Pulse hot-wire anemograph

Abstract

The utility model discloses a pulse hot-wire anemograph which comprises a detection element, a signal converter and a signal processor. The detection element at least comprises three groups of hot wires, the three groups of hot wires do not contact with each other, the three groups of hot wires comprise a group of pulse wires and two groups of mutually parallel sensing wires, and the sensing wires are wire harnesses made of thermistor materials with resistance values changing along with temperature changes of contacted airflow; the pulse wire is located between the two sets of sensing wires, and the pulse wire is perpendicular to the sensing wires. The signal converter is used for converting resistance change signals which are collected by the detection element and respectively correspond to the pulse wire and the sensing wire into electric signals; the signal processor is used for processing the electric signals output by the signal converter. Based on the above situation, the pulse hot-wire anemometer provided by the utility model can provide reference data related to the wind speed or wind direction in a flow field to testers at the same time, and effectively reduces the number of test equipment carried by the testers.

Description

Technical Field

[0001] The present application relates to the technical field of wind speed detection, and more specifically, to a pulse hot wire anemometer. Background Art

[0002] A hot wire anemometer is a speed measuring instrument that converts flow velocity signals into electrical signals. It is usually used to test the wind speed in a flow field. If the wind speed in a flow field needs to be tested, the tester needs to introduce other equipment to test the wind direction. Therefore, for the staff, it is not convenient to carry too many test equipment to complete the test of the wind speed and wind direction of the flow field at the same time. Utility Model Content

[0003] In view of this, the present application provides a pulse hot wire anemometer to solve the problem that the existing hot wire anemometer cannot test wind direction and wind speed at the same time.

[0004] In order to achieve the above objectives, the proposed solution is as follows:

[0005] On one hand, the present application provides a pulse hot wire anemometer, comprising: a detection element, a signal converter and a signal processor;

[0006] The detection element comprises at least: three groups of hot wires, and the three groups of hot wires do not contact each other, the three groups of hot wires include: one group of pulse wires and two groups of sensing wires parallel to each other, the sensing wires are wire bundles composed of thermistor materials whose resistance values ​​change with the temperature of the airflow in contact;

[0007] The pulse wire is located in the middle of the two groups of sensing wires, and the pulse wire is perpendicular to the sensing wires;

[0008] The detection element is used to output resistance change signals corresponding to the pulse wire and the sensor wire respectively, the output end of the detection element is connected to the input end of the signal converter, and the signal converter is used to convert the resistance change signals corresponding to the pulse wire and the sensor wire respectively collected by the detection element into electrical signals;

[0009] The output end of the signal converter is connected to the input end of the signal processor, and the signal processor is used to process the electrical signal output by the signal converter.

[0010] In a possible implementation, the detection element further includes: a base and a top cover, and at least two support rods are fixedly connected to the edge of the base for supporting the top cover;

[0011] Wherein, two ends of each group of the sensor wires are respectively fixed to the base and the top cover, and the two groups of the sensor wires are parallel to each other;

[0012] Two ends of the pulse wire are respectively fixed to the two support rods, and the pulse wire is located between the two sensing wires and is perpendicular to the sensing wires.

[0013] In a possible implementation, the heating wire is a metal wire or a carbon nanotube composite wire.

[0014] In a possible implementation, the outer surface of the carbon nanotube composite wire is wrapped with a metal layer.

[0015] In a possible implementation, the carbon nanotube composite wire is obtained by connecting two ends of a carbon nanotube wire and twisting the carbon nanotube single yarn along the axis, and the carbon nanotube wire is drawn from the carbon nanotube array.

[0016] In a possible implementation, the method further includes: a display connected to the output end of the signal processor, for displaying a processing result of the signal processor on the electrical signal output by the signal converter.

[0017] The pulse hot wire anemometer provided by the present application introduces three groups of hot wires in the detection element, namely two groups of mutually parallel sensing wires and one group of pulse wires located between the two sensing wires. The sensing wires are a bundle of wires composed of a thermistor material whose resistance value changes with the temperature of the airflow in contact. When using the pulse hot wire anemometer, the pulse wire will be heated and heated. Under the influence of the flowing airflow, that is, wind, the pulse wire transfers heat to the surrounding fluid, generating heat dissipation, which will cause the temperature of the pulse wire to change, and then the resistance value of the pulse wire will also change accordingly. At the same time, during the flow of the heated fluid heat mass, part of the heat will be transferred to any one of the two groups of sensor wires, thereby changing the resistance value of one group of sensor wires. The signal converter can convert the resistance change signals of the pulse wire and the sensor wire into electrical signals respectively. Because the direction of the group of sensor wires with changed resistance can be determined as the approximate wind direction, the electrical signal converted by the signal converter can contain information representing the wind direction. The pulse hot wire anemometer disclosed in this embodiment achieves the purpose of obtaining a signal representing wind direction information by improving the detection element. Subsequently, the staff can obtain reference data for calculating the wind direction and wind speed based on the results of processing the obtained electrical signals.

[0018] Based on the above situation, the pulse hot wire anemometer proposed in the present application can simultaneously provide the tester with reference data related to the wind speed or wind direction in the flow field, and effectively reduce the test equipment that the tester needs to carry. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0020] Figure 1 A schematic diagram of the structure of a pulse hot wire anemometer provided by an embodiment of the utility model;

[0021] Figure 2 A schematic diagram of the structure of a hot wire in a detection element provided by an embodiment of the utility model;

[0022] Figure 3 A side view of a hot wire in a detection element provided by an embodiment of the utility model;

[0023] Figure 4 A tensile stress curve of a carbon nanotube wire provided by an embodiment of the utility model;

[0024] Figure 5 A scanning electron microscope photograph of a carbon nanotube wire provided in an embodiment of the utility model;

[0025] Figure 6 A schematic diagram of the structure of a detection element provided in an embodiment of the utility model;

[0026] Figure 7 A schematic structural diagram of another pulse hot wire anemometer provided in an embodiment of the utility model.

[0027] Reference numerals:

[0028] 10-detection element; 20-signal converter; 30-signal processor; 40-display; 100-sensing wire; 200-pulse wire; 110-carbon nanotube single yarn; 112-metal layer; 300-support rod; 400-base; 500-top cover. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. In the description of the utility model, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the utility model. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood in specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions without contradictions or conflicts, all within the scope of protection required by the utility model.

[0030] like Figure 1 As shown, a schematic diagram of the structure of a pulse hot wire anemometer provided by an embodiment of the utility model is shown. The pulse hot wire anemometer includes: a detection element 10, a signal converter 20 and a signal processor 30.

[0031] like Figure 2 As shown, the detection element 10 of the utility model comprises at least: three groups of hot wires, and the three groups of hot wires do not contact each other, the three groups of hot wires include: a group of pulse wires 200 and two groups of parallel sensing wires 100, the sensing wires 100 are a bundle of wires made of thermistor materials whose resistance value changes with the temperature of the airflow in contact; the pulse wire 200 is located in the middle position of the two groups of sensing wires 100, and the pulse wire 200 is perpendicular to the sensing wires 100.

[0032] The detection element 10 is used to output resistance change signals corresponding to the pulse wire 200 and the sensor wire 100 respectively. The output end of the detection element 10 is connected to the input end of the signal converter 20. The signal converter 20 converts the resistance change signals corresponding to the pulse wire 200 and the sensor wire 100 of the detection element 10 into electrical signals; the output end of the signal converter 20 is connected to the input end of the signal processor 30. The signal processor 30 is used to process the electrical signal output by the signal converter 20.

[0033] The detection element 10 is mainly used to collect parameters corresponding to the flow direction and flow velocity of the ambient airflow, that is, the relevant parameters corresponding to the wind direction and wind velocity. The sensing wire and pulse wire, that is, the hot wire, in the detection element 10 are wire bundles with certain thermistor characteristics, that is, the resistance value of the hot wire changes with the change of temperature.

[0034] In the process of using the pulse hot wire anemometer, the pulse wire 200 is heated by heating elements or sending pulse voltages, so that the temperature of the pulse wire 200 rises, and the resistance value of the pulse wire 20 is stabilized at a fixed value. Under the influence of the flowing airflow, that is, wind, the pulse wire 200 transfers heat to the surrounding fluid and loses its own heat, which causes the temperature of the pulse wire 200 to change, and then the resistance value of the pulse wire 200 also changes accordingly.

[0035] It can be understood that the heat dissipation of the pulse wire 200 in the airflow is related to the flow velocity. The faster the flow velocity, the greater the heat dissipation, and the greater the change in resistance of the pulse wire. Conversely, the slower the flow velocity, the smaller the heat dissipation, and the smaller the change in resistance of the pulse wire. Therefore, the resistance change signal representing the change in resistance value of the heated pulse wire 200 in the fluid can contain information representing the flow velocity v of the fluid, that is, the wind speed.

[0036] The pulse wire 200 collects the resistance change signal representing the change in resistance value and sends it to the signal converter 20. The resistance change signal is converted into an electrical signal by the signal converter 20. The electrical signal is then processed by the signal processor 30 to obtain reference data that can represent the wind speed, such as the time when the resistance begins to change, the temperature or heat dissipation per unit time, the resistance change per unit time, etc.

[0037] Since the pulse wire 200 and the sensor wire 100 are not in contact with each other, when the pulse hot wire anemometer only heats the pulse wire, the sensor wire 100 will not theoretically produce resistance changes caused by temperature changes. However, since the pulse wire 200 transfers heat to the fluid, the heated fluid heat mass will transfer part of the heat to the sensor wire 100 in the flow direction during the flow process. Therefore, as the fluid flows, the heat emitted by the pulse wire 200 will be transferred to the sensor wires 100 on both sides of the pulse wire 200. Since the flow direction of the fluid is usually in one direction, the flowing fluid will only transfer heat to the sensor wire 100 on one side, and the direction of the sensor wire 100 that generates the resistance change signal can be determined as the approximate direction of the fluid flow.

[0038] The sensor wire 100 collects its own resistance change signal and outputs it to the signal converter 20, which converts the resistance change signal into an electrical signal. Because the direction of the group of sensor wires 100 with resistance change can be determined as the approximate wind direction, the electrical signal converted by the signal converter 20 can contain information representing the wind direction, such as the time when the resistance changes, the amount of resistance change, etc.

[0039] It can be understood that the direction of the sensor wire 100 generating the resistance change signal is only the approximate direction of the wind speed. Figure 3, a side view of a hot wire in a detection element provided by an embodiment of the utility model, wherein the x direction where the sensing wire 100 is located is the approximate direction of the wind speed, and the arrow direction of the line segment corresponding to the wind speed v is the actual wind direction, that is, it is at an angle with d direction, d is the distance between the pulse wire 200 and the sensing wire 100 in the vertical direction.

[0040] To improve the accuracy of the measured wind direction, in a possible implementation, the signal processor 30 processes the electrical signal representing the resistance change of the pulse wire 200 to obtain the flow velocity v of the fluid passing through the pulse wire 200, that is, the wind speed.

[0041] Considering that the heated fluid mass moves at a speed v, it flows to one of the two groups of sensing wires 100 after a time t. The fluid mass transfers part of the heat to the sensing wire 100, thereby changing the resistance value of the sensing wire. In this embodiment, the effect of heat diffusion on the flow time t of the fluid mass is ignored. Then, the flow time t of the fluid mass flying from the pulse wire 200 to one of the groups of sensing wires 100 can be referred to the following formula (1):

[0042]

[0043] Wherein, d represents the vertical distance between the pulse wire 200 and the sensing wire 100, It represents the angle between the fluid velocity and the reference direction, where the reference direction is the perpendicular direction between the pulse wire 200 and the sensing wire 100 .

[0044] Based on the above formula (1), the signal processor 30 can calculate the angle Testers can Determine the exact wind direction yourself.

[0045] To summarize, the pulse hot wire anemometer provided in the present application introduces three groups of hot wires in the detection element, namely two groups of parallel sensor wires and a group of pulse wires located between the two sensor wires. This structure allows the fluid heat mass to reach only one group of the two groups of sensor wires. Based on this, the direction of the flow velocity can be determined according to the different sensor wires reached by the fluid heat mass.

[0046] When using a pulse hot wire anemometer, the pulse wire will be heated and heated. Under the influence of the flowing airflow, that is, wind, the pulse wire transfers heat to the surrounding fluid, generating heat dissipation, which will cause the temperature of the pulse wire to change, and then the resistance value of the pulse wire will also change accordingly. At the same time, the heated fluid heat mass will also transfer part of the heat to any one of the two groups of sensor wires during the flow process, so that the resistance value of one group of sensor wires will change. The signal converter can convert the resistance change signals of the pulse wire and the sensor wire into electrical signals respectively, because the direction of the group of sensor wires with resistance change can be determined as the approximate wind direction, and the electrical signal converted by the signal converter can contain information representing the wind direction. The pulse hot wire anemometer disclosed in this embodiment, through the improvement of the detection element, realizes the purpose of obtaining the signal representing the wind direction information, and then in the future, the staff can process the obtained electrical signal according to the result, and obtain reference data that can calculate the wind direction and wind speed.

[0047] Based on the above situation, the pulse hot wire anemometer proposed in the present application can simultaneously provide the tester with reference data related to the wind speed or wind direction in the flow field, and effectively reduce the test equipment that the tester needs to carry.

[0048] Furthermore, other possible implementations of the pulse hot wire anemometer are described.

[0049] It is understandable that each set of hot wires used in the pulse hot wire anemometer should have certain thermal sensitivity characteristics. A set of hot wires at least includes a wire harness composed of a thermistor material whose resistance value changes with changes in its own temperature. Among them, the sensing wire 100 itself will not be heated up, but the airflow it contacts has a certain amount of heat. Therefore, the sensing wire 100 is a wire harness composed of a thermistor material whose resistance value changes with changes in the temperature of the airflow it contacts.

[0050] In a possible implementation, the hot wire is a metal wire or a carbon nanotube composite wire, wherein the carbon nanotube composite wire is obtained by connecting two ends of a carbon nanotube wire and twisting the carbon nanotube single yarn along the axis, and the carbon nanotube wire is drawn from the carbon nanotube array.

[0051] It is understandable that the thinner the hot wire in the pulse hot wire anemometer, the higher the sensitivity of the pulse hot wire anemometer. When the diameter of the ultra-fine wire made of metal or alloy reaches the micron level or even smaller, the metal wire is easy to break, and it is difficult to produce ultra-fine one-dimensional metal wire due to the limitation of current technological level. Therefore, carbon nanotube composite wire can be used. Figure 4The tensile stress curve of the carbon nanotube single yarn in the carbon nanotube wire provided by the embodiment of the utility model shows that the tensile strain rate of the carbon nanotube composite wire under a tensile stress of about 1000Mpa is about 3%, which has high strength and flexibility. The carbon nanotube composite wire stretched to a certain fineness is used as a hot wire to improve the sensitivity of the pulse hot wire anemometer.

[0052] Reference Figure 5 , a scanning electron microscope photo of a carbon nanotube wire provided by an embodiment of the utility model, wherein the outer surface of the carbon nanotube composite wire 100 is coated with a metal layer 112. A metal layer 112, such as a highly conductive metal such as copper or silver, can be uniformly coated on the outer surface of the carbon nanotube composite wire 100 by distillation, electroplating, etc., to improve the conductivity of the hot wire.

[0053] In one possible implementation, refer to Figure 6 , a schematic diagram of the structure of a detection element provided by an embodiment of the utility model, the detection element also includes: a base 400 and a top cover 500, and at least two support rods 300 are fixedly connected to the edge of the base 400 for supporting the top cover 500; wherein, the two ends of each group of sensor wires 100 are respectively fixed to the base 400 and the top cover 500, and the two groups of sensor wires 100 are parallel to each other; the two ends of the pulse wire 200 are respectively fixed to the two support rods 300, the pulse wire is in the middle of the two sensor wires 100, and is perpendicular to the sensor wire 100.

[0054] Each set of hot wires cannot maintain a fixed shape, so a supporting structure is needed to enable the three sets of hot wires to follow the Figure 2 The structural arrangement shown, Figure 6 The detection element shown in the figure supports each set of sensing wires with the help of a base and a top cover, and at the same time uses a support rod between the base and the top cover to fix the pulse wire so that the sensing wire and the pulse wire can be restored. Figure 2 The structure shown.

[0055] In another possible implementation, referring to Figure 7 , a schematic diagram of the structure of another pulse hot wire anemometer provided by an embodiment of the utility model, the pulse hot wire anemometer may also include: a display 40 connected to the output end of the signal processor 30, for displaying the processing result of the signal processor 30 on the electrical signal output by the signal converter 20.

[0056] Optionally, the output end of the signal processor 30 can also be connected to a communication module, and the communication module sends the processing result to a device end that is interconnected with the network or Bluetooth for the tester to view and identify the wind direction and wind speed of the test environment.

[0057] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pulse hot wire anemometer, characterized in that: include: Detection elements, signal converters and signal processors; The detection element comprises at least: three groups of hot wires, and the three groups of hot wires do not contact each other, the three groups of hot wires include: one group of pulse wires and two groups of sensing wires parallel to each other, the sensing wires are wire bundles composed of thermistor materials whose resistance values ​​change with the temperature of the airflow in contact; The pulse wire is located in the middle of the two groups of sensing wires, and the pulse wire is perpendicular to the sensing wires; The detection element is used to output resistance change signals corresponding to the pulse wire and the sensor wire respectively, the output end of the detection element is connected to the input end of the signal converter, and the signal converter is used to convert the resistance change signals corresponding to the pulse wire and the sensor wire respectively collected by the detection element into electrical signals; The output end of the signal converter is connected to the input end of the signal processor, and the signal processor is used to process the electrical signal output by the signal converter.

2. The pulse hot wire anemometer according to claim 1, characterized in that: The detection element further comprises: a base and a top cover, and at least two support rods are fixedly connected to the edge of the base for supporting the top cover; Wherein, two ends of each group of the sensor wires are respectively fixed to the base and the top cover, and the two groups of the sensor wires are parallel to each other; Two ends of the pulse wire are respectively fixed to the two support rods, and the pulse wire is located between the two sensing wires and is perpendicular to the sensing wires.

3. The pulse hot wire anemometer according to claim 1, characterized in that: The heating wire is a metal wire or a carbon nanotube composite wire.

4. The pulse hot wire anemometer according to claim 3, characterized in that: The outer surface of the carbon nanotube composite wire is wrapped with a metal layer.

5. The pulse hot wire anemometer according to claim 3, characterized in that: The carbon nanotube composite wire is obtained by connecting two ends of a carbon nanotube wire and twisting the carbon nanotube single yarn along the axis, and the carbon nanotube wire is drawn from a carbon nanotube array.

6. The pulse hot wire anemometer according to claim 1, characterized in that: Also includes: The display connected to the output end of the signal processor is used to display the processing result of the signal processor on the electrical signal output by the signal converter.

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