Wind tunnel device and method for measuring heat dissipation performance of heat generating equipment under low-speed airflow environment

Abstract

The application provides a wind tunnel device and method for measuring heat dissipation performance of a heating device in a low-speed airflow environment, comprising a wind tunnel body, an airflow stabilizing unit, an electric heating system, a low-speed airflow adjusting and measuring unit, a temperature measuring unit, a signal collector and a controller; the low-speed airflow adjusting and measuring unit comprises a variable frequency fan and a hot ball anemometer; the electric heating system comprises a power supply, a voltage regulator, an ammeter and the heating device connected in series; and the temperature measuring unit comprises an infrared thermometer and a thermocouple. The wind tunnel device and method for measuring heat dissipation performance of a heating device in a low-speed airflow environment have the following advantages: the wind tunnel device can measure the heat dissipation performance of various types of heating devices, is convenient to use, has high measurement result precision and is economical to operate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thermal testing, and particularly relates to a wind tunnel device and method for measuring heat dissipation performance of a heat generating device in a low-speed airflow environment. BACKGROUND

[0002] There are a large number of heat generating devices in large engineering sites, such as heat generating devices such as generator set operation heat dissipation, power disc cabinet, SFC equipment, etc. in the underground powerhouse of a pumped storage power station. One of the functions of the ventilation and air conditioning system is to take away and discharge the heat dissipation of the heat generating devices to the atmosphere. In order to maintain the thermal and humid environment of the underground powerhouse, it is necessary to determine the cooling capacity required by the ventilation and air conditioning system, i.e. the cooling load. An important factor in the calculation of the ventilation and air conditioning cooling load is the heat dissipation performance of the heat generating device. The main performance parameters of the heat dissipation performance of the heat generating device include the heat dissipation of the device and the convective heat transfer coefficient of the device surface under different wind speed environments. In the design of a scale model experiment for a research on the air conditioning ventilation airflow organization effect of a pumped storage power station powerhouse space, how to reasonably and effectively simulate the heat dissipation of the heat generating device is an important means to analyze the influence of the heat dissipation of large equipment on the airflow environment, and the key to the scale model experiment is to perform equivalent simulation of the heat dissipation characteristics of the heat generating device.

[0003] At present, the heat dissipation performance of the heat generating device is usually determined by wind tunnel experiment measurement. However, large-scale wind tunnel test has high investment cost and large test cost, and the test precision of the heat dissipation performance of the device in a low-speed airflow environment is not high. However, the heat dissipation of the device in the actual underground powerhouse space is basically in a low-speed airflow environment, and the environmental wind speed on the surface of the device is generally not more than 2 m / s. Therefore, from the technical and economic points of view, it is necessary to develop a small wind tunnel device for testing the heat dissipation performance of the device in a low-speed airflow environment to meet the measurement requirements of the heat dissipation and convective heat transfer coefficient of the heat generating device. SUMMARY

[0004] In view of the defects in the prior art, the present application provides a wind tunnel device and method for measuring the heat dissipation performance of a heat generating device in a low-speed airflow environment, which can effectively solve the above problems.

[0005] The technical scheme adopted by the present application is as follows:

[0006] The present application provides a wind tunnel device for measuring the heat dissipation performance of a heat generating device in a low-speed airflow environment, comprising: a wind tunnel body (1), an airflow stabilizing unit (2), an electric heating system (3), a low wind speed adjusting and measuring unit (4), a temperature measuring unit (5), a signal collector (6) and a controller (7);

[0007] The wind tunnel body (1) has an air inlet (1-1) at one end and an air outlet (1-2) at the other end; in the direction of air flow, the wind tunnel body (1) sequentially includes an expansion flow section (A1), an airflow stabilizing section (A2), a contraction flow section (A3), and a test section (A4) from the air inlet (1-1) to the air outlet (1-2).

[0008] The airflow stabilizing section (A2) is provided with the airflow stabilizing unit (2).

[0009] The low wind speed adjusting and measuring unit (4) includes a variable frequency fan (4-1) and a hot ball anemometer (4-2); the variable frequency fan (4-1) is installed at the air inlet (1-1); the hot ball anemometer (4-2) is installed at the test section (A4).

[0010] The electric heating system (3) includes a power supply (3-1), a voltage regulator (3-2), an ammeter (3-3), and a heating device (3-4) connected in series; wherein the heating device (3-4) is installed at the test section (A4).

[0011] The temperature measuring unit (5) includes a fan (5-1), an infrared thermometer (5-2), and a thermocouple (5-3); the fan (5-1) is suspended at the top of the test section (A4); the infrared thermometer (5-2) is suspended at the top of the test section (A4) and directly above the heating device (3-4); the thermocouple (5-3) is installed in the test section (A4).

[0012] The variable frequency fan (4-1), the hot ball anemometer (4-2), the voltage regulator (3-2), the ammeter (3-3), the infrared thermometer (5-2), and the thermocouple (5-3) are all connected to the signal collector (6); the signal collector (6) is connected to the controller (7).

[0013] Preferably, in the direction of air flow, the expansion flow section (A1) is a taper with gradually increasing cross section; the contraction flow section (A3) is a taper with gradually decreasing cross section; the airflow stabilizing section (A2) and the test section (A4) are cylindrical with equal cross sections.

[0014] Preferably, the cross-sectional diameter of the test section (A4) is smaller than that of the airflow stabilizing section (A2).

[0015] Preferably, the airflow stabilizing unit (2) includes a damping net (2-1) and a honeycomb device (2-2); two damping nets (2-1) are installed vertically inside the airflow stabilizing section (A2); the honeycomb device (2-2) is installed between the two damping nets (2-1).

[0016] Preferably, the number of the hot-ball anemometers (4-2) is multiple, and each of the hot-ball anemometers (4-2) is a telescopic hot-ball anemometer.

[0017] Preferably, the test section (A4) further comprises aluminum wire meshes (5-4), and each of the aluminum wire meshes (5-4) is installed on the front and back sides of the heating device (3-4) in the test section (A4), and a plurality of thermocouples (5-3) are evenly installed on each of the aluminum wire meshes (5-4).

[0018] Preferably, the test section (A4) is coated with a heat radiation reflection coating.

[0019] Preferably, the wind tunnel body (1) is made of a heat-preservation and heat-insulation material.

[0020] The application further provides a method for measuring the heat dissipation performance of a heating device in a low-speed airflow environment by using the wind tunnel device.

[0021] Step 1: a method for testing the heat dissipation of the heating device (3-4):

[0022] Step 1.1: turn on the variable frequency fan (4-1) and set the frequency of the fan to f1;

[0023] Step 1.2: turn on the fan (5-1) to ensure that the airflow temperature in the test section (A4) is evenly distributed, and then obtain the initial temperature T1 of the air in the test section (A4) by using the thermocouples (5-3) when the readings of the thermocouples (5-3) are stable.

[0024] Step 1.2: measure the cross-sectional average wind speed of the test section (A4) by using the following method

[0025] Divide the cross section of the test section (A4) into a plurality of rings according to the equal-area ring method, adjust the telescopic length of the probe head of each hot-ball anemometer (4-2), so that the probe head of each hot-ball anemometer (4-2) is located at the center of a corresponding ring, assume that there are n hot-ball anemometers (4-2), thus, each hot-ball anemometer (4-2) measures the wind speed of the corresponding ring, and then the average wind speed of the test section (A4) is obtained by averaging the wind speeds measured by the n hot-ball anemometers (4-2).

[0026] Step 1.3: then, turn on the heating device (3-4), adjust the voltage U to the rated value by using the voltage regulator (3-2), read the current I by using the ammeter (3-3) after a preset time, and obtain the power consumption P of the heating device (3-4) by using the following formula:

[0027] P = U * I

[0028] Step 1.4, after a preset time, when the temperature value of the thermocouple (5-3) is stable, the stable temperature T2 of the air is measured by the thermocouple (5-3), and the heat dissipation power q of the heating device (3-4) is obtained by the following formula:

[0029]

[0030] Wherein:

[0031] ρ is the density value of air at 20℃;

[0032] C P is the constant pressure specific heat value of air at 20℃;

[0033] A is the inner cross-sectional area of the test section (A4);

[0034] Step 1.5, adjust the value of the voltage U of the pressure regulator (3-2) to different values in turn, repeat steps 1.3-1.4, and perform tests to obtain the average wind speed , and the performance curve of the heat dissipation power q of the heating device (3-4) and the voltage U;

[0035] Adjust the fan frequency of the variable frequency fan (4-1) to change the average wind speed , and repeat steps 1.1-1.4 to obtain the performance curve of the heat dissipation power q of the heating device (3-4) and the average wind speed at the voltage U;

[0036] In addition, at each voltage U and average wind speed , the conversion rate between electrical energy and thermal energy of the heating device (3-4) is obtained by calculating the ratio of the heat dissipation power q of the heating device (3-4) to the power consumption P;

[0037] Step 2, test of the device surface convective heat transfer coefficient of the heating device (3-4)

[0038] Step 2.1, turn on the variable frequency fan (4-1) and set the fan frequency to f1;

[0039] Turn on the fan (5-1) to ensure uniform distribution of air flow temperature in the test section (A4), and obtain the initial temperature T1 of the air in the test section (A4) by the thermocouple (5-3) when the reading of the thermocouple (5-3) is stable;

[0040] Step 2.2, use the equal-area circular ring method to measure the average wind speed

[0041] Step 2.3, then, the heating device (3-4) is opened, the voltage U is adjusted to the rated value through the voltage regulator (3-2), after a preset time, the current I is read through the ammeter (3-3), and the power P consumed by the heating device (3-4) is obtained according to P=U*I

[0042]

[0043] Step 2.4, after a preset time, the temperature value of the thermocouple (5-3) is stable, the stable temperature T2 of the air is measured through the thermocouple (5-3), and the surface temperature T of the heating device is measured through the infrared temperature measuring instrument (5-2) ∞

[0044] Step 2.5, the heat dissipation power q of the heating device (3-4) is calculated;

[0045] Step 2.6, the following formula is used to obtain the convective heat transfer coefficient h:

[0046] h=q / A s (T ∞ -T2)

[0047] Wherein: A s is the contact surface area of the heating device and the air;

[0048] Step 2.7, the fan frequency of the variable frequency fan (4-1) is adjusted, so that the cross-sectional average wind speed The performance curve of the convective heat transfer coefficient h of the heating device (3-4) and the cross-sectional average wind speed is obtained by fixing the voltage value U and performing multiple tests.

[0049] The wind tunnel device and the method for measuring the heat dissipation performance of the heating device in the low-speed airflow environment provided by the application have the following advantages:

[0050] The wind tunnel device of the application can realize the heat dissipation performance measurement of various types of heating devices, and has the characteristics of convenient use, high measurement result precision, economical operation and the like. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 The structure schematic view of the wind tunnel device for measuring the heat dissipation performance of the heating device in the low-speed airflow environment provided by the application.

[0052] Figure 2 The cross-sectional temperature thermocouple arrangement schematic view of the test section of the wind tunnel device provided by the application.

[0053] In the figure:

[0054] ​​1 - wind tunnel body; 1-1 - air inlet; 1-2 - air outlet; A1 - diffuser section; A2 - flow stabilization section; A3 - convergent section; A4 - test section;

[0055] 2 - flow stabilization unit; 2-1 - damping net; 2-2 - honeycomb;

[0056] 3 - electric heating system; 3-1 - power supply; 3-2 - voltage regulator; 3-3 - ammeter; 3-4 - heating device;

[0057] 4 - low wind speed adjustment measurement unit; 4-1 - variable frequency fan; 4-2 - hot ball anemometer;

[0058] 5 - temperature measurement unit; 5-1 - fan; 5-2 - infrared thermometer; 5-3 - thermocouple; 5-4 - aluminum wire mesh;

[0059] 6 - signal collector;

[0060] 7 - controller. DETAILED DESCRIPTION

[0061] In order to make the technical problems solved by the present application, technical solutions and beneficial effects clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0062] The present application provides a small wind tunnel experimental device suitable for measuring the heat dissipation and convective heat transfer coefficient of a heating device in a low-speed airflow environment, which overcomes the problems of low measurement accuracy and large power consumption of existing wind tunnel devices in a low-speed airflow environment. The wind tunnel device of the present application can measure the heat dissipation performance of various types of heating devices, has the characteristics of easy to use, high measurement accuracy, economical operation, etc.

[0063] The device can simulate the heat dissipation of heating devices in a ventilation and air conditioning system. The heat dissipation and convective heat transfer coefficient curve of the heating device can be accurately obtained, providing an experimental platform for the study of convective heat transfer coefficient under different wind speeds. By turning on the fan in the test section of the wind tunnel body, the serious temperature gradient before and after the heat dissipation device is avoided. The device is optimized on the basis of the traditional large-scale wind tunnel test platform, the size of the experimental device is reduced, the problems of low measurement accuracy and single use of the existing device in a low-speed environment are overcome, and a comprehensive and flexible small wind tunnel device for testing the heat dissipation of equipment is provided.

[0064] Reference Figure 1 The present application provides a wind tunnel device for measuring the heat dissipation performance of a heating device in a low-speed airflow environment, comprising: a wind tunnel body 1, a flow stabilization unit 2, an electric heating system 3, a low wind speed adjustment measurement unit 4, a temperature measurement unit 5, a signal collector 6 and a controller 7.

[0065] The following will be described in detail:

[0066] (I) the wind tunnel body 1

[0067] The wind tunnel body 1 is sealed by heat insulation material, such as glass wool insulation color steel plate, and the model design should follow the Reynolds similarity criterion and Archimedes similarity criterion.

[0068] One end of the wind tunnel body 1 is the air inlet 1-1, and the other end is the air outlet 1-2; according to the wind direction, the wind tunnel body 1 from the air inlet 1-1 to the air outlet 1-2, in turn, includes the expansion section A1, the airflow stabilization section A2, the contraction section A3 and the test section A4; wherein, according to the wind direction, the expansion section A1 is a taper with gradually increasing cross section; the contraction section A3 is a taper with gradually decreasing cross section; the airflow stabilization section A2 and the test section A4 are cylindrical with equal cross section. The cross-sectional diameter of the test section A4 is smaller than that of the airflow stabilization section A2. With this structure, the airflow passes through the expansion section A1, the airflow stabilization section A2 and the contraction section A3 in turn, and enters the test section A4, which can ensure the stability of the airflow entering the test section A4 and improve the accuracy of the wind tunnel test results.

[0069] The test section A4 is coated with heat radiation reflective paint to reduce radiation heat transfer and ensure that the heat dissipation of the heating device is carried away by the wind tunnel airflow in a convective manner, which is conducive to improving the accuracy of the measurement results.

[0070] (II) airflow stabilization unit 2

[0071] The airflow stabilization section A2 is provided with the airflow stabilization unit 2; the airflow stabilization unit 2 includes a damping net 2-1 and a honeycomb device 2-2; the damping net 2-1 is installed vertically inside the airflow stabilization section A2, and the honeycomb device 2-2 is installed between the two damping nets 2-1.

[0072] By installing the damping net 2-1 and the honeycomb device 2-2, the effect of eliminating vortex and uniform airflow can be achieved.

[0073] (III) electric heating system 3

[0074] The electric heating system 3 includes a power supply 3-1, a voltage regulator 3-2, an ammeter 3-3 and a heating device 3-4 connected in series; wherein, the heating device 3-4 is installed in the test section A4; wherein, the voltage regulator 3-2 is used for voltage regulation and is provided with a fuse and other protection devices.

[0075] (IV) low wind speed adjustment and measurement unit 4

[0076] The low wind speed adjusting measuring unit 4 comprises a variable frequency fan 4-1 and a hot ball anemometer 4-2; the variable frequency fan 4-1 is installed on the air inlet 1-1; the wind speed in the wind tunnel is adjusted by changing the frequency of the variable frequency fan 4-1 to adjust the rotating speed of the fan.

[0077] The hot ball anemometer 4-2 is installed on the test section A4 and used for measuring the wind speed; as a preferred mode, the hot ball anemometer 4-2 is provided in a plurality of numbers, and each hot ball anemometer 4-2 is a retractable hot ball anemometer.

[0078] The controller 7 can output signals to adjust the frequency of the variable frequency fan 4-1 according to the wind speed value collected by the hot ball anemometer 4-2, so that the wind speed in the surrounding area of the tested heat generating equipment 3-4 is maintained in a low wind speed range, generally not more than 2 m / s.

[0079] (Five) temperature measuring unit 5

[0080] The temperature measuring unit 5 comprises a fan 5-1, an infrared thermometer 5-2 and a thermocouple 5-3;

[0081] The fan 5-1 is hung on the top of the test section A4; the fan 5-1 adopts a small fan, which is used for ensuring that the heat dissipation of the heat generating equipment is uniformly distributed in the airflow, reducing the vertical air temperature gradient and avoiding the existence of serious temperature gradient in the surrounding area of the heat generating equipment.

[0082] The infrared thermometer 5-2 is hung on the top of the test section A4 and located directly above the heat generating equipment 3-4;

[0083] The thermocouple 5-3 is installed in the test section A4; in the test section A4, one aluminum mesh 5-4 is installed on each of the front and rear sides of the heat generating equipment 3-4; a plurality of thermocouples 5-3 are uniformly installed on each aluminum mesh 5-4, and the wind tunnel body test section is measured by the thermocouples arranged in a mesh structure, so that the accuracy of the measurement result can be ensured.

[0084] (Six) signal collector 6 and controller 7

[0085] The signal collector 6 and the controller 7 form a control system; the variable frequency fan 4-1, the hot ball anemometer 4-2, the voltage regulator 3-2, the ammeter 3-3, the infrared thermometer 5-2 and the thermocouple 5-3 are connected with the signal collector 6; and the signal collector 6 is connected with the controller 7.

[0086] The application also provides a method for measuring the heat dissipation performance of a heat generating equipment in a low speed airflow environment, which comprises heat dissipation amount and convective heat transfer coefficient, and specifically comprises the following steps:

[0087] Step 1, heat dissipation test method of heat generating device 3-4:

[0088] Step 1.1, open the frequency converter fan 4-1, set the fan frequency to f1, for example, 50HZ;

[0089] Open the fan 5-1, and ensure uniform distribution of air flow temperature in the test section A4 by the fan 5-1. After the thermocouple 5-3 reading is stable, obtain the initial air temperature T1 of the test section A4 by the thermocouple 5-3;

[0090] Step 1.2, the following method is used to measure the cross-sectional average wind speed of the test section A4

[0091] The cross section of the test section A4 is a circular pipe, as shown in Figure 2 The cross section of the test section A4 is divided into multiple circular rings according to the equal area circular ring method. Adjust the extension length of the probe head of each hot ball anemometer 4-2 so that the probe head of each hot ball anemometer 4-2 is located at the center of the corresponding circular ring. Assuming that there are n hot ball anemometers 4-2, n is not less than 3, therefore, after the reading of the hot ball anemometer 4-2 is stable, the wind speed of the corresponding circular ring is measured by each hot ball anemometer 4-2, and then the average wind speed of the cross section of the test section A4 is obtained by averaging the wind speeds measured by the n hot ball anemometers 4-2 For example, if there are three hot ball anemometers 4-2, the wind speeds measured are v1, v2 and v3, then the cross-sectional average wind speed is

[0092] Step 1.3, then, open the heat generating device 3-4, adjust the voltage U to the rated value through the voltage regulator 3-2, after a preset time, when the voltage U is stable, read the current I through the ammeter 3-3, and use the following formula to obtain the power consumption P of the heat generating device 3-4: P=U*I;

[0093] Step 1.4, after a preset time, when the temperature value of the thermocouple 5-3 is stable, measure the stable air temperature T2 by the thermocouple 5-3, and obtain the heat dissipation power q of the heat generating device 3-4 by the following formula:

[0094]

[0095] Wherein:

[0096] ρ is the density value of air at 20℃, ρ=1.21kg / m 3 ;

[0097] C P is the specific heat value of air at 20℃, which is 1.005kJ / (kgK)

[0098] A is the inner cross-sectional area of test section A4;

[0099] Step 1.5, adjust the value of the voltage U of the voltage regulator 3-2 to different values in turn, repeat step 1.3-step 1.4, conduct tests, for example, conduct 3 tests, get the cross-sectional average wind speed The performance curve of the heat dissipation power q of the heat generating device 3-4 and the voltage U;

[0100] Adjust the fan frequency of the variable frequency fan 4-1, for example, 50HZ, 40HZ, 30HZ respectively, change the cross-sectional average wind speed The voltage U remains unchanged, repeat steps 1.1-1.4, conduct three tests, get the performance curve of the heat dissipation power q of the heat generating device 3-4 and the cross-sectional average wind speed Under the voltage U;

[0101] In addition, under each voltage U and cross-sectional average wind speed The conversion rate between electric energy and heat energy of the heat generating device 3-4 is obtained by calculating the ratio of the heat dissipation power q of the heat generating device 3-4 to the power consumption P;

[0102] Step 2, test the device surface convective heat transfer coefficient of the heat generating device 3-4

[0103] Step 2.1, turn on the variable frequency fan 4-1, set the fan frequency to f1, for example, 50HZ;

[0104] Turn on the fan 5-1, ensure that the air flow temperature of the test section A4 is uniformly distributed through the fan 5-1, and obtain the initial air temperature T1 of the test section A4 through the thermocouple 5-3 after the reading of the thermocouple 5-3 is stable;

[0105] Step 2.2, use the equal-area circular ring method to measure the cross-sectional average wind speed The specific method is the same as step 1.2;

[0106] Step 2.3, then, turn on the heat generating device 3-4, adjust the voltage U to the rated value through the voltage regulator 3-2, after a preset time, when the voltage U is stable, read the current I through the ammeter 3-3, and get the power consumption P of the heat generating device 3-4 according to P=U*I;

[0107] Step 2.4, after a preset time, when the temperature value of the thermocouple 5-3 is stable, measure the stable air temperature T2 through the thermocouple 5-3; when the value of the infrared temperature instrument 5-2 is stable, measure the surface temperature T ∞ of the heat generating device through the infrared temperature instrument 5-2;

[0108] Step 2.5, the heat dissipation power q of the heat generating device 3-4 is calculated, and the specific method is the same as that in step 1.4;

[0109] Step 2.6, the convective heat transfer coefficient h is obtained by using the following formula:

[0110] h=q / A s (T ∞ -T2)

[0111] Wherein: A s is the contact surface area of the heat generating device and the air;

[0112] Step 2.7, the fan frequency of the variable frequency fan 4-1 is adjusted, for example, 50HZ, 40HZ, 30HZ, so as to change the cross-sectional average wind speed The performance curve of the convective heat transfer coefficient h of the heat generating device 3-4 and the cross-sectional average wind speed is obtained by fixing the voltage value U and performing multiple tests, such as 3 times.

[0113] The wind tunnel device and method for measuring the heat dissipation performance of the heat generating device in the low-speed airflow environment provided by the application have the following advantages:

[0114] 1) The device has low investment cost and low operating cost

[0115] The variable frequency fan adjusts the wind speed, the controller analyzes the test results of the hot ball anemometer, and outputs the signal to adjust the frequency of the variable frequency fan, so that the wind speed in the surrounding area of the tested heat generating device is maintained in the low wind speed range, and the accurate measurement of the heat dissipation power of the heat generating device in the low-speed environment can be realized.

[0116] 2) The device can measure the convective heat transfer coefficient of the heat generating device, and can provide an experimental platform for the study of the convective heat transfer coefficient of the heat generating device under different wind speeds.

[0117] 3) The device measures and collects data through the thermocouple temperature measurement network, the infrared temperature measurement instrument and the control system, and can obtain the heat dissipation amount and the convective heat transfer coefficient of the heat generating device through real-time operation analysis of the controller.

[0118] 4) The device opens the fan in the test section of the wind tunnel body to avoid the existence of serious temperature gradient in front of and behind the heat generating device, and has higher temperature measurement accuracy compared with the traditional wind tunnel test table.

[0119] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the art, without departing from the principles of the application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the application.

Claims

1. A wind tunnel device for measuring heat dissipation performance of a heat generating device in a low-speed airflow environment, characterized by, The application relates to a wind tunnel device, which comprises a wind tunnel body, an airflow stabilizing unit, an electric heating system, a low-wind-speed adjusting and measuring unit, a temperature measuring unit, a signal collector and a controller. One end of the wind tunnel body is an air inlet, and the other end is an air outlet; according to the air flow direction, the wind tunnel body comprises, in sequence from the air inlet to the air outlet, an expansion flow section, an airflow stabilizing section, a contraction flow section and a test section; The airflow stabilizing unit is installed in the airflow stabilizing section; The low-wind-speed adjusting and measuring unit comprises a variable-frequency fan and a hot-ball anemometer; the variable-frequency fan is installed at the air inlet; and the hot-ball anemometer is installed at the test section; The electric heating system comprises a power supply, a voltage regulator, an ammeter and a heating device connected in series; the heating device is installed at the test section; The temperature measuring unit comprises a fan, an infrared temperature measuring instrument and a thermocouple; the fan is hung at the top of the test section; the infrared temperature measuring instrument is hung at the top of the test section and located directly above the heating device; and the thermocouple is installed in the test section; The variable-frequency fan, the hot-ball anemometer, the voltage regulator, the ammeter, the infrared temperature measuring instrument and the thermocouple are connected with the signal collector; and the signal collector is connected with the controller; According to the air flow direction, the expansion flow section is a taper with gradually increasing cross section; the contraction flow section is a taper with gradually decreasing cross section; and the airflow stabilizing section and the test section are cylindrical with equal cross sections; The airflow stabilizing unit comprises a damping net and a honeycomb device; two damping nets are vertically installed in the airflow stabilizing section; and the honeycomb device is installed between the two damping nets; The hot-ball anemometer is provided in multiple numbers, and each hot-ball anemometer is retractable; Aluminum wire meshes are further provided; one aluminum wire mesh is installed on each of the two sides of the heating device in the test section; and multiple thermocouples are uniformly installed on each aluminum wire mesh. The cross-sectional diameter of the test section is smaller than that of the airflow stabilizing section.

2. The wind tunnel apparatus for measuring heat dissipation performance of a heat generating device in a low-speed airflow environment according to claim 1, characterized by, The test section is coated with heat radiation reflection paint.

3. The wind tunnel apparatus for measuring heat dissipation performance of a heat generating device in a low-speed airflow environment according to claim 1, characterized by, The wind tunnel body is made of heat-preservation and heat-insulation materials.

4. The wind tunnel apparatus for measuring heat dissipation performance of a heat generating device in a low-speed airflow environment according to claim 1, characterized by, The application further discloses a testing method for the heat dissipation amount of the heating device.

5. A method of measuring the heat dissipation performance of a heat generating device in a low-speed airflow environment using the wind tunnel apparatus according to any one of claims 1 to 4, characterized by, Step 1.1, the variable-frequency fan is turned on, and the fan frequency is set as f1; Step 1.2, the fan is turned on, the airflow temperature in the test section is uniformly distributed through the fan, and the initial air temperature T1 of the test section is obtained through the thermocouple after the thermocouple reading is stable; Step 1.3, then, the heating device is turned on, the voltage U is adjusted to the rated value through the voltage regulator, the current I is read through the ammeter after a preset time, and the power consumption P of the heating device is obtained through the following formula: P=U*I; Step 1.

2. The cross-sectional average wind speed of the test section is measured in the following way : The cross section of the test section is divided into multiple rings according to the equal-area ring method, the extension length of the probe head of each hot ball anemometer is adjusted, the probe head of each hot ball anemometer is located at the center of a corresponding ring, it is assumed that there are n hot ball anemometers, therefore, the wind speed of the corresponding ring is measured by each hot ball anemometer, and the average wind speed of the cross section of the test section is obtained by averaging the wind speeds measured by the n hot ball anemometers ; Step 1.4, after a preset time, the thermocouple temperature value is stable, the stable air temperature T2 is measured through the thermocouple, and the heat dissipation power q of the heating device is obtained through the following formula: Wherein: P is the power consumption of the heating device; A is the inner cross-sectional area of the test section; q = p * C P *A* *( T2- T1); Step 2, the device surface convective heat transfer coefficient test of the heating device Step 2.1, the variable-frequency fan is turned on, and the fan frequency is set as f1; C P Cp is the specific heat of air at 20°C; ​ Step 1.5, adjust the value of the voltage U of the voltage regulator to different values in turn, repeat step 1.3-step 1.4, test, get the average wind speed of the current section Next, the performance curve of the heat dissipation power q of the heat generating device and the voltage U; Adjusting the fan frequency of the variable frequency fan to change the cross-sectional average wind speed , the voltage U remains unchanged, repeating steps 1.1-1.4, the heat dissipation power q of the heat generating device and the performance curve of the cross-sectional average wind speed when the voltage U is obtained; In addition, at each voltage U and cross-sectional average wind speed Next, by calculating the ratio of the heat dissipation power q of the heat generating device to the power consumption P, the conversion rate between the electric energy and the thermal energy of the heat generating device is obtained. ​ ​ Open the fan, ensure the air flow temperature of the test section is evenly distributed by the fan, and obtain the initial temperature T1 of the test section by the thermocouple after the reading of the thermocouple is stable; Step 2.2, the average wind speed of the test section is measured by the equal-area circular ring method ; Step 2.3, then, open the heating device, adjust the voltage U to a constant value through the voltage regulator, read the current I through the ammeter after a preset time, and obtain the power consumption P of the heating device according to P=U*I; Step 2.5, calculate the heat dissipation power q of the heating device; Step 2.6, obtain the convective heat transfer coefficient h by using the following formula: Step 2.4, after a preset time, when the thermocouple temperature value is stable, the stable temperature T2 of the air is measured by the thermocouple; when the value of the infrared temperature measuring instrument is stable, the surface temperature T of the heating equipment is measured by the infrared temperature measuring instrument ∞ ; ​ ​ h = q / A s (T ∞ - T2); wherein: A s A is the surface area of the heat generating device in contact with the air; Step 2.7, adjust the fan frequency of the variable frequency fan to change the average wind speed of the section , with fixed voltage value U, carry out multiple tests to obtain the performance curve of the heat generating equipment's convective heat transfer coefficient h and the average wind speed of the section .

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