CN116046321A - Wind tunnel device and method for measuring heat dissipation performance of heating equipment in low-speed airflow environment - Google Patents
Wind tunnel device and method for measuring heat dissipation performance of heating equipment in low-speed airflow environment Download PDFInfo
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Abstract
The invention provides a wind tunnel device and a method for measuring heat dissipation performance of heating equipment in a low-speed airflow environment, wherein the wind tunnel device comprises the following components: the device 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; the low wind speed adjusting and measuring unit comprises a variable frequency fan and a thermal bulb anemometer; the electric heating system comprises a power supply, a voltage regulator, an ammeter and heating equipment which are connected in series; the temperature measuring unit comprises an infrared thermometer and a thermocouple. The wind tunnel device and the method for measuring the heat radiation performance of the heating equipment in the low-speed airflow environment provided by the invention have the following advantages: the wind tunnel device can realize the measurement of the heat radiation performance of various heating equipment, and has the characteristics of convenient use, high measurement result precision, economical operation and the like.
Description
Technical Field
The invention belongs to the technical field of thermal testing, and particularly relates to a wind tunnel device and a method for measuring heat dissipation performance of heating equipment in a low-speed airflow environment.
Background
A large number of heating devices exist in a large-scale industrial site, such as heat dissipation devices in the running process of a generator set, a power panel cabinet, SFC devices and the like exist in an underground factory building of a pumped storage power station, and one of the functions of the ventilation air conditioning system is to take away the heat dissipation capacity of the heating devices and discharge the heat dissipation capacity to the atmosphere. To maintain the hot and humid environment of an underground plant, the amount of cooling, i.e., the cooling load, required by the ventilation and air conditioning system must be determined. An important factor in the calculation of the cooling load of a ventilation air conditioner is the heat dissipation performance of the heat generating equipment. The main performance parameters of the heat radiation performance of the heating equipment comprise the heat radiation capacity of the equipment and the convection heat exchange coefficient of the surface of the equipment under different wind speed environments. In the design of a proportional model experiment conducted by an air conditioner ventilation airflow organization effect research institute of a pumped storage power station factory building space, how to reasonably and effectively simulate heat dissipation of heating equipment is an important means for analyzing influence of heat dissipation capacity of large-scale equipment on airflow environment, and the key of the proportional model experiment is to conduct equivalent simulation of heat dissipation characteristics of the heating equipment.
At present, the heat dissipation performance of the heating equipment is usually determined by wind tunnel experiment measurement. But the large wind tunnel test has high investment cost and high test cost, and the test precision of the heat radiation performance of the equipment in a low-speed airflow environment is not high. However, in practice, the heat dissipation of the space equipment of the underground factory building is basically in a low-speed air flow environment, and the ambient air speed of the surface of the equipment is not more than 2m/s, so that from the technical and economical aspects, a small wind tunnel device for testing the heat dissipation performance of the equipment in the low-speed air flow environment needs to be developed, and the measurement requirements of the heat dissipation capacity and the convective heat transfer coefficient of the heat generating equipment are met.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides a wind tunnel device and a method for measuring the heat dissipation performance of heating equipment in a low-speed airflow environment, which can effectively solve the problems.
The technical scheme adopted by the invention is as follows:
the invention provides a wind tunnel device for measuring heat dissipation performance of heating equipment in a low-speed airflow environment, which comprises: the device comprises 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);
one end of the wind tunnel body (1) is an air inlet (1-1), and the other end is an air outlet (1-2); according to the wind flow direction, the wind tunnel body (1) sequentially comprises a flow expansion section (A1), an airflow stabilizing section (A2), a flow contraction section (A3) and a test section (A4) from the air inlet (1-1) to the air outlet (1-2);
the airflow stabilizing section (A2) is internally provided with the airflow stabilizing unit (2);
the low wind speed adjusting and measuring unit (4) comprises a variable frequency fan (4-1) and a hot bulb anemometer (4-2); the variable frequency fan (4-1) is arranged at the air inlet (1-1); the thermal ball anemometer (4-2) is arranged on the test section (A4);
the electric heating system (3) comprises a power supply (3-1), a voltage regulator (3-2), an ammeter (3-3) and heating equipment (3-4) which are connected in series; wherein the heating equipment (3-4) is arranged on the test section (A4);
the temperature measuring unit (5) comprises a fan (5-1), an infrared thermometer (5-2) and a thermocouple (5-3); the fan (5-1) is hung on the top of the test section (A4); the infrared thermometer (5-2) is hung at the top of the test section (A4) and is positioned right above the heating equipment (3-4); the thermocouple (5-3) is arranged in the test section (A4);
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 with the signal collector (6); the signal collector (6) is connected with the controller (7).
Preferably, according to the wind flow direction, the flow expansion section (A1) is a cone with a gradually enlarged section; the flow shrinkage section (A3) is a cone with a gradually smaller section; the airflow stabilizing section (A2) and the test section (A4) are cylindrical with equal cross sections.
Preferably, the cross-sectional diameter of the test section (A4) is smaller than the cross-sectional diameter of the air flow stabilizing section (A2).
Preferably, the air flow stabilizing unit (2) comprises a damping net (2-1) and a honeycomb (2-2); the number of the damping nets (2-1) is two, and the damping nets are vertically arranged in the airflow stabilizing section (A2); between the two damping nets (2-1), the honeycomb device (2-2) is installed.
Preferably, the number of the thermal ball anemometers (4-2) is a plurality, and each thermal ball anemometer (4-2) is a telescopic thermal ball anemometer.
Preferably, the aluminum wire mesh (5-4) is further included; in the test section (A4), one aluminum wire mesh (5-4) is respectively arranged at the front side and the rear side of the heating equipment (3-4); and a plurality of thermocouples (5-3) are uniformly arranged on each aluminum wire mesh (5-4).
Preferably, the test section (A4) is internally coated with a heat radiation reflective coating.
Preferably, the wind tunnel body (1) is made of heat insulation materials in a sealing mode.
The invention also provides a method for measuring the heat dissipation performance of the heating equipment in the low-speed airflow environment, which comprises the following steps:
step 1.1, turning on a variable frequency fan (4-1), and setting the fan frequency to be f 1 ；
The fan (5-1) is turned on, the air flow temperature of the test section (A4) is guaranteed to be uniformly distributed through the fan (5-1), and after the reading of the thermocouple (5-3) is stable, the initial air temperature T of the test section (A4) is obtained through the thermocouple (5-3) 1 ；
Step 1.2, the average wind speed of the section of the test section (A4) is measured in the following manner
Dividing the section of the test section (A4) into a plurality of circular rings according to an equal-area circular ring method, adjusting the telescopic length of the detection head of each thermal ball anemometer (4-2) to ensure that the detection head of each thermal ball anemometer (4-2) is positioned at the center of a corresponding circular ring, and supposing that n thermal ball anemometers (4-2) are shared, measuring the wind speed of the corresponding circular ring by each thermal ball anemometer (4-2), and then measuring the wind speed of n thermal ball anemometersThe average wind speed of the section of the test section (A4) is obtained by taking the average value of the wind speed measured by the thermal ball anemometer (4-2)
Step 1.3, then, opening the heating equipment (3-4), regulating the voltage U to a rated value through the voltage regulator (3-2), reading the current I through the ammeter (3-3) after the preset time, and obtaining the power consumption P of the heating equipment (3-4) by adopting the following formula:
P＝U*I
step 1.4, after the preset time, obtaining the air stabilization temperature T through the measurement of the thermocouple (5-3) after the temperature value of the thermocouple (5-3) is stabilized 2 The heat radiation power q of the heat generating device (3-4) is obtained by the following formula:
wherein:
ρ is the density value of air at 20 ℃;
C P the constant pressure specific heat value of air at 20 ℃;
a is the inner cross-sectional area of the test section (A4);
step 1.5, sequentially adjusting the value of the voltage U of the voltage regulator (3-2) to different values, repeating the steps 1.3-1.4, and performing a test to obtain the average wind speed at the current section
A performance curve of heat dissipation power q and voltage U of the heating equipment (3-4);
adjusting the fan frequency of the variable frequency fan (4-1) and changing the average wind speed of the section
The voltage U is kept unchanged, the steps 1.1 to 1.4 are repeatedly carried out, and when the voltage U is obtained, the heat dissipation power q of the heating equipment (3 to 4) and the section average wind speed +.>
Is a performance curve of (2);
in addition, at each voltage U and section average wind speed
Calculating the ratio of the heat radiation power q to the power consumption power P of the heating equipment (3-4) to obtain the conversion rate between the electric energy and the heat energy of the heating equipment (3-4);
step 2, testing the convection heat exchange coefficient of the equipment surface of the heating equipment (3-4)
Step 2.1, turning on a variable frequency fan (4-1), and setting the fan frequency to be f 1 ；
The fan (5-1) is turned on, the air flow temperature of the test section (A4) is guaranteed to be uniformly distributed through the fan (5-1), and after the reading of the thermocouple (5-3) is stable, the initial air temperature T of the test section (A4) is obtained through the thermocouple (5-3) 1 ；
Step 2.2, measuring the average wind speed of the section of the test section (A4) by adopting an equal-area circular ring method
Step 2.3, then, the heating device (3-4) is turned on, the voltage U is regulated to a rated value through the voltage regulator (3-2), after a preset time, the current I is read through the ammeter (3-3), and according to P=U×I
Obtaining the power consumption P of the heating equipment (3-4);
step 2.4, after the preset time, obtaining the air stabilization temperature T through the measurement of the thermocouple (5-3) after the temperature value of the thermocouple (5-3) is stabilized 2 The method comprises the steps of carrying out a first treatment on the surface of the When the infrared thermometer (5-2) has stable value, the surface temperature T of the heating equipment is obtained through the measurement of the infrared thermometer (5-2) ∞ ；
Step 2.5, calculating to obtain the heat dissipation power q of the heating equipment (3-4);
step 2.6, obtaining a convective heat transfer coefficient h by adopting the following formula:
h＝q/A s (T ∞ -T 2 )
wherein: a is that s Is the contact surface area of the heating device with the air;
step 2.7, adjusting the fan frequency of the variable frequency fan (4-1) so as to change the average wind speed of the section
A fixed voltage value U is adopted, and a plurality of tests are carried out to obtain the convection heat exchange coefficient h and the section average wind speed of the heating equipment (3-4)>
Is a performance curve of (2).
The wind tunnel device and the method for measuring the heat radiation performance of the heating equipment in the low-speed airflow environment have the following advantages:
the wind tunnel device can realize the measurement of the heat radiation performance of various heating equipment, and has the characteristics of convenient use, high measurement result precision, economical operation and the like.
Drawings
FIG. 1 is a schematic structural diagram of a wind tunnel device for measuring heat dissipation performance of heat generating equipment in a low-speed airflow environment.
FIG. 2 is a schematic diagram of the arrangement of a temperature thermocouple on the section of a test section of the wind tunnel device.
In the figure:
1-a wind tunnel body; 1-1-an air inlet; 1-2-air outlets; a1-a flow expansion section; a2-a gas flow stabilization section; a3-a condensed stream section; a4-test section;
2-an air flow stabilizing unit; 2-1-damping net; 2-2-cellular;
3-an electric heating system; 3-1-power supply; 3-2-voltage regulator; 3-3-ammeter; 3-4-heating equipment;
4-a low wind speed regulation measurement unit; 4-1-a variable frequency fan; 4-2-hot sphere anemometer;
5-a temperature measurement unit; 5-1-fans; 5-2-infrared thermometer; 5-3-thermocouple; 5-4-aluminum wire mesh;
6-a signal collector;
7-a controller.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The invention provides a small wind tunnel experiment device suitable for measuring the heat dissipation capacity and the convection heat transfer coefficient of heating equipment in a low-speed airflow environment, and solves the problems of low measurement accuracy and high wind tunnel power consumption of the conventional wind tunnel device in the low-speed airflow environment. The wind tunnel device can realize the measurement of the heat radiation performance of various heating equipment, and has the characteristics of convenient use, high measurement result precision, economical operation and the like.
The device can perform equivalent simulation of heat dissipation capacity on heating equipment in the ventilation air conditioning system. The heat dissipation capacity and convection heat transfer coefficient curve of the heating equipment can be accurately obtained, and an experimental platform is provided for the research of the convection heat transfer coefficients under different wind speeds. By starting the fan in the test section of the wind tunnel body, severe temperature gradients in front and back of the heat dissipation device are avoided. The device optimizes on the basis of the traditional large wind tunnel test bed, reduces the size of the experimental device, solves the problems of low measurement precision and single use of the traditional device in a low-speed environment, and provides a comprehensive, integrated, convenient and flexible device heat dissipation capacity test small wind tunnel device.
Referring to fig. 1, the present invention provides a wind tunnel device for measuring heat dissipation performance of a heat generating device in a low-speed airflow environment, including: the device comprises 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.
The following describes each main unit in detail:
The wind tunnel body 1 is made of heat-insulating materials in a sealing mode, for example, a color steel plate with glass wool for heat insulation, and the design of the model is in accordance with Reynolds similarity criteria and Archimedes similarity criteria.
One end of the wind tunnel body 1 is provided with an air inlet 1-1, and the other end is provided with an air outlet 1-2; according to the wind flow direction, the wind tunnel body 1 sequentially comprises a flow expansion section A1, an airflow stabilizing section A2, a flow shrinkage section A3 and a test section A4 from the air inlet 1-1 to the air outlet 1-2; the flow expansion section A1 is a cone with a gradually enlarged section according to the wind flow direction; the flow shrinkage section A3 is a cone with a gradually smaller section; the airflow stabilizing section A2 and the test section A4 are cylindrical with equal cross sections. The cross-sectional diameter of the test section A4 is smaller than that of the airflow stabilizing section A2. By adopting the structure, the air flow sequentially passes through the expansion section A1, the air flow stabilizing section A2 and the contraction section A3, enters the test section A4, can ensure the stability of the air flow entering the test section A4, and improves the accuracy of wind tunnel test results.
And the test section A4 is internally coated with heat radiation reflective paint, so that radiation heat transfer is reduced, heat dissipation capacity of heating equipment is guaranteed to be taken away by wind tunnel airflow in a convection mode, and accuracy of a measurement result is improved.
(II) air flow stabilization Unit 2
The airflow stabilizing unit 2 is arranged in the airflow stabilizing section A2; the airflow stabilizing unit 2 comprises a damping net 2-1 and a honeycomb device 2-2; the number of the damping nets 2-1 is two, and the damping nets are vertically arranged in the airflow stabilizing section A2; between the two damping nets 2-1, the honeycomb device 2-2 is installed.
By installing the damping net 2-1 and the honeycomb device 2-2, the effects of eliminating vortex and uniform air flow can be achieved.
(III) electrothermal System 3
The electric heating system 3 comprises a power supply 3-1, a voltage regulator 3-2, an ammeter 3-3 and heating equipment 3-4 which are connected in series; wherein the heating equipment 3-4 is arranged on the test section A4; the voltage regulator 3-2 is used for realizing voltage regulation, and is internally provided with a protection device such as a fuse.
(IV) Low wind speed Regulation measurement Unit 4
The low wind speed adjusting and measuring unit 4 comprises a variable frequency fan 4-1 and a hot bulb anemometer 4-2; the variable frequency fan 4-1 is arranged at the air inlet 1-1; the rotating speed of the fan is adjusted by changing the frequency of the variable frequency fan 4-1, so that the wind speed in the wind tunnel is adjusted.
The thermal ball anemometer 4-2 is installed in the test section A4 and is used for measuring wind speed. As a preferred mode, the number of the thermal ball anemometers 4-2 is plural, and each thermal ball anemometer 4-2 is a telescopic thermal ball anemometer.
The controller 7 can output signals to adjust the frequency of the variable frequency fan 4-1 according to the wind speed value acquired by the thermal bulb anemometer 4-2, so that the wind speed of the area around the tested heating equipment 3-4 is maintained in a low wind speed range and is generally not more than 2m/s.
(fifth) temperature measurement unit 5
The temperature measuring unit 5 comprises a fan 5-1, an infrared thermometer 5-2 and a thermocouple 5-3;
the fan 5-1 is hung on the top of the test section A4; the fan 5-1 adopts a small-sized fan, and is used for ensuring that the heat dissipating capacity of the heating equipment is uniformly distributed in the air flow, reducing the air temperature gradient in the vertical direction and avoiding the serious temperature gradient in the area nearby the heating equipment.
The infrared thermometer 5-2 is hung at the top of the test section A4 and is positioned right above the heating equipment 3-4;
the thermocouple 5-3 is arranged in the test section A4; wherein, in the test section A4, two aluminum screens 5-4 are respectively arranged at the front side and the rear side of the heating equipment 3-4; and a plurality of thermocouples 5-3 are uniformly arranged on each aluminum wire mesh 5-4, and the accuracy of the measurement result can be ensured by adopting the thermocouples which are arranged in a net structure to measure the temperature in the wind tunnel body test section.
The signal collector 6 and the controller 7 form a control system. The variable-frequency fan 4-1, the hot-bulb 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 with the signal collector 6; the signal collector 6 is connected with the controller 7.
The invention also provides a method for measuring the heat dissipation performance of the heating equipment in the low-speed airflow environment, wherein the heat dissipation performance of the heating equipment comprises the heat dissipation capacity and the heat convection coefficient, and the method specifically comprises the following steps of:
step 1.1, turning on a variable frequency fan 4-1, and setting the fan frequency to be f 1 For example 50HZ;
the fan 5-1 is started, the air flow temperature of the test section A4 is ensured to be uniformly distributed through the fan 5-1, and after the reading of the thermocouple 5-3 is stable, the initial air temperature T of the test section A4 is obtained through the thermocouple 5-3 1 ；
Step 1.2, measuring the average wind speed of the section of the test section A4 by the following method
The section of the test section A4 is a circular pipeline, as shown in fig. 2, the section of the test section A4 is divided into a plurality of circular rings according to an equal-area circular ring method, the telescopic length of the detection heads of each thermal ball anemometer 4-2 is adjusted, the detection heads of each thermal ball anemometer 4-2 are positioned at the center of a corresponding circular ring, n thermal ball anemometers 4-2 are assumed to be totally n, n is not less than 3, therefore, after the readings of the thermal ball anemometers 4-2 are stable, each thermal ball anemometer 4-2 measures the wind speed of the corresponding circular ring, and then the average wind speed of the measured wind speeds of the n thermal ball anemometers 4-2 is averaged to obtain the section average wind speed of the test section A4
For example, if there are three thermal ball anemometers 4-2, the wind speed is measured as v 1 、v 2 、v 3 Mean wind speed of section>
Step 1.3, then, the heating equipment 3-4 is turned on, the voltage U is regulated to a rated value through the voltage regulator 3-2, after the preset time, the current I is read through the ammeter 3-3 after the voltage U is stable, and the power consumption P of the heating equipment 3-4 is obtained by adopting the following formula: p=u×i;
step 1.4, after the preset time, measuring by the thermocouple 5-3 after the temperature value of the thermocouple 5-3 is stableThe air stabilization temperature T is obtained 2 The heat radiation power q of the heat generating device 3-4 is obtained by:
wherein:
ρ is the density value of air at 20 ℃, ρ=1.21 kg/m 3 ；
C P The specific heat value of air at 20 ℃ is 1.005 kJ/(kgK)
A is the inner cross-sectional area of the test section A4;
step 1.5, the voltage U value of the voltage regulator 3-2 is sequentially adjusted to different values, and the steps 1.3-1.4 are repeated to perform tests, for example, 3 tests are performed to obtain the average wind speed at the current section
A performance curve of heat dissipation power q and voltage U of the heating equipment 3-4;
adjusting fan frequencies of the variable frequency fan 4-1, e.g. 50HZ, 40HZ, 30HZ, respectively, to change the average wind speed of the section
The voltage U is kept unchanged, the steps 1.1-1.4 are repeatedly carried out, and three tests are carried out, so that when the voltage U is obtained, the heat dissipation power q and the section average wind speed of the heating equipment 3-4 are +.>
Is a performance curve of (2);
in addition, at each voltage U and section average wind speed
Calculating the ratio of the heat radiation power q to the power consumption power P of the heating equipment 3-4 to obtain the conversion rate between the electric energy and the heat energy of the heating equipment 3-4;
step 2, testing the convection heat exchange coefficient of the equipment surface of the heating equipment 3-4
Step 2.1, turning on the variable frequency fan 4-1, and setting the fan frequency to be f 1 For example, 50HZ;
the fan 5-1 is started, the air flow temperature of the test section A4 is ensured to be uniformly distributed through the fan 5-1, and after the reading of the thermocouple 5-3 is stable, the initial air temperature T of the test section A4 is obtained through the thermocouple 5-3 1 ；
Step 2.2, measuring and obtaining the average wind speed of the section of the test section A4 by adopting an equal-area circular ring method
The specific method is the same as that of the step 1.2;
step 2.3, then, opening the heating equipment 3-4, regulating the voltage U to a rated value through the voltage regulator 3-2, after the preset time, reading the current I through the ammeter 3-3 after the voltage U is stable, and obtaining the power consumption P of the heating equipment 3-4 according to P=U×I;
step 2.4, after the preset time, obtaining the air stabilization temperature T through the measurement of the thermocouple 5-3 after the temperature value of the thermocouple 5-3 is stabilized 2 The method comprises the steps of carrying out a first treatment on the surface of the When the value of the infrared thermometer 5-2 is stable, the surface temperature T of the heating equipment is obtained through measurement of the infrared thermometer 5-2 ∞ ；
Step 2.5, calculating to obtain the heat dissipation power q of the heating equipment 3-4; the specific method is the same as that of the step 1.4;
step 2.6, obtaining a convective heat transfer coefficient h by adopting the following formula:
h＝q/A s (T ∞ -T 2 )
wherein: a is that s Is the contact surface area of the heating device with the air;
step 2.7, adjusting fan frequency of the variable frequency fan 4-1 to be 50HZ, 40HZ or 30HZ, thereby changing section average wind speed
Fixing the voltage value U, and performing multiple tests, such as 3 times, to obtain the convection heat exchange coefficient h and the section average wind speed of the heating equipment 3-4>
Is a performance curve of (2).
The wind tunnel device and the method for measuring the heat radiation performance of the heating equipment in the low-speed airflow environment have the following advantages:
1) The device has low investment cost and low running cost
The variable frequency fan is arranged to adjust the wind speed, the controller analyzes the collected test result of the thermal ball anemometer, and the frequency of the variable frequency fan is adjusted by the output signal, so that the wind speed of the surrounding area of the tested heating equipment is maintained in a low wind speed range, and the accurate measurement of the heat dissipation power of the heating equipment in a low-speed environment can be realized.
2) The device can realize the measurement of the heat convection coefficient of the heating equipment, and can provide an experimental platform for the research of the heat convection coefficient of the heating equipment under different wind speeds.
3) The device measures and collects data through the thermocouple temperature measuring net, the infrared thermometer and the control system, and can obtain the heat dissipation capacity and the convection heat exchange coefficient of the heating equipment through real-time operation and analysis of the controller.
4) The device avoids serious temperature gradient existing before and after heating equipment by starting the fan in the wind tunnel body test section, and has higher temperature measurement precision compared with the traditional wind tunnel test bed.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which is also intended to be covered by the present invention.
Claims (9)
1. The utility model provides a measure wind tunnel device of heating equipment heat dispersion under low-speed air current environment which characterized in that includes: the device comprises 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);
one end of the wind tunnel body (1) is an air inlet (1-1), and the other end is an air outlet (1-2); according to the wind flow direction, the wind tunnel body (1) sequentially comprises a flow expansion section (A1), an airflow stabilizing section (A2), a flow contraction section (A3) and a test section (A4) from the air inlet (1-1) to the air outlet (1-2);
the airflow stabilizing section (A2) is internally provided with the airflow stabilizing unit (2);
the low wind speed adjusting and measuring unit (4) comprises a variable frequency fan (4-1) and a hot bulb anemometer (4-2); the variable frequency fan (4-1) is arranged at the air inlet (1-1); the thermal ball anemometer (4-2) is arranged on the test section (A4);
the electric heating system (3) comprises a power supply (3-1), a voltage regulator (3-2), an ammeter (3-3) and heating equipment (3-4) which are connected in series; wherein the heating equipment (3-4) is arranged on the test section (A4);
the temperature measuring unit (5) comprises a fan (5-1), an infrared thermometer (5-2) and a thermocouple (5-3); the fan (5-1) is hung on the top of the test section (A4); the infrared thermometer (5-2) is hung at the top of the test section (A4) and is positioned right above the heating equipment (3-4); the thermocouple (5-3) is arranged in the test section (A4);
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 with the signal collector (6); the signal collector (6) is connected with the controller (7).
2. The wind tunnel device for measuring heat radiation performance of heat generating equipment in low-speed airflow environment according to claim 1, wherein the flow expansion section (A1) is a cone with gradually enlarged section according to the airflow direction; the flow shrinkage section (A3) is a cone with a gradually smaller section; the airflow stabilizing section (A2) and the test section (A4) are cylindrical with equal cross sections.
3. Wind tunnel device for measuring the heat dissipation of a heat generating apparatus in a low air flow environment according to claim 2, characterized in that the cross-sectional diameter of the test section (A4) is smaller than the cross-sectional diameter of the air flow stabilizing section (A2).
4. Wind tunnel device for measuring the heat dissipation performance of a heat generating apparatus in a low velocity air flow environment according to claim 1, characterized in that the air flow stabilizing unit (2) comprises a damping net (2-1) and a honeycomb (2-2); the number of the damping nets (2-1) is two, and the damping nets are vertically arranged in the airflow stabilizing section (A2); between the two damping nets (2-1), the honeycomb device (2-2) is installed.
5. Wind tunnel device for measuring the heat dissipation of a heat generating apparatus in a low velocity air flow environment according to claim 1, characterized in that the number of said thermosphere anemometers (4-2) is plural and that each of said thermosphere anemometers (4-2) is a telescopic thermosphere anemometer.
6. Wind tunnel device for measuring the heat dissipation performance of a heat generating apparatus in a low-speed airflow environment according to claim 1, further comprising an aluminum wire mesh (5-1); in the test section (A4), one aluminum wire mesh (5-4) is respectively arranged at the front side and the rear side of the heating equipment (3-4); and a plurality of thermocouples (5-3) are uniformly arranged on each aluminum wire mesh (5-4).
7. Wind tunnel device for measuring the heat dissipation properties of heat generating equipment in a low velocity air flow environment according to claim 1, characterized in that the test section (A4) is internally coated with a heat radiation reflective coating.
8. The wind tunnel device for measuring the heat radiation performance of heating equipment in a low-speed airflow environment according to claim 1, wherein the wind tunnel body (1) is made of heat insulation materials in a sealing mode.
9. A method of measuring the heat dissipation of a heat generating device in a low velocity airflow environment as claimed in any one of claims 1 to 8, comprising the steps of:
step 1, a heat dissipation capacity testing method of heating equipment (3-4) comprises the following steps:
step 1.1, turning on a variable frequency fan (4-1) to set the fan frequency asf 1 ；
The fan (5-1) is turned on, the air flow temperature of the test section (A4) is guaranteed to be uniformly distributed through the fan (5-1), and after the reading of the thermocouple (5-3) is stable, the initial air temperature T of the test section (A4) is obtained through the thermocouple (5-3) 1 ；
Step 1.2, the average wind speed of the section of the test section (A4) is measured in the following manner
Dividing the section of the test section (A4) into a plurality of rings according to an equal-area ring method, adjusting the telescopic length of the detection head of each thermal ball anemometer (4-2) to ensure that the detection head of each thermal ball anemometer (4-2) is positioned at the center of a corresponding ring, and supposing that n thermal ball anemometers (4-2) are shared, measuring the wind speed of the corresponding ring by each thermal ball anemometer (4-2), and averaging the wind speeds measured by the n thermal ball anemometers (4-2) to obtain the section average wind speed of the test section (A4)
Step 1.3, then, opening the heating equipment (3-4), regulating the voltage U to a rated value through the voltage regulator (3-2), reading the current I through the ammeter (3-3) after the preset time, and obtaining the power consumption P of the heating equipment (3-4) by adopting the following formula:
P＝U*I
step 1.4, after the preset time, obtaining the air stabilization temperature T through the measurement of the thermocouple (5-3) after the temperature value of the thermocouple (5-3) is stabilized 2 The heat radiation power q of the heat generating device (3-4) is obtained by the following formula:
wherein:
ρ is the density value of air at 20 ℃;
C P the constant pressure specific heat value of air at 20 ℃;
a is the inner cross-sectional area of the test section (A4);
step 1.5, the voltage U value of the voltage regulator (3-2) is sequentially adjusted to different values, and the step 1.3-
Step 1.4, performing a test to obtain the average wind speed at the current section
A performance curve of heat dissipation power q and voltage U of the heating equipment (3-4);
adjusting the fan frequency of the variable frequency fan (4-1) and changing the average wind speed of the section
The voltage U is kept unchanged, the steps 1.1 to 1.4 are repeatedly carried out, and when the voltage U is obtained, the heat dissipation power q of the heating equipment (3 to 4) and the section average wind speed +.>
Is a performance curve of (2);
in addition, at each voltage U and section average wind speed
Calculating the ratio of the heat radiation power q to the power consumption power P of the heating equipment (3-4) to obtain the conversion rate between the electric energy and the heat energy of the heating equipment (3-4);
step 2, testing the convection heat exchange coefficient of the equipment surface of the heating equipment (3-4)
Step 2.1, turning on a variable frequency fan (4-1), and setting the fan frequency to be f 1 ；
The fan (5-1) is turned on, the air flow temperature of the test section (A4) is guaranteed to be uniformly distributed through the fan (5-1), and after the reading of the thermocouple (5-3) is stable, the initial air temperature T of the test section (A4) is obtained through the thermocouple (5-3) 1 ；
Step 2.2, measuring the average wind speed of the section of the test section (A4) by adopting an equal-area circular ring method
Step 2.3, then, opening the heating equipment (3-4), regulating the voltage U to a rated value through the voltage regulator (3-2), reading the current I through the ammeter (3-3) after the preset time, and obtaining the power consumption P of the heating equipment (3-4) according to P=U×I;
step 2.4, after the preset time, obtaining the air stabilization temperature T through the measurement of the thermocouple (5-3) after the temperature value of the thermocouple (5-3) is stabilized 2 The method comprises the steps of carrying out a first treatment on the surface of the When the infrared thermometer (5-2) has stable value, the surface temperature T of the heating equipment is obtained through the measurement of the infrared thermometer (5-2) ∞ ；
Step 2.5, calculating to obtain the heat dissipation power q of the heating equipment (3-4);
step 2.6, obtaining a convective heat transfer coefficient h by adopting the following formula:
h＝q/A s (T ∞ -T 2 )
wherein: a is that s Is the contact surface area of the heating device with the air;
step 2.7, adjusting the fan frequency of the variable frequency fan (4-1) so as to change the average wind speed of the section
A fixed voltage value U is adopted, and a plurality of tests are carried out to obtain the convection heat exchange coefficient h and the section average wind speed of the heating equipment (3-4)>
Is a performance curve of (2). />
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| CN116499697A (en) * | 2023-06-29 | 2023-07-28 | 中国航空工业集团公司沈阳空气动力研究所 | Wind tunnel inner wing type surface convection heat transfer distribution test measurement device and method |
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| CN116499697A (en) * | 2023-06-29 | 2023-07-28 | 中国航空工业集团公司沈阳空气动力研究所 | Wind tunnel inner wing type surface convection heat transfer distribution test measurement device and method |
| CN116499697B (en) * | 2023-06-29 | 2023-09-12 | 中国航空工业集团公司沈阳空气动力研究所 | Wind tunnel inner wing type surface convection heat transfer distribution test measurement device and method |
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