Device and method for testing ultra-micro flow of liquid propellant

Abstract

The invention relates to the technical field of liquid ultra-micro flow measurement, and particularly discloses a liquid propellant ultra-micro flow testing device and method, and the method comprises the steps: S1, applying pressure to a pressure source of a supply system to control the output of a liquid propellant, the output flow of the liquid propellant is controlled by adjusting parameters of an electromagnetic valve in a supply pipeline, and the ultra-micro flow of the output liquid propellant is achieved by continuously optimizing and adjusting the on-off frequency and the duty ratio of a pressure source and the electromagnetic valve. S2, obtaining the length of the liquid propellant flowing through the supply pipeline within a preset time through a camera, and calculating the liquid volume of the liquid propellant according to the length and the cross sectional area of the supply pipeline; and S3, the mass flow of the liquid propellant is calculated according to the liquid volume and the liquid density of the liquid propellant, and ultra-micro flow testing of the liquid propellant is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of liquid ultra-micro flow measurement, and in particular to a testing device and a testing method for the ultra-micro flow of a liquid propellant. Background Art

[0002] In liquid working fluid micro-thrusters, it is necessary to build a high-precision micro-flow supply system to transport liquid working fluid through micro-channels. The propellant supply of the supply system of high specific impulse and high total impulse liquid working fluid micro-thrusters is micro-flow or ultra-micro-flow supply. During the liquid working fluid ignition test in the micro-thruster combustion chamber, it is necessary to accurately measure and monitor the micro-flow liquid propellant flow. The measurement accuracy, precision and measurement range are of great significance to the development of liquid working fluid micro-thrusters and the evaluation of propulsion performance.

[0003] At present, the main methods used for measuring micro-flow and ultra-micro-flow are flow meter method, weighing method and pressure difference method. The flow meter method is to directly detect the performance of the liquid output device through the flow meter, but the flow meter itself needs to be calibrated by the mass method. In addition, the flow meter needs to be introduced into the pipeline, which is easy to affect the control of the flow at the supply end, increase the gas content of the pipeline and block the pipeline. The weighing method calculates the flow by measuring the mass change of the supplied liquid working fluid, but the micro-flow measurement operation time is long, and the liquid is easily affected by volatilization and residue. The measurement accuracy. The pressure difference method calculates the flow based on the pressure difference generated when the liquid working fluid flows in the pipeline. However, the measurement accuracy of ultra-micro flow is easily affected by the temperature in the environment and the vibration generated when the thruster is working.

[0004] Therefore, when measuring micro-flow, especially ultra-micro-flow, the accuracy, measurement precision and measurement range of the existing measurement methods cannot meet the requirements, and the operation time is long and the structure of the measurement device is complex, which limits the development and performance evaluation of micro-thrusters. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a testing device and method for ultra-micro flow of liquid propellant, so as to solve the problems that the existing flow testing device has a complex structure, a large volume, a long operation time of the testing method, and measurement accuracy, and the measurement precision and measurement range cannot meet the requirements.

[0006] The present invention provides a method for testing ultra-micro flow of liquid propellant, comprising: Step S1, controlling the output of liquid propellant by applying pressure to a pressure source of a supply system, controlling the flow rate of the liquid propellant output by adjusting the parameters of a solenoid valve in a supply pipeline, and achieving an ultra-micro flow rate of the liquid propellant output by continuously optimizing and adjusting the pressure source, the on-off frequency and the duty cycle of the solenoid valve; Step S2, obtaining, by means of a camera, the length of the liquid propellant flowing through the supply pipeline within a preset time, and calculating the liquid volume of the liquid propellant according to the length and the cross-sectional area of ​​the supply pipeline; Step S3, calculating the mass flow rate of the liquid propellant according to the liquid volume and the liquid density of the liquid propellant, and realizing ultra-micro flow test of the liquid propellant.

[0007] In a possible implementation, step S2 includes: The liquid volume of the liquid propellant output by the supply system within the preset time is calculated based on the cross-sectional area of ​​the supply pipeline, the initial position of the selected liquid level and the terminal position of the liquid level flowing through the supply pipeline within the preset time.

[0008] In a possible implementation, the calculating the liquid volume of the liquid propellant output by the supply system within the preset time according to the cross-sectional area of ​​the supply pipeline, the initial position of the selected liquid level, and the terminal position of the liquid level flowing through the supply pipeline within the preset time includes: The volume of liquid output by the supply system within the preset time is calculated according to the following formula : ; In the formula, is the cross-sectional area of ​​the supply pipeline, To select the initial position of the liquid surface, It is the end position of the liquid flowing through the pipeline within the preset time. is the inner diameter of the supply line.

[0009] In a possible implementation, step S3 includes: Calculating the volume flow rate output by the supply system according to the liquid volume and the preset time; The mass flow rate of the liquid propellant is obtained according to the volume flow rate and the density of the liquid propellant.

[0010] In a possible implementation, the calculating the volume flow rate output by the supply system according to the liquid volume and the preset time includes: The volume flow rate output by the supply system is calculated according to the following formula: : ; In the formula, For preset time, is the liquid volume of the liquid propellant.

[0011] In a possible implementation, obtaining the mass flow rate of the liquid propellant according to the volume flow rate and the density of the liquid propellant includes: The mass flow rate of the liquid propellant is calculated according to the following formula for: ; In the formula, is the density of the liquid propellant, is the volume flow rate output from the supply system; The average mass flow rate of liquid propellant is calculated according to the following formula for: ; In the formula, is the mass flow rate of liquid propellant, is the number of mass flow rate.

[0012] The present invention also provides a liquid propellant ultra-micro flow testing device for executing any of the above-mentioned liquid propellant micro-flow testing methods, comprising: a supply system, a solenoid valve, a scale, a supply pipeline, a camera and a timer; The supply pipeline is connected to the output end of the supply system, and the solenoid valve is arranged on the supply pipeline; The scale is arranged at the outlet of the solenoid valve and is used to measure the flow rate of the liquid propellant in the supply pipeline; The camera is aimed at the ruler to record the data on the ruler; the timer is used for timing.

[0013] In a possible implementation manner, the supply pipeline is a transparent pipeline.

[0014] In a possible implementation manner, the supply pipeline is a pipeline with a rectangular cross-section, a circular cross-section, a polygonal cross-section, or an irregular cross-section.

[0015] In a possible implementation, the flow output mode of the supply system is continuous output, interval mode output or pulse output.

[0016] The liquid propellant ultra-micro flow test device and test method provided by the present invention are simple to operate, short in test operation time, simple in test device structure, and simplified in test device, which is convenient for the development and use of liquid working fluid micro-thrusters; can realize fast, accurate, wide-range and high-precision measurement of the mass flow rate at the output end of the micro-flow supply system; can realize real-time recording of the liquid working fluid transport state in the micro-flow supply system, which is helpful for analyzing the influence of the mass flow supply of the micro-thruster on the thrust, provides data support for the development of the micro-thruster, and has better usability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a test method according to an embodiment of the present invention; Figure 2 A schematic diagram of a testing device provided in an embodiment of the present invention; Figure 3 A diagram of a power supply output signal for controlling a solenoid valve switch provided in an embodiment of the present invention; Figure 4 A diagram showing the initial position of the liquid level in a transparent pipeline provided by an embodiment of the present invention; Figure 5 A position diagram of the liquid level in the transparent pipeline after the solenoid valve provided by the embodiment of the present invention has been switched 1000 times; Figure 6 A cross-sectional view of a test transparent pipeline provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following detailed description of the embodiments of the present invention is further described in detail in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the preferred embodiments described, and the scope of the present invention is defined by the claims.

[0019] In the description of the present invention, it should be noted that, unless otherwise specified, “plurality” means two or more than two; the terms “first”, “second”, etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0020] Figure 2 A schematic diagram of a test device provided in an embodiment of the present invention, such as Figure 2 As shown, the liquid propellant micro-flow testing device provided by the present invention comprises: a supply system 1, a solenoid valve 2, a scale 3, a supply pipeline 4, a camera 5 and a timer 6; The supply pipeline 4 is connected to the output end of the supply system 1, and the solenoid valve 2 is arranged on the supply pipeline 4; The scale 3 is arranged at the outlet of the solenoid valve 2 and is used to measure the flow rate of the liquid propellant in the supply pipeline 4; The camera 5 is aimed at the ruler 3 and is used to record the data on the ruler 3; the timer 6 is used for timing.

[0021] In a possible implementation, the supply pipeline is a transparent pipeline. The transparent pipeline material can be quartz, polycarbonate, polyvinyl chloride, polyvinylidene fluoride, polyurethane, Teflon, etc. The inner diameter of the transparent pipeline can be ultra-micro inner diameter, small inner diameter and large inner diameter. In a possible implementation, the configuration of the transparent pipeline includes microchannel pipelines such as rectangular cross-section, circular cross-section, polygonal cross-section and irregular cross-section.

[0022] In a possible implementation, the accuracy of the ruler is 0.1 mm. The ruler can be a high-precision microscopic ruler, a high-precision film ruler, a grid ruler, etc.

[0023] In a possible implementation, the device for observing the liquid level position and the inner diameter of the pipeline can be a digital microscope, a high-speed camera, an optical microscope, a fluorescence microscope, an electron microscope, etc.

[0024] In a possible implementation, the timer may be an electronic timer, a high-precision multimedia timer, an atomic clock, etc.

[0025] Figure 1 A flow chart of a test method provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the present invention provides a method for testing ultra-micro flow of liquid propellant, comprising: Step S1, controlling the output of liquid propellant by applying pressure to the pressure source of the supply system, controlling the flow rate of the liquid propellant output by adjusting the parameters of the solenoid valve in the supply pipeline, and achieving an ultra-micro flow rate of the output liquid propellant by continuously optimizing and adjusting the pressure source, the on-off frequency and the duty cycle of the solenoid valve; Figure 3 The power output signal diagram of the solenoid valve switch provided by the embodiment of the present invention is as follows: Figure 3 As shown, the on-off voltage of the solenoid valve is 5V, the on-off frequency of the solenoid valve is 1Hz, and the on-off duty ratio is 1:1.

[0026] Specifically, the flow rate is controlled by adjusting the supply system pressure source, supply pipeline configuration and the on-off switching of the solenoid valve.

[0027] Supply pressure includes supply pressure generated by piston type, mechanical transmission shaft type and pneumatic type.

[0028] The ways of opening and closing pipeline valves include ball valves, gate valves, butterfly valves and other valves that can effectively control the opening and closing of pipelines.

[0029] The configuration of the transparent pipeline includes microfluidic pipelines with rectangular cross-section, circular cross-section and polygonal cross-section.

[0030] The pressure adjustment range of the supply system is 0-10MPa and the flow rate adjustment range is 0-1000µg / s.

[0031] In a possible implementation, the liquid propellant may be water, ethanol, liquid oxygen, energetic ionic liquid, magnetic fluid, liquid metal, kerosene, etc.

[0032] In a possible implementation, the flow output mode of the supply system can be continuous output, interval mode output and pulse output.

[0033] In a possible implementation, the flow rate test method of the supply system can be selected as the average flow rate measured multiple times at different liquid column lengths within a fixed time period, or can be selected as the average flow rate measured multiple times at a fixed liquid column length and different flow times.

[0034] In a possible implementation, the liquid level position difference may be measured by directly reading the scale interval and measuring with a microscope image measurement software.

[0035] In a possible implementation, the flow test value of the supply system may be an average flow over a period of time, or an instantaneous flow in a very short period of time.

[0036] In a possible implementation, the flow test value of the supply system may be a mass flow rate or a volume flow rate.

[0037] Step S2, obtaining the length of the liquid propellant flowing through the supply pipeline within a preset time through a camera, and calculating the liquid volume of the liquid propellant according to the length and the cross-sectional area of ​​the supply pipeline; In a possible implementation, step S2 includes: The liquid volume of the liquid propellant output by the supply system within the preset time is calculated based on the cross-sectional area of ​​the supply pipeline, the initial position of the selected liquid level, and the terminal position of the liquid level flowing through the supply pipeline within the preset time; In a possible implementation, the liquid volume of the liquid propellant output by the supply system within a preset time is calculated based on the cross-sectional area of ​​the supply pipeline, the initial position of the selected liquid surface, and the terminal position of the liquid surface flowing through the supply pipeline within a preset time, including: Calculate the volume of liquid delivered by the supply system within a preset time using the following formula : ; In the formula, is the cross-sectional area of ​​the supply pipeline, To select the initial position of the liquid surface, It is the end position of the liquid flowing through the pipeline within the preset time. is the inner diameter of the supply line.

[0038] Figure 4The initial position diagram of the liquid level in the transparent pipeline provided in the embodiment of the present invention uses a camera to record the flow state of the liquid level in the transparent pipeline, and selects the position on the ruler where the liquid volume is easy to calculate as the initial liquid level position.

[0039] Figure 5 A position diagram of the liquid level in the transparent pipe after the solenoid valve is switched 1000 times provided in an embodiment of the present invention is provided. A digital camera is used to record the flow state of the liquid level in the transparent pipe, and the position to which the liquid level flows within a fixed time is selected as the terminal liquid level position. When the solenoid valve works at 1 Hz, the time taken for the solenoid to switch 1000 times is 1000 s.

[0040] Figure 6 The cross-sectional diagram of the test transparent pipeline provided in the embodiment of the present invention is that a small section of the pipeline is cut off by a pipeline cutter, and the cross-section of the pipeline is observed by a camera. The hollow position inside the pipeline is the cross-section of the liquid surface, and the cross-sectional diameter is recorded as D. In this case, a transparent pipeline (FLUIGENT) with an inner diameter D of about 500μm and an outer diameter of 1 / 16in imported from France is selected as a volume measurement tool, and the inner diameter of the pipeline is measured and verified by a microscope system.

[0041] Step S3, calculating the mass flow rate of the liquid propellant according to the liquid volume and the liquid density of the liquid propellant, and realizing the ultra-micro flow rate test of the liquid propellant.

[0042] In a possible implementation, step S3 includes: The volume flow rate output by the supply system is calculated based on the liquid volume and the preset time; The mass flow rate of the liquid propellant is obtained based on the volume flow rate and the density of the liquid propellant.

[0043] In a possible implementation, calculating the volume flow rate output by the supply system according to the liquid volume and the preset time includes: The volume flow rate of the supply system output is calculated according to the following formula: : ; In the formula, For preset time, is the liquid volume of the liquid propellant.

[0044] In a possible implementation, obtaining the mass flow rate of the liquid propellant according to the volume flow rate and the density of the liquid propellant includes: The mass flow rate of liquid propellant is calculated according to the following formula for: ; In the formula, is the density of the liquid propellant, is the volume flow rate output from the supply system; In order to more accurately measure the value of mass flow in a certain period of time, the average value method of multiple measurements can also be used.

[0045] The average mass flow rate of liquid propellant is calculated according to the following formula for: ; In the formula, is the mass flow rate of liquid propellant, is the number of mass flow rate.

[0046] The application of the above-mentioned ultra-micro flow test method of liquid propellant in measurement is as follows: (1) Ultra-micro flow output and regulation steps of the supply system: Use solenoid valve and pressure source to regulate the flow output of the supply system.

[0047] First, a micro-flow test system was built to apply supply pressure to the supply pressure source of the supply system. The pneumatic pressure was controlled to 100 mbar, 200 mbar, 500 mbar and other conditions to achieve stable output of liquid propellant.

[0048] Then, the electrical parameters of the solenoid valve in the output pipeline are adjusted to control the flow output of the liquid propellant. The rated input voltage of the solenoid valve is 5V. The resistance of the solenoid valve coil is measured to be 27.19Ω. The program-controlled power supply is the input voltage of the solenoid valve, and the voltage-time curve is recorded.

[0049] Finally, the pressure source, the on-off frequency of the solenoid valve and the duty cycle are appropriately adjusted to achieve the output of ultra-micro flow. The on-off frequency of the solenoid valve is set to 1 Hz and the duty cycle is set to 1:1.

[0050] (2) Test steps for measuring the volume of liquid flowing through the pipeline in a fixed time: Connect the downstream outlet of the supply system to the measuring pipeline, straighten the measuring pipeline and place it horizontally. Use a digital microscope, electronic timer and high-precision ruler to measure the volume of liquid propellant flowing through the pipeline in a fixed time t. The measurement accuracy of the digital microscope is 1µm, the timing error of the electronic timer is 1ms, and the interval of the high-precision ruler is 0.1mm.

[0051] First, prepare all the testing tools and wait for the liquid level in the transparent tube to enter the field of view of the electron microscope.

[0052] Then, when the liquid level flows to a certain position, turn on the electronic timer and the recording function of the digital microscope to record the flow state and flow position of the liquid propellant. The length of the liquid level position difference can be directly read according to the ruler. When the liquid level position difference is small, the length difference of the liquid level position can also be measured by the ruler and the microscopic image. The digital microscope system is synchronized with a timer, and a high-precision timer can also be selected separately for timing.

[0053] Finally, a digital microscope or an optical microscope is used to measure the cross section of the transparent tube, and then the cross section of the liquid in the tube is determined. The interface of the transparent tube is circular, and the inner diameter is about 480µm±1µm. The same method is used to measure the volume of the liquid propellant flowing through multiple times.

[0054] (3) Calculation steps of ultra-micro flow mass flow rate: Use the above test results and the density of the liquid propellant to measure the mass flow rate of the liquid propellant in the supply system.

[0055] First, calculate the fixed time The output volume of the internal supply system is .

[0056] Next, calculate the volume flow rate of the supply system output When ADN-based liquid energetic propellant is selected, the volume flow rate calculated according to the above formula is 7.2nL / s.

[0057] Finally, using the liquid density The volume flow rate Convert to mass flow When ADN-based liquid energetic propellant is used, the density of the propellant is 1.37 g / cm 3 According to the mass flow calculation formula, the mass flow rate is 9.9 µg / s. In order to more accurately measure the mass flow rate in a certain period of time, the average value of the mass flow rate of the liquid propulsion in a certain period of time is obtained by using the average value of multiple measurements. .

[0058] The present invention firstly adjusts the flow rate of the supply system by adjusting the pressure source of the supply system and the solenoid valve to obtain a stable output of the ultra-micro flow rate of the liquid propellant. The transparent pipeline at the output end of the propellant is straightened at a high-precision ruler, and a digital microscope is used to measure the liquid level position of the liquid propellant at different times in the transparent pipeline and the flow state of the liquid propellant. The inner diameter area of ​​the pipeline and the liquid level difference of the liquid propellant are calculated by a digital microscope system and a high-precision ruler, and then the volume of the liquid propellant flowing in the pipeline within a fixed time is calculated. And according to the above-mentioned measured parameters, the volume flow rate and mass flow rate of the ultra-micro flow liquid propellant can be measured.

[0059] The testing device and testing method for ultrafine flow of liquid propellant provided by the present invention have simple structure and operation, high precision, large measuring range, and the test is not affected by the environment and test components, thus simplifying the testing device and testing method; rapid and accurate measurement of ultrafine flow under conditions of different types of propellants can be achieved; real-time recording of the supply situation of the liquid propellant supply system can be achieved, which is helpful for analyzing the transport characteristics of the propellant and the mechanism of thrust formation, and has better usability.

[0060] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for testing ultra-micro flow of liquid propellant, characterized in that: include: Step S1, controlling the output of liquid propellant by applying pressure to a pressure source of a supply system, controlling the flow rate of the liquid propellant output by adjusting the parameters of a solenoid valve in a supply pipeline, and achieving an ultra-micro flow rate of the liquid propellant output by continuously optimizing and adjusting the pressure source, the on-off frequency and the duty cycle of the solenoid valve; Step S2, obtaining, by means of a camera, the length of the liquid propellant flowing through the supply pipeline within a preset time, and calculating the liquid volume of the liquid propellant according to the length and the cross-sectional area of ​​the supply pipeline; Step S3, calculating the mass flow rate of the liquid propellant according to the liquid volume and the liquid density of the liquid propellant, and realizing ultra-micro flow test of the liquid propellant.

2. The testing method according to claim 1, characterized in that: The step S2 comprises: The liquid volume of the liquid propellant output by the supply system within the preset time is calculated based on the cross-sectional area of ​​the supply pipeline, the initial position of the selected liquid level and the terminal position of the liquid level flowing through the supply pipeline within the preset time.

3. The testing method according to claim 2, characterized in that: The method of calculating the liquid volume of the liquid propellant output by the supply system within the preset time according to the cross-sectional area of ​​the supply pipeline, the initial position of the selected liquid level, and the terminal position of the liquid level flowing through the supply pipeline within the preset time comprises: The volume of liquid output by the supply system within the preset time is calculated according to the following formula : ； In the formula, is the cross-sectional area of ​​the supply pipeline, To select the initial position of the liquid surface, It is the end position of the liquid flowing through the pipeline within the preset time. is the inner diameter of the supply line.

4. The testing method according to claim 1, characterized in that: The step S3 comprises: Calculating the volume flow rate output by the supply system according to the liquid volume and the preset time; The mass flow rate of the liquid propellant is obtained according to the volume flow rate and the density of the liquid propellant.

5. The testing method according to claim 4, characterized in that: The step of calculating the volume flow rate output by the supply system according to the liquid volume and the preset time comprises: The volume flow rate output by the supply system is calculated according to the following formula: : ； In the formula, For preset time, is the liquid volume of the liquid propellant.

6. The testing method according to claim 4, characterized in that: The step of obtaining the mass flow rate of the liquid propellant according to the volume flow rate and the density of the liquid propellant comprises: The mass flow rate of the liquid propellant is calculated according to the following formula for: ； In the formula, is the density of the liquid propellant, is the volume flow rate output from the supply system; The average mass flow rate of liquid propellant is calculated according to the following formula for: ； In the formula, is the mass flow rate of liquid propellant, is the number of mass flow rate.

7. A liquid propellant ultra-micro flow testing device, characterized in that: A method for testing a liquid propellant micro-flow rate according to any one of claims 1 to 6, comprising: a supply system, a solenoid valve, a scale, a supply pipeline, a camera and a timer; The supply pipeline is connected to the output end of the supply system, and the solenoid valve is arranged on the supply pipeline; The scale is arranged at the outlet of the solenoid valve and is used to measure the flow rate of the liquid propellant in the supply pipeline; The camera is aimed at the ruler to record the data on the ruler; the timer is used for timing.

8. The testing device according to claim 7, characterized in that: The supply pipeline is a transparent pipeline.

9. The testing device according to claim 7, characterized in that: The supply pipeline is a pipeline with a rectangular cross section, a circular cross section, a polygonal cross section or an irregular cross section.

10. The testing device according to claim 7, characterized in that: The flow output mode of the supply system is continuous output, interval mode output or pulse output.

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