CN116242530B - A dynamic pressure-sensitive paint calibration device and calibration method based on sinusoidal pressure - Google Patents
A dynamic pressure-sensitive paint calibration device and calibration method based on sinusoidal pressure Download PDFInfo
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- CN116242530B CN116242530B CN202310137270.6A CN202310137270A CN116242530B CN 116242530 B CN116242530 B CN 116242530B CN 202310137270 A CN202310137270 A CN 202310137270A CN 116242530 B CN116242530 B CN 116242530B
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Abstract
本发明公开的一种基于正弦压力的动态压敏漆校准装置及校准方法，属于校准试验技术领域。本发明包括进气口、喷口、多孔转盘、预压孔、复位装置、变径活塞、活塞缸、密封盖板、玻璃窗口、端盖、激光测振仪、压敏漆式样、传动带、玻璃窗口、压敏漆光源和光电倍增管。变径活塞缸侧壁玻璃窗口处安装有压敏漆光源和光电倍增管。复位装置安装于变径活塞缸内右侧。本发明通过电机带动转盘切割高速射流，射流冲击变径活塞，挤压密封压力室产生压力，由于高速射流受到周期性切割作用，通过活塞挤压，使得压力室产生正弦周期性变化的脉动压力，通过脉动压力实现动态压敏漆校准。本发明具有压力腔体、压力平均值及峰峰值可调、可溯源的优点。
The present invention discloses a dynamic pressure-sensitive paint calibration device and calibration method based on sinusoidal pressure, which belongs to the field of calibration test technology. The present invention includes an air inlet, a nozzle, a porous turntable, a pre-pressure hole, a reset device, a variable-diameter piston, a piston cylinder, a sealing cover plate, a glass window, an end cover, a laser vibrometer, a pressure-sensitive paint pattern, a transmission belt, a glass window, a pressure-sensitive paint light source and a photomultiplier tube. A pressure-sensitive paint light source and a photomultiplier tube are installed at the glass window on the side wall of the variable-diameter piston cylinder. The reset device is installed on the right side of the variable-diameter piston cylinder. The present invention drives the turntable to cut the high-speed jet through a motor, and the jet impacts the variable-diameter piston, squeezing the sealed pressure chamber to generate pressure. Since the high-speed jet is subjected to periodic cutting, it is squeezed by the piston, so that the pressure chamber generates a pulsating pressure with sinusoidal periodic changes, and the dynamic pressure-sensitive paint calibration is realized through the pulsating pressure. The present invention has the advantages of adjustable pressure cavity, pressure average value and peak-to-peak value, and traceability.
Description
Technical Field
The invention relates to a dynamic pressure-sensitive paint calibration device and a calibration method based on sinusoidal pressure, in particular to a sinusoidal pressure calibration device with a large pressure chamber and adjustable pressure, and belongs to the technical field of calibration tests.
Background
The pressure sensitive paint technology is a relatively novel aerodynamic test technology, is mainly used for measuring the model surface pressure in wind tunnel tests, is used as a pressure field parameter measurement technology, is widely applied because of being capable of providing more abundant and effective test data, and is an updated technology for replacing the conventional pressure measurement test technology. At present, dynamic performance calibration of pressure sensitive paint is basically carried out by using a shock tube calibration device to calibrate dynamic response characteristics, a shock tube generates very fast step pressure to act on the pressure sensitive paint, and response time characteristics of the pressure sensitive paint can be measured, but general dynamic pressure calibration also comprises amplitude-frequency characteristics and phase differences under sinusoidal pressures with different frequencies, and the parameters cannot be measured through the shock tube. Therefore, in order to obtain the amplitude waveform following characteristics of the pressure-sensitive paint under different frequencies, dynamic calibration based on sinusoidal pressure needs to be carried out, the pressure-sensitive paint is used as a pressure field measuring means, the geometric dimensions of pressure-sensitive surfaces of the pressure-sensitive paint are usually intersected and large due to process and function limitations, and the current sinusoidal pressure calibrating device is used for guaranteeing pressure waveforms and peak-to-peak values, and a pressure chamber is usually smaller, so that the pressure-sensitive paint calibrating requirement cannot be met.
Disclosure of Invention
Aiming at the requirements of large pressure cavity and small pulsation value in pressure-sensitive paint calibration, the invention mainly aims to provide a dynamic pressure-sensitive paint calibration device and a calibration method based on sinusoidal pressure, a motor drives a turntable to cut high-speed jet flow, the jet flow impacts a variable-diameter piston, the pressure chamber is extruded and sealed to generate pressure, and the high-speed jet is subjected to periodical cutting action, so that the pressure chamber generates sinusoidal periodically-changing pulsating pressure through piston extrusion, and dynamic pressure-sensitive paint calibration is realized through the pulsating pressure. The invention has the advantages of large pressure cavity, adjustable pressure average value and peak-to-peak value and traceability.
The invention aims at realizing the following technical scheme:
the invention discloses a dynamic pressure-sensitive paint calibrating device based on sinusoidal pressure, which comprises an air inlet, a nozzle, a porous turntable, a pre-pressing hole, a resetting device, a reducing piston, a piston cylinder, a sealing cover plate, a glass window, an end cover, a laser vibration meter, a pressure-sensitive paint pattern, a transmission belt, a glass window, a pressure-sensitive paint light source, a photomultiplier, a pressure chamber and a pre-pressing chamber.
A motor and a transmission device are adopted to drive a porous rotary table, periodical impact force is generated on a variable diameter piston through cutting high-pressure high-speed jet flow, sinusoidal pressure is further generated in a sealed pressure chamber, a main body of the device is a variable diameter piston cylinder, the left side of the piston cylinder is a sealed pressure chamber, a mounting hole is formed in the side wall of the pressure chamber and is used for mounting a pressure sensitive paint pattern, a glass window is formed in the left side of a cylinder body, the glass window is clamped and fixed through an end cover and a sealing cover plate, a containing cavity is formed in the right side of the piston cylinder, a reset device for resetting a piston is mounted in the containing cavity, a pre-pressing hole is formed in the right side of the cavity, a piston cylinder on the right side of the pressure chamber is attached to the left side of the porous rotary table, the right side of the rotary table is attached to a nozzle, a variable cross-section structure is arranged in the nozzle and is used for improving the speed of air flow, the right side of the nozzle is connected with the motor through a transmission belt, a laser vibration meter is mounted on the left side of the variable diameter piston cylinder, and a pressure sensitive paint light source and a photomultiplier are mounted on the glass window of the side wall of the variable diameter piston cylinder.
The pressure-sensitive paint light source is used for exciting the pressure-sensitive paint, and the photomultiplier is used for receiving fluorescent signals of the pressure-sensitive paint.
Preferably, the resetting device is a spring coil arranged on the right side in the reducing piston cylinder or an electromagnetic coil, and when the electromagnetic coil is adopted, the problems of insufficient service life of the spring and system vibration modes can be solved.
As a further preferable mode, the spring coil and the reducing piston form a second-order damping oscillation system, the natural frequency of the damping system is consistent with the upper limit of the device calibration frequency through adjusting the elastic coefficient of the spring coil and the mass of the reducing piston, and the pressure generated by jet flow at high frequency is improved by utilizing system resonance, namely the problem that the pressure generated by jet flow at high frequency is smaller is solved.
Preferably, a pre-pressing hole is formed in the right side of the diameter-variable piston cylinder, the right side of the piston cylinder is pre-pressed through air inflation of the pre-pressing hole, and the pre-pressing hole is used for adjusting the initial position of the diameter-variable piston and the initial pressure of the pressure chamber, so that incomplete sine pressure waveform in the pressure chamber caused by over-high or over-low air supply pressure is prevented.
Preferably, a laser vibration meter is arranged on the left side of the reducing piston cylinder, and real-time displacement of the inner piston can be monitored through a glass window on the left side.
Preferably, the right side of the reducing piston cylinder is attached to but not connected with the porous rotary table, the motor is connected with and drives the porous rotary table to rotate through a transmission belt, and a round hole is formed in the rotary table for cutting air flow.
Preferably, the inside of the nozzle is of a variable diameter structure, the jet speed is improved by changing the size and the shape of the inner diameter, the outlet of the nozzle is square, and the side length of the square is consistent with the diameter of a round hole on the porous turntable.
The invention discloses a dynamic pressure-sensitive paint calibration method based on sinusoidal pressure, which is realized based on the dynamic pressure-sensitive paint calibration device based on sinusoidal pressure. The dynamic pressure-sensitive paint calibration method based on sinusoidal pressure comprises the following steps:
Before calibration, proper spring coils and pistons are selected according to the upper limit of the calibration frequency, so that the self-oscillation frequency of a second-order oscillation system formed by the spring coils and the pistons is close to the upper limit of the calibration frequency. In order to ensure that the sine pressure waveform is not distorted, the porous wheel disc is required to ensure that the holes are uniform, and the diameter of the holes, which is about 2 times the arc length connecting the centers of the two holes, is satisfied.
The motor is used for driving the turntable to cut high-speed jet flow to generate periodic pulsating air flow as a pressure source, and a reducing piston structure is used for converting high-frequency pulsating pressure generated by the high-speed high-pressure air flow into a large-volume low-pulsation-value pressure field suitable for pressure sensitive paint calibration.
And the air is introduced into and discharged from the pre-pressing hole, and the initial pressure of the pre-pressing chamber is regulated, so that the initial pressure of the pressure chamber is changed, the initial pressure is the average value of the pulsating pressure, and the diameter and the shrinkage ratio of the inlet nozzle are regulated, so that the inlet pressure and the flow velocity are changed, and the pulsating pressure value suitable for different working conditions is generated.
The displacement deltal of the reducing piston is recorded by a laser vibrometer, and the pressure of the pressure chamber is calculated according to the displacement quantity of the reducing piston by pv=constant for the closed pressure cavity according to a gas state equation.
The test working conditions of the dynamic pressure sensitive paint calibration device comprise parameters of calibration frequency, sinusoidal pressure average value and pulsation value.
And the frequency is that the impact frequency of the air flow is changed by controlling the rotating speed of the motor according to the calibration requirement, so that the pressure change frequency is changed.
The average pressure value is obtained by connecting a pressure controller through a device pre-pressing hole and changing the initial pressure P 0 by adjusting the pressure of a pre-pressing chamber, namely the calibrated average pressure value.
The pulsation value of pressure is mainly pushed by an air source, so that the peak value and the peak value of the pulsation pressure can be adjusted by adjusting the air source pressure and the air inlet diameter.
Since the gas state equation pv=γrt, the pressure in the pressure chamber is inversely proportional to the pressure volume when the ambient temperature is unchanged, i.e., P 0V0＝PtVt.
The initial volume of the pressure chamber is:
The real-time pressure calculation formula in the pressure chamber is:
wherein:
Δl-piston displacement;
P t -real-time pressure in the pressure chamber;
P, 0-initial pressure of pressure chamber;
l 0 -piston initial distance;
d-piston diameter.
And according to piston movement displacement data DeltaL=f (t) recorded by a laser vibration meter, the dynamic characteristics of the pressure-sensitive paint are obtained by calculating the change of the pressure in the pressure chamber along with time and comparing, and the dynamic pressure-sensitive paint calibration is realized.
The beneficial effects are that:
1. according to the dynamic pressure-sensitive paint calibration device and method based on sinusoidal pressure, a motor drives a turntable to cut high-speed jet flow, the jet flow impacts a variable diameter piston, a sealing pressure chamber is extruded to generate pressure, the high-speed jet flow is extruded by the piston under the periodical cutting action, the pressure chamber generates sinusoidal periodically-changed pulsating pressure, and the dynamic pressure-sensitive paint amplitude following characteristic calibration, namely the dynamic pressure-sensitive paint calibration, is realized through the pulsating pressure.
2. According to the dynamic pressure-sensitive paint calibration device and the calibration method based on the sinusoidal pressure, the sinusoidal pressure is generated by directly impacting the piston through air flow, the air supply flow and the speed can be adjusted according to requirements, the sinusoidal pressures with different amplitudes can be further generated, and quantitative and accurate adjustment can be realized according to the constructed relational expression.
3. In order to solve the problem that the pressure chamber of a conventional inlet-outlet modulation type sine pressure generator is smaller, the dynamic pressure-sensitive paint calibration device and the calibration method based on sine pressure disclosed by the invention adopt a piston structure to improve the sine pressure; in addition, the spring coil and the reducing piston form a second-order damping oscillation system, and the natural frequency of the damping system is consistent with the upper limit of the device calibration frequency through adjusting the elastic coefficient of the spring coil and the mass of the reducing piston, so that the pressure generated by jet flow during high frequency is improved by utilizing system resonance.
4. According to the dynamic pressure-sensitive paint calibration device and the calibration method based on sinusoidal pressure, the pressure change in the pressure chamber is obtained by monitoring the position of the piston, so that the dynamic pressure absolute method calibration is realized.
Drawings
FIG. 1 is a front view of a dynamic pressure sensitive paint calibration device based on sinusoidal pressure in accordance with the present disclosure.
FIG. 2 is a top view of a dynamic pressure sensitive paint calibration device based on sinusoidal pressure in accordance with the present disclosure.
The device comprises a 1-air inlet, a 2-nozzle, a 3-porous rotary table, a 4-pre-pressing hole, a 5-spring coil, a 6-reducing piston, a 7-piston cylinder, an 8-sealing cover plate, a 9-glass window, a 10-end cover, an 11-laser vibration meter, a 12-pressure sensitive paint pattern, a 13-transmission belt, a 14-glass window, a 15-pressure sensitive paint light source, a 16-photomultiplier, a 17-pressure chamber and an 18-pre-pressing chamber.
Fig. 3 is a main structural view of the pressure chamber.
Detailed Description
The technical scheme of the invention is further specifically described below by way of examples and with reference to the accompanying drawings. The technical problems and the beneficial effects solved by the technical proposal of the invention are also described, and the described embodiment is only used for facilitating the understanding of the invention and does not have any limiting effect.
As shown in fig. 1 and 2, the dynamic pressure-sensitive paint calibration device based on sinusoidal pressure disclosed in this embodiment includes an air inlet 1, a nozzle 2, a porous turntable 3, a pre-pressing hole 4, a spring coil 5, a reducing piston 6, a piston cylinder 7, a sealing cover plate 8, a glass window 9, an end cover 10, a laser vibration meter 11, a pressure-sensitive paint pattern 12, a transmission belt 13, a glass window 14, a pressure-sensitive paint light source 15, a photomultiplier 16, a pressure chamber 17 and a pre-pressing chamber 18.
A motor and a transmission device are adopted to drive a multi-hole rotary table 3, periodical impact force is generated on a variable diameter piston 6 through cutting high-pressure high-speed jet flow, sinusoidal pressure is further generated in a sealed pressure chamber, a variable diameter piston cylinder 7 is arranged as a main body of the device, the left side of the piston cylinder 7 is a sealed pressure chamber, a mounting hole is formed in the side wall of the pressure chamber and is used for mounting a pressure sensitive paint pattern 12, meanwhile, a glass window 9 is formed in the left side of a cylinder body, a glass window 14 is formed in the side wall of the cylinder body and is tightly fixed through an end cover 10 and a sealing cover plate clamp 8, a containing cavity is formed in the right side of the piston cylinder, a spring coil 5 for piston reset is mounted in the containing cavity, a pre-pressing hole is formed in the right side of the cavity, initial pressure of the pre-pressing chamber 18 can be adjusted through the pre-pressing hole, a piston cylinder on the right side of the pressure chamber 17 is attached to the left side of the multi-hole rotary table 3, the right side of the rotary table is attached to a nozzle 2, a variable cross-section structure is arranged in the nozzle, the inside is used for improving the air flow speed, the right side of the nozzle is connected with the air inlet 1, the rotary table is connected with the motor through a transmission belt 13, a laser vibrometer 11 is mounted on the left side the side of the variable diameter piston cylinder, a glass window is mounted, a position of the glass window is used, a light source 15 is mounted at the position of the side of the variable diameter piston cylinder is, and a light source is.
The embodiment discloses a dynamic pressure-sensitive paint calibration method based on sinusoidal pressure, which is realized based on the dynamic pressure-sensitive paint calibration device based on sinusoidal pressure. The dynamic pressure-sensitive paint calibration method based on sinusoidal pressure comprises the following steps:
Before calibration, a proper spring coil 5 and a reducing piston 7 are selected according to the upper limit of the calibration frequency, so that the self-oscillation frequency of a second-order oscillation system formed by the spring coil and the reducing piston is close to the upper limit of the calibration frequency. To ensure that the sinusoidal pressure waveform is not distorted, the porous turntable 3 ensures that the openings are uniform and that the openings meet an opening diameter of approximately 2 times the arc length connecting the centers of the two holes.
The pressure-sensitive paint sample 12 is installed, the pressure chamber is sealed, proper gas is filled into the pressure chamber through the pre-pressing hole according to the measured pressure-sensitive paint range, the preset pressure P 0 is reached in the initial pressure chamber, the initial position of the variable-speed piston 7 is recorded by the laser vibration meter 11, the initial position is set as a zero point, the diameter of the pressure chamber is consistent with the diameter D of the piston, and the length is L 0.
The air inlet pressure P 1 is regulated, so that air flow passes through the porous turntable 3 to impact the reducing piston 7, the piston is impacted by high-speed high-pressure air flow to generate rightward displacement, and at the moment, the motor is switched on, so that the porous turntable 3 rotates. The round holes on the porous turntable and the square holes of the nozzle 2 are cut, so that the impact action of the air flow generates sinusoidal periodic variation, and the piston system is forced to vibrate under the impact of the air flow. The piston generates reciprocating motion under the action of impact and the pressure in the pressure cavities at two sides to form sinusoidal pressure, and the frequency is determined by the rotating speed of the turntable.
From the gas state equation pv=γrt, it is known that when the ambient temperature is unchanged, the pressure in the pressure chamber is inversely proportional to the pressure volume, i.e. P 0V0＝PtVt.
The initial volume of the pressure chamber is:
The real-time pressure calculation formula in the pressure chamber is:
wherein:
Δl-piston displacement;
p t is the real-time pressure in the pressure chamber;
p 0 -initial pressure in the pressure chamber;
l 0 -piston initial distance;
d-piston diameter.
In the test, a pressure-sensitive paint light source and a photomultiplier are turned on, a pressure-sensitive paint light intensity signal is acquired, then a measurement result of the pressure-sensitive paint is obtained, the change of the pressure in a pressure chamber along with time is calculated according to piston movement displacement data delta L=f (t) recorded by a laser vibration meter, the dynamic characteristics of the pressure-sensitive paint are obtained through comparison, and the dynamic pressure-sensitive paint calibration is realized.
While the foregoing detailed description has described the objects, aspects and advantages of the invention in further detail, it should be understood that the foregoing description is only illustrative of the invention, and is intended to cover various modifications, equivalents, alternatives, and improvements within the spirit and scope of the present invention.
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| CN111998997A (en) * | 2020-09-27 | 2020-11-27 | 中国航空工业集团公司北京长城计量测试技术研究所 | Low-temperature pulsating pressure calibration device |
| CN112378576A (en) * | 2020-10-29 | 2021-02-19 | 西北工业大学 | Optical pressure sensitive coating pressure calibrating device based on CCD camera |
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| CN208270147U (en) * | 2018-05-15 | 2018-12-21 | 中车青岛四方机车车辆股份有限公司 | Pressure sensitive coating calibrating installation and calibration system |
| CN110044545B (en) * | 2019-05-05 | 2020-11-20 | 西北工业大学 | Dual-use optical pressure-sensitive paint calibration chamber considering static and sinusoidal pressure variations |
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| CN111998997A (en) * | 2020-09-27 | 2020-11-27 | 中国航空工业集团公司北京长城计量测试技术研究所 | Low-temperature pulsating pressure calibration device |
| CN112378576A (en) * | 2020-10-29 | 2021-02-19 | 西北工业大学 | Optical pressure sensitive coating pressure calibrating device based on CCD camera |
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