A non-contact measurement method and device for convective heat transfer distribution on a model surface in a wind tunnel

Abstract

A non-contact measurement method and device for the convective heat transfer distribution of a model surface in a wind tunnel, belonging to the technical field of wind tunnel tests. The method of the present invention comprises the following steps: S1. Arranging a non-contact measurement device for the convective heat transfer distribution of a model surface in a wind tunnel in a wind tunnel, S2. Opening the wind tunnel; S3. Opening a laser heater of a non-contact measurement device for the convective heat transfer distribution of a model surface in a wind tunnel; S4. Turning off the wind tunnel fan; S5, data processing. The device of the present invention comprises a model body, a laser heater group and an infrared thermometer. The purpose of the research and development of the present invention is to solve the problem that the existing measurement methods are difficult to test the convective heat transfer distribution without modifying the model material and internal structure for tests with some special requirements. The reasonable arrangement of the device of the present invention can realize the non-contact measurement of the convective heat transfer distribution of the model surface in the wind tunnel under the condition of reducing the requirements of the test process on the model surface material and structure, and simplifying the complexity of data processing and test methods.

Description

Technical Field

[0001] The invention relates to a non-contact measurement method and device for the convective heat transfer distribution on a model surface in a wind tunnel, belonging to the technical field of wind tunnel testing. Background Art

[0002] Aircraft icing affects flight safety. Calculation of aircraft icing ice shape and icing protection design require surface convective heat transfer as input; and the measurement and estimation of infrared radiation during aircraft flight also require surface convective heat transfer as input. Convective heat transfer measurement is frequently used in wind tunnel tests, but for some test models, due to the purpose of the test and the model itself, the internal and external materials and structural characteristics of the model cannot be changed, and non-contact measurement methods are required for testing.

[0003] At present, the existing technologies related to the distribution of wind tunnel convective heat transfer coefficient or other convective heat transfer coefficient measurement are mostly at laboratory level and cannot be used in wind tunnels, or they are all contact measurement methods, which require modifications to the model itself and installation of sensors, etc. Existing non-contact measurement methods such as naphthalene sublimation method are relatively mature, but cannot measure the distribution of heat transfer coefficient. Other non-contact methods such as infrared, liquid crystal and other methods are only used for temperature measurement, and often cannot directly eliminate the measurement errors caused by environmental radiation and internal heat conduction of the structure.

[0004] Therefore, it is urgent to propose a non-contact measurement method and device for the convective heat transfer distribution on the model surface in a wind tunnel to solve the above technical problems. Summary of the invention

[0005] The purpose of the research and development of the present invention is to solve the problem that the existing measurement methods are difficult to test the convective heat transfer distribution without modifying the model material and internal structure for some special requirements of the test, and thus provide a non-contact measurement device and method for the convective heat transfer distribution of the model surface in a wind tunnel. The present invention can greatly simplify the complexity of data processing and test methods, and reduce the requirements of the test process on the model surface material and structure. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0006] The technical solution of the present invention:

[0007] Solution 1: A non-contact measurement method for convective heat transfer distribution on a model surface in a wind tunnel, comprising the following steps:

[0008] S1. Arranging a non-contact measuring device for the convective heat transfer distribution of a model surface in a wind tunnel in a wind tunnel, wherein the non-contact measuring device for the convective heat transfer distribution of a model surface comprises a laser heater group and an infrared thermometer;

[0009] The laser heater group and the infrared thermometer are respectively fixed on the outside of the wind tunnel wall, and the laser center passes through the optical glass on the wind tunnel wall and points to the position of the model body to be measured; the center position of the infrared thermometer is adjusted to the position of the model body to be measured, ensuring that the laser heater in the center heats the measured point, and the heating positions of other laser heaters surround the measured point;

[0010] S2, start the wind tunnel; wait for the wind tunnel parameters to stabilize and the tunnel wall temperature to stabilize;

[0011] S3, turn on the laser heater; adjust the power of the laser heater group so that the temperature of the measured point displayed on the infrared thermometer is T The temperature difference between the measured point and the surrounding temperature is not greater than 0.1 T , wait for the infrared thermometer temperature to stabilize, and record the input power P in-1 ;

[0012] S4. Turn off the wind tunnel fan; continue to adjust the power of the laser heater group so that the temperature of the measured point displayed on the infrared thermometer is T ±0.05 T The temperature difference between the measured point and the surrounding temperature is not greater than 0.1 T , wait for the infrared thermometer temperature to stabilize, and record the input power P in-2 ;

[0013] S5. Data processing: Calculate the convective heat transfer coefficient of the measured point through the above data, as follows:

[0014] ;

[0015] In the formula, h is the convective heat transfer coefficient; For the wind tunnel to flow static temperature; A The heating coverage area of ​​the measured point of the model body by the laser in the middle of the laser heater group; C is the convective heat transfer correction factor.

[0016] Solution 2: A non-contact measurement device for the convective heat transfer distribution of a model surface in a wind tunnel, which is applied to the non-contact measurement method for the convective heat transfer distribution of a model surface in a wind tunnel described in Solution 1, and comprises a model body, a laser heater group and an infrared thermometer;

[0017] The surface material radiation heat transfer absorption rate of the model body η Not less than 0.7;

[0018] The infrared thermometer is placed outside the wind tunnel wall, close to the laser heater group, avoiding the reflected light path caused by the laser on the surface of the model body, and measures the surface temperature of the model body through the optical glass. T .

[0019] Preferably, the laser heater group is composed of a plurality of laser heaters, the total number of laser heaters is not less than 5, one of the laser heaters is at the center position, and the input power of the laser heater at the center position is P in and actual heating power P The corresponding relationship obtained through calibration is as follows:

[0020] .

[0021] The present invention has the following beneficial effects:

[0022] 1. The laser heater group of the present invention can adjust the heating power of the measured point and its vicinity by separately adjusting the input power of the laser heater, thereby adjusting the temperature distribution of the measured point and its surroundings, and reducing the heat conduction from the measured point to the surroundings; adjusting the power of the laser heater to ensure that the temperature of the measured point is close when the wind tunnel is running and closed, and to ensure that the radiation heat exchange between the measured point and the wind tunnel environment is close; through the above two processing methods, a direct connection is established between the changes introduced by the convective heat transfer after the wind tunnel is started and the laser power, thereby minimizing the errors caused by other interference items and simplifying data processing.

[0023] 2. The reasonable arrangement of the device in the present invention enables all tests to be non-contact measurements. Except for the low requirement of laser heating on the surface reflectivity of the material, no additional modification of the test object is required, which increases the adaptability of the test model. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 It is a schematic diagram of the structure of a non-contact measurement device for the convective heat transfer distribution on the surface of a model in a wind tunnel;

[0026] Figure 2 It is a schematic diagram of the light spot when the laser heater group heats the model body;

[0027] Reference numerals:

[0028] In the figure, 1 is the model body, 2 is the laser heater group, 3 is the infrared thermometer, 4 is the optical glass, and 5 is the wind tunnel wall. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0030] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection (i.e., non-detachable connection) includes but is not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but is not limited to conventional detachable methods such as threaded connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can always be found in the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and hinge connection is selected for detachable connection.

[0031] Embodiment 1:

[0032] Combination Figure 1-Figure 2 This embodiment describes a measurement method of a non-contact measurement device for measuring convective heat transfer distribution on a model surface in a wind tunnel, comprising the following steps:

[0033] S1. Arrange a non-contact measuring device for convective heat transfer distribution on the surface of a model in a wind tunnel in a wind tunnel;

[0034] The model body 1, the laser heater group 2 and the infrared thermometer 3 are fixedly placed in the wind tunnel to obtain the surface radiation heat transfer absorption rate of the model body 1. η , the laser heater input power at the center of laser heater group 2 is obtained by calibration P in and actual heating power P The corresponding relationship is as follows:

[0035] ;

[0036] S2, start the wind tunnel;

[0037] Wait for the wind tunnel wind speed, total temperature of incoming air and other parameters to stabilize to the working conditions that need to be measured, the temperature of the wind tunnel wall 5 to stabilize, and the system inside the entire wind tunnel to be in an approximately steady state;

[0038] S3, turn on the laser heater;

[0039] Adjust the power of each laser heater in the laser heater group 2 so that the temperature of the measured point of the model body 1 displayed on the infrared thermometer 3 is T The temperature difference between the measured point and the surrounding temperature is not greater than 0.1T , wait for the temperature displayed by infrared thermometer 3 to stabilize, and record the input power P in-1 ;

[0040] S4, turn off the wind tunnel fan;

[0041] Wait for the wind tunnel wind speed to stop completely, adjust the power of each laser heater in the laser heater group 2, and make the infrared thermometer 3 display the temperature of the measured point of the model body 1 as T ±0.05 T The temperature difference between the measured point and the surrounding temperature is not greater than 0.1 T , wait for the temperature displayed by infrared thermometer 3 to stabilize, and record the input power P in-2 ;

[0042] S5. Data processing: Calculate the convective heat transfer coefficient of the measured point through the above data, as follows:

[0043] ;

[0044] In the formula, h is the convective heat transfer coefficient; For the wind tunnel to flow static temperature; A The heating coverage area of ​​the measured point of the model body by the laser in the middle of the laser heater group; C is the convective heat transfer correction coefficient, and its value can be taken as 20.

[0045] Embodiment 2:

[0046] Combination Figure 1 and Figure 2 The present embodiment is described as a non-contact measurement device for the convective heat transfer distribution of a model surface in a wind tunnel, which is applied to the non-contact measurement method for the convective heat transfer distribution of a model surface in a wind tunnel described in the first embodiment, comprising a model body 1, a laser heater group 2 and an infrared thermometer 3, wherein the model body 1 is a two-dimensional stretching model of an airfoil, the outer surface of the model body 1 is the measurement position of the convective heat transfer coefficient, and the surface material of the model body 1 has a radiation heat transfer absorption rate. η Not less than 0.7;

[0047] The laser heater group 2 is composed of 5 laser heaters, the power of each laser heater can be independently controlled, and one laser heater is at the center position; the input power of the laser heater at the center position P in and actual heating power P The corresponding relationship obtained through calibration is as follows:

[0048] ;

[0049] The laser heater group is fixed on the outside of the wind tunnel wall 5, and the center of the laser points to the position of the model body 1 to be measured through the optical glass 4, such as Figure 2 As shown, the light spots formed by 5 lasers on the surface of the model body 1 are distributed, and the 5 light spots are close but not overlapped.

[0050] The infrared thermometer 3 is placed outside the wind tunnel wall 5, close to the laser heater group 2, avoiding the reflected light path caused by the laser directly on the surface of the model body 1, and measures the surface temperature of the model body 1 through the optical glass 4. T .

[0051] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-contact measurement method for the convective heat transfer distribution of a model surface in a wind tunnel, characterized in that: The following steps are involved: S1. Arranging a non-contact measuring device for the convective heat transfer distribution of a model surface in a wind tunnel in a wind tunnel, wherein the non-contact measuring device for the convective heat transfer distribution of a model surface comprises a laser heater group and an infrared thermometer; The laser heater group and the infrared thermometer are respectively fixed on the outside of the wind tunnel wall, and the laser center passes through the optical glass on the wind tunnel wall and points to the position of the model body to be measured; the center position of the infrared thermometer is adjusted to the position of the model body to be measured, ensuring that the central laser heater heats the measured point, and the heating positions of other laser heaters surround the measured point; the input power of the central laser heater P in and actual heating power P The corresponding relationship obtained through calibration is as follows: ； S2, start the wind tunnel; wait for the wind tunnel parameters to stabilize and the tunnel wall temperature to stabilize; S3, turn on the laser heater; adjust the power of the laser heater group so that the temperature of the measured point displayed on the infrared thermometer is T The temperature difference between the measured point and the surrounding temperature is not greater than 0.1 T , wait for the infrared thermometer temperature to stabilize, and record the input power P in-1 ; S4. Turn off the wind tunnel fan; continue to adjust the power of the laser heater group so that the temperature of the measured point displayed on the infrared thermometer is T ±0.05T, the temperature difference between the measured point and the surrounding temperature is not greater than 0.1 T , wait for the infrared thermometer temperature to stabilize, and record the input power P in-2 ; S5. Data processing: Calculate the convective heat transfer coefficient of the measured point through the above data, as follows: ； In the formula, h is the convective heat transfer coefficient; For the wind tunnel to flow static temperature; A The heating coverage area of ​​the measured point of the model body by the laser in the middle of the laser heater group; C is the convective heat transfer correction factor; η is the radiation heat transfer absorption rate of the surface material of the model body.

2. A non-contact measuring device for the convective heat transfer distribution of a model surface in a wind tunnel, applied to the non-contact measuring method for the convective heat transfer distribution of a model surface in a wind tunnel as claimed in claim 1, characterized in that: It includes a model body (1), a laser heater group (2) and an infrared thermometer (3); The surface material radiation heat transfer absorption rate of the model body (1) η Not less than 0.7; The infrared thermometer (3) is placed outside the wind tunnel wall (5), close to the laser heater group (2), avoiding the reflected light path directly caused by the laser on the surface of the model body (1), and measures the surface temperature of the model body (1) through the optical glass (4). T 。 3. The non-contact measuring device for convective heat transfer distribution on the surface of a model in a wind tunnel according to claim 2, characterized in that: The laser heater group (2) is composed of a plurality of laser heaters, and the total number of laser heaters is no less than 5.

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