A frosting experimental device and its application

Abstract

The present application belongs to the technical field of observation equipment, and in particular, relates to a frosting experimental device and its application. Existing measuring devices cannot directly observe the surface flow field characteristics of the frost layer under supersonic conditions and the influence of shock waves on the frost layer, and there is no suitable model to predict the amount of frost. The present application provides a frosting experimental device, including a schlieren generating mechanism, a high-speed air duct and a temperature control mechanism. The schlieren generating mechanism includes a light source component and a schlieren observation component. The light source component is arranged on one side of the high-speed air duct, and the schlieren observation component is arranged on the other side of the high-speed air duct. The temperature control mechanism is arranged in the high-speed air duct. When the high-speed airflow in the high-speed air duct passes through the temperature control mechanism, the flow cross-sectional area changes, so that the airflow can reach a supersonic state at the temperature control mechanism. The surface flow field characteristics of the frost layer under supersonic conditions and the influence of shock waves on the frost layer can be observed intuitively and effectively.

Description

Technical Field

[0001] The present application belongs to the technical field of observation equipment, and in particular, relates to a frosting experimental device and its application. Background Art

[0002] With the development of the aerospace industry, the frosting characteristics and defrosting technology of wings have received widespread attention. At present, the main testing method is to use low-temperature wind tunnel technology to simulate the flight state of the aircraft to observe the frosting and defrosting characteristics of the wings. When the aircraft flies at supersonic speed, the disturbance does not have time to be transmitted to the front of the aircraft. The gas in front is compressed, forming a concentrated strong disturbance. At this time, an interface of the compression process appears, which is the shock wave. After the shock wave, the gas density will produce a large mutation. The shock wave has a certain influence on the thermophysical properties of the gas. However, the current research on the impact of shock waves on frosting at supersonic speeds is not in-depth enough.

[0003] The existing measuring devices cannot directly observe the flow field characteristics of the frost layer surface under supersonic conditions and the impact of shock waves on the frost layer, and there is no suitable model to predict the amount of frost. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] Based on the problem that existing measuring devices cannot directly observe the surface flow field characteristics of the frost layer under supersonic conditions and the impact of shock waves on the frost layer, the present application provides a frosting experimental device and its application.

[0006] 2. Technical solution

[0007] In order to achieve the above-mentioned objectives, the present application provides a frosting experimental device, including a schlieren generating mechanism, a high-speed air duct and a temperature control mechanism, the schlieren generating mechanism includes a light source assembly and a schlieren observation assembly, the light source assembly is arranged on one side of the high-speed air duct, the schlieren observation assembly is arranged on the other side of the high-speed air duct, and the temperature control mechanism is arranged in the high-speed air duct. When the high-speed airflow in the high-speed air duct passes through the temperature control mechanism, the flow cross-sectional area changes, so that the airflow can reach a supersonic state at the temperature control mechanism.

[0008] Another embodiment provided by the present application is: the light source assembly includes a light source and a first reflector arranged in sequence, a first concave mirror is arranged between the light source and the first reflector, and the schlieren observation assembly includes a second reflector, a blade and a high-speed camera arranged in sequence, a second concave mirror is arranged between the blade and the high-speed camera; the light emitted by the light source is reflected by the first reflector to the first concave mirror, passes through the high-speed air duct, is reflected by the second concave mirror to the second reflector, and then passes through the blade to form light and dark alternating schlieren on the high-speed camera.

[0009] Another implementation manner provided by the present application is: the high-speed air duct is made of a transparent material, and the light emitted by the light source assembly passes through the high-speed air duct to reach the schlieren observation assembly.

[0010] Another embodiment provided by the present application is: the temperature control mechanism includes a hollow sphere and filling and discharge pipelines connected to each other, the filling and discharge pipelines include a gas filling and discharge pipe and a liquid filling and discharge pipe, the gas filling and discharge pipe is connected to the hollow sphere, and the liquid filling and discharge pipe extends into the interior of the hollow sphere.

[0011] Another implementation manner provided by the present application is that the filling and discharging pipeline is connected to the support assembly.

[0012] Another embodiment provided by the present application is: the support assembly includes a base, the base is connected to the high-speed air duct through a plurality of flow channel support frames, a support platform is arranged on the base, and the filling and discharging pipeline is arranged on the support platform.

[0013] Another implementation manner provided by the present application is that the high-speed air duct is a cylindrical flow channel.

[0014] The present application also provides an application of the frosting experimental device, which can eccentrically arrange the cavity sphere in the flow channel, and use the device to observe the flow field characteristics of the frost layer surface under different flow velocity conditions and the influence of shock waves on the frost layer.

[0015] Another implementation manner provided by the present application is that the device is applied to a frosting experiment or a defrosting experiment.

[0016] 3. Beneficial effects

[0017] Compared with the prior art, the beneficial effects of the frosting experimental device provided by the present application are:

[0018] The frosting experimental device provided in the present application is an experimental device for observing the frosting and defrosting characteristics of an object in a supersonic flow field.

[0019] The frosting experimental device provided in the present application can intuitively and effectively observe the surface flow field characteristics of the frost layer under supersonic conditions and the influence of shock waves on the frost layer by using the schlieren method.

[0020] The frosting experimental device provided in the present application can measure parameters such as the front and rear pressure difference, fit the empirical correlation formula of the frost layer, form a corresponding relationship, and then achieve the function of reversely calculating the water vapor content of the inlet airflow through the pressure difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the frosting experimental device of the present application;

[0022] Figure 2It is a schematic diagram of the structure of the Schlieren generating mechanism of the present application;

[0023] Figure 3 It is a schematic diagram of the partial structure of the frosting experimental device of the present application;

[0024] Figure 4 It is a schematic diagram of the partial structure of the temperature control mechanism of the present application. DETAILED DESCRIPTION

[0025] Hereinafter, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without violating the principles of the present application, the features in the various embodiments can be combined to obtain new implementations, or certain features in certain embodiments can be replaced to obtain other preferred implementations.

[0026] The Schlieren method is a commonly used optical observation method. Its basic principle is to use the refractive index gradient of light in the measured flow field to measure the airflow density of the flow field. When the light passing through the measured flow field passes through the front blade of the high-speed camera, the high-density area is blocked by the blade due to large deflection, and appears as dark lines on the screen, while the low-density area is not blocked due to small deflection, and appears as bright lines on the screen.

[0027] See also Figures 1 to 4 The present application provides a frosting experimental device, including a Schlieren generating mechanism, a high-speed air duct and a temperature control mechanism, wherein the Schlieren generating mechanism includes a light source component and a Schlieren observation component, wherein the light source component is arranged on one side of the high-speed air duct, and the Schlieren observation component is arranged on the other side of the high-speed air duct, and the temperature control mechanism is arranged in the high-speed air duct, and when the high-speed airflow in the high-speed air duct passes through the cavity sphere 9 of the temperature control mechanism, the flow cross-sectional area changes, so that the airflow can reach a supersonic state at the maximum radius of the cavity sphere 9. The high-speed air duct and the cavity sphere 9 cooperate with each other to achieve the effect of a zoom nozzle, so that the airflow can reach a supersonic state when passing through the cavity sphere 9.

[0028] When the gas flows through the object to be measured (temperature control mechanism), due to the change in the flow channel area, the speed of the object to be measured reaches the speed of sound at the maximum radial radius, and the surface of the cavity object in the air duct can be frosted under supersonic airflow conditions; the Schlieren method is used to observe the characteristics of the shock wave around the frosted object in the supersonic air duct, and the impact of the shock wave on the frost layer; on both sides of the high-speed and low-temperature air duct, the Schlieren generation mechanism forms a projection in the high-speed air duct through the light source component and then observes it through the Schlieren observation component. The temperature control mechanism can achieve surface frost or defrost by adjusting the temperature.

[0029] Specifically, the temperature control mechanism is in a high-speed air duct, and the light source assembly absorbs light through the high-speed air duct onto the surface of the temperature control mechanism and then enters the Schlieren observation assembly. The Schlieren observation assembly observes the surface of the temperature control mechanism to observe the characteristics of frosting or defrosting at different flow rates from subsonic to supersonic.

[0030] Furthermore, the light source assembly includes a light source 1 and a first reflector 2 arranged in sequence, a first concave mirror 3 is arranged between the light source 1 and the first reflector 2, and the schlieren observation assembly includes a second reflector 5, a blade 6 and a high-speed camera 7 arranged in sequence, a second concave mirror 4 is arranged between the blade 6 and the high-speed camera 7; the light emitted by the light source 1 is reflected by the first reflector 2 to the first concave mirror 3, passes through the high-speed air duct, is reflected by the second concave mirror 4 to the second reflector 5, and then passes through the blade 6 to form light and dark alternating schlieren on the high-speed camera 7.

[0031] The light emitted by the light source 1 passes through the first reflector 2 and the first concave mirror 3, passes vertically through the high-speed air duct to be frosted, passes through the second concave mirror 4 and the second reflector 5, and enters the high-speed camera 7 through the blade 6 for imaging. Due to the deflection of light, light and dark schlieren can be generated to show the characteristics of shock waves.

[0032] See also Figure 2 There is no obstacle between the light source 1 and the first reflector 2, and the first concave mirror 3 is arranged on the optical path of the light reflected by the first reflector 2; the first concave mirror 3 is below the plane formed by the light source 1 and the first reflector 2. The second concave mirror 4 is above the plane formed by the second reflector 5 and the high-speed camera 7.

[0033] The gas passes through the cylindrical flow channel 8 and reaches the speed of sound at the maximum radial radius of the measured cavity sphere 9, that is, at the throat similar to the zoom nozzle. Frost forms on the surface of the cavity sphere 9 and a shock wave effect is generated, changing the surrounding gas density. Since the gas density in the area where the shock wave is generated changes suddenly, part of the light entering the frosted position of the high-speed air duct passes through the gas with high density, which will produce a large deflection and be blocked by the blade 6, showing dark lines on the screen, while part of the light passes through the gas with low density and is not blocked due to the small deflection, showing bright lines on the screen.

[0034] Furthermore, the high-speed air duct is a cylindrical flow channel 8, which ensures uniform flow in all directions and is transparent to achieve visualization of the device. The shape of the high-speed air duct and the temperature control mechanism is not limited, and a combination of a cylindrical channel 8 and a cavity sphere 9 can be used.

[0035] Furthermore, the temperature control mechanism includes a hollow sphere 9 and an filling and discharge pipeline 10 that are interconnected, and the filling and discharge pipeline 10 includes a gas filling and discharge pipe 14 and a liquid filling and discharge pipe 15. The gas filling and discharge pipe 14 is connected to the hollow sphere 9, and the liquid filling and discharge pipe 15 extends into the interior of the hollow sphere 9.

[0036] Specifically, the filling and discharging pipeline 10 is composed of two pipes, one is a gas filling and discharging pipe 14 connected to the cavity sphere 9, and the other is a liquid filling and discharging pipe 15 extending into the interior of the cavity sphere 9.

[0037] The filling and discharging pipeline 10 is used to fill the working fluid into the inner cavity of the measured cavity sphere 9 to cool or heat the cavity sphere 9; according to the experimental requirements, low-temperature liquid and high-temperature gas can be filled respectively to realize the frosting or defrosting experiment on the surface of the cavity sphere 9; and the filled working fluid undergoes phase change heat exchange in the cavity sphere 9 and is in the two-phase region, and the surface temperature of the cavity sphere 9 can be regarded as uniform and isothermal. In the frosting experiment, the filled low-temperature liquid absorbs heat and evaporates as gas and is discharged. In the defrosting experiment, the filled high-temperature gas releases heat and condenses as liquid and is discharged. The cavity sphere 9 is in the two-phase region; the cavity sphere 9 uses good thermal conductive materials, and the temperature at each location can be regarded as equal, and the temperature can be determined by measuring the internal pressure.

[0038] Specifically, depending on the different filling media, different experimental functions can be achieved, such as filling low-temperature liquid in a higher temperature airflow to cause frost on the surface of the hollow sphere 9; and filling high-temperature gas in a lower temperature airflow to defrost the frosted surface of the hollow sphere 9, thereby realizing the observation of the frosting and defrosting characteristics of objects under supersonic conditions.

[0039] By adjusting the temperature of the charged working fluid, a low-temperature working fluid can be charged under a high back pressure to cool the flow field near the cavity sphere 9, so that the airflow at the throat reaches a sonic state.

[0040] In the experiment, the hollow sphere 9 can be arranged eccentrically to observe the frosting and defrosting characteristics under different flow rates.

[0041] Furthermore, the temperature control mechanism extends from the outlet of the flow channel into the interior of the flow channel in the high-speed air channel; the cavity sphere 9 connected by the filling and discharging pipeline 10 is ensured to be coaxial with the flow channel in the axial direction.

[0042] In addition, parameters such as the front-to-back pressure difference can be measured to fit the empirical correlation of the frost layer and form a corresponding relationship, and then the water vapor content of the inlet airflow can be reversely calculated through the pressure difference.

[0043] Furthermore, the filling and discharging pipeline 10 is connected to a support assembly. The support assembly includes a base 13, which is connected to the high-speed air duct through a plurality of flow channel support frames 12, and a support platform 11 is provided on the base 13, and the filling and discharging pipeline 10 is provided on the support platform 11.

[0044] The support platform 11 and the flow channel support frame 12 are fixed on a base 13 with a through groove to ensure coaxiality in the axial direction.

[0045] Furthermore, the high-speed air duct is a cylindrical flow channel.

[0046] The key flow field parameters are monitored at the inlet, outlet and throat of the flow channel to fit the empirical correlation equation of frosting and form a corresponding relationship. The water vapor content of the inlet airflow can then be reversely inferred by the pressure difference.

[0047] Specifically, multiple sensors are arranged at the inlet and outlet and throat of the flow channel to monitor key operating parameters. The amount of frost is determined by the moisture content and flow rate of the inlet and outlet airflows. Then, the empirical correlation formula of the frost layer is fitted by parameters such as the front and rear pressure difference to obtain the law of frost formation, thereby achieving the purpose of reversely calculating the water vapor content of the inlet and outlet airflow through parameters such as the front and rear pressure difference.

[0048] The cavity sphere 9 is connected to the support platform 11 through the filling and discharge pipeline 10, extending from the flow channel outlet to the throat position, and ensuring that the cavity sphere 9 is inside the cylindrical flow channel, plays a role in changing the flow field, thereby changing the cross-sectional area of ​​the flow channel, achieving the effect of a zoom nozzle, and allowing the airflow to reach a supersonic state through the cavity sphere. The shape of the flow channel and the shape of the object being measured are not limited to this.

[0049] Although the present application is described above with reference to specific embodiments, it should be understood by those skilled in the art that many modifications may be made to the configurations and details disclosed in the present application within the principles and scope disclosed in the present application. The scope of protection of the present application is determined by the appended claims, and the claims are intended to cover all modifications contained in the equivalent literal meaning or scope of the technical features in the claims.

Claims

1. A frosting experimental device, characterized in that: It comprises a schlieren generating mechanism, a high-speed air duct and a temperature control mechanism, wherein the schlieren generating mechanism comprises a light source component and a schlieren observing component, wherein the light source component is arranged on one side of the high-speed air duct, the schlieren observing component is arranged on the other side of the high-speed air duct, and the temperature control mechanism is arranged in the high-speed air duct. When the high-speed airflow in the high-speed air duct passes through the temperature control mechanism, the airflow can reach a supersonic state at the temperature control mechanism due to the change in the flow cross-sectional area; the high-speed air duct is made of a transparent material; The light source assembly includes a light source and a first reflector arranged in sequence, a first concave mirror is arranged between the light source and the first reflector, and the schlieren observation assembly includes a second reflector, a blade and a high-speed camera arranged in sequence, a second concave mirror is arranged between the blade and the high-speed camera; the light emitted by the light source is reflected by the first reflector to the first concave mirror, passes through the high-speed air duct, is reflected by the second concave mirror to the second reflector, and then passes through the blade to form light and dark alternating schlieren on the high-speed camera.

2. The frosting experimental device according to claim 1, characterized in that: The light emitted by the light source assembly passes through the high-speed air duct and reaches the Schlieren observation assembly.

3. The frosting experimental device according to claim 1, characterized in that: The temperature control mechanism includes a hollow sphere and an injection and discharge pipeline connected to each other. The injection and discharge pipeline includes a gas injection and discharge pipe and a liquid injection and discharge pipe. The gas injection and discharge pipe is connected to the hollow sphere, and the liquid injection and discharge pipe extends into the interior of the hollow sphere.

4. The frosting experimental device according to claim 3, characterized in that: The filling and discharging pipeline is connected with the supporting assembly.

5. The frosting experimental device according to claim 4, characterized in that: The support assembly comprises a base, the base is connected to the high-speed air duct through a plurality of flow channel support frames, a support platform is arranged on the base, and the filling and discharging pipeline is arranged on the support platform.

6. The frosting experimental device according to claim 5, characterized in that: The high-speed air channel is a cylindrical flow channel.

7. An application of the frosting experimental device according to any one of claims 1 to 6, characterized in that: The device is used to observe the flow field characteristics of the frost layer surface and the influence of shock waves on the frost layer from subsonic to supersonic conditions.

8. The use of the frosting experimental device according to claim 7, characterized in that: The device is applied to a frosting experiment or a defrosting experiment.

Images