RU2322604C2 - Solid-propellant rocket engine - Google Patents

Abstract

FIELD: military equipment; solid-propellant rocket engines.

SUBSTANCE: proposed solid-propellant rocket engine has body and fitted-in restricted charge over outer surface with nonrestricted end face in contact with support surface of body in extreme longitudinal position. Cavity is made on nonrestricted end face of change whose area increases area of nonrestricted end face of charge by value equal to or insignificantly differing from area of surface of nonrestricted end face of charge in contact with support surface of body to provide pressure level in engine combustion chamber not exceeding maximum tolerable one. Area of surface of nonrestricted end face in contact with support surface of body is chosen to provide contact stresses in change lower than tolerable ones.

EFFECT: provision of reliable starting of rocket engine owing to prevention of pressure drop in engine combustion chamber lower than level of stable burning of charge.

3 cl, 2 dwg

Description

A known system for the automatic initiation of a solid fuel rocket engine (solid propellant rocket engine) of an artillery rocket projectile (ARS) from propellant combustion products (MH) through pyro-moderator columns (US patent No. 3404532, 1968, NKI 60-256, MKI F02K 9/00) [ one]. The rocket engine of the projectile includes a plug charge, armored on the outer surface and having an open (unarmored) end face. In the nozzle socket of the engine, closed by a plug, an igniter is placed, initiated through pyro-retarders.

When a propellant charge is triggered in the gun’s barrel, its combustion products initiate pyro-retardants, which after a certain delay time (after the projectile leaves the barrel) ignite the igniter and ignite the charge of solid fuel.

Also known is a rocket engine of an artillery shell (patent No. 2021544, Russian Federation, application No. 5035990 of 04/07/1992, MKL ⁵ F02K 9/08) [2], including a housing, an external charge armored on the outer surface, having an unarmored end face, a nozzle with an installed therein, a plug made in the form of a housing for the igniter and pyro-retarder and provided with a fixing element 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.

The advantages of two well-known rocket engines are: a high fuel fill rate due to the placement of igniters in the nozzle cavity and the ability to automatically start the engine after exiting the barrel by using pyro-moderators by the propellant combustion products in the gun barrel.

However, both known engines have inherent disadvantages. Let us explain this as follows.

It is known that a plug-in fuel charge is installed in the engine combustion chamber with axial and radial clearances and has the ability to move within these clearances under the influence of the pressure drop in the combustion chamber of the engine and inertial forces. So at the moment of ignition operation, its combustion products act on the unarmored end face of the charge and ignite it. The charge under the influence of a pressure differential within the axial clearance moves in the direction from the igniter (opposite the nozzle). At the moment of opening the nozzle plug and the pressure drop in the pre-nozzle volume, the pressure drop in the engine chamber has the opposite direction compared to the operation of the igniter. In addition, under the action of traction, an inertial force acts on the charge. Under the action of a pressure drop along the length of the combustion chamber and inertial force, the charge moves in the direction of the nozzle and, after the axial clearance is selected, the ignited unarmored end contacts the supporting surfaces of the engine housing. In this case, part of the burning surface of the unarmored end can go out, because the thickness of the fuel combustion zone is ≈ 100 microns or less [Research of solid propellant rocket engines. Edited by M. Samerfield, translated from English M .: IL, 1963, p.113] and when the burning surface of the charge comes in contact with the supporting surface of the engine housing, the softened, thin combustion zone is compressed and the surface is extinguished in these places. The remaining part of the surface (not in contact with the supporting surface) when the nozzle is opened may not provide a pressure level in the combustion chamber sufficient for stable combustion of the fuel. Under these conditions, the charge will burn unstable, which will lead to a prolonged exit to the mode (abnormal burning), or to complete extinction of the charge, especially at extreme negative values of the temperature of the operating range.

The problem to which the invention is directed, is to increase the reliability of the launch of solid propellant rocket motors. The technical result achieved in solving the problem is to eliminate the pressure drop in the combustion chamber of the engine below the stability level of the combustion of the fuel charge.

The solution to this problem is achieved by the fact that in a rocket engine of solid fuel, including a casing, an external charge armored on the outer surface, having an unarmored end face in contact with the supporting surface of the housing in an extreme longitudinal position, a recess is made on the unarmored end of the charge, the area of which increases the area of the unarmored end charge by an amount equal to or slightly different from the surface area of the unarmored end to provide a pressure level in the chamber engine noise is not more than the maximum allowable, while the surface area of the unarmored end contacting with the supporting surface of the housing is selected from the condition of providing contact stresses in the charge less than the maximum allowable.

In particular cases, the recess can be made in the form of a surface of revolution or an annular groove.

The invention is illustrated in graphic materials. Figure 1 shows a diagram of a solid propellant rocket motor made in accordance with claims 1 and 2 of the claims of the present invention. Figure 2 - diagram of a solid propellant rocket motor made in accordance with claim 3 of the formula.

The solid propellant solid-propellant rocket engine includes a housing 1, an additional charge 2, having an armored coating 3 on the outer surface and an unarmored end 4 in contact in the extreme longitudinal position with the supporting surface 5 of the housing 1. A recess 6 is made on the unarmored end 4 in the form of a surface of revolution, for example, a cylindrical surface. The surface of rotation of the recess 6 can be made conical, cylindrical-conical, spherical, etc. The surface 7 of the unarmored end 4, in contact in the extreme longitudinal position with the supporting surface 5 of the housing 1, is made from the condition of ensuring the strength of the charge 2 when exposed to operational and starting longitudinal overloads, i.e. surface area 7 should be such that contact stresses in charge 2 do not exceed the maximum permissible values for a given fuel. The surface area of the recess 6, in the considered embodiments, is made in the form of the surface of a circle 8 or ring 17 (FIG. 2) and a lateral cylindrical surface 9 or cylindrical surfaces 18 (FIG. 2). In this case, the area of the lateral cylindrical surface 9 (18), increasing the area of the flat (without recess) unarmored end face of the charge 2, should be equal to or slightly different from the surface area 7 in order to ensure that the pressure level in the combustion chamber of the engine is not more than the maximum allowable from the condition of the body one.

The igniter is indicated at 10 and can be made, for example, in the form of a percale bag with a hinge of smoky gun powder. The nozzle cap is indicated by 11, and the electric igniter located on the cap is indicated by 12. Numbers 13 and 14 indicate cushioning pads. Position 15 denotes the heat-shielding coating of the housing, and position 16 denotes the fastening elements of the nozzle plug. The axial longitudinal clearance between the charge 2 and the housing 1 (combustion chamber) of the engine is indicated by "δ".

The operation of the solid propellant rocket motor is as follows. When applying electric voltage to the electric igniter 12, it fires and initiates the igniter 10, the combustion products of which act on open (unarmored) sections of the surface of the fuel charge 2 and ignite them. Under the action of the pressure from the operation of the igniter 10, the charge 2 sharply moves in the longitudinal direction, selects the axial clearance "δ" and, having hit the gasket 13 of the front bottom, can bounce in the direction of the supporting surface 5 of the housing 1. When the nozzle plug opening pressure is reached in the combustion chamber of the engine the latter is opened and pressure is released from the pre-nozzle volume of the combustion chamber. Under the influence of inertial forces due to the appearance of traction force and the pressure drop in the combustion chamber of the engine, when the nozzle plug is opened, the charge 2 is also pressed against the supporting surface 5. At the places where the charge 2 contacts the supporting surface 5, extinction can occur. In this case, the gas inlet from the extinguished sections of the charge surface will be compensated by the gas inlet from the burning surface of the recess 6, which is sufficient to ensure that the pressure level in the combustion chamber of the engine is not lower than the pressure of stable combustion and the engine reliably enters the mode.

Thus, the present invention has improved the reliability of starting solid propellant rocket motors by eliminating the pressure drop in the engine chamber below the level of stable combustion of the fuel charge.

Claims (3)

1. A rocket engine of solid fuel, comprising a housing, a detached armored charge on the outer surface, having an unarmored end, contacting in an extreme longitudinal position with the supporting surface of the housing, characterized in that a recess is made at the unarmored end of the charge, the area of which increases the area of the unarmored end of the charge by a value equal to or slightly different from the surface area of the unarmored end of the charge in contact with the supporting surface of the housing, to ensure the pressure level in the combustion chamber of the engine is not more than the maximum allowable, while the surface area of the unarmored end in contact with the supporting surface of the housing is selected from the condition of providing contact stresses in the charge less than the maximum allowable. 2. The rocket engine of solid fuel according to claim 1, characterized in that the recess is made in the form of a surface of revolution. 3. The rocket engine of solid fuel according to claim 2, characterized in that the recess is made in the form of an annular groove.

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