A method and device for measuring quasi-static pressure of explosion in a confined space

Abstract

The present invention relates to a method and device for measuring the quasi-static pressure of explosion in a confined space. The measuring device comprises a photon Doppler velocimeter PDV, a sealing bolt, a slider, a positioning gasket, a sliding sleeve, an explosion tank and a calculation unit; the sliding sleeve is fixed to the upper part of the explosion tank cavity by threads; a cavity is arranged at the center of the sliding sleeve, and a movable slider is arranged in the cavity; the probe of the photon PDV is installed at the top of the center of the sliding sleeve through a probe holder; the sealing bolt is installed at the bottom opening of the explosion tank and is connected to the nut on the outer surface of the bottom of the explosion tank by threads; the photon Doppler velocimeter is used to measure the speed of the slider when the explosive explodes; and the calculation unit is used to obtain the quasi-static pressure of explosion in a confined space based on the speed of the slider. A non-contact method and device for measuring the quasi-static pressure of explosion in a confined space with a large charge volume ratio is realized.

Description

Technical Field

[0001] The invention relates to the technical field of explosion and impact, and in particular to a method and a device for measuring explosion quasi-static pressure in a confined space. Background Art

[0002] As a kind of energetic material with fast reaction and high energy density, explosives are widely used in civil industry as well as military fields such as aviation, aerospace, and national defense. As one of the most widely used state equations of explosion products, the correct calibration of the coefficients of the JWL state equation directly affects the reliability of the final explosive performance evaluation. When the explosive explodes in a confined space, due to the constraints of the structural boundary on the explosion products, the shock wave will continue to reflect and superimpose in the confined space. The high-temperature and high-pressure explosion gas products will mix evenly under the condition that they cannot diffuse in time, and gradually form a pressure field. At this time, it is called entering the quasi-static pressure stage. The low-pressure term coefficient of the JWL state equation can be calibrated by measuring the quasi-static pressure of the internal explosion. Therefore, the reasonable design of the explosion test device in a confined space and the precise measurement method are the indispensable technical prerequisites and material guarantees for the above research.

[0003] In order to measure the quasi-static pressure of explosions in confined spaces, researchers at home and abroad usually use closed explosion containers for explosion tests, and use pressure sensors to measure the quasi-static pressure values. Most of the existing measurement methods use direct pressure measurement methods. In order to accurately measure the quasi-static pressure generated by the explosion, the required sensors must not only have good low-frequency response characteristics, but also have high requirements for high overload resistance, and are not easily damaged by the initial transient shock wave pressure. Even so, when using traditional piezoelectric sensors, they are greatly affected by the light, heat and vibration of the explosion, so there are certain measurement errors during measurement; most of the existing measurement sensors use piezoelectric sensors. Due to the constraints of space, there are serious interferences such as waveform glitches when measuring pressure, and due to the influence of force majeure factors such as pressure relief, the signal value is not a platform value, and there is a lack of unified standards for how to post-process the pressure measurement data; when measuring the quasi-static pressure in a confined space, due to the difficulty of direct measurement, domestic research mainly focuses on small-volume volume ratios, generally not exceeding 10kg / m 3 ,There is a lack of research on the measurement of quasi-static pressure of explosion in a confined space under large charge-to-volume ratio. Summary of the invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a method and device for measuring the quasi-static pressure of an explosion in a confined space, so as to solve the problems in the prior art that direct measurement is difficult, the results are not accurate enough, and there is a lack of research on the measurement of the quasi-static pressure of an explosion in a confined space with a large explosive volume ratio.

[0005] On the one hand, an embodiment of the present invention provides a device for measuring the quasi-static pressure of explosion in a confined space, the device comprising a photon Doppler velocimeter, a sealing bolt, a slider, a positioning gasket, a sliding sleeve, an explosion can, and a computing unit;

[0006] The sliding sleeve is fixed to the upper part of the explosion tank cavity by means of threads;

[0007] A cavity is provided at the center of the sliding sleeve, and a movable sliding block is arranged in the cavity;

[0008] The bottom of the sliding sleeve contacts the explosion canister via a positioning gasket;

[0009] The probe of the photon Doppler velocimeter is installed at the top of the center of the sliding sleeve and is separated from the slider by a certain distance;

[0010] The sealing bolt is installed at the bottom opening of the explosion tank and is connected to the nut on the outer surface of the bottom of the explosion tank through a thread;

[0011] The photon Doppler velocimeter is used to measure the speed of the slider when the explosive explodes;

[0012] The calculation unit is used to obtain the explosion quasi-static pressure in the confined space based on the speed of the slider.

[0013] Furthermore, a detonator wire hole is arranged at the center of the sealing bolt. The detonator wire hole is located at a nut end of the sealing bolt with a diameter of d1 and a diameter of the other end of the nut, wherein d1>d2.

[0014] Furthermore, after the detonator wire is passed through the detonator wire hole, strong glue is poured into the detonator wire hole to prevent the leakage of the explosion product gas and ensure the sealing of the tank body.

[0015] Furthermore, the probe of the photon Doppler velocimeter is installed on the central top of the sliding sleeve through a probe holder.

[0016] Furthermore, two handles are symmetrically installed on the outer side wall of the sliding sleeve, and the handles are connected to the sliding sleeve through threads; and a handle is installed on the outer side of the explosion tank.

[0017] Furthermore, the slider body is a cylinder, the side surface of which is provided with an inner groove and a built-in O-shaped rubber ring.

[0018] On the other hand, an embodiment of the present invention provides a method for measuring the quasi-static pressure of an explosion in a confined space based on the above-mentioned inventive device, comprising: conducting an explosion experiment in a confined space based on the device;

[0019] Based on the speed of the slider at each sampling point measured by the photon Doppler velocimeter, the time of each sampling point is obtained to obtain the speed and time corresponding to each sampling point;

[0020] Perform polynomial fitting on the speed and time of each sampling point to generate the relationship between speed and time, and then obtain the relationship between acceleration and time;

[0021] The acceleration of the slider is obtained based on the relationship between acceleration and time and the time to reach the quasi-static pressure;

[0022] The quasi-static pressure p of the explosion in the confined space is obtained based on the mass of the slider, the cross-sectional area, and the acceleration of the slider as a.

[0023] Furthermore, the time to reach the quasi-static pressure is the time Δt that the wave moves in the slider, and the formula is:

[0024]

[0025] Among them, l b is the slider length; v c is the propagation speed of the wave in the slider.

[0026] Furthermore, the polynomial fitting is:

[0027] The velocity and time of each sampling point are fitted using a third-order polynomial.

[0028] Furthermore, the quasi-static explosion pressure p in the confined space is calculated by the following expression:

[0029]

[0030] Among them, M is the mass of the slider, S is the cross-sectional area of ​​the slider, the acceleration of the slider at the moment of quasi-static pressure is a, and d is the diameter of the slider.

[0031] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0032] 1. The indirect measurement method based on the slider speed is used to measure the quasi-static pressure of the explosion in the confined space, avoiding the shortcomings of the traditional piezoelectric sensor that is easily damaged during the measurement process and is affected by light, heat and vibration.

[0033] 2. An indirect measurement method based on slider speed is used to measure the quasi-static pressure of explosions in confined spaces, avoiding the influence of factors such as inconsistent data selection standards and excessive output data waveform oscillations that interfere with reading during the measurement process of traditional piezoelectric sensors. The data post-processing is simple and the physical concepts are clear.

[0034] 3. The device has a strong overload resistance and can be used for quasi-static pressure measurement under a larger drug volume ratio.

[0035] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0037] Figure 1 It is a schematic diagram of a device for measuring quasi-static pressure of explosion in a confined space according to the present invention;

[0038] Figure 2 This is a schematic diagram of the sealing bolt structure of a device for measuring quasi-static pressure of explosion in a confined space according to the present invention;

[0039] Figure 3 The invention discloses speed-time data and a polynomial fitting curve measured by a photon Doppler velocimeter in a method for measuring quasi-static pressure of explosion in a confined space.

[0040] Reference numerals:

[0041] 1-Sealing bolt;

[0042] 2- Slider;

[0043] 3- Positioning gasket;

[0044] 4- Sliding sleeve;

[0045] 5- Explosive canister. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0047] A specific embodiment of the present invention discloses a device for measuring the quasi-static pressure of explosion in a confined space, such as Figure 1 As shown, the measuring device includes a photon Doppler velocimeter, a sealing bolt, a slider, a positioning gasket, a sliding sleeve, an explosion can and a computing unit;

[0048] The sliding sleeve is fixed to the upper part of the explosion tank cavity by means of threads;

[0049] A cavity is provided at the center of the sliding sleeve, and a movable sliding block is arranged in the cavity;

[0050] The bottom of the sliding sleeve contacts the explosion can through a positioning gasket; specifically, a positioning gasket is used at the bottom of the sliding sleeve to protect the track from being scratched by debris after the explosion so as to facilitate reuse.

[0051] The probe of the photon Doppler velocimeter is installed at the top of the center of the sliding sleeve and is separated from the slider by a certain distance;

[0052] The sealing bolt is installed at the bottom opening of the explosion tank and is connected to the nut on the outer surface of the bottom of the explosion tank through a thread;

[0053] The photon Doppler velocimeter is used to measure the speed of the slider when the explosive explodes;

[0054] The calculation unit is used to obtain the explosion quasi-static pressure in the confined space based on the speed of the slider.

[0055] Specifically, based on the speed of the slider at each sampling point measured by the photon Doppler velocimeter, the time of each sampling point is obtained to obtain the speed and time corresponding to each sampling point; polynomial fitting is performed on the speed and time of each sampling point to generate a relationship between speed and time, and then the relationship between acceleration and time is obtained; based on the relationship between acceleration and time and the time to reach a quasi-static pressure, the acceleration of the slider is obtained; based on the mass of the slider, the cross-sectional area, and the acceleration of the slider a, the quasi-static pressure p of the explosion in the confined space is obtained.

[0056] A detonator wire hole is arranged at the center of the sealing bolt. The detonator wire hole is located at the sealing bolt with a nut and has a diameter of d1 at one end and a diameter of d2 at the other end, wherein d1>d2.

[0057] After passing the detonator wire through the detonator wire hole, inject strong glue into the detonator wire hole to prevent the leakage of explosion product gas and ensure the sealing of the tank body.

[0058] The probe of the photon Doppler velocimeter is installed on the central top of the sliding sleeve through a probe fixture.

[0059] Two handles are symmetrically mounted on the outer side wall of the sliding sleeve, and the handles are connected to the sliding sleeve via threads; and a handle is mounted on the outer side of the explosion tank.

[0060] Specifically, the two handles on the outer wall of the sliding sleeve are used to increase the force arm when the sliding sleeve is rotated counterclockwise during installation. A handle is installed on the outer side of the explosion tank to facilitate the movement of the device.

[0061] The slider body is a cylinder, the side surface of which is provided with an inner groove and an O-shaped rubber ring.

[0062] In a specific embodiment of the present invention, three inner grooves are formed on the side surface of the slider, and an O-shaped rubber ring is built in, so that the slider can avoid direct contact with the slide rail and the air tightness is increased to achieve a sealed effect as much as possible.

[0063] The track on which the slider moves in the cavity is called the slide rail. The hardness of the material used for the slider must be lower than that of the sliding sleeve material to avoid scratching the inner wall of the slide rail.

[0064] The explosion tank is cylindrical in shape, and the wall of the explosion tank needs to have a certain thickness to avoid deformation due to excessive charge mass and reduce the influence of heat conduction on the experiment. The explosion tank can be placed on a base with an opening in the center, and the detonator line in the sealing bolt extends to the outside through the center opening of the base.

[0065] Sealing bolt structure Figure 2 As shown, after the sealing bolt is installed with the detonator line, the two sides are filled with glue before installation. The diameters of the two ends of the detonator line hole are designed to be large and small, in order to facilitate the filling of super glue. Explosives and detonators are pre-placed in the explosion tank, and the detonator is located in the reserved hole in the center of the explosive. The sealing bolt and the explosion tank are fixed with nuts, and the bottom of the nut of the sealing bolt is in contact with the explosion tank with a washer, and the washer is used to increase friction. The detonator line triggers the detonator to detonate the explosive through an electrical signal. A bracket is arranged above the sliding sleeve, and a through hole is provided in the center of the bracket. The photon Doppler velocimeter is arranged on the bracket. The probe of the photon Doppler velocimeter is placed in the through hole and installed on the top of the center of the sliding sleeve through the probe holder. Multiple rubber plates and steel plates are used above the bracket to recover the projectile after the explosion. The photon Doppler velocimeter PDV is an instrument that uses the photon Doppler velocimetry method to measure the target speed-time curve. It has the advantages of non-contact measurement, fast dynamic response, and good measurement accuracy. During measurement, the PDV probe is fixed on the track in the sliding sleeve cavity by the probe holder and arranged in the forward direction of the slider. It is used to measure the speed-time curve of the slider when the explosive explodes. In order to prevent damage to the probe due to explosion vibration, the PDV is arranged at a position separated from the device and there is a certain gap.

[0066] In a specific embodiment of the present invention, the specific dimensions of the measuring device are as follows: the track size of the sliding sleeve is Φ20mm×160mm, with a built-in Φ20mm×50mm copper slider, and the mass is 141g; the cylindrical explosion tank size is Φ170mm×270mm, the internal main body cavity design size is Φ70mm×150mm, and the volume is 587cm 3 ; The distance between PDV and the top of the explosion tank is about 100mm.

[0067] Another specific embodiment of the present invention discloses a method for measuring the quasi-static pressure of explosion in a confined space, and the specific steps include S1-S4.

[0068] Step S1, carrying out an explosion experiment in a confined space based on the device.

[0069] Taking 10g 8701 explosive as an example, the above device is used to obtain the quasi-static pressure of its explosion in a confined space. During the measurement, an electrical signal is applied to the detonator wire from the outside, and the electrical signal is transmitted to the detonator through the detonator wire to detonate the explosive in the explosion tank. After the explosive explodes, a large amount of high-temperature and high-pressure gas products are generated, which push the slider to move in the sliding sleeve. At the same time, the speed-time curve of the slider movement is measured using PDV.

[0070] Step S2: based on the speed of the slider at each sampling point measured by the photon Doppler velocimeter, the time of each sampling point is obtained to obtain the speed and time corresponding to each sampling point.

[0071] Specifically, the sampling points of speed and time measured by the photon Doppler velocimeter during the explosion are transmitted to an external computer in real time via a data line.

[0072] Step S3: Perform polynomial fitting on the speed and time of each sampling point to generate a relationship between speed and time, and then obtain a relationship between acceleration and time.

[0073] The polynomial fit is:

[0074] The velocity and time of each sampling point are fitted using a third-order polynomial.

[0075] Since the measurement is inevitably interfered by electrical signals, the speed obtained by the photon Doppler velocimeter is fitted with a third-order polynomial about time to obtain a smooth curve, and a relationship between speed and time is generated.

[0076] The original PDV measured data and fitting curve are as follows: Figure 3 shown.

[0077] The velocity relationship obtained by fitting in a specific embodiment of the present invention is as follows:

[0078] v=1.52426+51.62468t-9.75831t 2 +1.96947t 3 .

[0079] Taking the first-order differential of the above formula, the acceleration expression of the slider is as follows:

[0080] a=51.62468-19.51662t+5.90841t 2 .

[0081] Step S4, obtaining the acceleration of the slider based on the relationship between acceleration and time and the time to reach the quasi-static pressure.

[0082] The time to reach the quasi-static pressure is the wave movement time Δt in the slider. The formula is:

[0083]

[0084] Among them, l b is the slider length; v c is the propagation speed of the wave in the slider.

[0085] Specifically, by conducting quasi-static pressure simulation experiments, it can be known that the specific l b The length and v c The ratio of enables the calculated Δt to be equal to the time to reach quasi-static state.

[0086] The acceleration a at the time t=Δt is taken as the acceleration of the slider at the time of the quasi-static pressure action.

[0087] The initial acceleration a of the slider obtained in the specific embodiment of the present invention is 51.6 km / s 2 .

[0088] Step S5, obtaining the explosion quasi-static pressure p in the enclosed space based on the mass of the slider, the cross-sectional area, and the slider acceleration a.

[0089] The quasi-static explosion pressure p in the confined space is calculated by the following expression:

[0090]

[0091] Among them, M is the mass of the slider, S is the cross-sectional area of ​​the slider, the acceleration of the slider at the moment of quasi-static pressure is a, and d is the diameter of the slider.

[0092] In the specific embodiment of the present invention, the quasi-static pressure of 10g 8701 explosives exploding in a confined space, the copper slider has a mass of 141g and a diameter of 20mm, and the measured value is 23.05MPa.

[0093] Compared with the prior art, the present embodiment provides a method and device for measuring the quasi-static pressure of an explosion in a confined space, which adopt an indirect measurement method based on the slider speed to measure the quasi-static pressure of the explosion in a confined space, thereby avoiding the shortcomings of traditional piezoelectric sensors that are easily damaged during the measurement process and are affected by light, heat and vibration. The indirect measurement method based on the slider speed is used to measure the quasi-static pressure of the explosion in a confined space, thereby avoiding the influence of factors such as inconsistent data selection standards and excessively violent output data waveform oscillations that interfere with reading during the measurement process of traditional piezoelectric sensors. The data post-processing operation is simple and the physical concepts are clear. The device has a strong overload resistance and can be used for quasi-static pressure measurement under a larger drug volume ratio.

[0094] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0095] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A device for measuring quasi-static pressure of explosion in a confined space, characterized in that: The measuring device comprises a photon Doppler velocimeter, a sealing bolt, a sliding block, a positioning gasket, a sliding sleeve, an explosion can and a computing unit; The probe of the photon Doppler velocimeter is mounted on the top of the center of the sliding sleeve through a probe holder; A bracket is arranged above the sliding sleeve, a through hole is provided in the center of the bracket, a photon Doppler velocimeter is arranged on the bracket, a probe of the photon Doppler velocimeter is placed in the through hole and installed on the top of the center of the sliding sleeve through a probe holder; The sliding sleeve is fixed to the upper part of the explosion tank cavity by means of threads; A cavity is provided at the center of the sliding sleeve, and a movable sliding block is arranged in the cavity; The bottom of the sliding sleeve contacts the explosion canister via a positioning gasket; The probe of the photon Doppler velocimeter is installed at the top of the center of the sliding sleeve and is separated from the slider by a certain distance; The sealing bolt is installed at the bottom opening of the explosion tank and is connected to the nut on the outer surface of the bottom of the explosion tank through a thread; A detonator wire hole is arranged at the center of the sealing bolt. The detonator wire hole is located at a nut end of the sealing bolt with a diameter of d1 and a diameter of the other end of the nut, wherein d1>d2; Explosives and detonators are pre-placed in the blasting tank, and the detonator is located in the reserved hole in the center of the explosives; The photon Doppler velocimeter is used to measure the speed of the slider when the explosive explodes; The calculation unit is used to obtain the quasi-static pressure of the explosion in the confined space based on the speed of the slider, including: obtaining the time of each sampling point based on the speed of the slider at each sampling point measured by the photon Doppler velocimeter, and obtaining the speed and time corresponding to each sampling point; Perform polynomial fitting on the speed and time of each sampling point to generate the relationship between speed and time, and then obtain the relationship between acceleration and time; The acceleration of the slider is obtained based on the relationship between acceleration and time and the time to reach the quasi-static pressure; The quasi-static pressure p of the explosion in the confined space is obtained based on the mass of the slider, the cross-sectional area, and the acceleration of the slider as a.

2. The device for measuring quasi-static explosion pressure in a confined space according to claim 1, characterized in that: After passing the detonator wire through the detonator wire hole, inject strong glue into the detonator wire hole to prevent the leakage of explosion product gas and ensure the sealing of the tank body.

3. The device for measuring quasi-static explosion pressure in a confined space according to claim 1, characterized in that: Two handles are symmetrically mounted on the outer side wall of the sliding sleeve, and the handles are connected to the sliding sleeve via threads; and a handle is mounted on the outer side of the explosion tank.

4. The device for measuring quasi-static explosion pressure in a confined space according to claim 1, characterized in that: The slider body is a cylinder, the side surface of which is provided with an inner groove and an O-shaped rubber ring.

5. The method for measuring the quasi-static pressure of explosion in a confined space of the device according to claim 1, comprising: Carry out explosion experiments in a confined space based on the device; Based on the speed of the slider at each sampling point measured by the photon Doppler velocimeter, the time of each sampling point is obtained to obtain the speed and time corresponding to each sampling point; Perform polynomial fitting on the speed and time of each sampling point to generate the relationship between speed and time, and then obtain the relationship between acceleration and time; The acceleration of the slider is obtained based on the relationship between acceleration and time and the time to reach the quasi-static pressure; The quasi-static pressure p of the explosion in the confined space is obtained based on the mass of the slider, the cross-sectional area, and the acceleration of the slider as a.

6. The method for measuring the quasi-static pressure of explosion in a confined space of the device according to claim 5, characterized in that: The time to reach the quasi-static pressure is the wave movement time Δt in the slider. The formula is: Among them, l b is the slider length; v c is the propagation speed of the wave in the slider.

7. The method for measuring the quasi-static pressure of explosion in a confined space of the device according to claim 6, characterized in that: The polynomial fit is: The velocity and time of each sampling point are fitted using a third-order polynomial.

8. The method for measuring the quasi-static pressure of explosion in a confined space according to the device of claim 7, characterized in that: The quasi-static explosion pressure p in the confined space is calculated by the following expression: Among them, M is the mass of the slider, S is the cross-sectional area of ​​the slider, the acceleration of the slider at the moment of quasi-static pressure is a, and d is the diameter of the slider.

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