Device and method for generating liquid drops in flow field of supersonic wind tunnel

Abstract

The invention belongs to the technical field of supersonic wind tunnel experiment fluid mechanics, and discloses a device and method for achieving supersonic wind tunnel flow field droplet generation, and the device for achieving supersonic wind tunnel flow field droplet generation comprises a plurality of nozzles; the device comprises a test section, a spray pipe, a spray pipe diaphragm, a heating section, a quick valve, a high-pressure gas source, an injector filled with a condensation nucleus solution, an injector filled with water, a vacuum gauge, a pressure sensor, a thermocouple, a vacuum pump set, a diluted gas tank and a reversing valve, the method for generating the supersonic wind tunnel flow field liquid drops comprises the following steps: step 1, determining the requirements of the test working condition on the temperature, pressure and components of test gas; 2, test gas meeting the working condition requirement is configured in the heating section; and step 3, opening the quick valve, breaking the nozzle diaphragm, forming a stable supersonic flow field in the test section by the gas through the nozzle, and carrying liquid drops formed by cooling in the flow field. According to the invention, liquid drop condensation formation of a supersonic flow field under a specific working condition is realized.

Description

Technical Field

[0001] The present application relates to a device and method for realizing droplet generation in a supersonic wind tunnel flow field, and belongs to the technical field of supersonic wind tunnel experimental fluid mechanics. Background Art

[0002] Supersonic wind tunnel testing is the main means of conducting relevant basic aerodynamic research and supersonic aircraft engineering design. Its greatest advantage is that it can conduct a large number of ground tests at a relatively low cost, obtain relevant aerodynamic and thermal physical laws, and provide basic measurement data for aerodynamic research and aircraft engineering design.

[0003] The Ludwig tube mode is one of the main modes for establishing supersonic wind tunnel flow fields with Mach numbers of 2-4. The main body of the Ludwig tube wind tunnel is mainly composed of a long tube heating section with equal diameter, one end of which is the front-stage high-pressure gas source, and the other end is equipped with a diaphragm or a fast valve connected to the nozzle, test section and vacuum tank. After the membrane is broken, the high-pressure gas in the heating section will expand toward the vacuum area downstream of the nozzle, generating a beam of expansion waves. After the expansion wave, there will be a section of uniform airflow for test measurement.

[0004] The current supersonic wind tunnel tests have increasingly higher requirements for simulation effects, one of which is the requirement for droplets in the wind tunnel flow field, so as to facilitate the study of the impact of droplets on the surface of the aircraft or the change trend of droplets after flying over the shock wave. However, the current supersonic wind tunnels lack the equipment and methods to generate larger droplets and ensure that the droplets do not turn into ice crystals, which restricts the further development of related experiments. Summary of the invention

[0005] In order to solve the problem of generating larger droplets in a supersonic wind tunnel flow field and ensure that the droplets do not turn into ice crystals, the present application provides a device and method for realizing droplet generation in a supersonic wind tunnel flow field.

[0006] Technical solution 1 adopted in this application: A device for realizing droplet generation in a supersonic wind tunnel flow field, comprising: a test section, a nozzle, a nozzle diaphragm, a heating section, a fast valve, a high-pressure gas source, a syringe filled with a condensation nucleus solution, a syringe filled with water, a vacuum gauge, a pressure sensor, a thermocouple, a vacuum pump group, a dilution gas tank and a reversing valve; The nozzle and the heating section are connected via a nozzle diaphragm, and the heating section and the high-pressure gas source are connected via a quick valve; The heating section is equipped with a syringe of condensation nucleus solution, a syringe filled with water, a vacuum gauge, a pressure sensor and a thermocouple; The vacuum gauge, pressure sensor and thermocouple are used to measure the vacuum pressure, pressure and temperature of the gas inside the heating section in real time; The vacuum pump group and the dilution gas tank are connected to the heating section through a reversing valve, and the vacuum pump group is used for extracting and pressurizing the gas inside the heating section.

[0007] Furthermore, the heating temperature range of the heating section is 300-950K, which ensures that the static pressure of the supersonic flow field after the nozzle is between 6 kPa-10 kPa and the static temperature is between 273-313K, so that the water vapor condenses into droplets rather than ice crystals.

[0008] Furthermore, the pressure in the heating section is 10 kPa-1000 kPa.

[0009] Technical solution 2 adopted in this application: A method for realizing droplet generation in a supersonic wind tunnel flow field is implemented by using a device for realizing droplet generation in a supersonic wind tunnel flow field as described in technical solution 1, and comprises the following steps: Step 1: Determine the pressure, temperature and water vapor concentration of the required test gas in the heating section according to the test conditions, and thereby determine the mass of water that needs to be passed into the heating section; Step 2: Turn on the vacuum pump group to extract the original gas inside the heating section, and observe the vacuum gauge until the original gas inside is completely extracted; then use a syringe filled with condensation nucleus solution and a syringe filled with water to introduce water and condensation nuclei into the heating section, and start heating the heating section to gradually turn the introduced water into water vapor gas. The mass of the introduced water is determined by step 1; then, introduce dilution gas into the heating section, continue to heat the heating section, control the temperature and pressure inside the heating section, and make the injected water and condensation nucleus solution completely evaporate into water vapor and floating condensation nuclei; control the temperature and pressure inside the heating section to allow the test gas to slowly reach the target requirements.

[0010] Step 3: Open the quick valve, the nozzle diaphragm ruptures, and the test gas passes through the nozzle to form a stable supersonic flow field in the test section, and the flow field will contain droplets formed by cooling.

[0011] Furthermore, the test gas includes water vapor gas and dilution gas.

[0012] This application has the following beneficial effects: The present application can freely configure the heating section test gas with specific water vapor and condensation nucleus concentrations, configure the temperature and pressure in the heating section according to the nozzle Mach number, and condense water vapor into droplets rather than ice crystals in the supersonic flow field static pressure behind the nozzle between 6 kPa-10 kPa, that is, the static temperature is between 273 and 313K. This achieves the condensation formation of droplets in the supersonic flow field under specific working conditions, solves the problem of generating larger droplets in the supersonic wind tunnel flow field and ensuring that the droplets do not turn into ice crystals, and fills the gap in the insufficient simulation capabilities of specific working conditions such as the force analysis of droplets impacting an aircraft and the droplets passing through shock waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the device structure for droplet generation in supersonic wind tunnel flow field.

[0014] In the figure: 1. test section, 2. nozzle, 3. nozzle diaphragm, 4. heating section, 5. quick valve, 6. high-pressure gas source, 7. syringe filled with condensation nucleus solution, 8. syringe filled with water, 9. vacuum gauge, 10. pressure sensor, 11. thermocouple, 12. vacuum pump group, 13. dilution gas tank, 14. reversing valve. DETAILED DESCRIPTION

[0015] The following will be combined with the attached Figure 1 The present application is described in detail. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of the structure and technical common knowledge is omitted to avoid unnecessary confusion of the concept of the present application.

[0016] Embodiment 1: Combination Figure 1 The present application discloses a device for realizing droplet generation in a supersonic wind tunnel flow field, comprising: a test section 1, a nozzle 2, a nozzle diaphragm 3, a heating section 4, a fast valve 5, a high-pressure gas source 6, a syringe filled with a condensation nucleus solution 7, a syringe filled with water 8, a vacuum gauge 9, a pressure sensor 10, a thermocouple 11, a vacuum pump group 12, a dilution gas tank 13 and a reversing valve 14; The nozzle 2 is connected to the heating section 4 via a nozzle diaphragm 3, and the heating section 4 is connected to the high-pressure gas source 6 via a quick valve 5; The heating section 4 is sequentially connected with: a syringe 7 of condensation nucleus solution, a syringe 8 filled with water, a vacuum gauge 9, a pressure sensor 10, a thermocouple 11, a vacuum pump group 12 and a dilution gas tank 13; The vacuum gauge 9, pressure sensor 10 and thermocouple 11 are used to measure the vacuum pressure, pressure and temperature of the gas inside the heating section 4 in real time. The vacuum pump group 12 and the dilution gas tank 13 realize the extraction and pressurization of the gas inside the heating section 4 through the reversing valve 14.

[0017] Furthermore, the vacuum pressure of the gas inside the heating section 4 is 6 kPa-10 kPa, and the pressure is 10 kPa-1000 kPa.

[0018] Furthermore, the heating section 4 has the ability to heat the internal gas to a temperature range of 300-950K, ensuring that the static pressure of the supersonic flow field after the nozzle 2 is between 6 kPa-10 kPa and the static temperature is between 273-313K, within which range the water vapor condenses into droplets rather than ice crystals.

[0019] Embodiment 2: The present application also discloses a method for realizing droplet generation in a supersonic wind tunnel flow field, which is realized by using the device for realizing droplet generation in a supersonic wind tunnel flow field described in Embodiment 1, and comprises the following steps: Step 1: Determine the pressure, temperature and water vapor concentration of the required test gas in the heating section 4 according to the test conditions, thereby determining the mass of water that needs to be introduced into the heating section 4; Step 2, turn on the vacuum pump group 12 to extract the original gas inside the heating section 4, and observe the vacuum gauge 9 until the original gas inside is completely extracted; then use the syringe 7 filled with condensation nucleus solution and the syringe 8 filled with water to introduce water and condensation nuclei into the heating section 4, and start heating the heating section 4 to gradually turn the introduced water into water vapor gas, and the quality of the introduced water is determined by step 1; then, introduce dilution gas into the heating section 4, continue to heat the heating section 4, control the temperature and pressure inside the heating section 4, so that the injected water and condensation nucleus solution completely evaporate into water vapor and floating condensation nuclei; control the temperature and pressure inside the heating section 4 to allow the test gas to slowly reach the target requirements.

[0020] Step 3: Open the quick valve 5, the nozzle diaphragm 3 ruptures, and the test gas passes through the nozzle 2 to form a stable supersonic flow field in the test section 1, and the flow field will contain droplets formed by cooling.

[0021] Furthermore, the test gas includes water vapor gas and dilution gas.

[0022] Working principle and process: In the heating section 4, the test gas with a specific pressure, temperature and water vapor concentration is prepared by means of a vacuum pump group 12, a dilution gas 13, a syringe 7 filled with a condensation nucleus solution and a syringe 8 filled with water. The specific method is as follows: First, the gas inside the heating section 4 is evacuated by the vacuum pump group 12, and a known mass of water and condensation nucleus solution is injected into the heating section 4 according to the internal volume of the heating section 4 and the temperature, pressure and water vapor concentration of the target test gas. Then, the gas inside the heating section 4 is heated, and the dilution gas 13 is introduced into the heating section 4 at the same time, and the temperature and pressure inside the heating section 4 are controlled to meet the target test gas requirements.

[0023] In this process, the injected water and condensation nucleus solution will completely evaporate into water vapor and floating condensation nuclei. The guidelines for configuring the temperature and pressure inside the heating section 4 are: According to the three-phase diagram of water, in order to ensure that the water vapor in the supersonic flow field after the nozzle 2 condenses into droplets, it is necessary to configure the temperature and pressure inside the heating section 4 according to the Mach number of the nozzle 2, to ensure that the static pressure of the supersonic flow field after the nozzle 2 is between 6 kPa-10 kPa, and the static temperature is between 273-313K, that is, the static temperature is between 0 and 40 ° C. In this temperature and pressure range, the water vapor condenses into droplets rather than ice crystals.

[0024] The test gas containing a specific concentration of water vapor and condensation nuclei inside the heating section 4 will rapidly cool down due to expansion after passing through the nozzle 2 after the nozzle diaphragm 3, thereby quickly gathering water molecules on the condensation nuclei to condense into the required droplets, thereby realizing a supersonic flow field with droplets in the test section 1.

[0025] Based on the above working principle, the present application provides a device and method for realizing droplet generation in a supersonic wind tunnel flow field, which solves the problem of generating larger droplets in a supersonic wind tunnel flow field and ensuring that the droplets do not turn into ice crystals.

[0026] The above embodiments are merely illustrative of the principles and effects of the present application, and are not intended to limit the present application. Anything within the technical concept disclosed in the present application, and any simple replacement or change based on the technical solution of the present application, shall fall within the protection scope of the present application.

Claims

1. A device for realizing droplet generation in a supersonic wind tunnel flow field, characterized in that: include: A test section (1), a nozzle (2), a nozzle diaphragm (3), a heating section (4), a quick valve (5), a high-pressure gas source (6), a syringe filled with a condensation nucleus solution (7), a syringe filled with water (8), a vacuum gauge (9), a pressure sensor (10), a thermocouple (11), a vacuum pump unit (12), a dilution gas tank (13) and a reversing valve (14); The nozzle (2) and the heating section (4) are connected via a nozzle diaphragm (3), and the heating section (4) and the high-pressure gas source (6) are connected via a quick valve (5); The heating section (4) is equipped with a syringe (7) containing a condensation nucleus solution, a syringe (8) filled with water, a vacuum gauge (9), a pressure sensor (10) and a thermocouple (11); The vacuum gauge (9), pressure sensor (10) and thermocouple (11) are used to respectively measure the vacuum pressure, pressure and temperature of the gas inside the heating section (4) in real time; The vacuum pump group (12) and the dilution gas tank (13) are connected to the heating section (4) via a reversing valve (14); the vacuum pump group (12) is used to extract and pressurize the gas inside the heating section (4).

2. The device for realizing droplet generation in a supersonic wind tunnel flow field according to claim 1, characterized in that: The heating temperature range of the heating section (4) is 300-950K, ensuring that the static pressure of the supersonic flow field after the nozzle (2) is between 6 kPa-10 kPa and the static temperature is between 273-313K, so that the water vapor condenses into droplets rather than ice crystals.

3. The device for realizing droplet generation in a supersonic wind tunnel flow field according to claim 1, characterized in that: The pressure in the heating section (4) is 10 kPa-1000 kPa.

4. A method for realizing droplet generation in a supersonic wind tunnel flow field, implemented by using a device for realizing droplet generation in a supersonic wind tunnel flow field according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Determine the pressure, temperature and water vapor concentration of the required test gas in the heating section (4) according to the test conditions, thereby determining the mass of water that needs to be introduced into the heating section (4); Step 2: Turn on the vacuum pump group (12) to extract the original gas inside the heating section (4), and observe the vacuum gauge (9) until the original gas inside is completely extracted; then use a syringe (7) filled with a condensation nucleus solution and a syringe (8) filled with water to introduce water and condensation nuclei into the heating section (4), and start heating the heating section (4) so ​​that the introduced water gradually turns into water vapor gas, and the mass of the introduced water is determined by step 1; then, introduce dilution gas into the heating section (4), continue to heat the heating section (4), control the temperature and pressure inside the heating section (4), so that the injected water and condensation nucleus solution completely evaporate into water vapor and floating condensation nuclei; control the temperature and pressure inside the heating section (4) so ​​that the test gas slowly reaches the target requirement; Step 3: Open the quick valve (5), the nozzle diaphragm (3) ruptures, and the test gas passes through the nozzle (2) to form a stable supersonic flow field in the test section (1), and the flow field will contain droplets formed by cooling.

5. The method for realizing droplet generation in a supersonic wind tunnel flow field according to claim 4, characterized in that: The test gas includes water vapor gas and dilution gas.

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