heat, thermal conductivity and surface emissivity of the thermocouple wire. The fluid parameters in the stagnation cavity include the qualitative temperature T of the airflow. f , air velocity V, air flow Mach number M, air flow static pressure P s , airflow density ρ, airflow specific heat ratio k, airflow specific heat C p , airflow dynamic viscosity μ, airflow thermal conductivity λ and Prandtl number P r Among them, the accuracy of simulation calculation and the temperature of thermal node T g The convergence criterion is determined according to the actual situation. The qualitative temperature of the airflow is T f , air velocity V, air flow Mach number M, air flow static pressure P s , the wall temperature of the stagnation cavity T W , Thermocouple wire root temperature T b The values ​​of the airflow specific heat ratio k and airflow specific heat C can be directly extracted from the model obtained by the final iteration. p (also called constant pressure specific heat), airflow dynamic viscosity μ, airflow thermal conductivity λ and Prandtl number P r The value of is based on the qualitative temperature T of the airflow f and static air pressure P s The airflow density ρ can be directly extracted from the model obtained by the final iteration, or it can be obtained based on the airflow qualitative temperature T f and static air pressure P s In addition, the fluid parameters in the stagnation cavity and the wall temperature T W You can use the value of a single point or the average of multiple points. Using the average for analysis has higher accuracy.

[0052] By applying this configuration, a total temperature sensor performance analysis method is provided. The method establishes a structural model for the preliminarily determined sensor structure, and establishes a finite element mesh model based on the structural model. With the help of CFD simulation analysis, the values ​​of the key parameters affecting the temperature measurement performance, such as the fluid parameters in the stagnation cavity, the wall temperature in the stagnation cavity, and the root temperature of the thermocouple wire, are obtained. Then, combined with the heat transfer theory, the radiation error, conduction error, and velocity error are calculated respectively, and then the comprehensive error is obtained. This method comprehensively considers the influencing factors of multiple dimensions, and through the technical means of CFD simulation grading and theoretical calculation, it realizes the accurate evaluation of the temperature measurement performance of the high-temperature total temperature sensor. It is simple and practical, easy to implement and effective, and has strong feasibility. It can provide necessary support for the performance analysis of the high-temperature total pressure sensor. Compared with the prior art, the technical solution of the present invention can solve the technical problem that the prior art cannot accurately analyze the temperature measurement performance of the total temperature sensor used in a high-temperature environment during the design stage, resulting in a long development cycle.

[0053] Furthermore, in the embodiment of the present invention, according to the material property parameters of each part structure, the fluid parameters in the stagnation cavity, the wall temperature T W and the root temperature of the thermocouple wire T b The velocity error ΔT of the sensor measuring the total temperature is obtained by numerical calculation V , Radiation error ΔT r and conduction error ΔT c include:

[0054] According to the Prandtl number P r , airflow specific heat ratio k and airflow Mach number M or according to Prandtl number P r , air velocity V and air specific heat C p Calculate the speed error ΔT of the sensor measuring the total temperature V ;

[0055] According to the airflow density ρ, airflow velocity V, airflow dynamic viscosity μ, Prandtl number P r The convective heat transfer coefficient h is calculated by the airflow thermal conductivity λ;

[0056] According to the surface emissivity ε of the hot node of the thermocouple wire and the hot node temperature T g , convection heat transfer coefficient h and stagnation cavity wall temperature T W Calculate the radiation error ΔT of the total temperature measured by the sensor r ;

[0057] According to the hot node temperature T of the thermocouple wire g , Thermocouple wire root temperature T b , convection heat transfer coefficient h, thermal conductivity λ0 of thermocouple wire, and calculate the conduction error ΔT of the total temperature measured by the sensor c .

[0058] Please refer to Figure 2 The temperature measurement principle of the sensor is that during the flight of a high-speed aircraft, a positive shock wave is formed in front of the stagnation point; the airflow is decelerated by the shock wave, and part of the kinetic energy is converted into the internal energy of the fluid medium. Then, the subsonic fluid enters the stagnation cavity, completes a stagnation, and the fluid kinetic energy is converted into internal energy again. When the airflow inside the stagnation cavity approaches the hot end of the wire, the airflow is stagnant again, and the stagnant fluid transfers heat to the wire through convection heat exchange with the hot end. According to the physical process of temperature measurement by the sensor, it is found that due to the existence of velocity error, radiation error, and conduction error, the indicated temperature of the sensor is always lower than the theoretical total temperature. The derivation process of velocity error, radiation error, and conduction error is as follows:

[0059] 1) Speed ​​error

[0060] Without considering the radiation and conduction of the hot end, when the temperature of the airflow is measured with a thermocouple temperature sensor, there will be viscous dissipation and heat conduction from the inside to the outside inside the temperature boundary layer near the hot end surface. When the process reaches equilibrium, the hot end surface temperature is the effective airflow temperature T j Since for fluid media with Prandtl numbers less than 1, the viscous effect is weaker than the boundary layer heat conduction, the effective temperature of the airflow is always less than the theoretical total temperature T t , the difference between the total temperature and the effective temperature of the airflow is the velocity error.

[0061] According to the definition of the coefficient of restitution:

[0062]

[0063] In the above formula, T f represents the qualitative temperature of the airflow, that is, the static temperature of the fluid, and γ represents the recovery coefficient. When calculating the recovery coefficient of the bare even wire, T f The value is the static temperature of the fluid after one stagnation in the stagnation cavity; when calculating the recovery coefficient of the entire sensor, T f The value is the static temperature corresponding to the aircraft's altitude.

[0064] Assume that the recovery coefficient of the stagnation cavity is γ z , the recovery coefficient of the bare even wire is γ o , the total restitution coefficient of the sensor is γ s According to the definition of the coefficient of restitution, the coefficient of restitution represents the ratio of kinetic energy converted into internal energy after the fluid is stagnant. Please refer to Figure 3, if the velocity of the fluid in front of the shock wave outside the stagnation cavity is known to be V1, the velocity of the fluid inside the stagnation cavity is V2, and the imaginary velocity of the fluid near the even wire is V3 (due to the viscosity of the fluid, there is a velocity boundary layer, and the fluid velocity close to the hot end surface of the even wire is zero, but due to the temperature gradient away from the even wire, the heat is transferred outward, so the surface temperature of the even wire is lower than the theoretical total temperature of the fluid. This effect can be equivalent to the airflow on the surface of the even wire not being fully stagnant, retaining some kinetic energy), then the following relationship is obtained:

[0065]

[0066] According to equations (2), (3) and (4), we can conclude that:

[0067]

[0068] According to formula (5), it can be seen that the total hysteresis coefficient of the sensor is affected by the recovery coefficient of the hysteresis cavity. It increases with the increase of the recovery coefficient of the hysteresis cavity. When there is no hysteresis cavity, the total recovery coefficient of the sensor is equal to the recovery coefficient of the bare wire. The recovery coefficient used in formula (7) and formula (8) is P r is the Prandtl number of the gas inside the stagnation cavity. When calculating the velocity error, all the extracted parameters belong to the air inside the stagnation cavity. At this time, the airflow has experienced the stagnation of the stagnation cavity, and the even wire is in a bare state relative to the air in the cavity. Therefore, the restitution coefficient used in equations (7) and (8) can be calculated by the calculation formula of the restitution coefficient of the bare even wire.

[0069] According to the total temperature theory calculation formula:

[0070]

[0071] The effective temperature of the air flow can be derived as:

[0072]

[0073] Combining equations (6) and (7) we can get the velocity error expression:

[0074]

[0075] That is to say, in the embodiment of the present invention, the following formula can be used according to the Prandtl number P r , airflow specific heat ratio k and airflow Mach number M to calculate the velocity error ΔT of the total temperature measured by the sensor V :

[0076]

[0077] In the above formula, γ o The recovery coefficient of the bare thermocouple wire, T tIndicates the theoretical calculated value of total temperature.

[0078] Or according to the Prandtl number P by the following formula r , air velocity V and air specific heat C p Calculate the speed error ΔT of the sensor measuring the total temperature V :

[0079]

[0080] 2) Radiation error

[0081] During high-speed flight, due to the high theoretical total temperature, the radiation effect of the hot end surface of the thermocouple becomes obvious. In the sensor product equipped with a stagnation cavity, there is thermal radiation between the thermocouple temperature measurement node and the inner wall of the stagnation cavity. The error caused by the radiation heat exchange between the hot end and the inner wall of the stagnation cavity is the radiation error.

[0082] Assuming that the airflow velocity V is taken as the average value, the total temperature is taken as the qualitative temperature, and the wire diameter is d, the Reynolds number R is calculated by combining the airflow density ρ, airflow velocity V and airflow dynamic viscosity μ. e for:

[0083]

[0084] According to the Reynolds number R e and Prandtl number P r Calculate the Nusselt number N u for:

[0085]

[0086] According to the Nusselt number N u The convective heat transfer coefficient h at the hot end is calculated by the airflow thermal conductivity λ:

[0087]

[0088] Furthermore, the following formula is used according to the hot node surface emissivity ε of the thermocouple wire and the hot node temperature T of the thermocouple wire: g , convection heat transfer coefficient h and stagnation cavity wall temperature T W Calculate the radiation error ΔT of the total temperature measured by the sensor r :

[0089]

[0090] In the above formula, σ represents the blackbody radiation constant.

[0091] 3) Conduction error

[0092] When using a thermocouple to measure the air flow temperature, the temperature at the root of the thermocouple isb Usually less than the hot end indication temperature T g , so the heat will be transferred backward along the thermocouple wire. In order to simplify the calculation, the above process is simplified to a one-dimensional heat conduction problem. That is, in the embodiment of the present invention, the following formula is used according to the hot node temperature T of the thermocouple wire. g , Thermocouple wire root temperature T b , convection heat transfer coefficient h, thermal conductivity λ0 of thermocouple wire, and calculate the conduction error ΔT of the total temperature measured by the sensor c :

[0093]

[0094] In the above formula, L represents the length of the thermocouple wire extending out of the support end face, that is, Figure 1 The length of the exposed even wire from the medium hot node 21 to the front end of the even wire support 30, S represents the circumference of the even wire end face, and A represents the cross-sectional area of ​​the even wire.

[0095] Further, according to the analysis, it can be known that the deviation directions of the speed error, radiation error, and conduction error are consistent. Therefore, the present invention uses the following formula according to the speed error ΔT V , Radiation error ΔT r and conduction error ΔT c The comprehensive error ΔT of the total temperature measured by the sensor is calculated:

[0096] ΔT=ΔT V +ΔT r +ΔT c .

[0097] Furthermore, the values ​​of the fluid parameters in the stagnation chamber are all average values.

[0098] In order to facilitate a clearer understanding of the total temperature sensor performance analysis method provided by the present invention, the above-mentioned processes will be described in detail below using practical application examples. Relevant technical personnel in the field should know that this example is only for the purpose of facilitating a clearer understanding of the total temperature sensor performance analysis method provided by the present invention, and does not impose any technical limitation on it.

[0099] like Figure 4 As shown in the figure, taking a certain flight condition as the analysis background, firstly, by analyzing the composition of the sensor, clarifying the material properties of each component, using CFD simulation analysis tools to obtain the temperature, density, and velocity distribution of the fluid inside the stagnation cavity under the calculation condition, and then using heat transfer theory to calculate the sensor velocity error, radiation error, and conduction error. Specifically including:

[0100] (I) Simulation analysis

[0101] 1) Clarify the composition of the sensor and determine the material properties of each component, such as density, specific heat, thermal conductivity, surface emissivity and other parameters. For example, a certain type of ultra-high temperature total temperature sensor is mainly composed of thermocouple wire, ceramic sleeve, total pressure seat, and common nut, where the thermocouple material is platinum-rhodium alloy; the ceramic tube material is aluminum oxide; the total pressure seat and nut material are high-temperature alloy;

[0102] 2) Establish a three-dimensional structural model. In order to reduce the difficulty of meshing and control the calculation scale during the model establishment process, the sensor structure is changed and simplified. For example, check whether there are sharp angles in the model, and change the sharp angles without affecting the key performance of the product; omit the structural design details that do not affect the calculation results. For example, the installation window between the ceramic tube and the total pressure seat is not reflected in the simulation calculation model; the installation thread for the total pressure seat and the nut is also omitted;

[0103] 3) In the CFD simulation software, boundary conditions are set according to the calculation conditions, and turbulence models and radiation models are selected. Usually, the outer boundary of the flow field can be set as the pressure far field boundary, and the turbulence model uses the K-ω model. To simplify the calculation, the inner and outer surfaces of the stagnation cavity are simplified to adiabatic walls, and the simulation calculation is carried out using polyhedral meshes. The simulation results are as follows: Figures 5 to 8 As shown in the figure, the fluid parameters and inner wall temperature in the stagnation cavity are extracted for the subsequent total temperature error theoretical calculation, for example, the average velocity of the air flow inside the stagnation cavity The average pressure in the stagnation cavity is P≈56kPa; the average static temperature in the stagnation cavity is T f ≈1450K; average density in the stagnation cavity ρ≈0.165kg / m 3 ; The wall temperature is T W =1250K;

[0104] (II) Error calculation

[0105] According to the simulation data, the Mach number of the airflow inside the stagnation cavity is M≈0.15, and the theoretical total temperature is T t =1456K, bare wire recovery coefficient γ o =0.84, k=1.4, ΔT is calculated according to formula (8) V =1.04K.

[0106] According to the Northern Hemisphere Standard Atmosphere Model, the static temperature T at a specific height can be obtained. ∞ =223.65K, then the total recovery coefficient of the sensor is The restitution coefficient of the stagnation cavity is

[0107] Combined with the simulation analysis results, the horizontal velocity of the air flow inside the stagnation cavity is about V = 168m / s; taking the total temperature as the qualitative temperature, the dynamic viscosity of the fluid medium inside the stagnation cavity is μ = 5.3×10 -5 kg / (m·s); density ρ=0.165kg / m 3 , the diameter of the wire is d = 0.5 mm, then according to (9) we can calculate R e =262.

[0108] Prandtl number is P r =0.71, according to (10) we can calculate N u =9.3, the thermal conductivity of the fluid medium in the stagnation cavity is λ = 0.0915 W / (m·s), and according to (11) h = 1702.4 W / (m 2 ·K).

[0109] Wherein, the hot end blackness ε=0.22; the black body radiation constant σ=5.67×10 -8 W / (m 2 ·K 4 ), assuming the wall temperature is T W = 1250K (according to engineering experience, the difference between the wall temperature of the stagnation cavity and the theoretical total temperature is less than 200K), and the preliminary estimate of the wire indication temperature T g =1443K, the radiation error ΔT is calculated according to (12) r =13.88K.

[0110] The circumference of the even wire end face S = 0.00157m, the cross-sectional area of ​​the even wire A = 1.96×10^-7m 2 , thermal conductivity of the wire λ o =80w / (m·K); the length of the even wire extending from the support end face is L=5mm. If the temperature of the even wire root is T b = 1436K (according to engineering experience, the temperature difference between the root of the wire and the hot end does not exceed 7K), then the thermal conductivity error ΔT is calculated according to (13): c =1.75K.

[0111] So the comprehensive error ΔT=ΔT V +ΔT r +ΔT c =16.67K.

[0112] In summary, the present invention provides a total temperature sensor performance analysis method, which establishes a structural model for the preliminarily determined sensor structure, and establishes a finite element mesh model based on the structural model, and obtains the numerical values ​​of the key parameters affecting the temperature measurement performance, such as the fluid parameters in the stagnation cavity, the wall temperature in the stagnation cavity, and the root temperature of the thermocouple wire by means of CFD simulation analysis, and then calculates the radiation error, conduction error, and speed error respectively in combination with the heat transfer theory, and then obtains the comprehensive error. This method comprehensively considers the influencing factors of multiple dimensions, and realizes the accurate evaluation of the temperature measurement performance of the high-temperature total temperature sensor through the technical means of CFD simulation grading and theoretical calculation. It is simple and practical, easy to implement and effective, and has strong feasibility, and can provide necessary support for the performance analysis of the high-temperature total pressure sensor. Compared with the prior art, the technical solution of the present invention can solve the technical problem that the prior art cannot accurately analyze the temperature measurement performance of the total temperature sensor used in a high-temperature environment during the design stage, resulting in a long development cycle.

[0113] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0114] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A total temperature sensor performance analysis method, characterized in that: The sensor comprises a stagnation structure, a thermocouple wire and a thermocouple wire support, the stagnation structure has a stagnation cavity, the thermocouple wire is arranged in the stagnation cavity through the thermocouple wire support, and the method comprises: Establishing a structural model of the sensor, and establishing a finite element mesh model based on the structural model; Based on the finite element mesh model, the thermal node temperature T of the thermocouple wire is iteratively calculated according to the boundary conditions, turbulence model, radiation model, material property parameters of each part of the sensor structure and the sensor working condition through CFD fluid simulation. g , when the calculated hot node temperature T g The iteration is stopped when convergence occurs, and the fluid parameters in the stagnation cavity and the wall temperature T in the stagnation cavity are obtained according to the final result of the iteration. W and the root temperature of the thermocouple wire T b The value of According to the material properties of each part of the structure, the fluid parameters in the stagnation cavity, the wall temperature T W and the root temperature of the thermocouple wire T b The speed error ΔT of the sensor measuring the total temperature is obtained by numerical calculation V , Radiation error ΔT r and conduction error ΔT c ; According to the speed error ΔT V , Radiation error ΔT r and conduction error ΔT c The comprehensive error ΔT of the total temperature measured by the sensor is calculated.

2. The method according to claim 1, characterized in that The material properties of each structure include material density, material specific heat, material thermal conductivity and material surface emissivity.

3. The method according to claim 2, characterized in that The fluid parameters in the stagnation chamber include the qualitative temperature T of the airflow f , air velocity V, air flow Mach number M, air flow static pressure P s , airflow density ρ, airflow specific heat ratio k, airflow specific heat C p , airflow dynamic viscosity μ, airflow thermal conductivity λ and Prandtl number P r .

4. The method according to claim 3, characterized in that According to the material properties of each part of the structure, the fluid parameters in the stagnation cavity, the wall temperature T W and the root temperature of the thermocouple wire T b The speed error ΔT of the sensor measuring the total temperature is obtained by numerical calculation V , Radiation error ΔT r and conduction error ΔT c include: According to the Prandtl number P r , airflow specific heat ratio k and airflow Mach number M or according to Prandtl number P r , air velocity V and air specific heat C p The speed error ΔT of the sensor measuring the total temperature is calculated V ; According to the airflow density ρ, airflow velocity V, airflow dynamic viscosity μ, Prandtl number P r The convective heat transfer coefficient h is calculated by the airflow thermal conductivity λ; According to the surface emissivity ε of the hot node of the thermocouple wire and the hot node temperature T g , convection heat transfer coefficient h and stagnation cavity wall temperature T W The radiation error ΔT of the total temperature measured by the sensor is calculated r ; According to the hot node temperature T of the thermocouple wire g , Thermocouple wire root temperature T b , convection heat transfer coefficient h, thermal conductivity λ0 of the thermocouple wire, and the conduction error ΔT of the total temperature measured by the sensor can be calculated. c .

5. The method according to claim 4, characterized in that According to the following formula, the Prandtl number P r , the airflow specific heat ratio k and the airflow Mach number M to calculate the speed error ΔT of the total temperature measured by the sensor V : In the above formula, γ o The recovery coefficient of the bare thermocouple wire, T t Indicates the theoretical calculated value of total temperature.

6. The method according to claim 4, characterized in that According to the following formula, the Prandtl number P r , air velocity V and air specific heat C p The speed error ΔT of the sensor measuring the total temperature is calculated V :

7. The method according to claim 4, characterized in that The following formula is used based on the surface emissivity ε of the thermocouple wire's hot node and the temperature T of the thermocouple wire's hot node. g , convection heat transfer coefficient h and stagnation cavity wall temperature T W The radiation error ΔT of the total temperature measured by the sensor is calculated r : In the above formula, σ represents the blackbody radiation constant.

8. The method according to claim 4, characterized in that The following formula is used to calculate the hot junction temperature T of the thermocouple wire: g , Thermocouple wire root temperature T b , convection heat transfer coefficient h, thermal conductivity λ0 of the thermocouple wire, and the conduction error ΔT of the total temperature measured by the sensor can be calculated. c : In the above formula, L represents the length of the thermocouple wire extending from the supporting end face, S represents the circumference of the thermocouple wire end face, and A represents the cross-sectional area of ​​the thermocouple wire.

9. The method according to claim 1, characterized in that: According to the speed error ΔT, the following formula is used V , Radiation error ΔT r and conduction error ΔT c The comprehensive error ΔT of the total temperature measured by the sensor is calculated as: ΔT=ΔT V +ΔT r +ΔT c 。 10. The method according to any one of claims 1 to 9, characterized in that The values ​​of the fluid parameters in the stagnation chamber are all average values.

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