RU2647256C1 - Method of increasing the distance of the rocket-propelled grenade - Google Patents

Abstract

FIELD: weapons and ammunition.

SUBSTANCE: invention relates to the field of rocket technology, in particular to the rocket engines of active-rocket shells launched from the barrel of an artillery gun, and consists in a method for increasing the range of an active-missile projectile. On the trajectory of the projectile's flight, the charge of solid fuel is ignited by the products of the igniter's combustion located in the premolar volume and initiated by the products of combustion of the rate reducer. Ignition of the rate reducer charges is carried out by the products of the combustion of pyrocartridges that are triggered when the projectile is launched from the gun barrel and placed in a closed cavity formed by a perforated diaphragm separating the pre-nozzle volume and nozzle diffuser, and cut by the nozzle cover located in its outlet section. Charges of the rate reducer are made in the form of truncated cones, the bases of which are directed towards the exit section of the nozzle, and hermetically placed through thermoinsulating gaskets in the perforations of the diaphragm. Height of the rate reducer's charges is determined by an algebraic formula including the optimal value of the ignition delay time of the solid fuel charge, which is predetermined from a series of outwardly ballistic calculations of the range of flight of a specific active-missile projectile.

EFFECT: invention makes it possible to provide an increase in the range of the active-rocket projectile and reliable ignition of its charge of solid fuel.

1 cl, 5 dwg, 3 tbl

Description

The invention relates to the field of rocket technology, in particular, to rocket engines of active rockets (ARS), launched from the barrel of an artillery gun, and can be used in the development of rocket engines included in the flight path of the APC.

A feature of the external ballistics of the ARS is that at the time of departure from the gun’s barrel the projectile has a maximum (muzzle) speed [1]. In this case, the projectile experiences maximum resistance from the environment, proportional to the square of its speed. The inclusion of a solid propellant rocket engine (RDTT) of an active rocket directly at the time of the projectile's departure from the barrel does not allow efficient use of the solid propellant rocket propulsion to increase the flight range of the APC. To increase the efficiency of the ARS, it is advisable to launch the solid propellant rocket engine on the flight path of an active-rocket projectile using various methods and devices for ignition delay (moderators) [2-6].

Known rocket engine artillery shell [2], containing a housing with a charge of solid fuel and a nozzle, a plug installed in it with an annular protrusion in contact with the outer surface of the nozzle, fixing its element, an ignitor and a knife-type stabilizer block. The igniter is located on the plug in the conical body and is equipped with a moderator mounted on the nozzle exit side. The stabilizers overlap the end of the moderator, and the locking element is made in the form of a tube, one end of which is fastened to the nozzle in its critical section, and the other end is provided with protrusions covering the igniter body.

Known rocket engine of solid fuel of an active-reactive projectile [3], comprising a housing with a nozzle block and a charge of solid fuel, a plug installed in the nozzle block with a central channel in which the pyro-retarder is placed, and channels in its bottom facing the nozzle exit, located in housing from the side of the pyro-moderator igniter. Moreover, the channels in the bottom of the plug are made radial, at the entrance of which curvilinear recesses are formed.

Known rocket engine artillery shell [4], containing a combustion chamber with a charge of solid fuel, a nozzle, a pyrotechnic initiator delayed action installed in the nozzle plug channel. The engine additionally contains a perforated disk and a ball, and in the plug from the nozzle exit side the channel is made with expansion towards the initiator. The ball is placed in the cavity of the channel, and a perforated disk is installed between the channel and the initiator, and the holes in the disk are made with a diameter smaller than the diameter of the ball.

Known active-rocket projectile [5], which contains a rocket engine of solid fuel, a nozzle plug with a pyro-moderator, a charge of solid fuel and an ignitor. A semi-closed cavity is made at the rear end of the projectile, while the moderator is buried in this cavity. At the end of the moderator from the rear end of the projectile mounted throttle washer, made with at least one transverse diametrical groove. The width of the groove is made smaller than the diameter of the throttle washer.

Closest to the technical solution of the claimed invention is a method for implementing the ignition delay of a charge of solid fuel in the APC using a device containing a conical plug with an igniter and moderator, overlapping the outlet of the nozzle [6]. At the end of the wall of the plug facing the charge, an annular protrusion is made, on which a membrane in the form of a cup with a flanging is installed with a gap relative to the end filled with a sealing compound.

The main disadvantage of the known technical solutions is that an additional solid fuel charge (moderator) is initiated by powder propellant gases in the gun’s barrel, the pressure of which is several thousand atmospheres. This reduces the reliability of the initiation and operation of the marching solid propellant rocket-propelled rocket. Firstly, exposure to high pressure gases can lead to disruption of the internal ballistic of solid propellant rocket engines, deformation of the charge, and destruction of the engine. Secondly, when a projectile leaves the gun barrel, spontaneous damping of the moderator charge is possible due to a sharp pressure drop [7]. Known technical solutions, in addition to the complexity of the design of most of them, do not provide a controlled and optimal value of the ignition delay time of the solid propellant rocket engine.

The technical result of the present invention is to increase the flight range of the APC and increase the reliability of initiation of solid propellant rocket-propelled rocket.

The technical result of the invention is achieved by the fact that a method has been developed to increase the flight range of an active-rocket projectile, which includes igniting, on the flight path, the charge of solid fuel by the products of combustion of an igniter located in a pre-nozzle volume and initiated by the products of combustion of a moderator. Ignition of the charge of the moderator is carried out by the combustion products of the pyro cartridge, which are fired when the projectile leaves the gun barrel and is placed in a closed cavity formed by a perforated diaphragm separating the nozzle volume and the nozzle diffuser and the nozzle cover cut off located in its exit section. The moderator charges in the form of truncated cones, the bases of which are directed towards the exit section of the nozzle, are hermetically placed through thermally insulating gaskets in the perforations of the diaphragm. The height of the charges of the moderator is determined from the ratio

,

,

where h is the height of the charges of the moderator;

ρ is the charge density of the moderator;

S is the total combustion surface of the charges of the moderator;

R is the gas constant of the combustion products of the moderator;

T is the temperature of the combustion products of the moderator;

p ₀ - atmospheric pressure;

V is the volume of the closed cavity;

u ₀ is the burning rate of the moderator at atmospheric pressure;

v is an exponent in the dependence of the burning speed of the moderator on pressure u = u ₀ (p / p ₀ ) ^v ;

u is the burning rate of the moderator at a pressure p;

p is the pressure in the closed cavity;

t _ign is the ignition delay time of the solid fuel charge.

The ignition delay time of a solid fuel charge is previously determined from a series of external ballistic calculations of the dependence of the flight range of a specific active-rocket projectile on the ignition delay time of a solid fuel charge, as the value of the ignition delay time, which ensures the maximum flight range.

The invention is illustrated by a diagram of an active-rocket projectile that implements the inventive method (Figure 1). The APC rocket engine comprises a housing 1 with a solid fuel charge 2 and a nozzle block. An igniter hitch 23 is placed in the pre-nozzle volume 3. A perforated diaphragm 4 is installed in the supercritical section of the nozzle, in which the charges of the moderator 21 are hermetically placed through the heat-insulating gaskets 22. The charges of the moderator 21 are made in the form of truncated cones, the bases of which are directed towards the exit section of the nozzle. A base 8 is installed in the nozzle diffuser 6, which is fastened to the outlet part of the diffuser 6 by means of a rolling nozzle 13 with a nozzle cover 13 and rolled onto the outlet part of the diffuser 6. On the base 8, a cup 19 is fixed along the axis of which a movable rod 14 with a console mounted on it 18. From the base 8, on the console 18, the impactors 16 are installed, and on the charge side 2, the console 18 relies through the spring 20 to the perforated diaphragm 4. On the base 8, pyrocartridges 15 are placed opposite the impactors 16. The console 18 has perforations 17 for passage oduktov combustion squib 15 in the closed cavity 5. On the rod 14 is formed with a tapered portion 11 of the base 8, coupled with the conical cavity 9 at the base 8, and the notched flange 10 which is sandwiched between the base 8 and cut by the nozzle cap 13.

The rocket engine of an active-missile shell works as follows. When the projectile moves in the gun’s barrel under the action of a high pressure of propellant propellant gas, the protruding edge of the flange 10 is cut off, and the rod 14 with the console 18 fixed to it moves towards the perforated diaphragm 4 and compresses the spring 20. In this case, the conical section 11 of the rod 14 mates with the conical cavity 9 in the base 8, preventing the breakthrough of powder gases into the closed cavity 5. After the projectile leaves the gun barrel, the pressure of the powder gases on the sheared nozzle cover 13 decreases sharply, while the rod 14 with the fixed and with it, under the action of the spring 20, the cantilever 18 moves back and acts by the impactors 16 on the squibs 15. The combustion products of the squibs through the perforations 17 in the cantilever 18 enter a closed cavity 5 and ignite the end surfaces of the charges of the moderator 21. Thermal insulating pads 22 prevent the penetration of powder gases into the pre-nozzle volume from the closed cavity 5 until the charges of the moderator 21 are completely burned out. After the charges of the moderator 21 are burned out for a predetermined time t _{ign the} combustion products through perforations of the diaphragm 4 They are injected from the closed cavity 5 into the pre-nozzle volume and ignite the igniter hitch 23. The products of the igniter 23 ignite the charge of solid fuel 2. When the set pressure in the combustion chamber reaches the specified pressure, the rolling 7 of the nozzle cover 13 is cut off, allowing all elements of the ignition system to escape from the nozzle diffuser 6 ( diaphragm 4, cup 19, base 8, etc.). Thus, the launch of the solid propellant rocket engine on the flight path through a strictly controlled time t _ign , determined by the burning rate and the height of the charges of the moderator 21 is ensured.

The achievement of the positive effect of the invention is provided by the following factors.

1. Ignition of the moderator charges by the combustion products of the pyro cartridge, located in a closed cavity between the perforated diaphragm and the nozzle cover being cut off, located in its outlet section, ensures the autonomy of the end surfaces of the moderator charges (without contact with high-pressure propellant gases).

2. The operation of the squib when the active-rocket projectile leaves the gun barrel provides a clear fixation of the ignition charge of the moderator and, accordingly, provides a controlled amount of delay time for ignition of the charge of solid fuel.

3. The implementation of the moderator charges in the form of truncated cones, the bases of which are directed towards the outlet section of the nozzle, prevents the moderator charges from escaping into the pre-nozzle volume under pressure in a closed cavity until they are completely burned.

4. The tight placement of the retarder charges in the perforations of the diaphragm provides reliable isolation of the pre-nozzle volume from the combustion products of the retarder in a closed cavity for a given time of combustion of the retarder charges.

5. The placement of moderator charges in the perforations of the diaphragm through thermally insulating gaskets reduces heat loss from the combustion wave of the moderator charges into the material of the diaphragm. This ensures the stability of combustion of the charges of the moderator.

6. The ratio for determining the height of the charges of the moderator

provides the optimal value for the ignition delay time of a solid fuel charge, at which the APC flight range is maximum.

To derive relation (1), we consider the equations of conservation of mass in a closed cavity between the perforated diaphragm and the nozzle cover being cut off

where t is time;

ρ _g is the density of the gaseous products of combustion of the moderator;

ρ is the charge density of the moderator;

V is the volume of the closed cavity;

S is the total combustion surface of the charges of the moderator;

u is the burning rate of the moderator.

In accordance with the equation of state of Mendeleev - Clapeyron

where p is the pressure in the closed cavity;

R is the gas constant of the combustion products of the moderator;

T is the temperature of the combustion products of the moderator.

Substituting (3) in (2), we obtain

We take the law of the rate of combustion of the moderator in the form [8]:

where u ₀ is the burning speed of the moderator at atmospheric pressure;

p ₀ - atmospheric pressure;

v is an exponent in the dependence of the burning speed of the moderator on pressure.

Substituting (5) into equation (4) and performing integration, we obtain:

The height of the charges of the moderator is determined by the equation

Taking into account (5), (6), we obtain the desired relation

which reduces to (1).

Implementation example

As an example of the implementation of the proposed method, we consider the movement of an active-reactive projectile with a caliber of 76 mm (ZIS-3) [9], which houses a solid-propellant rocket engine with a tube-channel charge, booked along end surfaces, with dimensions 40 / 8-150 mm. The total initial mass of the APC is 6.6 kg, the mass of the solid fuel charge (gunpowder N) is 0.29 kg (4.3% of the mass of the projectile).

According to the results of the internal ballistic calculation of solid propellant solid propellant rocket engine carried out according to the methodology [10], the main characteristics of the APC solid propellant engine are obtained:

- the diameter of the critical section of the nozzle d _cr - 9.2 mm;

- diameter of the nozzle exit section d _a = 27.8 mm;

- operating pressure in the combustion chamber in marching mode p _k = 8.0 MPa;

- engine thrust P = 778N;

- mass second consumption of combustion products G = 0.35 kg / s;

- specific impulse of thrust J = 2214 m / s;

- while the SRM t _* = 0.82 s.

To determine the optimal value of the ignition delay time of the solid fuel charge t _ign, a series of external ballistic calculations of the APC flight range was carried out when firing a gun with an initial (muzzle) velocity of U ₀ = 680 m / s, angle θ ₀ = 45 °.

The calculations were performed for an inert projectile (without solid propellant rocket) and for a rocket with solid propellant rocket with varying ignition delay time t _ign .

The motion of an inert body in the air is determined by the system of equations of external ballistics [10]

where U is the velocity of the projectile;

F is the drag force;

m is the mass of the projectile;

g is the acceleration of gravity;

θ is the angle between the velocity vector and the local horizon line;

y is the vertical coordinate;

x is the horizontal coordinate.

The system of equations of motion of the APC in the active section includes a modified equation for the speed of motion taking into account the thrust of the rocket engine and an additional equation of change in the mass of the APC during TRT combustion

where P is the traction force of the solid propellant rocket engine;

ρ _T is the density of solid fuel;

u _T is the burning rate of solid fuel;

S _T is the combustion surface area of solid fuels.

The drag force was calculated by the formula

,

,

where C _x is the drag coefficient;

ρ _in - air density;

S _m - the area of the mid-section of the projectile.

The drag coefficient C _{x was} calculated using approximation formulas depending on the Mach number [10].

According to the results of the calculations, the flight range of the ZIS-3 inert shell (without solid propellant rocket) is x _k = 13.7 km, which agrees well with the results of field tests (x _k = 13.3 km) [9].

The results of parametric calculations of the movement of an active rocket with solid propellant rocket engine for different ignition delay times t _ing are shown in Table 1 (x _k is the flight range, t _k is the flight time).

The generalized results of the calculations of the movement of an active missile ZIS-3 are shown in table 2 (U _to - the final velocity of the projectile).

The calculated time dependences of the APC speed are shown in FIG. 2, and the APC motion paths are shown in FIG. 3, where a is an inert projectile (without TRT charge); b - shell with solid propellant rocket engine at t _ign = 0 s; c - shell with solid propellant rocket engine at t _ing = 19 s.

The calculation results show that when using a tubular-channel charge of ballistic (gunpowder N) fuel, the projectile flight range is increased by 10% (at t _ign = 0 s) and by 20% (at t _ign = 19 s) compared to inert projectile.

We calculate the height h of the charge of the moderator (average diameter 5 mm), which provides the necessary delay time for ignition of the solid propellant charge. The main characteristics of the composition of the moderator TZS-20 are shown in table 3 [8].

In FIG. Figure 4 shows a graph of the dependence of the height of the moderator h depending on the required value of the ignition delay time t _ign for various values of the free volume of the closed cavity, calculated by the relation (1). For a time t _ign = 19 s, the height of the moderator charge is h = 14 mm with a free volume V = 10 cm ³ . In FIG. Figure 5 shows the values of the maximum pressure p in a closed cavity during combustion of the charges of the moderator for different values of the free volume calculated by the formula (6). The pressure value substantially depends on the free volume and for V = 10 cm ^{3 it} is p = 12.7 MPa.

Thus, from the above example it follows that the claimed method of increasing the flight range of an active-rocket projectile ensures the achievement of the technical result of the invention — increasing the flight range by providing a controlled and optimal ignition delay time of the solid propellant solid propellant charge and increasing the reliability of the initiation of solid propellant rocket ignition excluding the effect of high pressure gases propelling charge in the gun barrel.

LITERATURE

1. Serebryakov M.E. Internal ballistics. - M .: Oborongiz, 1949 .-- 670 p.

2. RF patent №2021544, IPC F02K 9/08. Rocket engine of an artillery shell / Sokolov G.F., Mironov Yu.I., Berkovich B.C. - Publ. 10/15/1994 g.

3. RF patent No. 2037065, IPC F02K 9/08. Rocket engine of solid propellant rocket / Sokolov G.F., Vasina E.A., Morozov V.D., Koshelev E.V. - Publ. 06/09/1995 g.

4. RF patent No. 2059859, IPC F02K 9/08. Rocket engine of an artillery shell / Babichev V.I., Aleshichev I.A., Sokolov G.F., Rodin L.A. - Publ. 05/10/1996

5. RF patent No. 2075033, IPC F42B 10/38. Active rocket / Babichev V.I., Kolotilin S.V. - Publ. 03/10/1997

6. RF patent No. 2080468, IPC F02K 9/08, F42B 10/38. Rocket engine of an artillery shell / Babichev V.I., Sokolov G.F., Mironov Yu.I., Berkovich B.C. - Publ. 05/15/1997

7. Raizberg B.A., Erokhin B.T., Samsonov K.P. Fundamentals of the theory of working processes in solid fuel rocket systems. - M.: Mechanical Engineering, 1972. - 383 p.

8. Demyanenko D.B., Dudyrev A.S., Strakhov I.G., Tsynbal M.N. A complex of new pyrotechnic retardants for temporary pyroautomatics devices and initiation tools. // Izv. St. Petersburg State Technological University (Technical University). 2012, No. 16 (42). - S. 3-7.

9. Shirokorad A.B. A missile with a rocket heart // Popular mechanics. 2012, No 5 (115).

10. Stepanov V.P. The dynamics of the flight of rockets. Tutorial. - Tomsk: Publishing house of Tomsk University, 1977. - 560 p.

Claims (15)

1. A method of increasing the flight range of an active-reactive projectile, including ignition on the flight path of a solid fuel charge by an igniter combustion product located in a pre-nozzle volume and initiated by a moderator combustion product, characterized in that the moderator charges are ignited by the combustion products of the igniter firing when the projectile leaves gun barrel and placed in a closed cavity formed by a perforated diaphragm that separates the pre-nozzle volume and nozzle diffuser, and cut the nozzle cap located in its outlet section, and the moderator charges in the form of truncated cones, the bases of which are directed towards the nozzle exit section, are hermetically placed through heat-insulating gaskets in the perforations of the diaphragm, and the height of the moderator charges is determined from the ratio

, where h is the height of the charges of the moderator; ρ is the charge density of the moderator; S is the total combustion surface of the charges of the moderator; R is the gas constant of the combustion products of the moderator; T is the temperature of the combustion products of the moderator; p ₀ - atmospheric pressure; V is the volume of the closed cavity; u ₀ is the burning rate of the moderator at atmospheric pressure; ν is the exponent in the dependence of the burning speed of the moderator on the pressure u = u ₀ (p / p ₀ ) ^ν ; u is the burning rate of the moderator at a pressure p; p is the pressure in the closed cavity; t _ign is the ignition delay time of the solid fuel charge. 2. The method according to p. 1, characterized in that the ignition delay time of a solid fuel charge is preliminarily determined from a series of external ballistic calculations of the dependence of the flight range of a specific active-reactive projectile on the ignition time of a solid fuel charge as the ignition delay time providing the maximum flight range.

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