RU2263811C2 - Solid-propellant rocket engine - Google Patents

Abstract

FIELD: aircraft industry; rocketry.

SUBSTANCE: proposed solid-propellant rocket engine has combustion chamber with nozzle unit, multigrain powder charge, igniter and electroigniter. Cylindrical post is secured on front bottom of combustion chamber of end of which support with central threaded hole is installed coaxially to chamber. Said support is made in form of multiarm star. Cavities of multiarm star are mated with cylindrical surfaces of charge grains. Conical recess is made on other end of support from which cylindrical gas outlet channels are laid getting into cavities of multiarm star. Spherical space with symmetrical projections is formed on inner surface of nozzle unit. Inner surface of projections is mated with outer surface of one of grains of powder charge. Area of one through section between projections with powder charge fitted in exceeds area of charge grain channel. Support in form of multiarm star is made mainly of nonmetal material.

EFFECT: prevention of nondesigned increased of pressure at beginning and end of engine operation, and also vibratory combustion of charge, reduced spread of output characteristics in temperature range of operation, improved reliability if engine.

3 cl, 2 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 unit of the powder charge of the igniter and electric igniter, located on the longitudinal axis of the engine. Insert multi-cup charge used in the well-known engine and consisting of several cylindrical channel checkers, assembled in one package, allows to increase the accuracy of hit of unguided shells. The increase in accuracy is associated with an increase in the rate of descent of the projectile from the guides of the launcher, since a multi-cup charge provides a large second flow rate and engine thrust at a given level of maximum pressure in the combustion chamber with a short operating time. In addition, when using a plug-in multi-cup charge, it is possible to realize a volumetric coefficient of the chamber filling up to 0.70 (the charge takes up to 70% of the free volume of the engine’s combustion chamber) with a relatively short operating time.

However, when using a charge with a relatively large elongation (the ratio of the diameter of the checker channel to its length exceeding 1: 15-20) from a number of ballistic compositions with a low content of condensed particles in the combustion products of the combustion chamber of a working engine, non-calculated pressure fluctuations with a large amplitude can occur , while the pressure may exceed the maximum permissible value. This phenomenon is caused by vibrational combustion of the fuel due to the tangential vibrations of the gas column in the cavity of the charge channels and the combustion chamber. The consequences of vibrational combustion can be: cracking of the charge and its subsequent destruction, local burnouts of the engine housing after vibrational cracking of heat-shielding coatings, the harmful effects of vibrational loads on the onboard equipment of a guided projectile, fatigue failure of engine structural elements, and reduction of traction impulse.

In addition, after a long stay at an elevated temperature during storage and operation, the axis of the charge checkers may bend. This leads to a local increase in the flow velocity in the bent channel over a large radius and can contribute to faster combustion of the checkers at the bend and to the destruction of the charge at the end of the engine operation, which can lead, in turn, to an unaccounted increase in pressure and a decrease in the total thrust impulse.

The disadvantage of the prototype should also include the difficulty of fixing the checkers of the charge from rotation relative to the longitudinal axis of the engine during transportation. This leads to the fact that the charge rubs against the supporting surfaces of the gratings, which leads to the formation of powder chips in the chamber and an unacceptable increase in pressure when the engine is triggered.

The objective of the invention is to prevent an uncalculated increase in pressure at the beginning and end of engine operation, as well as the exclusion of vibrational combustion of the charge, which will reduce the dispersion of output characteristics in a wide temperature range of operation and thereby increase engine reliability.

This object is achieved by the fact that in a rocket engine of solid fuel containing a combustion chamber with a nozzle block, a powder charge, an igniter and an electric igniter, a cylindrical strut is fixed on the front bottom of the combustion chamber, at the end of which a support with a central through threaded hole is installed, made in in the form of a multipath star, the troughs of which mate with the cylindrical surfaces of the charge checkers, while at the other end of the support there is a conical recess, from which vedeny cylindrical hot gas flues that go into depression multibeam stars. A spherical cavity with symmetrically located protrusions is formed on the inner surface of the nozzle block, the inner surface of which is mated with the outer surface of one of the checkers of the powder charge, while the area of one passage section between the protrusions when the powder charge is established is larger than the area of the channel of the charge checker. The support in the form of a multipath star is made mainly of non-metallic material.

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

- to exclude the possibility of rotation of the fuel charge checkers relative to the longitudinal axis due to the introduction of a support in the form of a multi-beam star into the engine structure, which will reduce the likelihood of the formation of powder chips in the chamber and will exclude an unacceptable pressure increase when the engine is triggered;

- significantly reduce the curvature of the axis of the checkers during prolonged exposure to elevated temperatures during storage and operation due to the introduction of a support in the form of a multi-beam star fixed to the engine’s combustion chamber using a strut. This will exclude the possibility of a local increase in the flow velocity in a bent channel over a large radius and destruction of the charge at the end of the engine operation, which will, in turn, eliminate an unaccounted pressure increase at the end of the engine operation and a decrease in the total thrust impulse;

- to exclude the possibility of vibrational combustion due to the placement of structural elements made of non-combustible material in the engine chamber and passage sections of the charge (strut, support, protrusions made in a spherical cavity), which will violate the conditions for the occurrence of ordered acoustic vibrations. In addition, a conical recess made in the support, from which cylindrical gas exhaust channels are made, extending into the hollows of the multi-beam star and made on the inner surface of the nozzle block is a spherical cavity with symmetrically located protrusions, the inner surface of which is mated with the outer surface of one of the powder charge pieces, forming the cross-sections between the protrusions when the powder charge is installed with an area larger than the area of the channel of the charge checkers, provide flow turbulence in ntralnoy and bottom of the engine combustion chamber, which also contributes to the damping of vibrations and acoustic vibration combustion.

The invention is illustrated by graphic materials, where Fig. 1 shows a diagram of an engine with a strut, support and protrusions made in a spherical cavity, Fig. 2 is a cross section of the engine in the region of the radial holes of the support.

The proposed engine comprises a combustion chamber 1 with a nozzle block 2, a powder charge 3 fixed in the chamber using a support grill 11, an igniter 4, an electric igniter 5. A cylindrical stand 6 is fixed on the front bottom of the combustion chamber 1, at the end of which a support 7 s is mounted coaxially with the chamber a central through threaded hole of non-metallic material in the form of a multi-beam star, the troughs of which mate with the cylindrical surfaces of the charge checkers 3. A conical recess is made at the loose end of the support 7 of, from which made cylindrical hot gas flues 8, go into depression multibeam stars. A spherical cavity with symmetrically located protrusions 9 is formed on the inner surface of the nozzle block 2, the inner surface of which mates with the outer surface of one of the checkers 10 of the powder charge 3, while the area of one passage section between the protrusions when the powder charge is installed is larger than the area of the channel of the charge checkers.

The functioning of the proposed engine is as follows. After giving the start command, the electric igniter is triggered 5. The flame force from the electric igniter ignites the igniter 4. The resulting combustion products, spreading over the volume of the combustion chamber, ignite the charge 3. A cylindrical rack 6 with a support 7 fixed to it, in which cylindrical gas exhaust channels 8 are made, protruding into the hollows of the multipath star and the spherical cavity of the nozzle block 2 with symmetrically located protrusions 9, the inner surface of which is mated with the outer surface ited one of the blocks 10 of gunpowder charge 3 provide during operation of the engine damping acoustic oscillations charge combustion 3. The products of combustion of gunpowder charge 3, bleeding through the nozzle block 2 of the engine, create thrust, thereby providing acceleration of the projectile to the target speed.

The proposed implementation of a solid fuel rocket engine will eliminate the uncalculated increase in pressure at the beginning and end of engine operation, as well as exclude vibrational combustion of the charge, which will reduce the dispersion of the output characteristics of the engine in a wide temperature range of operation and thereby increase the reliability of the engine and the entire projectile.

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 containing a combustion chamber with a nozzle block, a multi-cup powder charge, an igniter and an electric igniter, characterized in that a cylindrical strut is mounted on the front bottom of the combustion chamber, at the end of which there is a support with a central through threaded hole made coaxially with the chamber, made in the form of a multipath star, the troughs of which mate with the cylindrical surfaces of the charge checkers, while at the other end of the support there is a conical recess, from which Cylindrical gas outlet channels extending into the troughs of a multipath star are given. 2. The rocket engine according to claim 1, characterized in that on the inner surface of the nozzle block a spherical cavity is formed with symmetrically located protrusions, the inner surface of which is mated with the outer surface of one of the checkers of the powder charge, while the area of one passage section between the protrusions when the powder is installed the charge is larger than the area of the channel of the charge checkers. 3. The rocket engine according to claim 1, characterized in that the support in the form of a multipath star is made of non-metallic material.

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