Pressure sensor dynamic calibration system based on concave focusing ultrasonic transducer

Abstract

The invention discloses a pressure sensor dynamic calibration system based on a concave focusing ultrasonic transducer. The device comprises an ultrasonic transducer which is used for generating focused ultrasonic waves and inducing the cavitation phenomenon to be generated; the signal generator is connected with the ultrasonic transducer and is used for generating a driving signal to drive the ultrasonic transducer; the pressure sensor fixing device is used for fixing a calibrated pressure sensor and a standard pressure sensor, so that the pressure sensing surfaces of the calibrated pressure sensor and the standard pressure sensor can be aligned with the focus of the ultrasonic transducer; the container is used for accommodating a liquid medium and mounting a fixing device of the ultrasonic transducer and the pressure sensor; and the data acquisition and processing device is used for acquiring response signals of the standard pressure sensor and the calibrated pressure sensor and performing data processing to complete dynamic calibration. The high-intensity pulse focused ultrasound is used for inducing cavitation, and compared with laser-induced cavitation, complex light path adjustment and cavitation bubble positioning processes are avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of dynamic calibration of pressure sensors, and is particularly suitable for dynamic calibration of microsecond pulse pressure sensors in liquid medium (such as water, oil). BACKGROUND

[0002] In the fields of aviation, aerospace and ocean engineering, the dynamic characteristics of pressure sensors are of great significance. For example, in the measurement of pressure changes on the surface of a cross-medium missile body, the monitoring of the combustion process of aviation kerosene in an aero-engine, and the study of the anti-explosion performance of a warship, the measurement accuracy and response capability of the pressure sensor are directly related to the performance and safety of the system. Therefore, it is necessary to regularly calibrate the pressure sensor to ensure the accuracy and reliability of its output data.

[0003] Existing dynamic calibration methods mainly include the shock tube method, the sinusoidal pressure method, the fast-opening valve method and the drop hammer method. Among them, the shock tube method, as the most typical method, generates microsecond step pressure signals through high-pressure gas to calibrate the dynamic response of the sensor. However, the shock tube method is mainly suitable for gas environment, and the device is large in size and complex in operation. On the other hand, due to the difference in structural response of the sensor in gas and liquid media, the calibration results in gas environment may lead to accuracy deviation when applied to water measurement.

[0004] To realize the dynamic calibration of pressure sensors in water medium, existing research has adopted the laser-induced cavitation method, which uses the microsecond pulse pressure generated by the collapse of the cavitation bubble to simultaneously excite the standard sensor and the calibrated sensor, and combines the comparison algorithm to perform dynamic calibration. However, this method relies on a high-intensity laser system, which is large in size, complex in light path adjustment, and difficult in cavitation positioning, limiting its promotion in practical applications.

[0005] Therefore, it is urgent to develop a pressure sensor dynamic calibration system that is compact in structure, simple in operation, low in cost, and suitable for liquid medium environment, to improve the calibration efficiency and enhance the practicality of the system. SUMMARY

[0006] In view of the problems of large and complex laser equipment, high light path requirements, single cavitation bubble generation only under highly focused conditions, and difficulty in controlling the focal point in the process of laser-induced cavitation for dynamic pressure sensor calibration, the present application proposes a calibration system using a concave focusing ultrasonic transducer. The present application excites the ultrasonic transducer with a sinusoidal signal of dozens of cycles to generate high-intensity focused ultrasound, which induces a single spherical cavitation bubble at the focal point, replacing the laser-induced cavitation method, thereby avoiding the problems of complex light path arrangement and difficult cavitation positioning of the laser system. The pressure shock wave generated by the collapse of the cavitation bubble is used to dynamically calibrate the pressure sensor.

[0007] A dynamic calibration system for a pressure sensor based on a concave focusing ultrasonic transducer, comprising:

[0008] an ultrasonic transducer for generating focused ultrasonic waves and inducing cavitation;

[0009] a signal generator connected to the ultrasonic transducer for generating a driving signal to drive the ultrasonic transducer;

[0010] a pressure sensor fixing device for fixing a pressure sensor to be calibrated and a standard pressure sensor so that the pressure sensing surfaces of the pressure sensor to be calibrated and the standard pressure sensor can be aligned with the focal point of the ultrasonic transducer;

[0011] a container for containing a liquid medium and mounting the ultrasonic transducer and the pressure sensor fixing device;

[0012] a data acquisition and processing device for acquiring the response signals of the standard pressure sensor and the pressure sensor to be calibrated and performing data processing to complete dynamic calibration.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] (1) High-intensity pulsed focused ultrasound is used to induce cavitation, which avoids the complex light path adjustment and bubble positioning process compared with laser-induced cavitation;

[0015] (2) The system structure is miniaturized and easy to operate, and is suitable for various complex application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A dynamic calibration system for a pressure sensor based on a concave focusing ultrasonic transducer;

[0017] Figure 2 A pressure sensor installation schematic diagram;

[0018] Figure 3 A timing diagram for focused ultrasonic-induced cavitation;

[0019] Figure 4 A pulse pressure signal generated by cavitation. DETAILED DESCRIPTION

[0020] The present application will be further described below in conjunction with the drawings and examples.

[0021] As Figure 1 and Figure 2As shown, the embodiments of the present application include an experimental box 1, an upper computer 2, an ultrasonic signal generator 3, a collection card 4, a concave focusing ultrasonic transducer 5, an open circular tube 6, an open circular tube support 7, a collet 8, a pressure sensor to be calibrated 9, a standard pressure sensor 10, a scale 11, and a mounting groove 12.

[0022] The concave focusing ultrasonic transducer has a fixed focus point located on the central axis of the open circular tube, and is used to generate focused ultrasonic waves and induce the generation of a single cavitation bubble.

[0023] The ultrasonic signal generator includes a digital signal generation module and a power amplification module, and is used to generate a sinusoidal signal and drive the concave focusing ultrasonic transducer.

[0024] The collet is used to fix the pressure sensor to be calibrated and the standard pressure sensor.

[0025] The open circular tube is used to mount the collet to ensure the coaxiality of the pressure sensors, and the tube body is marked with a scale for accurate adjustment of the position of the pressure sensors. The tube is provided with a square window directly opposite the concave focusing ultrasonic transducer.

[0026] The experimental box is used to fix the open circular tube and mount the concave focusing ultrasonic transducer.

[0027] The upper computer is used to control the ultrasonic signal generator and perform data collection and processing, calculate the calibration function and the dynamic response characteristic parameters of the pressure sensor to be calibrated through a comparison calibration algorithm, and complete the dynamic calibration thereof.

[0028] Further, the concave focusing ultrasonic transducer is mounted at the geometric center position of the bottom of the experimental box and connected with the ultrasonic signal generator, and the ultrasonic signal generator is controlled to operate by the upper computer. The collet for fixing the pressure sensors is mounted in the open circular tube, and the two pressure sensors are inserted into the tube after being fixed by the collet. The outer wall of the open circular tube is provided with a scale, and after the collet is fixed, the position of the collet can be adjusted to keep the distance between the pressure sensing surfaces of the two pressure sensors and the center of the scale consistent, so as to ensure that the measurement positions of the two sensors are symmetrical and equidistant.

[0029] The calibration system adopts a concave focusing ultrasonic transducer with a high resonance frequency, and the resonance frequency thereof is about 3 MHz. At this frequency, the wavelength of the ultrasonic wave in water is:

[0030]

[0031] wherein is the sound wave propagation speed in water, about 1500 m / s, is the frequency 3×10 6 High-frequency ultrasonic waves have a short wavelength, and after focusing, the cavitation effect can be concentrated in the focal point area, thereby improving the stability of the cavitation position.

[0032] The system working process of the embodiment of the present application is as follows:

[0033] The experimental box is filled with liquid, a concave focusing ultrasonic transducer is installed at the geometric center of the bottom, and two supports for fixing the open circular tube are symmetrically installed at both sides of the concave focusing ultrasonic transducer (see Figure 2 ). The middle part of the open circular tube is provided with a downward opening, which is aligned with the focal point direction of the concave focusing ultrasonic transducer, so as to facilitate the focused ultrasonic waves to enter the tube. A scale is engraved on the outer wall of the open circular tube, and a mounting groove is arranged, so as to facilitate the fixed connection with the support and ensure the stability of the structure.

[0034] After the installation of the device is completed, the focal point of the concave focusing ultrasonic transducer is located at the axis center of the open circular tube, and the longitudinal position corresponds to the midpoint of the scale. By adjusting the position of the collet, the pressure sensing surfaces of the two pressure sensors are equidistant from the midpoint of the scale, so as to ensure that the sensor measurement area is aligned with the cavitation focal point, thereby synchronously receiving the pulse pressure wave caused by cavitation.

[0035] When starting the calibration experiment, the host computer controls the ultrasonic signal generator to operate, and a digital signal generation module emits a high-frequency sinusoidal signal of tens of microseconds, the frequency of which matches the frequency of the ultrasonic signal generator. After the signal is amplified by a power amplifier, it drives the concave focusing ultrasonic transducer to generate focused ultrasonic waves and induce a single cavitation bubble at the focal point (see Figure 3 ).

[0036] Subsequently, the acquisition card simultaneously records the response signals of the standard pressure sensor and the calibrated pressure sensor, and transmits the data to the host computer for analysis. Figure 4 A typical response waveform is shown, which shows that a high-amplitude pulse pressure peak appears at about 93.4 μs, about 0.15 MPa, and the pulse width is about 200 ns. The results prove that the cavitation pressure wave induced by focused ultrasound has sufficient amplitude and time resolution, which can meet the needs of dynamic calibration of pressure sensors.

[0037] Since the cavitation shock pressure signal is very complex, it is impossible to accurately obtain the process of pressure change with time, so it is impossible to solve it according to the traditional dynamic characteristic model. The dynamic calibration method of comparison is adopted. When the natural frequency of the standard pressure sensor is much larger than the natural frequency of the calibrated sensor, only the Fourier transform ratio of the output response signals of the standard pressure sensor and the calibrated pressure sensor is required

[0038]

[0039] ​​The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dynamic calibration system for a pressure sensor based on a concave focused ultrasonic transducer, characterized in that: include: Ultrasonic transducer, used to generate focused ultrasonic waves and induce cavitation; a signal generator, connected to the ultrasonic transducer, and configured to generate a driving signal to drive the ultrasonic transducer; A pressure sensor fixing device, used to fix the calibrated pressure sensor and the standard pressure sensor so that the pressure-sensitive surfaces of the calibrated pressure sensor and the standard pressure sensor can be aligned with the focus of the ultrasonic transducer; A container for containing a liquid medium and for mounting a fixture of the ultrasonic transducer and the pressure sensor; The data acquisition and processing device is used to acquire the response signals of the standard pressure sensor and the calibrated pressure sensor, and perform data processing to complete dynamic calibration.

2. The pressure sensor dynamic calibration system according to claim 1, characterized in that: The ultrasonic transducer is a concave focused ultrasonic transducer, the focus of which is fixed and located on the central axis of the container.

3. The pressure sensor dynamic calibration system according to claim 2, characterized in that: The resonance frequency of the concave focused ultrasonic transducer is 2 MHz to 5 MHz.

4. The pressure sensor dynamic calibration system according to claim 1, characterized in that: The signal generator includes a digital signal generating module and a power amplifying module, which are used to generate a high-frequency sinusoidal signal and drive the ultrasonic transducer.

5. The pressure sensor dynamic calibration system according to claim 4, characterized in that: The frequency of the high-frequency sinusoidal signal matches the resonant frequency of the ultrasonic transducer.

6. The pressure sensor dynamic calibration system according to claim 1, characterized in that: The pressure sensor fixing device includes a collet and an open circular tube. The collet is used to fix the calibrated pressure sensor and the standard pressure sensor. The open circular tube is used to install the collet and ensure the coaxiality of the sensor.

7. The pressure sensor dynamic calibration system according to claim 6, characterized in that: The outer wall of the open circular tube is provided with a scale for accurately adjusting the position of the pressure sensor so that the pressure-sensitive surfaces of the calibrated pressure sensor and the standard pressure sensor are equidistant from the focus of the ultrasonic transducer.

8. The pressure sensor dynamic calibration system according to claim 1, wherein the data acquisition and processing device includes an acquisition card and a host computer, the acquisition card is used to acquire the response signals of the standard pressure sensor and the calibrated pressure sensor, and the host computer is used to control the signal generator and perform data processing.

9. The pressure sensor dynamic calibration system according to claim 8, characterized in that: The host computer adopts a comparison calibration algorithm to complete the dynamic calibration of the calibrated pressure sensor by calculating the ratio of the Fourier transform of the output response signal of the standard pressure sensor and the output response signal of the calibrated pressure sensor.

10. The pressure sensor dynamic calibration system according to claim 1, characterized in that: The system is suitable for dynamic calibration of microsecond pulse pressure sensors.

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