System and method for measuring kinematic viscosity of aviation hydraulic oil

Abstract

The invention provides an aviation hydraulic oil kinematic viscosity measuring system and method, and belongs to the field of aviation hydraulic oil viscosity measurement, and the measuring system comprises a constant-flux pump, a vacuum pump, a liquid inlet cup, a digital acquisition system, a vibrating string main body device, a waste liquid bottle and a thermodetector; the constant-flux pump, the vacuum pump and the liquid inlet cup are gathered and connected to the input end of the vibrating string main body device, the waste liquid bottle is connected to the output end of the vibrating string main body device, and the digital acquisition system and the thermodetector are connected to the interior of the vibrating string main body device through the measuring end of the vibrating string main body device; wherein the vibrating wire main body device is internally provided with a vibrating wire, the digital acquisition system comprises a control terminal, a signal generator and a bidirectional digital lock-in amplifier, and the control terminal is connected with the signal generator, the bidirectional digital lock-in amplifier and the thermodetector. The control terminal controls the signal generator to send an input signal to the vibration wire and controls the bidirectional digital lock-in amplifier to collect an output signal of the vibration wire, and the control terminal calculates the viscosity of the aviation hydraulic oil.

Description

Technical Field

[0001] The present application belongs to the technical field of aviation hydraulic oil viscosity measurement, and in particular relates to a system and method for measuring the kinematic viscosity of aviation hydraulic oil. Background Art

[0002] Hydraulic oil is an important component of the aircraft hydraulic system, and its viscosity is one of the key factors that determine the performance of the aircraft hydraulic system. Viscosity is an indicator of the resistance to fluid flow, which directly affects the fluidity and power transmission efficiency of hydraulic oil in the aircraft hydraulic system. Hydraulic oil with higher viscosity has poor fluidity, which will increase the pressure loss inside the aircraft hydraulic system, resulting in energy waste and reduced response speed of the aircraft hydraulic system, while excessive viscosity will cause difficulty in oil absorption and heating of the aircraft hydraulic system. Oil with lower viscosity has good fluidity and can improve the response speed and efficiency of the aircraft hydraulic system, but too low viscosity may cause insufficient lubrication, increase wear and internal leakage, thereby reducing the overall performance of the aircraft hydraulic system. Hydraulic oil with appropriate viscosity is crucial to ensure the efficient and reliable operation of the aircraft hydraulic system. Regular oil analysis and maintenance are required to ensure that the aircraft hydraulic system maintains stable operation. Summary of the invention

[0003] The purpose of the present application is to provide a system and method for measuring the kinematic viscosity of aviation hydraulic oil to solve or alleviate at least one problem in the background technology.

[0004] On the one hand, the technical solution of the present application is: an aviation hydraulic oil kinematic viscosity measurement system, including: a horizontal flow pump, a vacuum pump, a liquid inlet cup, a digital acquisition system, a vibrating string main body device, a waste liquid bottle and a temperature meter;

[0005] The advection pump, vacuum pump and liquid inlet cup are gathered and connected to the input end of the vibration string main body device, and aviation hydraulic oil is introduced into the vibration string main body device through the liquid inlet cup. The vacuum pump is used to evacuate the vibration string main body device, and the advection pump is used to provide the use environment pressure of the aviation hydraulic oil;

[0006] The waste liquid bottle is connected to the output end of the vibrating string main body device, and the digital acquisition system and the temperature measuring instrument are connected to the inside of the vibrating string main body device through the measuring end of the vibrating string main body device;

[0007] Among them, there is a vibrating wire inside the vibrating string main body device, and the digital acquisition system includes a control terminal, a signal generator and a bidirectional digital phase-locked amplifier. The control terminal is connected to the signal generator, the bidirectional digital phase-locked amplifier and the temperature meter. The control terminal controls the signal generator to send an input signal to the vibrating wire and controls the bidirectional digital phase-locked amplifier to collect the output signal of the vibrating wire. The control terminal obtains the induced voltage by comparing the output signal with the reference signal sent to the phase-locked amplifier, and then obtains the vibration period of the vibrating wire, and obtains the viscosity of the aviation hydraulic oil by solution.

[0008] In an optional embodiment of the present application, the voltage detection range of the bidirectional digital lock-in amplifier 43 is 2nV to 1V, and the accuracy of phase measurement is not less than 0.01°.

[0009] In an optional embodiment of the present application, the signal generator generates a signal frequency with a resolution of μHz.

[0010] In an optional embodiment of the present application, a circulating constant temperature bath is further included to maintain the vibrating string body device within a predetermined temperature range.

[0011] In an optional embodiment of the present application, the circulating bath uses dimethyl silicone oil and anhydrous ethanol as constant temperature media.

[0012] On the other hand, the present application provides a method for measuring the kinematic viscosity of aviation hydraulic oil using any of the above-mentioned systems for measuring the kinematic viscosity of aviation hydraulic oil, comprising:

[0013] Step S10: Determine the operating temperature and pressure range of the aviation hydraulic oil, and perform pressure tests on the vibration string main body device at different temperatures. The pressure during the pressure test is the maximum pressure of the aviation hydraulic oil to ensure that the sealing of the measurement system is not affected by temperature changes.

[0014] Step S20, calibrating the parameters of the vibrating wire in the vibrating string main body device using a calibration liquid, after evacuating the air through a vacuum pump, the control terminal vibrates the vibrating wire through a signal generator, and collects the internal damping of the vibrating wire in a vacuum environment through a bidirectional digital lock-in amplifier to complete the parameter calibration of the vibrating wire;

[0015] Step S30, measuring the vibration period of the vibration wire in the vibration string main body device 50 under various pressure conditions of the aviation hydraulic oil and different temperatures, and obtaining the viscosity value of the aviation hydraulic oil through settlement at the control terminal.

[0016] In an optional embodiment of the present application, the operating temperature range of the aviation hydraulic oil is 218.15K to 408.15K, and the pressure range is 0.1MPa to 30MPa.

[0017] In an optional embodiment of the present application, in step S10, pressure testing the vibrating string main body device at different temperatures includes:

[0018] Testing the vibrating string main body device 50 to a pressure of 30 MPa at room temperature;

[0019] Testing the vibrating string main body device 50 to a pressure of 30 MPa at a high temperature;

[0020] The vibrating string main body device 50 is pressure tested to 30 MPa in a low temperature state.

[0021] In an optional embodiment of the present application, step S30 specifically includes:

[0022] Step S21: adjusting the temperature of the circulating bath to a predetermined temperature, evacuating the vibrating string main body device to a predetermined pressure, and performing vacuum calibration on the vibrating string main body device to obtain the internal damping of the vibrating string main body device;

[0023] Step S22: Calibrate the parameters of the vibrating wire using the viscosity data of the calibration fluid at a predetermined temperature and the minimum pressure state of the aviation hydraulic oil, that is, adjust the parameters of the vibrating wire under the above conditions so that the measured viscosity meets the viscosity data of toluene.

[0024] Step 23: Measure the viscosity values ​​of the calibration fluid for the aviation hydraulic oil pressure range within the known temperature range and compare them with the existing viscosity data to verify the reliability of the measurement system.

[0025] In an optional embodiment of the present application, the calibration fluid is toluene.

[0026] In an optional embodiment of the present application, the predetermined temperature is 298.15K, and the predetermined pressure is below 10Pa.

[0027] In an optional embodiment of the present application, step S30 specifically includes:

[0028] Step S31: setting the pressure of the advection pump according to the test requirements or the use environment pressure of the aviation hydraulic oil;

[0029] Step S32: start the circulating bath to the temperature to be measured, and after the temperature displayed by the temperature meter is stable, measure the vibration period of the vibrating wire in the vibrating string main body device through the digital acquisition system;

[0030] Step S33: After completing one measurement, adjust the temperature of the circulating bath to the next temperature point and continue measuring;

[0031] Step S34: after all the temperature measurements under one pressure condition are completed, the pressure of the advection pump is set and the measurements of different temperatures under the next set of pressure conditions are performed;

[0032] Step S35: Using nonlinear regression to fit the resonance curve into an expression of amplitude and phase, and obtaining the viscosity value of the fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0035] Figure 1 This is a schematic diagram of the aviation hydraulic oil kinematic viscosity measurement point system of this application. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0037] like Figure 1 As shown, the present application provides an aviation hydraulic oil kinematic viscosity measuring system, the measuring system 100 includes: a horizontal flow pump 10, a vacuum pump 20, a liquid inlet cup 30, a digital acquisition system 40, a vibrating string main body device 50, a waste liquid bottle 60 and a thermometer 70.

[0038] The horizontal flow pump 10, the vacuum pump 20 and the liquid inlet cup 30 are connected to the input end of the vibration string main body device 50 through the electromagnetic valves V1 to V3 respectively, and the output end of the vibration string main body device 50 is connected to the waste liquid bottle 60 through the electromagnetic valve V5. The digital acquisition system 40 and the temperature meter 70 extend into the vibration string main body device 50 through the measuring end of the vibration string main body device 50 to measure the viscosity of the aviation hydraulic oil.

[0039] The measured aviation hydraulic oil flows into the vibrating string main body device 50 through the liquid inlet cup 30, and the vacuum pump 20 is used to evacuate the vibrating string main body device 50 and the connecting pipeline to remove impurities in the pipeline. The advection pump 10 is used to deliver the aviation hydraulic oil to the vibrating string main body device 50 after the aviation hydraulic oil enters the pipeline through the liquid inlet cup 30. The pressure of the advection pump 10 can be set according to the actual use environment pressure of the aviation hydraulic oil.

[0040] In some embodiments of the present application, a solenoid valve V4 is provided at the front end of the vibrating string main body device 50, which is used to control the overall flow of the vibrating string main body device 50 by the horizontal flow pump 10, the vacuum pump 20 and the liquid inlet cup 30. Furthermore, a solenoid valve V6 is also provided at the front end of the vibrating string main body device 50, which is used to drain the aviation hydraulic oil at the front end of the vibrating string main body device 50 or to protect the system.

[0041] The digital acquisition system 40 includes a control terminal 41, a signal generator 42 and a bidirectional digital phase-locked amplifier 43. The control terminal 41 is connected to the signal generator 42, the bidirectional digital phase-locked amplifier 43 and the temperature measuring instrument 70. The vibrating string main body device 50 has a vibrating wire inside. The signal generator 42 and the bidirectional digital phase-locked amplifier 43 are connected to the vibrating wire of the vibrating string main body device 50. The control terminal 41 is used to control the signal generator 42 to send an input signal to the vibrating wire and to control the bidirectional digital phase-locked amplifier 43 to collect the output signal of the vibrating wire. The induced voltage is obtained by comparing the output signal with the reference signal sent to the phase-locked amplifier 43, and then the vibration period of the vibrating wire is obtained. The viscosity of the aviation hydraulic oil can be obtained by solving the calculation.

[0042] In the present application, the induced voltage generated by the vibrating wire of the vibrating string main body device 50 in the magnetic field is in the microvolt (μV) level, so the voltage detection range of the bidirectional digital phase-locked amplifier 43 used in the present application is 2nV~1V, the accuracy of the phase measurement is not less than 0.01°, and the resolution of the signal frequency generated by the signal generator 41 is μHz.

[0043] In the present application, the measuring system further includes a circulating constant temperature bath 80, which is used to keep the vibrating string main body device 50 within a certain temperature range. The circulating bath 80 uses dimethyl silicone oil and anhydrous ethanol as constant temperature media to control the temperature of the vibrating string main body device 50 within a certain range.

[0044] The measurement system provided in the present application has a simple and compact structure, requires few samples, is suitable for measurements under extreme conditions such as low temperature and high pressure, has high measurement accuracy, and is easy to realize automated measurement.

[0045] In addition, based on the above-mentioned aviation hydraulic oil kinematic viscosity measuring system 100, the present application also provides an aviation hydraulic oil kinematic viscosity measuring method, comprising the following steps:

[0046] Step S10: Determine the operating temperature and pressure range of the aviation hydraulic oil, and perform pressure tests on the vibrating string main body device 50 at different temperatures. The pressure during the pressure test is the maximum pressure of the aviation hydraulic oil to ensure that the sealing of the measurement system is not affected by temperature changes.

[0047] In the present application, the operating temperature range of the aviation hydraulic oil is 218.15K to 408.15K, and the pressure range is 0.1MPa to 30MPa. Therefore, in step S10 of the present application, the process of pressure testing the vibrating string main body device 50 at different temperatures includes:

[0048] Step S11: testing the pressure of the vibrating string main body device 50 to 30 MPa at room temperature;

[0049] Step S12: testing the pressure of the vibrating string main body device 50 to 30 MPa at a high temperature;

[0050] Step S13: Pressure testing the vibrating string main body device 50 to 30 MPa in a low temperature state.

[0051] It can be understood that in the above pressure testing process, the pressure tests can be carried out in the normal temperature state, the high temperature state and the low temperature state in sequence from low to high temperature, or in sequence from high to low temperature.

[0052] Step S20: After the vacuum is evacuated by the vacuum pump 20, the control terminal 41 makes the vibrating wire vibrate through the signal generator 41, and then the internal damping of the vibrating wire in the vacuum environment is collected through the bidirectional digital phase-locked amplifier 42 to complete the vacuum damping calibration of the vibrating wire, and then the calibration liquid is used to calibrate the parameters of the vibrating wire in the vibrating string main body device 50.

[0053] In a preferred embodiment of the present application, the calibration fluid is toluene, and before calibration, a relationship curve between temperature, pressure and damping of toluene can be obtained through known data.

[0054] In the present application, the parameters of the vibrating wire include length, radius and material, etc. By changing the length, radius and material of the vibrating string in the vibrating string main body device 50, the kinematic viscosity measurement range of the aviation hydraulic oil can be changed.

[0055] In the present application, the specific process of measuring the internal damping of the vibrating string main body device 50 includes:

[0056] Step S21: adjusting the temperature of the circulating bath 80 to a predetermined temperature, evacuating the vibrating string main body device 50 to a predetermined pressure, and performing vacuum calibration on the vibrating string main body device 50 to obtain the internal damping of the vibrating string main body device 50;

[0057] Step S22: Calibrate the parameters of the vibrating wire using the viscosity data of the toluene calibration fluid at a predetermined temperature (298.15K) and the minimum pressure of aviation hydraulic oil (0.1MPa), that is, adjust the parameters of the vibrating wire under the above conditions so that the measured viscosity meets the viscosity data of toluene.

[0058] Step 23: Measure the viscosity of the toluene calibration solution in the temperature range of 273.15K to 363.15K and the pressure range of 0 to 30MPa, and compare it with the existing viscosity data to verify the reliability of the measurement system.

[0059] In some embodiments of the present application, the predetermined temperature is 298.15K, and the predetermined pressure is below 10Pa.

[0060] Step S30 : measuring the vibration period of the vibration wire in the vibration string main body device 50 under various pressure conditions of the aviation hydraulic oil and different temperatures, and obtaining the viscosity value of the aviation hydraulic oil through the settlement of the control terminal 41 .

[0061] Specifically, step S30 of the present application includes the following process:

[0062] Step S31: setting the pressure of the advection pump 10 according to the test requirements or the use environment pressure of the aviation hydraulic oil;

[0063] Step S32: start the circulating bath 80 to the temperature to be measured, and after the temperature displayed by the temperature measuring instrument 70 is stable, measure the vibration period of the vibrating wire in the vibrating string main body device 50 through the digital acquisition system 40;

[0064] Step S33: After completing one measurement, adjust the temperature of the circulating bath 80 to the next temperature point and continue measuring;

[0065] Step S34: After all the temperature measurements under one pressure condition are completed, the pressure of the advection pump 10 is set and the measurements of different temperatures under the next set of pressure conditions are performed;

[0066] Step S35: Using nonlinear regression to fit the resonance curve into an expression of amplitude and phase, and obtaining the viscosity value of the fluid.

[0067] The aviation hydraulic oil viscosity measuring point system and method provided in the present application can conveniently measure the viscosity of the aviation hydraulic oil, so that the oil in the aircraft hydraulic system always maintains an appropriate viscosity, improves the response speed and efficiency of the aircraft hydraulic system, and reduces the wear and leakage of the aircraft hydraulic system.

[0068] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A system for measuring the kinematic viscosity of aviation hydraulic oil, characterized in that: include: Horizontal flow pump, vacuum pump, liquid inlet cup, digital acquisition system, vibrating string main device, waste liquid bottle and thermometer; The advection pump, vacuum pump and liquid inlet cup are gathered and connected to the input end of the vibration string main body device, and aviation hydraulic oil is introduced into the vibration string main body device through the liquid inlet cup. The vacuum pump is used to evacuate the vibration string main body device, and the advection pump is used to provide the use environment pressure of the aviation hydraulic oil; The waste liquid bottle is connected to the output end of the vibrating string main body device, and the digital acquisition system and the temperature measuring instrument are connected to the inside of the vibrating string main body device through the measuring end of the vibrating string main body device; Among them, there is a vibrating wire inside the vibrating string main body device, and the digital acquisition system includes a control terminal, a signal generator and a bidirectional digital phase-locked amplifier. The control terminal is connected to the signal generator, the bidirectional digital phase-locked amplifier and the temperature meter. The control terminal controls the signal generator to send an input signal to the vibrating wire and controls the bidirectional digital phase-locked amplifier to collect the output signal of the vibrating wire. The control terminal obtains the induced voltage by comparing the output signal with the reference signal sent to the phase-locked amplifier, and then obtains the vibration period of the vibrating wire, and obtains the viscosity of the aviation hydraulic oil by solution.

2. The aviation hydraulic oil kinematic viscosity measuring system according to claim 1, characterized in that: The voltage detection range of the bidirectional digital lock-in amplifier 43 is 2nV to 1V, and the accuracy of phase measurement is not less than 0.01°.

3. The aviation hydraulic oil kinematic viscosity measuring system according to claim 1, characterized in that: The signal generator generates a signal frequency with a resolution of μHz.

4. The aviation hydraulic oil kinematic viscosity measuring system according to claim 1, characterized in that: Also included is a circulating constant temperature bath for maintaining the vibrating string body assembly within a predetermined temperature range.

5. The aviation hydraulic oil kinematic viscosity measuring system according to claim 4, characterized in that: The circulating bath uses dimethyl silicone oil and anhydrous ethanol as constant temperature media.

6. A method for measuring the kinematic viscosity of aviation hydraulic oil using the aviation hydraulic oil kinematic viscosity measuring system according to any one of claims 1 to 5, characterized in that: include: Step S10: Determine the operating temperature and pressure range of the aviation hydraulic oil, and perform pressure tests on the vibration string main body device at different temperatures. The pressure during the pressure test is the maximum pressure of the aviation hydraulic oil to ensure that the sealing of the measurement system is not affected by temperature changes. Step S20, calibrating the parameters of the vibrating wire in the vibrating string main body device using a calibration liquid, after evacuating the air through a vacuum pump, the control terminal vibrates the vibrating wire through a signal generator, and collects the internal damping of the vibrating wire in a vacuum environment through a bidirectional digital lock-in amplifier to complete the parameter calibration of the vibrating wire; Step S30, measuring the vibration period of the vibration wire in the vibration string main body device 50 under various pressure conditions of the aviation hydraulic oil and different temperatures, and obtaining the viscosity value of the aviation hydraulic oil through settlement at the control terminal.

7. The aviation hydraulic oil kinematic viscosity measuring system according to claim 6, characterized in that: The operating temperature range of the aviation hydraulic oil is 218.15K to 408.15K, and the pressure range is 0.1MPa to 30MPa.

8. The aviation hydraulic oil kinematic viscosity measuring system according to claim 7, characterized in that: In step S10, pressure testing the vibrating string main body device at different temperatures includes: Testing the vibrating string main body device 50 to a pressure of 30 MPa at room temperature; Testing the vibrating string main body device 50 to a pressure of 30 MPa at a high temperature; The vibrating string main body device 50 is pressure tested to 30 MPa in a low temperature state.

9. The aviation hydraulic oil kinematic viscosity measuring system according to claim 7 or 8, characterized in that: Step S30 specifically includes: Step S21: adjusting the temperature of the circulating bath to a predetermined temperature, evacuating the vibrating string main body device to a predetermined pressure, and performing vacuum calibration on the vibrating string main body device to obtain the internal damping of the vibrating string main body device; Step S22: Calibrate the parameters of the vibrating wire using the viscosity data of the calibration fluid at a predetermined temperature and the minimum pressure state of the aviation hydraulic oil, that is, adjust the parameters of the vibrating wire under the above conditions so that the measured viscosity meets the viscosity data of toluene. Step 23: Measure the viscosity values ​​of the calibration fluid for the aviation hydraulic oil pressure range within the known temperature range and compare them with the existing viscosity data to verify the reliability of the measurement system.

10. The aviation hydraulic oil kinematic viscosity measuring system according to claim 9, characterized in that: The calibration fluid is toluene.

11. The aviation hydraulic oil kinematic viscosity measuring system according to claim 10, characterized in that: The predetermined temperature is 298.15K, and the predetermined pressure is below 10Pa.

12. The aviation hydraulic oil kinematic viscosity measuring system according to claim 11, characterized in that: The step S30 specifically includes: Step S31: setting the pressure of the advection pump according to the test requirements or the use environment pressure of the aviation hydraulic oil; Step S32: start the circulating bath to the temperature to be measured, and after the temperature displayed by the temperature meter is stable, measure the vibration period of the vibrating wire in the vibrating string main body device through the digital acquisition system; Step S33: After completing one measurement, adjust the temperature of the circulating bath to the next temperature point and continue measuring; Step S34: after all the temperature measurements under one pressure condition are completed, the pressure of the advection pump is set and the measurements of different temperatures under the next set of pressure conditions are performed; Step S35: Using nonlinear regression to fit the resonance curve into an expression of amplitude and phase, and obtaining the viscosity value of the fluid.

Images