A method for calculating heat transfer coefficient in high-temperature circular workpiece cooling process

Abstract

The application relates to the technical field of temperature measurement and heat transfer coefficient calculation methods, in particular to a heat transfer coefficient calculation method for a high-temperature circular workpiece in a cooling process, which comprises the following steps: step 1, arranging thermocouples by adopting a circular workpiece point arrangement scheme designed by the application, punching holes in the circular workpiece, and inserting the thermocouples; step 2, heating the circular workpiece to 800-1600 DEG C, and taking out; step 3, cooling the circular workpiece by using high-speed airflow, recording temperature change data of each point by using a temperature recorder, and exporting the data; and step 4, reading the temperature data of step 3 by using a reverse heat transfer method program, and calculating heat transfer coefficients of each point. The application can measure temperature change conditions of the circular workpiece in multiple dimensions, ensures the accuracy and comprehensiveness of temperature data of the circular workpiece, and can quickly calculate heat transfer coefficients of any position of the circular workpiece under different working conditions by using a verified three-dimensional simulation model.

Description

Technical Field

[0001] This invention relates to the technical field of temperature measurement and heat transfer coefficient calculation methods, and particularly to a method for calculating the heat transfer coefficient of a high-temperature circular workpiece during the cooling process. Background Technology

[0002] In the heat treatment of nickel-based superalloys, the cooling rate significantly affects their mechanical properties. On the one hand, as the cooling rate increases, the precipitated phase structure gradually becomes finer and more dispersed, and the superalloy achieves higher strength and hardness. On the other hand, an excessively fast cooling rate can cause greater stress and deformation in the superalloy material, leading to cracking and high residual stress. This contradictory requirement makes the determination of the cooling rate, i.e., the convective heat transfer coefficient, in the heat treatment of nickel-based superalloys particularly important.

[0003] In calculating convective heat transfer coefficients, the heat transfer coefficient during quenching is time-dependent, making its calculation complex. Furthermore, the convective heat transfer coefficient depends on several complex factors, such as fluid properties, velocity, temperature gradient, and the geometry and surface characteristics of the object, which are often impossible to measure directly. It typically requires estimation through inverse calculations based on experimental temperatures or simulation methods. However, existing inverse heat transfer methods are often limited by the difficulty of measuring workpiece temperature. During workpiece quenching, a large temperature gradient often exists within the workpiece, and conventional temperature sensors are usually point- or surface-based, resulting in insufficient accuracy in reflecting the overall temperature. Additionally, a large temperature gradient implies significant temperature non-uniformity in different regions within the workpiece, necessitating a comprehensive consideration of temperature distribution across different areas. To overcome these problems, multi-point or multi-sensor measurement methods are usually employed to acquire temperature data from different parts, and then appropriate methods are used to synthesize this data to predict the temperature and heat transfer coefficient of different parts of the workpiece. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for calculating the heat transfer coefficient of a high-temperature circular workpiece during the cooling process. This method can measure the temperature change of the circular workpiece in multiple dimensions and perform calculations using a verified three-dimensional simulation model, which can quickly calculate the heat transfer coefficient at any position of the circular workpiece under different working conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for calculating the heat transfer coefficient during the cooling process of a high-temperature circular workpiece includes the following steps:

[0007] Step 1: Using a thermocouple placement method, drill holes in the circular workpiece and insert thermocouples;

[0008] Step 2: Heat the round workpiece to 800-1600℃ and remove it;

[0009] Step 3: Cool the circular workpiece with high-speed airflow, record the temperature change data at each point with a temperature recorder, and export the data;

[0010] Step 4: Use the reverse heat transfer method program to read the temperature data from Step 3 and calculate the heat transfer coefficient at each point.

[0011] Step 5: Perform 1:1 three-dimensional modeling of the circular workpiece and the high-speed airflow cooling process, mesh the model, set the gas flow rate, temperature and pressure boundary conditions according to the actual operating conditions, use the simple algorithm, set the points at the same locations as the experimental thermocouples as the monitoring points, and perform three-dimensional simulation calculations.

[0012] Step 6: Export the temperature data and heat transfer coefficient data of the monitoring points calculated by the three-dimensional simulation, and compare them with the heat transfer coefficients of each point calculated by the reverse heat transfer method program in Step 4. If the error is greater than 5%, readjust the simulation calculation method until the error is within an acceptable range. Then the three-dimensional simulation calculation model is considered to have been verified.

[0013] Step 7: Using a validated 3D simulation model, the heat transfer coefficient at any position on the circular workpiece is quickly calculated by changing the gas flow rate and the distance between the gas nozzle and the workpiece.

[0014] Preferably, in step 1, the specific steps are as follows:

[0015] Step 1.1: Select vertical section 1-1 as 0°, and rotate sections 2-2, 3-3 and 4-4 counterclockwise by 45° in sequence, with A1 as the center;

[0016] Step 1.2: Temperature measurement points B and E are located at a radius of 1 / 2 on section 1-1;

[0017] Step 1.3: Temperature measurement point C is located at a radius of 1 / 2 on section 2-2;

[0018] Step 1.4: On section 3-3, A2 is located at 1 / 4 of the radius, A3 is located at 1 / 2 of the radius, A3' is located at 1 / 2 of the radius, A4 is located at 3 / 4 of the radius, and A5 is located at the edge. The edge of the hole is 0-5mm away from the wall.

[0019] Step 1.5: Temperature measurement point D is located at 1 / 2 radius on section 4-4;

[0020] Step 1.6: Section 5-5 passes through the midpoint between A1 and B and point A3', and drills a hole at E' directly below point A3';

[0021] Among them, the five temperature measuring points A1, A2, A3, A4, and A5 are used to measure the radial temperature distribution of the workpiece;

[0022] Five temperature measuring points, A3, B, C, D, and E, are used to measure the axial temperature distribution of the workpiece.

[0023] The depth of holes A1, A2, A3, A4, A5, and A3' is 1 / 2 the height of the circular workpiece; the depth of hole B is 1 / 3 the height; the depth of hole D is 2 / 3 the height; and the depth of holes E and E' is 5 / 6 the height.

[0024] Meanwhile, temperature measurement points A3 and A3' are used for radial temperature verification, while temperature measurement points E and E' are used to verify whether the temperatures at different angles with the same radius and depth on a circular workpiece are consistent.

[0025] Preferably, in step 1, the diameter of the hole matches that of the thermocouple, so that the thermocouple can just fit into the hole.

[0026] Preferably, in step 1, the thermocouple adopts an armored or corundum sheath structure, the thermocouple collecting end is in close contact with the bottom of the hole, and the gap is sealed with refractory mud.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention employs an 11-point thermocouple arrangement to measure the radial and axial temperature gradient changes of a circular workpiece during gas quenching and cooling. It records temperature data from multiple dimensions during the quenching process. Specifically, points A1, A2, A3, A4, and A5 measure the radial temperature distribution, while points A3, B, C, D, and E measure the axial temperature distribution. Points A3 and A3' are used for radial temperature verification, and points E and E' verify the consistency of temperatures at different angles and at the same radius and depth of the circular workpiece. This ensures the accuracy and comprehensiveness of the temperature data for the circular workpiece, avoiding large errors in heat transfer coefficient calculation caused by incomplete temperature data recording.

[0029] 2. This invention simultaneously compares and verifies the heat transfer coefficient calculated by the reverse heat transfer method with that calculated by the three-dimensional simulation model, ensuring the reliability of the three-dimensional simulation model calculation. Using the verified three-dimensional simulation model to calculate the heat transfer coefficient at any position of a circular workpiece under different working conditions is a fast, convenient, and accurate method that avoids the tedious work of numerous experiments, significantly saving time and economic costs. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the thermocouple placement strategy for the circular workpiece according to the present invention;

[0031] Figure 2This is a physical diagram of the thermocouple arrangement on the circular workpiece of the present invention;

[0032] Figure 3 This is a cross-sectional view of the thermocouple arrangement at each section of the circular workpiece of the present invention;

[0033] Figure 4 This is a flowchart illustrating the process of measuring the heat transfer coefficient of a circular workpiece during gas cooling, as described in this invention.

[0034] Figure 5 This is a schematic diagram of the temperature curves of 11 thermocouples inside a circular workpiece measured according to the present invention.

[0035] Figure 6 This is a schematic diagram of the heat transfer coefficient fitting curves over time at different locations in this invention;

[0036] Figure 7 The temperature distribution and heat transfer coefficient distribution diagrams for the circular workpiece are obtained from the simulation calculation of the present invention when the airflow velocity is 60 m / s. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] Reference Figure 1-7 A method for calculating the heat transfer coefficient of a high-temperature circular workpiece during cooling is presented. The circular workpiece used here is an alloy cylinder with a diameter of 180 mm and a height of 100 mm. S-type corundum sheathed thermocouples with a diameter of 6 mm are used, and each thermocouple hole has the same diameter of 6.6 mm. The method includes the following steps:

[0039] Step 1: Using a thermocouple placement method, drill holes in the circular workpiece and insert thermocouples;

[0040] Step 2: Heat the round workpiece to 1100℃ and remove it;

[0041] Step 3: Cool the circular workpiece with a high-speed airflow, record the temperature change data at each point using a temperature recorder, and export the data, such as... Figure 5 As shown;

[0042] Step 4: Use the reverse heat transfer method program to read the temperature data from Step 3 and calculate the heat transfer coefficient at each point, such as... Figure 6 As shown;

[0043] Step 5: Perform 1:1 three-dimensional modeling of the circular workpiece and the high-speed airflow cooling process, mesh the model, set boundary conditions such as gas velocity, temperature, and pressure according to actual operating conditions, use the simple algorithm, set the points at the same locations as the experimental thermocouples as monitoring points, and perform three-dimensional simulation calculations.

[0044] Step 6: Export the temperature data and heat transfer coefficient data of the monitoring points calculated by the three-dimensional simulation, and compare them with the heat transfer coefficients of each point calculated by the reverse heat transfer method program in Step 4. If the error is greater than 5%, readjust the simulation calculation method until the error is within an acceptable range. Then the three-dimensional simulation calculation model is considered to have been verified.

[0045] Step 7: Using a validated 3D simulation model, the heat transfer coefficient at any position on the circular workpiece is quickly calculated by changing factors such as gas flow rate and the distance between the gas nozzle and the workpiece. Figure 7 As shown.

[0046] Specifically, in step 1, the specific steps are as follows:

[0047] Step 1.1: Select vertical section 1-1 as 0°, and rotate sections 2-2, 3-3 and 4-4 counterclockwise by 45° in sequence, with A1 as the center;

[0048] Step 1.2: Temperature measurement points B and E are located at a radius of 1 / 2 on section 1-1;

[0049] Step 1.3: Temperature measurement point C is located at a radius of 1 / 2 on section 2-2;

[0050] Step 1.4: On section 3-3, A2 is located at 1 / 4 of the radius, A3 is located at 1 / 2 of the radius, A3' is located at 1 / 2 of the radius, A4 is located at 3 / 4 of the radius, and A5 is located at the edge. The edge of the hole is 5mm away from the wall.

[0051] Step 1.5: Temperature measurement point D is located at 1 / 2 radius on section 4-4;

[0052] Step 1.6: Section 5-5 passes through the midpoint between A1 and B and point A3'. The drilling position of temperature measuring point E' is 72.63mm from the edge of the section, and the drilling of E' extends to 33.33mm directly below point A3'. The drilling depth of each temperature measuring point is shown in the respective section diagrams.

[0053] Among them, the five temperature measuring points A1, A2, A3, A4, and A5 are used to measure the radial temperature distribution of the workpiece;

[0054] Five temperature measuring points, A3, B, C, D, and E, are used to measure the axial temperature distribution of the workpiece.

[0055] The depth of holes A1, A2, A3, A4, A5, and A3' is 1 / 2 the height of the circular workpiece (i.e., 50mm), the depth of hole B is 1 / 3 the height (i.e., 33.33mm), the depth of hole D is 2 / 3 the height (i.e., 66.67mm), and the depth of holes E and E' is 5 / 6 the height (i.e., 83.33mm).

[0056] Meanwhile, temperature measuring points A3 and A3' are used for radial temperature verification, and temperature measuring points E and E' are used to verify whether the temperature is consistent at different angles and the same radius of a circular workpiece. The drilling depth dimensions of the holes at each temperature measuring point are as follows: Figure 1-3 As shown.

[0057] Specifically, in step 1, the diameter of the hole matches that of the thermocouple so that the thermocouple can just fit into the hole.

[0058] Specifically, in step 1, the thermocouple adopts an armored or corundum sheath structure, the thermocouple collecting end is in close contact with the bottom of the hole, and the gap is sealed with refractory mud.

[0059] In summary, this invention employs an 11-point thermocouple arrangement to measure the radial and axial temperature gradient changes of a circular workpiece during gas quenching and cooling. It records temperature data from multiple dimensions during the quenching process. Specifically, points A1, A2, A3, A4, and A5 measure the radial temperature distribution, while points A3, B, C, D, and E measure the axial temperature distribution. Points A3 and A3' are used for radial temperature verification, and points E and E' verify the consistency of temperatures at different angles and at the same radius on the circular workpiece. This ensures the accuracy and comprehensiveness of the temperature data, avoiding large errors in heat transfer coefficient calculations caused by incomplete temperature data. Furthermore, the heat transfer coefficient calculated by the reverse heat transfer method is compared with that calculated by the 3D simulation model, ensuring the reliability of the 3D simulation model. Using a validated 3D simulation model to calculate the heat transfer coefficient at any position on a circular workpiece under different working conditions is a fast, convenient, and accurate method that avoids the tedious work of numerous experiments, significantly saving time and economic costs.

[0060] The descriptions and practices disclosed in this invention are readily apparent and understandable to those skilled in the art, and various modifications and refinements can be made without departing from the principles of this invention. Therefore, any modifications or improvements made without departing from the spirit of this invention should also be considered within the scope of protection of this invention.

Claims

1. A method for calculating the heat transfer coefficient during the cooling process of a high-temperature circular workpiece, characterized in that, Includes the following steps: Step 1: Using a thermocouple placement method, drill holes in the circular workpiece and insert thermocouples; Step 2: Heat the round workpiece to 800-1600℃ and remove it; Step 3: Cool the circular workpiece with high-speed airflow, record the temperature change data at each point with a temperature recorder, and export the data; Step 4: Use the reverse heat transfer method program to read the temperature data from Step 3 and calculate the heat transfer coefficient at each point. Step 5: Perform 1:1 three-dimensional modeling of the circular workpiece and the high-speed airflow cooling process, mesh the model, set the gas flow rate, temperature and pressure boundary conditions according to the actual operating conditions, use the simple algorithm, set the points at the same locations as the experimental thermocouples as the monitoring points, and perform three-dimensional simulation calculations. Step 6: Export the temperature data and heat transfer coefficient data of the monitoring points calculated by the three-dimensional simulation, and compare them with the heat transfer coefficients of each point calculated by the reverse heat transfer method program in Step 4. If the error is greater than 5%, readjust the simulation calculation method until the error is within an acceptable range. Then the three-dimensional simulation calculation model is considered to have been verified. Step 7: Using a validated three-dimensional simulation model, the heat transfer coefficient at any position of the circular workpiece is quickly calculated by changing the gas flow rate and the distance between the gas nozzle and the workpiece. In step 1, the specific steps are as follows: Step 1.1: Select the vertical section (1-1) as 0°, and rotate sections (2-2), (3-3), and (4-4) counterclockwise by 45° in sequence, with A1 as the center; Step 1.2: Temperature measurement points B and E are located at a radius of 1 / 2 on section (1-1); Step 1.3: Temperature measurement point C is located at a radius of 1 / 2 on section (2-2); Step 1.4: On section (3-3), A2 is located at 1 / 4 of the radius, A3 is located at 1 / 2 of the radius, A3' is located at 1 / 2 of the radius, A4 is located at 3 / 4 of the radius, and A5 is located at the edge. The edge of the hole is 0-5mm away from the wall. Step 1.5: Temperature measurement point D is located at 1 / 2 radius on section (4-4); Step 1.6: Section (5-5) passes through the midpoint between A1 and B and point A3', and drills a hole at E' directly below point A3'; Among them, the five temperature measuring points A1, A2, A3, A4, and A5 are used to measure the radial temperature distribution of the workpiece; Five temperature measuring points, A3, B, C, D, and E, are used to measure the axial temperature distribution of the workpiece. The depth of holes A1, A2, A3, A4, A5, and A3' is 1 / 2 the height of the circular workpiece; the depth of hole B is 1 / 3 the height; the depth of hole D is 2 / 3 the height; and the depth of holes E and E' is 5 / 6 the height. Meanwhile, temperature measurement points A3 and A3' are used for radial temperature verification, while temperature measurement points E and E' are used to verify whether the temperatures at different angles with the same radius and depth on a circular workpiece are consistent.

2. The method for calculating the heat transfer coefficient during the cooling process of a high-temperature circular workpiece according to claim 1, characterized in that, In step 1, the hole is matched with the diameter of the thermocouple.

3. The method for calculating the heat transfer coefficient during the cooling process of a high-temperature circular workpiece according to claim 2, characterized in that, In step 1, the thermocouple adopts an armored or corundum sheath structure, the thermocouple collecting end is in close contact with the bottom of the hole, and the gap is sealed with refractory mud.

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