RU2246633C2 - Solid-propellant rocket engine - Google Patents

Abstract

FIELD: rocketry.

SUBSTANCE: proposed solid-propellant rocket engine consists of combustion chamber with nozzle unit, powder charge, igniter and electric igniter. High-pressure chamber in head part of engine is formed by circular cavity in engine housing and perforated disk. Holes in perforated disk open into radial cavities made in disk from side of powder charge. Igniter is made in form of weighted amount of powder placed in sealed case made of combustion material and is arranged inside high-pressure chamber. Electric igniter is installed at angle to longitudinal axis of engine. Longitudinal axis of electric igniter lies in one plane with row of holes of perforated disk and rail cavity.

EFFECT: provision of reliable and uniform ignition of charge at reduced spread of characteristics within wide temperature range, improved reliability of engine.

3 cl, 3 dwg

Description

The invention relates to the field of rocket technology, namely to rocket engines of solid fuel, and can find application in the starting engines of unguided shells and guided missiles.

Known rocket engine of solid fuel, adopted by the authors for the prototype [1], consisting of a combustion chamber with a nozzle block, a powder charge, an igniter and an electric igniter located on the longitudinal axis of the engine. An ignitor with a thin-walled body made of aluminum alloy, inside of which is placed smoke gun powder or a pyrotechnic composition located at the front bottom of the combustion chamber on its axis, provides reliable ignition of the charge and reliable operation of the engine in the absence of strict requirements for the dispersion of output characteristics.

However, to ensure its guaranteed operation from the initiating device, it is necessary that the ignition of the powder occurs in a closed volume at a relatively high pressure. After the destruction of the housing, the composition housed in it is discharged into the combustion chamber and as a result of an abrupt increase in volume, the pressure drops. As a result, the combustion intensity of the igniter composition decreases, and part of its grains may even be extinguished. This leads to the fact that the charge ignition process stretches in time, i.e. the time for the engine to reach steady-state operation increases. With an increase in the time the engine reaches the steady state operation, various parts of the surface of the powder charge are heated unevenly, which can lead to an unaccounted increase in the rate of fuel combustion in areas ignited with delay, since they manage to warm up to a great depth. As a result of an uncalculated increase in the burning rate, the pressure level in the combustion chamber may exceed the maximum permissible value, which will lead to the destruction of the engine. To eliminate such a phenomenon, the mass of the igniter must obviously be increased, as well as the margin of safety of the walls of the combustion chamber, which ultimately leads to a heavier structure. In addition, due to the uneven distribution of the igniter composition over the volume of the combustion chamber, the ignition of the charge does not occur simultaneously in length and radius. This can lead to a deviation of the combustion surface of the charge from the calculated one and to an unacceptable increase in the scatter of the output characteristics of the engine, especially when it is used at low temperatures. The presence of a housing igniter that collapses when the igniter is activated can lead to damage to its fragments, which is also unacceptable.

The objective of the invention is to ensure reliable ignition of the charge by eliminating the delay of ignition and the associated increase in pressure in the combustion chamber of the engine, as well as ensuring uniform ignition of the charge, which will reduce the dispersion of output characteristics in a wide temperature range of operation and thereby increase the reliability of the engine.

The problem is achieved in that in a solid propellant rocket engine consisting of a combustion chamber with a nozzle block, a powder charge, an igniter and an electric igniter, in contrast to the prototype, a high pressure chamber is formed in the engine head, formed by an annular recess in the engine housing and a perforated disk, the holes of which are brought into radial recesses made in the disk from the side of the powder charge. The igniter is made in the form of a sample of fine powder placed in a sealed case made of combustible material and placed inside the high-pressure chamber, and the electric igniter is installed at an angle to the longitudinal axis of the engine, while the longitudinal axis of the electric igniter lies in the same plane as the row of holes of the perforated disk and the radial recess . An annular gas channel is formed between the motor housing and the perforated disk. As the material for the case, a polymeric material is used, the thickness of its wall on the disk side being less than the thickness of the case.

The implementation of the rocket engine of solid fuel in accordance with the invention will allow:

- to provide a gas inlet distributed over the cross section of the combustion chamber from the igniter due to holes made in the radial recesses of the disk, and an annular gas channel between the engine housing and the perforated disk. In this case, unburned particles of igniter composition are ejected into the volume of the combustion chamber evenly over its cross section. This will allow almost simultaneously to ignite the charge over the entire surface and thereby reduce the dispersion of the output characteristics in a wide temperature range of operation. The annular gas-water channel allows to reduce the pressure build-up in the high-pressure chamber in the event that the disk openings are blocked by unburned fragments of the case body at negative temperatures. Radial recesses on the surface of the disk from the side of the combustion chamber make it possible to exclude overlapping openings connecting the high-pressure chamber to the combustion chamber by a charge during its thermal expansion;

- reduce the weight of the combustion chamber of the engine by placing a case with an igniter composition in the high pressure chamber. Placing the igniter in a separate chamber allows, by selecting the volume of the latter and the area of the holes connecting it to the engine combustion chamber, to burn the igniter composition in it at high pressure without increasing the pressure level in the combustion chamber;

- to increase the contact surface of the igniter composition with the force of flame of the electric igniter due to the fact that it is installed at an angle to the longitudinal axis of the engine, and also to lower the maximum pressure level in the high-pressure chamber due to the fact that ignition of the igniter composition does not occur simultaneously in its volume;

- to increase the reliability of ignition of the igniter composition at negative temperatures due to the case of the case made of combustible polymer material. Since the polymer strength increases at negative temperatures, the destruction of the sealed case occurs at a higher pressure than at positive temperatures, which increases the stability of ignition of the composition placed in the case. Due to the fact that the wall thickness of the case on the disk side is less than the rest of the casing, its earlier destruction is ensured, while the differential pressure is pressed to the bottom of the annular cavity, preventing overlapping holes in the disk.

The invention is illustrated by graphic materials, where Fig. 1 shows a diagram of an engine with an annular cavity in the front bottom, Fig. 2 shows the arrangement of holes in the radial recesses of the disk, Fig. 3 shows the orientation of the axis of the electric igniter relative to the radial recess with openings.

The proposed engine consists of a combustion chamber with a nozzle block 1, a powder charge 2, an igniter in the form of a sealed case with fine-propellant powder inside 8, placed in a high pressure chamber 3, formed by an annular recess in the engine housing and a perforated disk 4, the openings of which 6 are brought into radial recesses 5 made in the disk from the side of the powder charge.

Ignition of the igniter composition is carried out using an electric igniter 9, mounted at an angle to the longitudinal axis of the engine. Between the perforated disk 4 and the engine casing is made an annular gas channel 7.

The functioning of the proposed engine is as follows. After giving the start command, the electric igniter 9 is triggered. The force of the flame from the electric igniter breaks through the sealed polymer case with fine powder inside 8 and, passing through the igniter, ignites it around itself. The resulting combustion products, spreading throughout the volume of the case, ignite the rest of the igniter composition. Simultaneously with its ignition, the thin wall of the case, which faces the disk 4, is destroyed. As a result of the expiration of the products of ignition of the ignition composition, the case is pressed against the front bottom of the high-pressure chamber 3 by pressure drop, thereby eliminating the possibility of overlapping holes 6 in the disk 4 connecting the high-pressure chamber 3 in which the case is placed, with a combustion chamber. As the fine-dispersed gunpowder placed in the case is ignited, the latter is destroyed and the combustion products of the igniter composition and the unburned particles of the gunpowder enter the combustion chamber through the openings 6 and the annular gas channel 7 between the generatrix of the disk 4 and the engine case, igniting the charge 2. The combustion products of the powder charge 2, expiring through the nozzle of the engine, create traction, thereby ensuring acceleration of the projectile to a given speed.

The proposed implementation of a solid propellant rocket engine will ensure reliable ignition of the charge by eliminating the ignition delay and the associated increase in pressure in the combustion chamber of the engine, as well as ensure uniform ignition of the charge, which will reduce the dispersion of output characteristics in a wide temperature range of operation and thereby increase reliability engine and the entire projectile as a whole.

Sourse of information

1. Fundamentals of the design and construction of aircraft. V.N. Novikov, B.M. Avkhimovich, V.E. Veitin - M.: Mechanical Engineering, 1991, pp. 119, 127.

Claims (3)

1. A rocket engine of solid fuel, consisting of a combustion chamber with a nozzle block, a powder charge, an igniter and an electric igniter, characterized in that a high-pressure chamber is formed in the head of the engine, formed by an annular recess in the engine housing and a perforated disk, the openings of which are led out into the radial recesses made in the disk from the side of the powder charge, the igniter is made in the form of a sample of fine powder placed in a sealed case of combustible material, and n inside the high-pressure chamber, and the electric igniter is installed at an angle to the longitudinal axis of the engine, while the longitudinal axis of the electric igniter lies in the same plane as the row of holes of the perforated disk and the radial recess. 2. The solid fuel rocket engine according to claim 1, characterized in that an annular gas channel is formed between the engine body and the perforated disk. 3. The rocket engine of solid fuel according to claim 1 or 2, characterized in that the material for the case uses a polymeric material, and the thickness of its wall on the disk side is less than the thickness of the case.

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