RU2772746C1 - Device for determining the pulse of explosion of an explosive charge/ammunition in the near zone - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to the field of testing and measuring equipment, in particular to devices for measuring the characteristics of the explosion of a munition or explosive charge in the near zone from the target object being hit, when the distance from the munition or charge to the target does not exceed 10 calibers. The device contains a supporting structure consisting of a shelf with a horizontal surface and a vertical rack for its attachment to a throwable body placed on it, exposed to the damaging factors of the explosion. The rack is made with a central through channel, the shelf is made with a through hole communicating with the rack channel, the thrown body is made in the form of a sphere, additionally the device contains a high-pressure air/gas source connected by a pneumatic line to the rack channel. The coupling of the rack channel with the hole in the shelf can be made in the form of a Laval nozzle. A compressor or a powder pressure accumulator can be used as a high-pressure air/gas source in the device.

EFFECT: increase in the accuracy of measurements, as well as ensuring the possibility of using automated systems for collecting and processing information.

4 cl, 3 dwg

Description

The invention relates to the field of testing and measuring technology, specifically to devices for measuring the characteristics of an explosion of an ammunition or an explosive charge (HE), in the so-called near zone from the object (target) to be struck, when the distance from the ammunition / charge to the target does not exceed 10 calibers, and the target is subjected to the combined action of gaseous products of the explosion, fragments (body/shell) and shock wave (SW).

A device for measuring the impulse of an explosion in the near zone III is known, containing a support structure consisting of a shelf with a horizontal surface and a vertical rack/racks for its fastening and a missile body (or a set of missile bodies) placed on the shelf.

The principle of its operation is based on the movement of a body of known mass with a given surface, exposed to the damaging factors of an explosion (in particular, SW), - based on the known mass of the body and the measured value of its movement under the action of an explosion from its original position, the momentum and pressure on the SW front.

In this device, as projectile bodies, prisms are used that are oriented with respect to the explosive charge with their side faces, and the side edges of the prisms are shorter than the sides of their bases. Thus, the loaded surface of the projectile, exposed to the damaging factors of the explosion of the charge (gaseous products of the explosion, fragments of the body / shell and SW) is its side face.

The disadvantage of the device is that before the projectile body is brought into a state of free movement under the action of the damaging factors of the explosion, it is subjected to the action of an oppositely directed friction force before leaving the surface of the shelf. In this case, part of the explosion energy is spent on overcoming the friction force between the projectile body and the shelf surface, which reduces the accuracy of the results obtained.

Closest to the proposed invention in terms of technical essence and the achieved result is the device /2/, also containing a support structure consisting of a shelf with a horizontal surface and a vertical rack for its fastening with a projectile placed on it, exposed to damaging explosion factors. Here, cylindrical projectiles are used, oriented to the point of explosion by the side surface of the cylinder, and their plane-parallel movement is assumed.

Under the action of shock waves at the beginning of the movement along the horizontal surface of the shelf, they acquire rotational motion relative to the longitudinal axes, sliding friction is replaced by rolling friction, due to which the energy consumption to overcome the friction forces in the "throwing body - shelf" system is significantly reduced.

However, in this case, at the same time, some part of the energy/momentum of the explosion that is not taken into account is spent on acquiring rotational motion by the body. And with the subsequent movement of the rotating cylinder in the air, the Magnus effect will appear - a physical phenomenon that occurs when a liquid or gas flows around a rotating body. A force is formed that acts on the body and is directed perpendicular to the direction of flow, in this case, perpendicular to the direction of linear movement of the missile cylinder, which leads to a decrease in the accuracy of measurements, and, as a result, subsequent calculations.

In addition, the intended means of measuring the linear displacements of the thrown elements - a tape measure - does not allow to achieve high measurement accuracy.

The technical objective of the invention is to eliminate the above disadvantages of the prototype device, first of all, to increase the accuracy of measurements, as well as to provide the possibility of using automated systems for collecting and processing information.

The solution to the problem is achieved by the fact that in a known device for determining the impulse of an explosive charge/ammunition in the near zone, containing a support structure consisting of a shelf with a horizontal surface and a vertical rack for its fastening with a projectile placed on it, exposed to damaging explosion factors, in accordance with the invention, the rack is made with a central through channel, the shelf - with a through hole communicating with the channel of the rack, the projectile body is made in the form of a sphere, while the device additionally contains a high-pressure air/gas source connected by a pneumatic line to the channel of the rack.

Thus, the main distinguishing features of the proposed technical solution are:

- execution of a rack with a central through channel;

- implementation of the shelf with a through hole communicating with the rack channel;

- execution of a thrown body in the form of a sphere;

- the presence in the design of an additional source of high-pressure air / gas connected by a pneumatic line to the channel of the rack.

The spherical shape of the projectile, which is placed on a horizontal shelf when determining the impulse of the charge explosion, due to the presence of a hole in the shelf, which communicates with the channel in the rack, connected in turn via a pneumatic line to a high pressure source, allows immediately before detonation to bring the projectile body with an air / gas jet into levitating (suspended) state relative to the shelf. Thus, mechanical contact and, accordingly, friction between the thrown body and the shelf are eliminated, and the energy of the explosion will be almost completely spent on throwing the body.

As an example, the invention is illustrated with graphical information:

In FIG. 1 schematically shows an example of the implementation of the device with preliminary placement on the shelf of the supporting structure of the spherical projectile body.

In FIG. 2 - a device with a levitating projectile immediately before the explosion of the explosive charge.

In FIG. 3 is an example of placing several devices on different measuring beams of the test site.

To simplify the images, the set of control and recording equipment, as well as the corresponding communication and engineering lines, are not shown in the illustrations.

A device for determining the impulse of an explosion of an explosive charge/ammunition in the near zone (Fig. 1, 2) contains a support structure consisting of a shelf 1 with a horizontal surface and a vertical rack 2 for its fastening and a spherical projectile body 3 placed on the shelf, subject to damaging factors explosion. The rack is made with a central through channel 4, the shelf - with a through hole 5 communicating with the rack channel, the high-pressure air/gas source 6 is connected by a pneumatic line 7 to the rack channel through a shut-off and control valve 8.

The explosive charge/ammunition 9 is mounted on an individual support rack 10; R is the distance between the centers of mass of the charge and the projectile, H is the height of the center of mass of the charge relative to the earth's surface, h is the required height of the center of mass of the projectile before detonation of the explosive charge/ammunition.

The operation of the device is as follows (Fig. 1). On the shelf of the support structure 1, fixed on the rack 2, a missile body 3 exposed to the damaging factors of the explosion is placed in such a way that it blocks the hole in the shelf 5.

The tested explosive charge/ammunition 9 is installed on its own stand 10 with a given distance R between the centers of mass of the charge and the projectile.

Before detonating the explosive charge/ammunition 9, it is necessary that its center of mass and the center of mass of the projectile body 3 be located in the same horizontal plane, i.e. at the same height H from the earth's surface (Fig. 2). Since the center of mass of the projectile body 3 is initially located below the center of mass of the charge 9 by a certain value h, before the charge is detonated from the high pressure source 6, through the shut-off and control valve 8, air/gas is supplied to the pneumatic line 7, then to the through channel 4 of the rack 2 and along it - into the hole 5 of the support 1 associated with it, the exit from which is previously blocked by the projectile body. Under the action of a high-pressure gas jet on the lower surface of the projectile body 3, it first rises, opening the exit of the gas jet from the hole 5 in the support 1, and then begins to levitate steadily in the jet, in accordance with Bernoulli's law /3/.

In a jet flowing around a thrown body, the air speed is greater, and the pressure is less than in the surrounding still air. As a result, forces act on the spherical projectile from the sides, which keep it in the jet, and from below - aerodynamic pressure, which balances the force of gravity.

Thus, under the condition of stable levitation over the support 1, the weight of the projectile body 3 is compensated by the dynamic pressure of the gas jet flowing from the hole 5, i.e. equality holds:

where M is the mass of the thrown body, kg;

g - acceleration of gravity, 9.81 m / s ² ;

C _x - coefficient of aerodynamic resistance;

S - midsection area of the projectile body, m ² ;

ρ - gas density, kg/m ³ ;

V - gas jet velocity, m/s.

It follows from this dependence that, under other unchanged conditions, the observance of the above equality primarily depends on the velocity of the gas jet V flowing out of hole 5.

Therefore, in order to increase the dynamic head, it is necessary to locally increase the speed of the gas jet V, for which it is expedient to connect the channel 4 of the rack 2 with the hole 5 in the shelf 1 in the form of a Laval nozzle.

The required required levitation height h of the projectile body 3 immediately before the explosion is determined by the ratio of the diameters of the hole 5 and the projectile body 3, as well as the speed of the gas jet V. For specific weight and size characteristics of the projectile body, the levitation height h is set by adjusting the gas flow, for example, by means of a shut-off and control valve 8.

As a source of high-pressure air/gas 6, a compressor or a powder pressure accumulator (PAD) can be used.

To carry out more accurate measurements when testing an explosive charge / ammunition, several devices can be used simultaneously, with the placement of identical missile bodies at different distances from the charge, for example R ± AR (Fig. 3) or with different weight and size characteristics placed at the same distances, but at different measuring beams of the test area.

When the charge 9 is detonated, the projectile body 3 levitating above the shelf 1 at a relative height h under the influence of the damaging factors of the explosion is “knocked out” of the gas jet, acquires horizontal speed and leaves the shelf 1 without friction.

Fixing the movement of the missile body can be carried out using standard high-speed recording equipment from the moment the charge is detonated until the moment the missile body falls on the surface of the test site. According to the resulting film, the recognition of the nature of the movement of each thrown body is determined, and as a result, the determination of the speed acquired by it and the resulting impulse. Moreover, according to the nature of the trajectory of the movement of the projectile body (cinema), it can be additionally determined, in the case of the presence, acquired by the body along with the translational, of the rotational component of the momentum by the accompanying deviation of the trajectory from a straight line (in projection onto a horizontal surface) to a curved one under the action of the Coriolis force. With known mass and size characteristics of the projectile body, in this case, both the Coriolis force itself and the magnitude of the rotational component of the momentum acquired by it can be analytically determined. And then, by appropriate recalculation, - the value of the hypothetically maximum possible momentum of translational movement.

For more accurate results, you can shoot from multiple angles at the same time, such as horizontal and vertical.

The shooting process can be carried out in automatic mode, the analysis and processing of the obtained films, the determination of their results by mathematical processing of the impulse and pressure of the SW can also be carried out automatically, using modern software and hardware. This will improve the accuracy of measurements, significantly reduce labor costs, and provide the possibility of using automated systems for collecting and processing information.

Sources of information taken into account when describing the application:

1) Patent CN No. 105606650А, G01N 25/54, Method for testing cylindrical charging near-field energy distribution character, 2016.

2) M. Held, Blast Load Diagnostic, Propellants Explos. Pyrotech. 2009, 34, 194 - 209 - prototype.

3) Tennis ball in the air jet, - https://www.youtube.com/watch?v=uBQjeqTWXys.

Claims (4)

1. A device for determining the impulse of an explosion of an explosive charge / ammunition (HE) in the near zone, containing a support structure consisting of a shelf with a horizontal surface and a vertical rack for its fastening with a projectile placed on it, exposed to damaging explosion factors, characterized in that that the rack is made with a central through channel, the shelf - with a through hole communicating with the channel of the rack, the projectile body is made in the form of a sphere, while the device additionally contains a high-pressure air/gas source connected by a pneumatic line to the rack channel. 2. The device according to claim. 1, characterized in that the connection of the rack channel with the hole in the shelf is made in the form of a Laval nozzle. 3. The device according to claim 1, characterized in that it additionally contains a compressor as a source of high-pressure air/gas. 4. The device according to claim. 1, characterized in that it additionally contains a powder pressure accumulator as a source of high pressure air / gas.

Images