A transient cylindrical interface high temperature contact thermal resistance test device and method

Abstract

The present invention provides a transient cylindrical interface high-temperature contact thermal resistance test device and method, belonging to the field of thermal resistance testing technology. The device includes a digital temperature control system, a temperature field test system, and a data acquisition and post-processing system. The digital temperature control system includes a temperature controller, a high-temperature heating furnace transformer, a cooling cavity with a valve, a cooling circulation water pump, and a 16-way temperature dynamic inspection instrument. The split high-temperature heating furnace in the temperature field test system is connected to the column through a furnace frame, and the test assembly is placed inside the heating furnace. The extended section of the cooling cavity is assembled with a cooling circulation water pipeline, and the pipeline is connected to the cooling circulation water pump. A pressure-sensitive film sensor is laid at the interface of the test assembly, and an armored thermocouple is arranged on the surface of the test assembly and connected to the temperature dynamic inspection instrument. The device realizes real-time testing of the interface contact thermal resistance of heterogeneous material cylinders with an interface contact pressure between 0-85MPa and a heating end temperature between 30-1400℃.

Description

Technical Field

[0001] The invention relates to the technical field of thermal resistance testing, and in particular to a transient cylindrical interface high-temperature contact thermal resistance testing device and method. Background Art

[0002] In the conductive thermal protection structure, the contact thermal resistance between the built-in high-temperature heat pipe and the surrounding heat-resistant composite material structure has a decisive influence on the effect of thermal protection. The larger the contact thermal resistance, the worse the thermal protection effect. Especially in the startup phase of the high-temperature heat pipe, if the interface contact thermal resistance is too large, the heat near the stagnation point cannot be smoothly transferred to the inside of the heat pipe, resulting in the stagnation point temperature being too high and burning the entire thermal structure. When designing and evaluating the safety of the conductive thermal protection structure, overestimating the contact thermal resistance will make the entire thermal protection structure too bulky and inefficient, and underestimating the contact thermal resistance will bring safety hazards to the structure. Therefore, a reliable high-temperature contact thermal resistance model must be established first.

[0003] At present, the research methods of contact thermal resistance are mainly divided into theoretical analysis, experimental research and numerical simulation. In theoretical research, it is usually based on an idealized single-point contact model or multi-point contact model, and two rough contact surfaces are equivalent to the contact between a smooth surface and a rough surface. Although experimental research can give accurate values ​​of interface contact thermal resistance under different conditions, if it is in the preliminary design stage of the structure, it is necessary to choose between different material combinations. Then, if experimental research is carried out for all possible material combinations, the workload is too large. At this time, a reliable contact thermal resistance model is needed to estimate the cylindrical interface contact thermal resistance between different material combinations. Therefore, it is necessary to establish a numerical simulation model of contact thermal resistance.

[0004] It is worth noting that most of the current research on contact thermal resistance, whether theoretical analysis, numerical simulation or experimental research, focuses on the contact thermal resistance between two planes, while there are fewer studies on the contact thermal resistance between two concentric cylinders. The application background of the existing few studies on cylindrical interface contact thermal resistance is often concentrated in the field of tube-sheet heat exchangers, and the test temperature is often around 100 degrees Celsius, while there is almost no research on the high-temperature contact thermal resistance of the cylindrical interface between heat-resistant composite materials widely used in conductive thermal protection structures. High temperature will affect the thermodynamic parameters of the material such as elastic modulus, yield strength, thermal conductivity, thermal expansion coefficient, etc., thereby affecting the micro-contact state and contact thermal resistance of the interface. On the other hand, the plane interface contact thermal resistance can be simply expressed as a function of the interface stress, while for the cylindrical interface, the interface stress is often uncontrollable and will be affected by the external thermal environment, forming a complex thermomechanical coupling problem. The expression of contact thermal resistance is no longer a deterministic functional relationship. During the development of the entire thermomechanical coupling behavior, the contact thermal resistance is constantly changing, forming a complex nonlinear coupling relationship with the contact state, interface stress and interface temperature. Therefore, it is necessary to develop a set of equipment that can be used for experimental research on high-temperature contact thermal resistance of cylindrical interfaces, laying the foundation for the calculation and analysis of thermal-mechanical coupling including contact thermal resistance. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a transient cylindrical interface high-temperature contact thermal resistance test device and method, which can test the cylindrical interface contact thermal resistance of heterogeneous materials under different assembly gaps, assembly stresses, surface roughness, thermal boundary conditions, etc. In view of the characteristics of the continuous change of the interface contact thermal resistance in the process of stabilization, the high-precision and low-latency armored thermocouple sensor is used to improve the test accuracy of the contact thermal resistance, and the automatic identification feedback insulation of the digital display temperature control system ensures the reliability of the test environment. The device realizes the real-time test of the heterogeneous material cylindrical interface contact thermal resistance with an interface contact pressure between 0-85MPa and a heating end temperature between 30-1400℃.

[0006] The device includes a digital temperature control system, a temperature field test system, and a data acquisition and post-processing system;

[0007] Among them, the digital display temperature control system includes a temperature controller, a high-temperature heating furnace transformer, a cooling chamber, a cooling circulation water pump and a temperature dynamic inspection instrument; the temperature field test system includes a split-type high-temperature heating furnace, a furnace frame and a column; the data acquisition and post-processing system includes a pressure-sensitive film sensor, an armored thermocouple, a pressure acquisition instrument, a computer and a temperature sensor;

[0008] The split high temperature heating furnace is installed on the column through the furnace frame, the test assembly is placed inside the split high temperature heating furnace, the cooling cavity runs through the split high temperature heating furnace and the test assembly, and is fixed on the split high temperature heating furnace through a horizontal support ring, the extended section of the cooling cavity is assembled with the cooling circulating water pipeline, and the cooling circulating water pipeline is connected to the cooling circulating water pump;

[0009] A pressure-sensitive film sensor is laid at the interface of the test component. Temperature measuring holes are left on the upper and lower surfaces of the test component. Armored thermocouples are inserted into the temperature measuring holes. Temperature sensors are installed on the inner and outer surfaces of the test component.

[0010] The data of the armored thermocouple is transmitted to the temperature dynamic inspection instrument, the data of the pressure sensitive film sensor is transmitted to the pressure acquisition instrument, and the data of the temperature dynamic inspection instrument and the pressure acquisition instrument are transmitted to the computer;

[0011] The temperature controller transmits the signal to the computer, the temperature controller controls the high temperature heating furnace transformer, and the high temperature heating furnace transformer adjusts the temperature of the split-type high temperature heating furnace.

[0012] Among them, a heat insulation device is arranged on the outside of the double-opening high-temperature heating furnace, and the double-opening high-temperature heating furnace doors are fixed by locks after being closed.

[0013] The temperature in the split-type high-temperature heating furnace can be adjusted within the range of 30-1400℃.

[0014] The double-open high-temperature heating furnace has a square double-open structure, which is conducive to uniform heating of materials and placement and fixation of test components. Its power supply and control measurement system are self-contained, independently controlling and measuring the temperature of the sample under stress conditions and displaying it; the PID method is used to control the temperature, which is accurate and stable, and can achieve rapid heating. The shell of the high-temperature heating furnace is made entirely of iron materials, and the insulation material is a new type of fiber molding product, which has the advantages of light weight and good insulation performance.

[0015] The folding shaft sleeves of the double swing arms of the furnace frame and the folding shaft sleeves of the split-type high-temperature heating furnace are inserted into the folding shaft to connect the two together; the swing arms of the furnace frame and the heating furnace can rotate in the plane to adjust the plane position of the heating furnace; the columns are fixed on the mobile support vehicle between the main machine workbench and the crossbeam, and the height and position of the split-type high-temperature heating furnace can be adjusted.

[0016] The test method using the test device comprises the following steps:

[0017] S1: Prepare a cylindrical test component based on two different materials for the inner and outer layers, drill temperature measurement holes at different radial positions of the test component, and process the contact surface of the test component as required;

[0018] S2: Measure the thermal conductivity, specific heat capacity and density of the test components at different temperatures in advance;

[0019] S3: Lay a pressure-sensitive film sensor at the interface of the test assembly of S1, and fix the test assembly in a split-type high-temperature heating furnace. Lead the data line of the pressure-sensitive film sensor through the reserved hole, then lock the lock of the split-type high-temperature heating furnace, and insert the sixteen armored thermocouples into the corresponding temperature measuring holes of the test assembly in sequence according to the numbers given by the temperature dynamic inspection instrument, and then tighten the armored thermocouples with nuts to prevent them from falling off during the test;

[0020] S4: Fill the gaps between the armored thermocouple and the pressure-sensitive film sensor with thermal insulation quartz wool to prevent heat loss during the test;

[0021] S5: Adjust the angle of the split high-temperature heating furnace to ensure that the split high-temperature heating furnace is horizontally centered; pass the cooling cavity through the test assembly and the split high-temperature heating furnace, adjust the height of the cooling cavity by rotating the horizontal support ring, then assemble the extended section of the cooling cavity with the cooling circulating water pipeline, and fill the gap between the cooling cavity and the split high-temperature heating furnace with thermal insulation quartz wool;

[0022] S6: Connect the data cables of the armored thermocouple and the pressure-sensitive film sensor to the temperature dynamic inspection instrument and the pressure acquisition instrument respectively, and connect the data cable of the acquisition system to the computer. Then, start the temperature controller of the digital temperature control system for preheating, and ensure that the data of each system can be dynamically displayed and recorded on the computer;

[0023] S7: Set the target temperature through the temperature controller, turn on the control switch to conduct the test, and as the split-type high-temperature heating furnace continues to heat up, heat is transferred radially in the test component, and the interface pressure of the test component gradually increases due to the high-temperature expansion;

[0024] S8: The temperature controller performs temperature feedback identification through the temperature sensors on the outer wall of the cooling chamber and the inner wall of the heating furnace. When the temperature is lower than the set target temperature, the split high-temperature heating furnace is started; when the temperature is higher than the set target temperature, the cooling circulation water pump is started to maintain the temperature of the inner and outer walls of the test assembly constant;

[0025] S9: The pressure-sensitive film sensor and the armored thermocouple transmit data to the temperature dynamic inspection instrument and the pressure acquisition instrument, and then transmit the data to the computer after data processing, and record and feedback the interface pressure at the current time step and the temperature at different cylindrical structure positions in real time;

[0026] S10: When the temperature-time history curves of all armored thermocouples no longer increase significantly, that is, the test assembly enters the steady-state heat transfer stage, turn off the heating switch of the temperature controller and end data recording;

[0027] S11: The temperature-time history data of the measuring point are measured by armored thermocouples. Based on the finite element numerical solution of the transient heat conduction problem, the contact thermal resistance of the cylindrical interface is calculated by the inverse problem processing method.

[0028] As mentioned above, the calculation process of the cylindrical interface contact thermal resistance in S11 is as follows:

[0029] The calculation model of transient temperature field of test components is:

[0030]

[0031] Where: T i is the temperature field, i represents the inner component 1 and the outer component 2, that is, T1 and T2 represent the temperature fields of the inner component 1 and the outer component 2 respectively, T H , T C are the high and low temperature boundary temperatures of the test assembly, given as 300℃ and 30℃, respectively. i (T i ),ρ i (T i ), C i (T i ) are the thermal conductivity, density and specific heat capacity of the material, t is the time, r in is the inner diameter of the inner component 1, r c is the contact interface radius, which is the outer diameter of the inner component 1 and the inner diameter of the outer component 2, r out is the outer diameter of the outer component 2, T0 is the initial temperature field, R c (t) is the contact thermal resistance of the cylindrical interface, T1(r c )、T2(r c ) are the inner component 1 and the outer component 2 at the contact interface r c The temperature at the location;

[0032] The transient interface thermal contact resistance is solved as a nonlinear constrained optimization problem. When the functional J[R c (t)] is minimized, that is, the calculated value of the temperature field of the test component T(r m ,t) and the measured value Y(r m ,t n ) is approximately the same, and the interface contact thermal resistance R c The value of (t):

[0033]

[0034] Where: t F is the total time of transient conduction process, r m Corresponding to the locations of the sixteen thermocouple sensor measurement points, t n is n time steps, L is the axial length of the test component;

[0035] The following conjugate gradient method is used for iterative calculation to quickly obtain the convergent solution of contact thermal resistance. First, given R c The initial value of (t) is obtained by using the Galerkin finite element method according to the calculation model of formula (1) to obtain the temperature field T of the test component. Similar to the model of formula (1), the sensitivity equation and the adjoint equation are solved by the finite element method to obtain the calculated temperature field sensitivity function ΔT i With the accompanying function λ i :

[0036]

[0037] According to the previous iteration The value of the interface contact thermal resistance is obtained by the known quantity obtained by the above solution in the next iteration step. Update:

[0038]

[0039] Where: t represents the current time, the superscript k-1, k represents the iteration step, that is, P k (t) is the fastest descent direction of iteration step k at time t, and the following is similar, β k is the search step length, γ k is the conjugate coefficient, J′k(t) is the gradient direction, T and Y correspond to T(r m ,t) and Y(r m ,t n ), ΔT is the overall temperature field sensitivity function, λ1 and λ2 are the temperature field adjoint functions corresponding to T1 and T2 generated by the adjoint problem respectively;

[0040] The convergence condition of the iteration is:

[0041]

[0042] Where ε is the convergence accuracy and σ is the temperature residual.

[0043] The beneficial effects of the above technical solution of the present invention are as follows:

[0044] In the above scheme, the high-temperature heating system can ensure the realization of a constant temperature condition in the furnace for a long time, and can achieve a long-term stability of the furnace temperature in the range of 30-1400℃. The cooling cavity is cooled and heat exchanged by circulating water, which increases the heat exchange area between the cooling cavity and the low-temperature end of the component to be tested. The flow rate of the cooling circulating water pump is automatically adjusted to make the temperature of the low-temperature end of the component to be tested close to the temperature of the cooling medium, ensuring the high-precision realization of the contact thermal resistance test principle. In response to the transient temperature changes of the test components, the armored thermocouples with low-latency response and the dynamic acquisition of the pressure acquisition instrument and the temperature dynamic inspection instrument with real-time adjustable steps improve the measurement accuracy of transient contact thermal resistance. The high-performance post-processing system provides technical support for the data storage and post-processing of transient processes and reduces calculation errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the overall structure of the transient cylindrical interface high temperature contact thermal resistance testing device of the present invention;

[0046] Figure 2 It is a cross-sectional schematic diagram of the high-temperature heating furnace of the device of the present invention;

[0047] Figure 3 A schematic diagram of a model of a component to be tested and a high-temperature heating furnace of the device of the present invention;

[0048] Figure 4 It is a flow chart of calculating the cylindrical interface contact thermal resistance of the transient cylindrical interface high temperature contact thermal resistance testing method of the present invention;

[0049] Figure 5 The temperature-time history curve of each armored thermocouple measuring point in the specific implementation conditions of the present invention;

[0050] Figure 6 The calculated values ​​of the interface pressure and the transient cylindrical interface contact thermal resistance are measured by the pressure-sensitive film sensor of the specific implementation conditions of the present invention.

[0051] Among them: 1-temperature controller; 2-high temperature heating furnace transformer; 3-double-open high temperature heating furnace; 4-cooling cavity; 5-cooling circulation water pump; 6-temperature dynamic inspection instrument; 7-furnace frame; 8-column; 9-test component; 10-pressure sensitive film sensor; 11-armored thermocouple; 12-pressure acquisition instrument; 13-computer; 14-temperature measuring hole; 15-lock; 16-temperature sensor; 17-cooling circulation water pipeline; 18-reserved hole, 19-fixed column, 20-horizontal support ring. DETAILED DESCRIPTION

[0052] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0053] The invention provides a transient cylindrical interface high-temperature contact thermal resistance testing device and method.

[0054] like Figure 1 As shown, the device includes a digital temperature control system, a temperature field test system, and a data acquisition and post-processing system;

[0055] The digital temperature control system includes a temperature controller 1, a high temperature heating furnace transformer 2, a cooling cavity 4, a cooling circulation water pump 5 and a temperature dynamic inspection instrument 6; the temperature field test system includes a split high temperature heating furnace 3, a furnace frame 7 and a column 8; the data acquisition and post-processing system includes a pressure sensitive film sensor 10, an armored thermocouple 11, a pressure acquisition instrument 12, a computer 13 and a temperature sensor 16;

[0056] The split high temperature heating furnace 3 is installed on the column 8 through the furnace frame 7, the test assembly 9 is placed inside the split high temperature heating furnace 3, the cooling cavity 4 passes through the split high temperature heating furnace 3 and the test assembly 9, and is fixed to the split high temperature heating furnace 3 through the horizontal support ring 20, the extended section of the cooling cavity 4 is assembled with the cooling circulating water pipeline 17, and the cooling circulating water pipeline 17 is connected to the cooling circulating water pump 5;

[0057] like Figure 2 As shown, a pressure-sensitive film sensor 10 is laid at the interface of the test assembly 9, temperature measuring holes 14 are left on the upper and lower surfaces of the test assembly 9, armored thermocouples 11 are inserted into the temperature measuring holes 14, and temperature sensors 16 are installed on the inner and outer surfaces of the test assembly 9;

[0058] The data of the armored thermocouple 11 is transmitted to the temperature dynamic inspection instrument 6, the data of the pressure sensitive film sensor 10 is transmitted to the pressure acquisition instrument 12, and the data of the temperature dynamic inspection instrument 6 and the pressure acquisition instrument 12 are transmitted to the computer 13;

[0059] The temperature controller 1 transmits a signal to the computer 13 , and the temperature controller 1 controls the high-temperature heating furnace transformer 2 , and the high-temperature heating furnace transformer 2 adjusts the temperature of the split-type high-temperature heating furnace 3 .

[0060] Among them, a heat insulation device is arranged outside the split-type high-temperature heating furnace 3, and the furnace doors of the split-type high-temperature heating furnace 3 are fixed by a lock 15 after being joined.

[0061] When the device is used, the hollow cooling cavity and the cylindrical test component are placed in a high-temperature heating furnace as a whole. The cooling cavity has an extended section that is assembled with the upper and lower cooling circulating water pipes, which forces cooling on the inner wall of the component to achieve radial flow of heat inside the component. There are temperature sensors of the digital temperature control system on the inner and outer walls of the component. Four groups of four are arranged at radially symmetrical positions of the component to measure its radial temperature distribution. A pressure-sensitive film is laid at the cylindrical interface of the test component to output the interface contact pressure data in real time. After measuring the temperature-time history data of each radial measuring point, based on the finite element numerical solution of the transient heat conduction problem and using the solution idea of ​​the inverse problem, the transient contact thermal resistance of the cylindrical interface is given by the conjugate gradient steepest descent method. According to the interface pressure measured by the pressure-sensitive film sensor, a stress-related contact thermal resistance model under transient high temperature is established.

[0062] Specifically, the steps are as follows:

[0063] S1: Figure 3 , prepare a cylindrical test component 9 with an inner component 1 made of iron and an outer component 2 made of stainless steel, with an axial length of 0.10 m, and the r of the cylindrical test component 9 composed of iron and stainless steel in 、r c 、r out The relevant dimensions are 0.04m, 0.08m, and 0.12m respectively, and according to the position of the reserved hole 18 of the split high-temperature heating furnace 3, the temperature measuring hole 14 is punched at the corresponding position of the cylindrical test component 9. The punching position of the temperature measuring hole 14 corresponds to the reserved hole 18 one by one and is located on the same vertical line. Therefore, the radius position r of the test component 9 corresponding to the temperature measuring hole 14 is m They are 0.05m, 0.06m, 0.07m, 0.075m, 0.085m, 0.09m, 0.10m, and 0.11m respectively. The hole spacing between the reserved hole 18 and the temperature measuring hole 14 should be greater than the diameter of the armored thermocouple 11 by 2mm, that is, the hole spacing is 3mm. The temperature measuring hole 14 has a depth of 5mm and is an elliptical hole, which is beneficial to increase the contact area between the armored thermocouple 11 and the temperature measuring hole 14;

[0064] S2: Before this experiment, the thermal conductivity k of the test component 9 at different temperatures was measured. i (T i ), specific heat capacity C i (T i ), density ρ i (T i );

[0065] S3: Lay the pressure-sensitive film sensor 10 at the interface of the test assembly 9 of S1, and fix the test assembly 9 in the split-type high-temperature heating furnace 3 through the fixing clamp 19 to ensure that the connection is firm during the test process. The data line of the pressure-sensitive film sensor 10 is led out through the reserved hole 18, and then the lock 15 of the split-type high-temperature heating furnace 3 is locked; and the sixteen armored thermocouples 11 are inserted into the temperature measuring holes 14 corresponding to the test assembly in sequence according to the numbers given by the temperature dynamic inspection instrument 6, and then the armored thermocouples 13 are fastened by nuts to prevent them from falling off during the test;

[0066] S4: Fill the reserved holes 18 where the armored thermocouple 11 and the pressure-sensitive film sensor 10 are located with heat-insulating quartz wool to prevent heat loss during the test;

[0067] S5: adjust the angle of the split high-temperature heating furnace 3, rotate the double swing arms of the furnace frame 7 to adjust the plane position of the furnace body, move the upper bracket of the column to adjust the height of the split high-temperature heating furnace 3, ensure that the position of the split high-temperature heating furnace 3 is horizontally centered, pass the cooling cavity 4 through the test assembly 9 and the split high-temperature heating furnace 3, the horizontal support ring 20 of the cooling cavity 4 can be firmly assembled with the high-temperature heating furnace 3, adjust the cooling cavity 4 to a suitable height by rotating the threaded horizontal support ring 20, then assemble the extended section of the cooling cavity 4 with the cooling circulating water pipeline 17, and fill the gap between the cooling cavity 4 and the split high-temperature heating furnace 3 with thermal insulation quartz wool;

[0068] S6: Connect the data lines of the armored thermocouple 11 and the pressure-sensitive film sensor 10 to the temperature dynamic inspection instrument 6 and the pressure acquisition instrument 12 respectively, and connect the data line of the acquisition system to the computer 13, then start the temperature controller 1 of the digital temperature control system to preheat for 5 minutes, and ensure that the data of each system can be dynamically displayed and recorded on the computer 13;

[0069] S7: The temperature of the high-temperature heating furnace is set to 300°C and the temperature of the cooling control end is set to 30°C through the temperature controller 1, and then the control switch is turned on to conduct the test. As the split-type high-temperature heating furnace 3 continues to heat and increase in temperature, heat is transferred radially in the test assembly 9, and at the same time, the interface pressure of the test assembly 9 gradually increases due to the high-temperature expansion;

[0070] S8: The temperature controller 1 performs temperature feedback identification through the temperature sensors 16 of the outer wall of the cooling chamber and the inner wall of the heating furnace. When the temperature of the inner wall of the heating furnace is lower than 300°C, the split high-temperature heating furnace is started. When the temperature of the outer wall of the cooling chamber is higher than 30°C, the cooling circulation water pump is started to maintain the temperature of the inner and outer walls of the test assembly 9 constant.

[0071] S9: As time goes by, the pressure-sensitive film sensor 10 and the armored thermocouple 11 transmit data to the temperature dynamic inspection instrument 6 and the pressure acquisition instrument 12, and then transmit the data to the computer 13 after data processing, and record and feedback the interface pressure at the current time step and the temperature at different armored thermocouple 11 measuring points in real time. At the same time, the computer can display the temperature-time history curve of the armored thermocouple 11 measuring point;

[0072] S10: When the temperature-time history curves of all the armored thermocouples 11 measuring points no longer increase significantly, that is, the test assembly 9 enters the steady-state heat transfer stage, the heating switch of the temperature controller is turned off, and the data recording is ended. The temperature-time history curve recorded in real time under this working condition is as follows: Figure 5 As shown;

[0073] S11: Using the sixteen temperature measuring points arranged radially symmetrically in the test assembly 9, the armored thermocouple 11 measures the temperature-time history data of the measuring points. Since the iron and stainless steel of the test assembly 9 are isotropic materials, and in order to reduce the test and calculation errors, for the temperature measuring points at the radially symmetrical positions, the average temperature of the two measuring points is taken as the temperature measurement value of the position in the actual calculation, thereby obtaining the temperature field Y(r m ,t n ); Based on the numerical solution of transient heat conduction problem, the contact thermal resistance of cylindrical interface is given by the inverse problem treatment method;

[0074] The calculation method of the cylindrical interface contact thermal resistance in the above S11 is as follows:

[0075] The calculation model of transient temperature field of test components is:

[0076]

[0077] Where: T i is the temperature field, i represents the inner component 1 iron and the outer component 2 stainless steel, that is, T1 and T2 represent the temperature fields of the inner component 1 iron and the outer component 2 stainless steel, respectively, T H , T C are the high and low temperature boundary temperatures of the test assembly, given as 300℃ and 30℃, respectively. i (T i ),ρ i (T i ), C i (T i ) are the thermal conductivity, density and specific heat capacity of the two materials, t is the time, r in is the inner diameter of the inner layer component 1 iron, r c is the contact interface radius, which is the outer diameter of the inner component 1 iron and the inner diameter of the outer component 2 stainless steel, r outis the outer diameter of the stainless steel of the outer component 2, T0 is the initial temperature field, R c (t) is the contact thermal resistance of the cylindrical interface, T1(r c )、T2(r c ) are the inner component 1 iron and the outer component 2 stainless steel at the contact interface r c The temperature at the location;

[0078] The transient interface thermal contact resistance is solved as a nonlinear constrained optimization problem. When the functional J[R c (t)] is minimized, that is, the calculated value of the temperature field of the test component T(r m ,t) and the measured value Y(r m ,t n ) is approximately the same, and the interface contact thermal resistance R c The value of (t):

[0079]

[0080] Where: t F is the total time of the transient conduction process, that is, the test time is 154min, r m Corresponding to the positions of the sixteen thermocouple sensor measuring points, in order to improve the accuracy, the temperature measuring points on both sides of the interface of the test assembly 9 are densely distributed, as described in S1, t n is n time steps, given by the data acquisition frequency of once every 2 seconds, and L is the axial length of the test component 9, i.e., 0.1 m;

[0081] The following conjugate gradient method is used for iterative calculation to quickly obtain the convergent solution of contact thermal resistance. First, given R c The initial value of (t) is obtained by using the Galerkin finite element method according to the calculation model of formula (6) to obtain the temperature field T of the test component. Similar to the model of formula (6), the sensitivity equation and the adjoint equation are solved by the finite element method to obtain the calculated temperature field sensitivity function ΔT i With the accompanying function λ i :

[0082]

[0083] According to the previous iteration The value of the interface contact thermal resistance is obtained by the known quantity obtained by the above solution in the next iteration step. Update:

[0084]

[0085] Where: t represents the current time, the superscript k-1, k represents the iteration step, that is, P k(t) is the fastest descent direction of iteration step k at time t, and the following is similar, β k is the search step length, γ k is the conjugate coefficient, J ′k (t) is the gradient direction, T and Y correspond to T(r m ,t) and Y(r m ,t n ), ΔT is the overall temperature field sensitivity function, λ1 and λ2 are the temperature field adjoint functions corresponding to T1 and T2 generated by the adjoint problem respectively;

[0086] The convergence condition of the iteration is:

[0087]

[0088] Where ε is the convergence accuracy and σ is the temperature residual.

[0089] Specifically, Figure 4 First, obtain the geometric parameters r of the test component 9 in 、r c 、r out , L, material parameter k i (T i ),ρ i (T i ), C i (T i ), based on the temperature-time history data of the thermocouple measuring point and the measuring point position r m Given the temperature field measurement value Y(r m ,t n ), and the time history data of interface stress can provide a reference for the subsequent analysis of the influence of transient interface contact thermal resistance parameters. The transient interface contact thermal resistance R in S11 above c (t) The detailed iterative calculation process is as follows:

[0090] 1) Initialize the interface contact thermal resistance R c (t);

[0091] 2) Based on the obtained geometric and material parameters, the temperature field T of the test component is obtained by using the Galerkin finite element method according to the transient calculation model of formula (6): i , from which the overall temperature field T can be obtained;

[0092] 3) Calculate the interface contact thermal resistance functional using equation (7) and give the current iteration step k, that is, the contact thermal resistance is The calculated value of the temperature field at the measuring point is T k (r m ,t) and the measured value Y(r m ,t n ) error;

[0093] 4) If the functional convergence condition (10) is met, output the interface contact thermal resistance result, otherwise go to step 5) to continue iterative calculation;

[0094] 5) Also using the Galerkin finite element method to solve the sensitivity equation and adjoint equation of formula (8), we can get the temperature field sensitivity function ΔT i With the accompanying function λ i , from which we can get the overall temperature field sensitivity function ΔT of the current iteration step k and the adjoint function λ k ;

[0095] 6) According to formula (9), solve the fastest descent direction P of the next iteration step k+1 k (t), search step length β k , conjugate coefficient γ k , gradient direction J′ k (t), Update the interface thermal contact resistance And return to step 2) to perform the calculation of the next iteration step until the result converges;

[0096] S12: Using the temperature data collected by the temperature rise curve of S10, the inverse problem of contact thermal resistance is solved by the least square method to avoid inaccurate calculation results caused by measurement errors. c (t) Perform multi-interval result correction and calculate the transient interface contact thermal resistance of the iron and stainless steel test components 9 at the constant temperature boundary of 30℃-300℃ as follows: Figure 6 As shown, of course, it takes a certain amount of time for the heat flux in the transient process to be transferred to the interface, so the interface contact thermal resistance at this time defaults to the initial contact thermal resistance of the interface, that is, Figure 6 The horizontal straight line segment of the interface thermal resistance curve is shown in Figure 1. Due to the difference in thermal expansion coefficients between the inner component 1 iron and the outer component 2 stainless steel, an interface pressure is generated at the interface, such as Figure 6 As shown in the interface pressure curve, it gradually increases with time, which correspondingly increases the heat conduction contact area between the iron and stainless steel interfaces, causing the interface contact thermal resistance value to drop rapidly.

[0097] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A transient cylindrical interface high temperature contact thermal resistance test method, characterized in that: The steps include: S1: Prepare a cylindrical test component based on two different materials for the inner and outer layers, drill temperature measurement holes at different radial positions of the test component, and process the contact surface of the test component as required; S2: Measure the thermal conductivity, specific heat capacity and density of the test components at different temperatures in advance; S3: Lay a pressure-sensitive film sensor at the interface of the test assembly of S1, and fix the test assembly in a split-type high-temperature heating furnace. Lead the data line of the pressure-sensitive film sensor through the reserved hole, then lock the lock of the split-type high-temperature heating furnace, and insert the sixteen armored thermocouples into the corresponding temperature measuring holes of the test assembly in sequence according to the numbers given by the temperature dynamic inspection instrument, and then tighten the armored thermocouples with nuts to prevent them from falling off during the test; S4: Fill the gaps between the armored thermocouple and the pressure-sensitive film sensor with thermal insulation quartz wool to prevent heat loss during the test; S5: Adjust the angle of the split high-temperature heating furnace to ensure that the split high-temperature heating furnace is horizontally centered; pass the cooling cavity through the test assembly and the split high-temperature heating furnace, adjust the position of the cooling cavity by rotating the horizontal support ring, then assemble the cooling cavity extension section with the cooling circulating water pipeline, and fill the gap between the cooling cavity and the split high-temperature heating furnace with thermal insulation quartz wool; S6: Connect the data cables of the armored thermocouple and the pressure-sensitive film sensor to the temperature dynamic inspection instrument and the pressure acquisition instrument respectively, and connect the data cable of the acquisition system to the computer. Then, start the temperature controller of the digital temperature control system for preheating, and ensure that the data of each system can be dynamically displayed and recorded on the computer; S7: Set the target temperature through the temperature controller, turn on the control switch to conduct the test, and as the split-type high-temperature heating furnace continues to heat up, heat is transferred radially in the test component, and the interface pressure of the test component gradually increases due to the high-temperature expansion; S8: The temperature controller performs temperature feedback identification through the temperature sensors on the outer wall of the cooling chamber and the inner wall of the heating furnace. When the temperature is lower than the set target temperature, the split high-temperature heating furnace is started; when the temperature is higher than the set target temperature, the cooling circulation water pump is started to maintain the temperature of the inner and outer walls of the test assembly constant; S9: The pressure-sensitive film sensor and the armored thermocouple transmit data to the temperature dynamic inspection instrument and the pressure acquisition instrument, and then transmit the data to the computer after data processing, and record and feedback the interface pressure at the current time step and the temperature at different cylindrical structure positions in real time; S10: When the temperature-time history curves of all armored thermocouples no longer increase significantly, the test assembly enters the steady-state heat transfer stage, the heating switch of the temperature controller is turned off, and data recording ends; S11: Using armored thermocouples to measure the temperature-time history data of the measuring point, based on the finite element numerical solution of the transient heat conduction problem, the contact thermal resistance of the cylindrical interface is calculated by the inverse problem processing method; The calculation process of the cylindrical interface contact thermal resistance in S11 is as follows: The calculation model of transient temperature field of test components is: Where: T i is the temperature field, i represents the inner component 1 and the outer component 2, that is, T1 and T2 represent the temperature fields of the inner component 1 and the outer component 2 respectively, T H , T C are the high and low temperature boundary temperatures of the test assembly, given as 300℃ and 30℃, respectively. i (T i ),ρ i (T i ), C i (T i ) are the thermal conductivity, density and specific heat capacity of the material, t is the time, r in is the inner diameter of the inner component 1, r c is the contact interface radius, which is the outer diameter of the inner component 1 and the inner diameter of the outer component 2, r out is the outer diameter of the outer component 2, T0 is the initial temperature field, R c (t) is the contact thermal resistance of the cylindrical interface, T1(r c )、T2(r c ) are the inner component 1 and the outer component 2 at the contact interface r c The temperature at the location; The transient cylindrical interface high temperature contact thermal resistance is solved as a nonlinear constrained optimization problem. When the functional J[R c (t)] is minimized, that is, the calculated value of the temperature field of the test component T(r m ,t) and the measured value Y(r m ,t n ) is approximately the same, and the interface contact thermal resistance R c The value of (t): Where: t F is the total time of transient conduction process, r m Corresponding to the locations of the sixteen thermocouple sensor measurement points, t n is n time steps, L is the axial length of the test component; The following conjugate gradient method is used for iterative calculation to quickly obtain the convergent solution of contact thermal resistance. First, given R c The initial value of (t) is obtained by using the Galerkin finite element method according to the calculation model of formula (1) to obtain the temperature field T of the test component. The sensitivity equation and the adjoint equation are solved by the finite element method to obtain the calculated temperature field sensitivity function ΔT i With the accompanying function λ i : Where i = 1, 2; According to the previous iteration The value of the interface contact thermal resistance is obtained by the known quantity obtained by the above solution in the next iteration step. Update: Among them: P k (t)=J ′k (t)+γ k P k-1 (t) Where: superscript k-1, k represents the iteration step, that is, P k (t) is the fastest descent direction of iteration step k at time t, β k is the search step length, γ k is the conjugate coefficient, J′ k (t) is the gradient direction, T and Y correspond to T(r m ,t) and Y(r m ,t n ), ΔT is the overall temperature field sensitivity function, λ1 and λ2 are the temperature field adjoint functions corresponding to T1 and T2 generated by the adjoint problem respectively; The convergence condition of the iteration is: Where ε is the convergence accuracy and σ is the temperature residual.

2. A device based on the transient cylindrical interface high temperature contact thermal resistance test method according to claim 1, characterized in that: Including digital temperature control system, temperature field test system, data acquisition and post-processing system; Among them, the digital display temperature control system includes a temperature controller, a high-temperature heating furnace transformer, a cooling chamber, a cooling circulation water pump and a temperature dynamic inspection instrument; the temperature field test system includes a split-type high-temperature heating furnace, a furnace frame and a column; the data acquisition and post-processing system includes a pressure-sensitive film sensor, an armored thermocouple, a pressure acquisition instrument, a computer and a temperature sensor; The split high temperature heating furnace is installed on the column through the furnace frame, the test assembly is placed inside the split high temperature heating furnace, the cooling cavity runs through the split high temperature heating furnace and the test assembly, and is fixed on the split high temperature heating furnace through a horizontal support ring, the extended section of the cooling cavity is assembled with the cooling circulating water pipeline, and the cooling circulating water pipeline is connected to the cooling circulating water pump; A pressure-sensitive film sensor is laid at the interface of the test component. Temperature measuring holes are left on the upper and lower surfaces of the test component. Armored thermocouples are inserted into the temperature measuring holes. Temperature sensors are installed on the inner and outer surfaces of the test component. The data of the armored thermocouple is transmitted to the temperature dynamic inspection instrument, the data of the pressure sensitive film sensor is transmitted to the pressure acquisition instrument, and the data of the temperature dynamic inspection instrument and the pressure acquisition instrument are transmitted to the computer; The temperature controller transmits the signal to the computer, the temperature controller controls the high temperature heating furnace transformer, and the high temperature heating furnace transformer adjusts the temperature of the split-type high temperature heating furnace.

3. The device for testing the transient cylindrical interface high temperature contact thermal resistance according to claim 2, characterized in that: A heat insulation device is arranged outside the double-opening high-temperature heating furnace, and the double-opening high-temperature heating furnace doors are fixed by locks after being closed.

4. The device for testing the transient cylindrical interface high temperature contact thermal resistance according to claim 2, characterized in that: The temperature in the split-type high-temperature heating furnace is adjustable within the range of 30-1400°C.

5. The device for testing the transient cylindrical interface high temperature contact thermal resistance according to claim 2, characterized in that: The split-type high-temperature heating furnace is a square split-type structure.

6. The device for testing the transient cylindrical interface high temperature contact thermal resistance according to claim 2, characterized in that: The folding shaft sleeves of the double swing arms of the furnace frame and the folding shaft sleeves of the split-type high-temperature heating furnace are inserted into the folding shaft to connect the two together; the swing arms of the furnace frame and the heating furnace can rotate in a plane to adjust the plane position of the heating furnace; the columns are fixed on a mobile support vehicle between the main machine workbench and the crossbeam, and the height position of the split-type high-temperature heating furnace can be adjusted.

Images