RU71158U1 - ROCKET LAUNCHER - Google Patents

Abstract

The invention relates to the field of reactive grenade launchers, in which grenade throwing occurs as a result of the operation of a pulsed rocket engine (IRDTT), which is part of the structure.

The purpose of the invention: to reduce the danger zone that occurs when fired from a rocket-propelled grenade launcher, by eliminating from it a portion of the propelling force of the elements of the forcing unit (UV) and the attachment unit (UK) of the grenade by changing their designs.

Achieving the goal is carried out by changing the design of the UV, placed in the IRDTT nozzle and made in the form of a cone-shaped hollow rod-gas duct, connected by three legs, separated from each other by an angle of 120 °, with the rear end of the launch tube.

A celluloid circle is attached to the lower part of the rod, covering the critical section of the nozzle from a breakthrough by powder gases until it reaches a boost pressure. Thus, UV performs not only its function, but also the function of the UK grenade.

As a result of the functioning of the utility model of a rocket-propelled grenade launcher, the dimensions of the danger zone arising from the shot are significantly reduced due to the exclusion of the portion of the forceful propellant effect of UV elements from it.

Description

The invention relates to the field of rocket-propelled grenade launchers, in which grenade throwing occurs as a result of the operation of a pulsed rocket engine using solid fuel (IRDTT), which is part of the design of the grenade.

The disadvantage of existing grenade launchers with the reactive principle of throwing grenades is the presence of a danger zone that occurs when fired in the sub-populated space, and has a dangerous effect on the shooter.

The hazardous area diagram is shown in Fig. 1

The components of the danger zone are:

- plot of the thermal effect of the flowing supersonic jet from the IRDTT nozzle;

- plot of the impact of the shock wave (HC) arising from the expiration of the gas-powder jet;

- plot propellant impact elements of the forcing unit (UV) IRDTT and mounting unit (UK) grenades in the container launch tube launcher.

The length of sections of the danger zone is:

- for the plot of the thermal effect of the jet - 1.5 m;

- for the site of power impact of hydrocarbons - 3.0 m;

- for the area of propellant impact - from 20 to 40 m.

The presence of a dangerous zone limits or makes it impossible to shoot from a grenade launcher in rooms of a limited volume or closed type, which significantly reduces the combat effectiveness of its use in a battle in the city.

Known grenade launcher, comprising: a launch tube (container) (1) with a trigger mechanism (trigger), a rocket launcher (2) placed in the tube and fixed in it by the Criminal Code [1].

The aim of the invention is to reduce the danger zone that occurs when fired from a grenade launcher, due to the exclusion from it of the site of the propelling effect of UV and UK grenade elements.

Achieving the goal is carried out by changing the design of the UV, placed in the IRDTT nozzle (3) and made in the form of a cone-shaped hollow rod-gas duct (4) connected by three legs (5), separated from each other by an angle of 120 °, with the rear end launch tube. Thus, UV performs not only its function, but also the function of the UK grenade. A celluloid circle (6) is attached to the cylindrical part of the rod, which closes the critical section of the nozzle from the breakthrough of powder gases until the force pressure is reached.

A diagram of the claimed grenade launcher is shown in figure 1, and a diagram of the mounting of the gas rod to the launch tube is shown in figure 2.

The geometrical dimensions of the rod-gas duct were determined as a result of solving the main problem of the internal ballistics of the IRDTT and the problem of the leakage of a stream of powder gases on the rod-gas duct located in

the gas-dynamic path formed by the combination of the internal surfaces of the combustion chamber and the IRDTT nozzle, the starting device, as well as the outer surface of the rod. The design scheme of the gas-dynamic path is shown in Fig. 2.

The following characteristic sections can be distinguished in the diagram:

1 section - has a constant cross-sectional length, but variable along the length of the path and over time, the section is free for the passage of powder gases due to the presence of a burning charge (variable porosity);

2 section - has a variable cross-sectional length;

3 section - has a cross-section that is variable in length and time, due to the movement of the grenade in the pipe;

4 section - has a constant cross-sectional length.

As the rod UV cone advances from the nozzle, section 3 degenerates and section 4 appears between the nozzle and the cone. After complete combustion of the charge, section 1 is transformed into section 4.

Thus, three main periods of gas flow in the tract can be distinguished:

1 period - UV cone in the nozzle - the charge is on;

2 period - UV cone outside the nozzle - the charge is on;

3 period - UV cone outside the nozzle - the charge burned out.

The greatest difficulty in modeling is the gas flow in the 1st period in the area of sections 2-3, since its calculation allows us to determine:

- a change in the flow rate and traction characteristics of the nozzle due to the overlapping by the cone of the rod of the UV part of its critical section and (or) the cross section of the supersonic part as a function of time;

- change in power loading (static and dynamic components) of the rod UV cone as a result of the influence of the gas flow and the dynamics of a possible violation of the balance of the design of the grenade launcher.

During the period under consideration, in this zone there is a rather complex, spatially inhomogeneous, unsteady gas flow in the channel with a cross-section varying in length and time, the structure of which is mainly due to:

- acceleration of the flow of powder gases to supersonic speeds in the nozzle;

- the interaction of the gas stream with a rod UV cone. If, when the gas moves through a pipe of variable cross-section, the velocity components V _y and V _z (the axis is directed along the pipe) can be neglected, then, considering that the velocity components V _x and the parameters p, ρ and Т are averaged over the entire cross section of the pipe, we can obtain the equations movements not containing transverse velocity components.

The following assumptions were used to construct the mathematical model:

1) the gas phase is compressible, we neglect the mass and dissipative forces in it (with the exception of the consideration of interfacial interaction);

2) the condensed phase is incompressible and gas tight, consists of tube-shaped powder elements;

3) during the whole time of combustion of the powder, the condition of equivalence of the gas flow in the annulus and in the channels of the powder tubes is satisfied;

4) the thermochemical reactions that occur during the formation, expansion and cooling of powder gases are not considered in detail, the composition of the powder gases, the value of the force of the powder (ƒ), the gas constant (R) and the adiabatic exponent (k) are assumed to be constant;

5) we neglect the deformations of the combustion chamber, the rod UV, the launch tube (i.e., the geometric parameters of the elements forming the gas-dynamic path are unchanged throughout the entire time of the shot);

6) the charge is stationary relative to the combustion chamber during the calculation time;

7) forcing is instantaneous; it occurs at the moment the force pressure is reached;

8) we neglect shock wave processes.

The assumptions made do not contradict the model of gas flow in a channel of variable cross section.

Taking into account the assumptions, the design diagram describing the working process in the gas-dynamic path under study has the form shown in Fig. 3.

For the convenience of modeling charge burning, we select the coordinate system associated with the grenade. In this case, the reference point is associated with the bottom

combustion chamber, and the positive direction of the coordinate axis is selected from the bottom of the chamber to the nozzle (in the direction of the outflow of powder gases). The movement of the grenade will be equivalent to the extension of the launch tube.

Based on the approach proposed above, the system of equations of gas dynamics, describing the movement of gases in a path, has the form:

where ρ is the density of the powder gases;

V is the velocity of the powder gases;

ε is the internal energy of the powder gases;

P is the pressure of the powder gases;

φ is the relative area of the powder section, free for the passage of gases (porosity of the charge), ;

ω is the mass of the charge;

S is the cross-sectional area;

δ is the density of the powder;

- the relative volume of burnt powder;

G is the gas inlet per unit length of charge, ;

L is the length of the charge.

In the process of movement, the gas is "braked" as a result of friction against the charge. The friction force directed in the direction opposite to the movement of gases is determined by the dependence:

where P is the perimeter of combustion,

n _mp is the number of tubes in the charge;

D _mp , d _mp - outer and inner diameters of the powder tube;

N is the blowing parameter,

C _x is the flow resistance coefficient;

d _e - effective hydraulic diameter,

ν _g is the kinematic viscosity coefficient of the gas;

Re is the Reynolds number.

In addition, to the system (1) it is necessary to add the equation of charge burning (2) and the equation of state of the gas (3)

where λ are the characteristics of the form;

z is the relative thickness of the burnt vault.

The main difference between this mathematical model and the existing one for IRDTT is that the gas path in the region of the supersonic part of the nozzle in the initial period of expiration is formed by the inner surface of the nozzle and the surface of the conical part of the rod. In the case of quasi-one-dimensional modeling, it is sufficient to describe the cross-sectional area at each point along the length of the nozzle to describe it

where S _c is the cross-sectional area of the nozzle at a given point along the length of the nozzle;

S _ct is the cross-sectional area of the cone of the UV rod at this point along the length of the nozzle at a given time.

As a result of the "movement" of the UV rod, which in the general case has a variable cross section (cone), the cross-sectional area of the gas path changes according to:

where V _ct is the velocity of the gas-rod (in the adopted calculation scheme it is equal to the speed of a grenade with the opposite sign).

The movement of the grenade occurs due to:

- thrown mass of gases (traction) (ρ _c V _c ² S _c );

- force acting on a charge

- force acting on the bottom of the chamber (PSφ) ₀ ;

- the force acting on the walls of the chamber

- pressure difference of the powder gases S _mp {P _c -P _a ).

Therefore, the equation of motion of the grenade will take the following form:

where m _gr - grenade mass;

V _gr - grenade speed;

S ₀ is the cut-off area of the solid propellant nozzle;

ρ _s , V _c - density, gas velocity at the exit of the solid propellant nozzle.

We solve the system of equations (1) ... (3) by the finite-difference method. To this end, we will transform it to a form convenient for solution. After transformations of the equations, the system is written in the form:

The resulting system is a quasilinear differential equation that determines, for given boundary and initial conditions, the gas-dynamic characteristics of the ballistic processes in the grenade launcher of the proposed scheme.

The initial conditions for the calculation are the values of gas-dynamic parameters obtained as a result of modeling the process of ignition of the powder charge.

At the initial moment, the speed along the entire length of the chamber is 0. Prior to opening the UV, the calculation area is limited by the bottom of the IRDTT body and the forcing unit. At these borders, non-leakage conditions are set. When the gas pressure equal to the forcing pressure is reached in the calculation cell adjacent to the UV to the left of the UV, the UV opens, and the calculation region expands to the cut of the breech of the PU. At x = xa, pressure and density

PS is taken equal to atmospheric values (after opening the rod forcing unit).

The grenade begins to move if the thrust of the engine becomes greater than the bonding force of the grenade with the launch tube - the force of breaking.

To solve the system of gas-dynamic equations, we apply the finite-difference method of lines, tested in solving similar problems, and providing results with satisfactory accuracy.

The step of numerical integration over time of the heat equation was determined from the condition of stability of the form:

In the calculations, the parameters of the grenade and propulsion system were taken with the corresponding parameters of the 6G25 RPG-26 grenade. The calculation results in the form of graphical dependencies are presented in Fig. 4.

Validation of the developed mathematical models was carried out by comparing the calculated values of the parameters with the experimental data obtained by testing the standard

RPG-26 analogue. In this case, in the calculations, the value of the cross-sectional area of the UV rod was taken S _ct = 0.

An analysis of the values of the functioning parameters obtained for the RPG-26 showed sufficient accuracy of the developed physical and mathematical models. The discrepancy between the results and the experimental values does not exceed 2% in the initial velocity (calculated value V ₀ = 139 m / s), the charge burns out before leaving the pipe and the maximum gas pressure does not exceed the permissible value.

Analysis of the obtained values of the pressure of the powder gases for the grenade launcher of the proposed design showed that the presence of a rod with a diameter of 8 mm in the path of gas flow leads to an increase in the maximum gas pressure in the combustion chamber by 1 MPa and a decrease in the initial velocity of the grenade by 2 m / s.

The presence in the gas-dynamic path of the proposed design of the rod, fixedly mounted in the launch tube, makes it necessary to determine the amount of recoil energy that can occur at the time of the shot.

The recoil energy was determined by the dependence:

where I is the momentum of the force acting on the rod.

where P is the pressure of the powder gases;

S _ct is the area of the rod affected by the gas flow;

τ is the friction force of the gas on the rod.

The calculation of the recoil energy that can occur during a shot from the proposed grenade launcher was carried out for various values of the diameter of the rod located in the critical section and in the supersonic part of the nozzle. The results of calculating the recoil energy in

depending on the diameter of the UV rod are shown in Fig. 5.

The calculations showed that with a UV rod diameter of 8 mm, the resulting recoil energy does not exceed the permissible value determined by the technical documentation for the grenade launcher and equal to 9.8 J. A further increase in the diameter of the UV rod, as can be seen from the analysis of the graphical dependence of Fig. 5, will lead to a significant increase in recoil energy.

In addition, an assessment was made of the effect of the arising recoil energy on the accuracy of shooting and is presented in Fig. 6.

Analysis of the obtained calculation results shows that the recoil energy arising from a grenade launcher of the proposed design scheme enters the range of permissible values, and,

therefore, does not affect the accuracy of shooting.

Structurally, to eliminate the possible recoil of the grenade launcher by reducing the area of the outlet cross section of the launch tube, as a result of placing in it the rod remaining after the shot and the legs securing it to the tube, its output part has an enlarged cone-shaped profile B shown in FIG. 2.

The proposed grenade launcher operates as follows: during a shot, when the trigger is triggered and a heat pulse arrives through the internal cavity of the gas rod into the combustion chamber of the IRDTT, the powder charge ignites and the pressure of the powder gases in the engine is created. When the nozzle opening pressure (forcing pressure) is reached, the celluloid circle is cut off, the expiration of the gas-powder jet and the movement of the grenade begin, while the powder gases flow onto the gas rod and the tabs fastening it to the pipe. Due to the shape and certain geometric dimensions of the rod and legs, as well as the profile of the back of the pipe, the possibility of a recoil impulse is excluded, which is confirmed by mathematical calculations and experiment.

In official circulation, the grenade with the help of a gas rod is fixed with a launch tube and is limited from axial movements.

As a result, during the functioning of the claimed design of the grenade launcher, the dimensions of the danger zone arising from the shot were significantly reduced due to the exclusion of the portion of the forceful propellant effect of UV elements from it.

Experimental studies of the claimed grenade launcher were carried out by the authors in two stages.

At the first stage, the zone of expansion of the elements of the rod UV IRDTT was determined by firing from a grenade launcher at an angle of elevation of the pipe of 1 degree. To intercept the elements during firing, a plywood shield with a height of 3 meters and a width of 6 meters from 4 mm plywood was used. To determine the angle of the elements, the UV shield was installed at a distance of 6 meters from the breech

grenade launcher. To determine the dangerous range of the elements, the shield was installed at a distance of 30 meters, and then moved closer to the official section. After each shot, the target environment was inspected. The inspection results are presented in table 1.

Table 1 Target Survey Results Shot Number Distance to shield Availability and number of holes one thirty are absent 2 thirty are absent 3 25 are absent four 25 are absent 5 twenty are absent 6 twenty are absent 7 fifteen are absent 8 fifteen are absent 9 10 are absent 10 10 are absent eleven 6 are absent 12 6 are absent 13 3 are absent fourteen 3 are absent

The results of the first stage of experimental research have proved the performance of the grenade launcher of the proposed scheme. An analysis of the results of Table 1 showed that the grenade launcher does not have a propellant site for the elements of the rod UV IRDTT, and the dimensions of the danger zone were reduced to the zone of force impact of the nozzle shock wave.

The second stage of experimental research was carried out in accordance with paragraph 4.2 (Typical methods for determining ergonomic indicators. Determination of recoil energy of a grenade launcher). At this stage, the determination of the recoil energy, which can occur when firing a grenade launcher of the proposed design, was carried out. The scheme of the second stage of experimental research is presented in Fig. 7.

Experimental studies were carried out by firing from a model grenade launcher mounted on a special pendulum device.

The model grenade launcher was mounted in two clips, suspended on thin rods, 2060 mm long. The angle of deviation during the shot was fixed on a special scale with divisions (in degrees) using the pointer.

Before firing, a grenade launcher, clips and rods were weighed. After each shot, the recoil energy was calculated according to the dependence:

where Q _total - the total mass of the grenade launcher, two clips and 0.5 the mass of the rods, kg;

Q _total - - the mass of the grenade launcher in the combat position, kg;

L is the length of the rods, m;

α is the angle of deviation of the rods during the shot, deg.

The measurement results of the second stage of research are presented in table.2.

table 2 The results of measurements of α and calculation of E _syst . Shot Number α, city E _syst ., J one 14.66 6.8 2 14.66 6.8 3 3 p.m. 7.2 four 15.33 7.5 5 14.66 6.8

The results of experiments processed according to the method described above are presented in table.3.

Table 3 The results of the processing of the experiment to determine the recoil energy No. Defined Parameters Values p / p one The estimated value of the recoil energy that occurs when shot, J. 7.25 2 The experimental value of the recoil energy arising from shot: 2.1 - assessment of mathematical expectation, J; 7.02 2.2 - estimate of the standard deviation, J; 0.319 2.3 - confidence interval for estimating mathematical expectation with confidence probability β = 0.95 J 6.65 ... 7.38

Thus, the conducted experimental studies have confirmed the possibility of reducing the size of the danger zone to the size of the site of the force impact of the HC through the use of the proposed structural and design solution of the rocket-propelled grenade launcher, which indicates the achieved objective of the invention.

Claims (1)

A rocket-propelled grenade launcher, including a launch tube (container), a trigger mechanism (trigger), a rocket-propelled grenade, containing a rocket engine with a forcing unit (UV), placed in the pipe and secured in it with a mounting unit (CC), characterized by a modified UV design, placed in the nozzle of a rocket engine and made in the form of a cone-shaped hollow rod-gas duct, on the cylindrical part of which a celluloid circle is fastened, covering the critical section of the nozzle from the breakthrough of powder gases until the force is reached Hovhan connected by three feet spaced from each other at an angle of 120 °, with the rear end of the launch tube, for fixing the grenade in the service handling exceptions UV ejection elements at the time of firing.