阅读说明：本技术 用于可视化高速爆燃波传播状态和特性的测量装置及方法 (Measuring device and method for visualizing propagation state and characteristics of high-speed detonation wave ) 是由 张博 程俊 刘洪� 于 2021-07-28 设计创作，主要内容包括：本发明提供一种用于可视化高速爆燃波传播状态和特性的测量装置,包括设于激波管实验平台的激波管的侧壁上的纹影视窗、设于纹影视窗的两侧的一对主镜,设于主镜的光路上游的高频LED光源、设于主镜的光路下游的高速相机,以及与高频LED光源、高速相机均相连的数字延时发生器。本发明还提供相应的测量方法。本发明的测量装置包括与LED光源与高速相机相连的信号触发系统,使得光源闪光频率与高速相机拍摄频率同步,从而可以实现对于爆燃波传播的全过程捕捉。本发明组成简单,操作性好,降低了纹影实验中对于高速爆燃波的捕捉难度。(The invention provides a measuring device for visualizing the propagation state and characteristics of high-speed deflagration waves, which comprises a schlieren window arranged on the side wall of a shock wave tube experiment platform, a pair of primary mirrors arranged at two sides of the schlieren window, a high-frequency LED light source arranged at the upstream of the light path of the primary mirrors, a high-speed camera arranged at the downstream of the light path of the primary mirrors, and a digital delay generator connected with the high-frequency LED light source and the high-speed camera. The invention also provides a corresponding measuring method. The measuring device comprises a signal triggering system connected with the LED light source and the high-speed camera, so that the light source flashing frequency is synchronous with the high-speed camera shooting frequency, and the whole process of deflagration wave propagation can be captured. The method has simple composition and good operability, and reduces the difficulty of capturing the high-speed detonation wave in the schlieren experiment.)

1. A measuring device for visualizing the propagation state and characteristics of high-speed deflagration waves is arranged on a shock tube experimental platform which comprises a shock tube (1), and an air passage control system (2), an ignition system (3) and a data acquisition system (4) which are arranged on the shock tube (1), the device is characterized by comprising a schlieren window (51) arranged on the side wall of a shock tube (1) of a shock tube experiment platform, a pair of main mirrors (52) arranged at two sides of the schlieren window (51), a high-frequency LED light source (53) arranged at the upstream of the light path of the main mirrors (52), and a high-speed camera (54) arranged at the downstream of the light path of the main mirrors (52), and the digital delay generator (55) is connected with the high-frequency LED light source (53) and the high-speed camera (54), and the peak frequency of the high-frequency LED light source (53) is 20000Hz-200000 Hz.

2. The measurement device for visualizing the propagation status and characteristics of high-speed deflagration waves according to claim 1, characterized in that said ignition system (3) comprises an ignition head (31) mounted at one end of the shock tube and a pulse igniter (32) associated with the ignition head (31).

3. The measurement device for be used for visual high-speed deflagration wave propagation state and characteristic of claim 1, characterized in that, gas circuit control system (2) is connected with shock tube (1) through seting up the interface of giving vent to anger on shock tube (1), and gas circuit control system (2) includes gas circuit control panel (20) that links to each other with the interface of giving vent to anger, and fuel bottle (21), oxidant high-pressure gas cylinder (22), gas mixing jar (23) and vacuum pump (24) that link to each other with gas circuit control panel (20), fuel bottle (21), oxidant high-pressure gas cylinder (22), gas mixing jar (23) and vacuum pump (24) all with gas circuit control panel (20) are connected.

4. The measurement device for visualizing propagation state and characteristics of high-speed deflagration wave according to claim 1, characterized in that, the data acquisition system (4) includes pressure sensors (41) and ion probes (42) installed at equal intervals in the length direction of the shock tube, the pressure sensors (41) and the ion probes (42) are in one-to-one correspondence, and the corresponding pressure sensors (41) and ion probes (42) are installed with the same cross section as each other.

5. Measuring device for visualizing the propagation status and characteristics of high-speed deflagration waves according to claim 4, characterized in that said pressure sensor (41) and ion probe (42) are both connected to a data acquisition hardware (43).

6. The measurement device for visualizing the propagation status and characteristics of high-speed deflagration waves according to claim 4, characterized in that said digital delay generator (55) is connected to an ion probe (42) located in front of the schlieren window (51), or to a timing control board.

7. The measurement device for be used for visual high-speed detonation wave propagation state and characteristic of claim 1, characterized in that, high frequency LED light source (53) sets up to launch LED light all the way, along the light path of LED light convex mirror (56), slit (57), first speculum (581), primary mirror (52), second speculum (582), edge (59) and high-speed camera (54) arrange in proper order.

8. A measurement method for visualizing propagation states and characteristics of a high-speed detonation wave, comprising:

step S1: building a measuring device for visualizing the propagation state and characteristics of the high-speed detonation wave according to any one of claims 1-7 on a shock tube experimental platform;

step S2: on the premise of ensuring good shock tube air tightness, a gas circuit control system (2) is adopted to pump the shock tube (1) to a vacuum state and then inject fuel-oxidant mixed gas;

step S3: setting the exposure time of a high-frequency LED light source (53) on a digital delay generator (55) and the flash time of a high-speed camera (54) to start and end simultaneously;

step S4: triggering the ignition system (3), and then sending a triggering signal to the high-frequency LED light source (53) and the high-speed camera (54) to start a shock tube detonation experiment; at the same time, a high speed camera (54) is employed to acquire and store data.

9. The measurement method for visualizing the propagation state and characteristics of high-speed detonation waves according to claim 8, characterized in that said step S3 further comprises: and turning on the high-frequency LED light source (53), the high-speed camera (54) and the data acquisition system (4) and enabling the high-frequency LED light source, the high-speed camera and the data acquisition system to be in a standby state.

10. The measurement method for visualizing propagation state and characteristics of high-speed detonation waves according to claim 8, characterized in that said digital delay generator (55) is connected to an ion probe (42) located in front of schlieren window (51), and in said step S4, the digital delay generator (55) sends trigger signals to the high-frequency LED light source (53) and the high-speed camera (54) through a fixed delay after receiving flame signals captured by said ion probe (42) in front of schlieren window (51).

Technical Field

The invention belongs to the technical field of detonation experiments, and particularly relates to a measuring device and method for visualizing propagation states and characteristics of high-speed detonation waves.

Background

A deflagration wave is a combustion wave that propagates at subsonic speeds. The method is widely applied to the fields of daily industrial production safety and power propulsion. Deflagration is easy to transition from deflagration to detonation through DDT (deflagration to detonation) process due to strong instability of the deflagration, so that the deflagration is a research hotspot in the fields of combustion and detonation physics. The composition of the deflagration wave can be briefly described as a coupling structure of leading shock wave-induction zone-flame surface. Generally, with the self-acceleration of the flame, the leading shock wave will continuously become stronger due to the acceleration of the combustion rate and the increase of the heat release, so as to further increase the pressure and temperature of the induction zone, making it easier to burn, and with the gradual acceleration of the flame to catch up with the leading shock wave, the detonation will be transformed into detonation after the two coincide. Therefore, the research on the propagation characteristics of the detonation waves and the structural change of the detonation waves improves the evaluation and prevention capability of the detonation hazard of the combustible gas, or realizes the technical innovation in the field of power propulsion by utilizing the detonation waves, and has very important scientific significance and application value.

At present, the research on the deflagration phenomenon mainly takes a data measurement method and a smoke trace method as main points. The data measurement method mainly comprises pressure signal measurement and optical signal measurement. A related representative product is the PREWAQ type explosive pressure wave test device of edison corporation, usa. The burning wave velocity is mainly measured by using optical fibers to receive optical signals, and the burning wave velocity measuring device is generally expensive and short in service life. The smoke trace method is based on the principle that combustion waves can drive carbon particles to move when passing through the surface layer of thin carbon particles, and the motion trail is left, so that the deflagration/detonation propagation state is traced back.

The prior art has the following disadvantages: the data measurement method lacks visual cognition on the evolution form of the detonation wave in the propagation process, and can reproduce the state change of the detonation wave in the propagation process only through the captured real-time pressure/optical signal; the same is true of the smoke trace method, which analyzes the morphological evolution of the combustion wave during propagation by "cell" morphology of the specific structure left on the smoked foil during propagation of the combustion wave. The above methods cannot directly recognize the real-time detonation wave propagation process.

The schlieren technology is used in the research of deflagration waves more frequently as a traditional flow dynamics visualization research method, but the DDT (deflagration transition detonation) process is developed rapidly and is finished within a few microseconds, so that the requirement on precise control of time in the shooting process is higher. High-frequency lasers are commonly used at home and abroad in a matching way, but the lasers are expensive and heavy; however, the incandescent lamp is only suitable for visualization of low-speed flame wave propagation, the flame propagation speed is mostly about 100m/s, and for high-speed deflagration waves, especially when the flame propagation speed is more than 500m/s, the incandescent lamp as the light source can cause overexposure of the camera, and the shooting effect is poor.

Disclosure of Invention

The invention aims to provide a measuring device and a method for visualizing the propagation state and characteristics of a high-speed detonation wave, so as to capture the whole process of detonation wave propagation and ensure clear images.

In order to achieve the purpose, the invention provides a measuring device for visualizing the propagation state and characteristics of a high-speed deflagration wave, which is arranged on a shock tube experiment platform, wherein the shock tube experiment platform comprises a shock tube, an air path control system, an ignition system and a data acquisition system which are arranged on the shock tube, the measuring device comprises a schlieren window arranged on the side wall of the shock tube experiment platform, a pair of main mirrors arranged on the two sides of the schlieren window, a high-frequency LED light source arranged on the upstream of the light path of the main mirrors, a high-speed camera arranged on the downstream of the light path of the main mirrors, and a digital delay generator connected with the high-frequency LED light source and the high-speed camera.

The ignition system comprises an ignition head arranged at one end of the shock tube and a pulse igniter connected with the ignition head.

The gas circuit control system is connected with the shock tube through a gas inlet and outlet interface arranged on the shock tube, the gas circuit control system comprises a gas circuit control panel connected with the gas inlet and outlet interface, and a fuel bottle, an oxidant high-pressure gas bottle, a gas mixing tank and a vacuum pump which are connected with the gas circuit control panel, and the fuel bottle, the oxidant high-pressure gas bottle, the gas mixing tank and the vacuum pump are all connected with the gas circuit control panel.

The data acquisition system comprises pressure sensors and ion probes which are arranged on the length direction of the shock tube at equal intervals, the pressure sensors correspond to the ion probes one by one, and the corresponding pressure sensors and the corresponding ion probes are arranged on the same cross section.

The pressure sensor and the ion probe are connected with a data acquisition hardware.

The digital time delay generator is connected with an ion probe positioned in front of the schlieren window or connected with a time sequence control board.

The high-frequency LED light source is set to emit LED light of one path, and a convex mirror, a slit, a first reflecting mirror, the main mirror, a second reflecting mirror, a knife edge and the high-speed camera are sequentially arranged along the light path of the LED light.

In another aspect, the present invention provides a measurement method for visualizing propagation states and characteristics of a high-speed detonation wave, comprising:

s1: a measuring device for visualizing the propagation state and the propagation characteristic of the high-speed detonation wave is built on a shock tube experimental platform;

s2: on the premise of ensuring good air tightness of the shock tube, a gas circuit control system is adopted to pump the shock tube to a vacuum state and then inject fuel-oxidant mixed gas;

s3: setting the exposure time of a high-frequency LED light source and the flash time of a high-speed camera on a digital delay generator to start and end simultaneously;

s4: triggering an ignition system, and then sending a trigger signal to a high-frequency LED light source and a high-speed camera to start a shock tube detonation experiment; at the same time, a high-speed camera is used to collect and store data.

The step S3 further includes: and turning on the high-frequency LED light source, the high-speed camera and the data acquisition system and enabling the high-frequency LED light source, the high-speed camera and the data acquisition system to be in a standby state.

The digital delay generator is connected with an ion probe positioned in front of the schlieren window, and in the step S4, the digital delay generator sends a trigger signal to the high-frequency LED light source and the high-speed camera by receiving a flame signal captured by the ion probe in front of the schlieren window and then carrying out fixed delay.

The measuring device for visualizing the propagation state and the characteristics of the high-speed detonation wave comprises a signal triggering system connected with an LED light source and a high-speed camera, so that the light source flashing frequency is synchronous with the high-speed camera shooting frequency, and the detonation wave propagation processes at different development stages can be shot by synchronizing the corresponding high-frequency LED light source and the high-speed camera, so that the whole process capture of detonation wave propagation is realized; meanwhile, the peak frequency of the high-frequency LED light source is 20000Hz-200000Hz, the problem of image blurring caused by overexposure under a high-speed camera can be solved, and the propagation state and the characteristics of high-speed detonation waves with the propagation speed of 500m/s or more can be accurately captured.

In addition, the measuring device for visualizing the propagation state and characteristics of the high-speed detonation wave of the invention connects the digital delay generator 55 with the ion probe 42 in front of the schlieren window 51, so that the ion probe 42 in front of the schlieren window 51 controls the high-frequency LED light source 53 and the high-speed camera 54 to synchronously start and work through the digital delay generator 55, and the detonation wave propagation processes in different development stages can be more flexibly shot. Therefore, the invention has simple composition and good operability, and reduces the difficulty of capturing the high-speed detonation wave in the schlieren experiment. The invention can be applied to the measurement of the propagation and evolution process of the high-speed deflagration wave of the combustible gas, and has wide application prospect in the visual research aiming at the detonation dynamics, the combustion dynamics and the fluid dynamics.

Drawings

Fig. 1 is a schematic structural diagram of a shock tube experimental system in which the measuring device for visualizing the propagation state and characteristics of the high-speed deflagration wave is located.

Fig. 2 is a schematic connection diagram of a measurement device for visualizing high velocity deflagration wave propagation conditions and characteristics, according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of the trigger signal synchronization of the high-frequency LED light source and the high-speed camera employed by the measuring apparatus for visualizing the propagation state and characteristics of the high-speed deflagration wave shown in fig. 2.

Fig. 4 is a schlieren picture of the propagation process of the detonation wave obtained by the measuring device for visualizing the propagation state and the characteristics of the high-speed detonation wave.

Detailed Description

The present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.

Fig. 1 shows a measurement device for visualizing the propagation state and characteristics of a high-speed deflagration wave, which is installed on a shock tube experimental platform, according to an embodiment of the invention. The shock tube experiment platform comprises a shock tube 1, and an air path control system 2, an ignition system 3 and a data acquisition system 4 which are arranged on the shock tube 1.

The ignition system 3 includes an ignition head 31 mounted at one end of the shock tube and a pulse igniter 32 connected to the ignition head 31. The ignition system 3 is connected with the shock tube 1 through an ignition head 31, and the ignition head 31 is powered by a pulse igniter 32.

The gas circuit control system 2 is connected with the shock tube 1 through a gas inlet and outlet interface arranged on the shock tube 1. The air inlet and outlet port may be disposed at any position in the length direction of the shock tube 1, and in this embodiment, the air inlet and outlet port is disposed at a position away from the ignition system 3 in the length direction of the shock tube 1. The gas path control system 2 comprises a gas path control panel 20 connected to the gas inlet and outlet ports, and a fuel bottle 21 (such as a methane bottle), an oxidant high-pressure gas bottle 22 (such as an oxygen high-pressure gas bottle), a gas mixing tank 23 and a vacuum pump 24 connected to the gas path control panel 20, wherein the fuel bottle 21, the oxidant high-pressure gas bottle 22, the gas mixing tank 23 and the vacuum pump 24 are all connected to the gas path control panel 20 through respective corresponding hoses and valves 25.

Therefore, the fuel in the fuel bottle 21 and the oxidant in the oxidant high-pressure gas bottle 22 are filled into the gas mixing tank 23 according to a certain proportion through the gas circuit control panel 20 and are uniformly mixed to obtain a fuel-oxidant mixed gas, and then the fuel-oxidant mixed gas is injected into the shock tube 1 in a vacuum state; after the reaction of the fuel and the oxidizing agent in the shock tube 1 is completed, the formed exhaust gas is extracted from the shock tube 1 by the vacuum pump 24.

The data acquisition system 4 includes pressure sensors 41(PCB 113B21 series) and ion probes 42 mounted at equal intervals in the length direction of the shock tube, and a data acquisition hardware 43, wherein the pressure sensors 41 and the ion probes 42 are in one-to-one correspondence, and the corresponding pressure sensors 41 and the ion probes 42 are mounted at the same cross section with each other. Pressure sensor 41 is used for acquireing the pressure signal, and ion probe 42 is used for acquireing the flame signal, and pressure sensor 41 and ion probe 42 all link to each other with data acquisition hardware 43. The data acquisition hardware 43 is used for acquiring and filtering pressure and flame signals.

As shown in fig. 2, the measuring apparatus for visualizing the propagation state and characteristics of the high-speed deflagration wave of the present invention includes a schlieren window 51 disposed on the sidewall of the shock tube 1 of the shock tube experimental platform, a pair of primary mirrors 52 disposed on both sides of the schlieren window 51, a high-frequency LED light source 53 disposed on the upstream of the optical path of the primary mirror 52, a high-speed camera 54 (model number is Phantom V710L) disposed on the downstream of the optical path of the primary mirror 52, and a digital delay generator 55 connected to both the high-frequency LED light source 53 and the high-speed camera 54. The digital delay generator 55 is connected to an ion probe 42 of the data acquisition system 4 in front of the schlieren window 51 to receive the flame signal captured by the ion probe 42, or the digital delay generator 55 may be connected to a timing control board. In this embodiment the digital delay generator 55 is connected to the ion probe 42 10cm in front of the schlieren window 51.

Thus, the primary mirror 52, high frequency LED light source 53, high speed camera 54 and digital delay generator 55 comprise a digital schlieren system.

Specifically, the high-frequency LED light source 53 is configured to emit a path of LED light, and a convex mirror 56, a slit 57, a first reflecting mirror 581, the main mirror 52, a second reflecting mirror 582, a knife edge 59, and the high-speed camera 54 are sequentially arranged along an optical path of the LED light. The pair of primary mirrors 52 are arranged coaxially and the optical axis is perpendicular to the length direction of the shock tube 1. The primary mirrors 52 are each 30cm in diameter. In other embodiments, the specific diameter of the primary mirror 52 may be purchased according to actual experimental requirements.

The high-frequency LED light source 53 is a high-power stroboscopic LED light source, and is configured to be switchable between stroboscopic and normally-on modes, the operating voltage of the high-frequency LED light source 53 in the normally-on mode cannot be higher than 4.3V, the peak frequency of the high-frequency LED light source 53 in the stroboscopic mode is 20000Hz-200000Hz, the maximum power of the high-frequency LED light source 53 in the normally-on mode is 90W, the maximum power of the stroboscopic mode can exceed 147W, the peak safety voltage of the light source is 18V, the single continuous operation time cannot exceed 10 seconds, the recommended operating voltage range is 4.5-18V, and the corresponding relationship between the operating voltage and the frequency is shown in the following table 1.

The high-speed camera 4 is a VEO 710L high-speed camera to which Phantom belongs. The maximum shooting frequency can reach 70000 fps. The maximum resolution can reach 1280 × 800.

The digital delay generator 5 is DG645 from Stanford research system. With 1 input signal and 8 output signals. The input signal of the digital delay generator 5 can be given by a timing control board, or can be given by the signal of a specific sensor (for example, the pressure sensor 41 or the ion probe 42), and the output signal is mainly used for triggering the high-frequency LED light source 53 and the high-speed camera 54 to work synchronously.

TABLE 1 correspondence between operating voltage and frequency

LED Voltage/V	Peak duty cycle%	Peak frequency/Hz	Exposure time/. mu.s
				5.0	50	200000	1
6.0	45	200000	1
				7.0	30	200000	1
8.0	20	200000	1
				10.0	10	100000	1
12.0	8	80000	1
				14.0	5	50000	1
16.0	4	40000	1
				18.0	2	20000	1

Based on the measurement device for visualizing the propagation state and the characteristic of the high-speed detonation wave, the realized measurement method for visualizing the propagation state and the characteristic of the high-speed detonation wave specifically comprises the following steps:

step S1: as shown in fig. 2, the measuring device for visualizing the propagation state and characteristics of the high-speed deflagration wave is built on a shock tube experimental platform; the shock tube experiment platform comprises a shock tube 1, and an air path control system 2, an ignition system 3 and a data acquisition system 4 which are arranged on the shock tube 1.

Step S2: on the premise of ensuring good shock tube air tightness, a gas circuit control system 2 is adopted to pump the shock tube 1 to a vacuum state and then inject fuel-oxidant mixed gas;

wherein, the fuel in the fuel bottle 21 and the oxidant in the oxidant high-pressure gas bottle 22 are filled into the gas mixing tank 23 according to a certain proportion through the gas circuit control panel 20 and are uniformly mixed to obtain the fuel-oxidant mixed gas.

Step S3: setting the exposure time of the high-frequency LED light source 53 and the flash time of the high-speed camera 54 on the digital delay generator 55 to start and end simultaneously, so that the trigger signals of the high-frequency LED light source 53 and the high-speed camera 54 are shown in FIG. 3;

in the present embodiment, the exposure frequency of the high-frequency LED light source 53 and the flash frequency of the high-speed camera 54 are 100000Hz, and the exposure time of the high-frequency LED light source 53 and the flash time of the high-speed camera 54 are 5 μ s per cycle.

Further, step S3 includes: turning on the high-frequency LED light source 53, the high-speed camera 54 and the data acquisition system 4 and keeping the high-frequency LED light source, the high-speed camera 54 and the data acquisition system 4 in a standby state;

step S4: triggering the ignition system 3, and then sending a trigger signal to the high-frequency LED light source 53 and the high-speed camera 54 to start a shock tube detonation experiment, so as to form a flame wave propagating at a high speed, even a detonation wave, in the shock tube; meanwhile, the high-speed camera 54 employing the measuring apparatus for visualizing the propagation state and characteristics of the high-speed detonation wave collects and stores data.

In the process, the digital delay generator 55 sends a trigger signal to the high-frequency LED light source 53 and the high-speed camera 54, so that the high-frequency LED light source 53 and the high-speed camera 54 are synchronously started and operated. In the measurement, the high frequency LED light source 53 is operated in a strobe mode. In this embodiment, the digital delay generator 55 is connected to an ion probe 42 located in front of the schlieren window 51, and in the step S4, the digital delay generator 55 sends the trigger signal to the high-frequency LED light source 53 and the high-speed camera 54 by receiving the flame signal captured by the ion probe 42 in front of the schlieren window 51 and then by a fixed delay. In this embodiment, the ion probe 42 is located 10cm in front of the schlieren window 51 with a fixed delay of 0.2 ms.

Fig. 4 shows the propagation process of the high-speed detonation wave recorded by the visual synchronous measurement system based on the high-frequency LED light source and the high-speed camera. As can be seen from fig. 4, the measurement device and method for visualizing the propagation state and characteristics of the high-speed deflagration wave of the present invention can accurately capture the propagation state and characteristics of the high-speed deflagration wave with a propagation speed of 500m/s or more, the high-frequency LED light source 53 and the high-speed camera 54 are controlled by the ion probe 42 installed in front of the schlieren window 51 of the shock tube 1 via the digital delay generator 55 to start and operate synchronously, so that the deflagration wave propagation processes at different development stages can be more flexibly photographed, and the high-frequency LED light source can also ensure that the problem of image blurring caused by overexposure does not occur under the low-frequency camera.

The above embodiments are merely preferred embodiments of the present invention, which are not intended to limit the scope of the present invention, and various changes may be made in the above embodiments of the present invention. All simple and equivalent changes and modifications made according to the claims and the content of the specification of the present application fall within the scope of the claims of the present patent application. The invention has not been described in detail in order to avoid obscuring the invention.