RU2783054C1 - Dual-mode solid propellant rocket engine - Google Patents

Abstract

FIELD: rocketry.

SUBSTANCE: invention relates to the field of rocketry, namely to solid propellant rocket engines. A dual-mode solid propellant rocket engine comprises a body, a front bottom with an igniter, a rear bottom with a gas duct and a nozzle block, and a solid fuel charge with an internal cylindrical channel having slots on the side of the front bottom and fastened to the body with a protective and fastening layer, while the length of the slots is 0.4-0.7 of the total length of the solid fuel charge, and the ratio of the burning area of ​​the slotted part of the channel is 5-8 to the burning area of ​​the cylindrical part of the channel.

EFFECT: invention provides dual-mode operation of the engine - starting and marching modes of operation, and increasing the reliability of its operation.

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Description

The invention relates to the field of rocket technology, namely to solid propellant rocket engines, and can be used in the development of new models of single-chamber dual-mode rocket engines.

There are single-mode (single-pulse), multi-mode and multi-pulse propulsion systems. Multi-pulse ones differ from multi-mode ones in the possibility of providing a pause between modes, and multi-mode ones can be implemented in a single charge (single-chamber ones).

There are various schemes of single-chamber multi-mode solid propellant rocket engines (SSRMs), which differ in the shape of the charges. The forms of charges are very diverse and are determined by the requirements imposed on them: the magnitude and nature of the change in thrust, the operating time, as well as the characteristics and composition of the selected fuel.

Charges can be classified according to the location of the burning surface relative to the axis of the engine, 3 types of charges are defined:

1. Charges in which the combustion surfaces are not parallel to the axis of the engine (for example, end). Solid propellant rocket engines with such charges have a high passive mass, low thrust and a long operating time.

2. Charges whose combustion surfaces are parallel to the axis of the engine. The charges of this group completely exclude, or vice versa, a constant flow of combustion products around the internal surfaces of the engine housing. Solid propellant rocket motors with such charges have high thrust and short operating time.

3. Charges in which the combustion surfaces are partially not parallel to the longitudinal axis of the engine. In most cases, the products of fuel combustion are allowed to flow around the internal surfaces of the engine housing. This category includes charges slotted or with profiled ends.

In the practical implementation of solid propellant rocket engines, combined charges are often used, combining different forms of charges.

A solid propellant rocket engine is known (patent for the invention of the Russian Federation No. 2152529, IPC F02K 9/08, publication date 07/10/2000), containing a body with a bottom and a free volume at the bottom, a charge of solid fuel fastened to the body, with an axial channel, a nozzle block with inlet and outlet cones, an insert installed in the critical section of the nozzle block, an ignition unit and a nozzle plug. The charge channel is successively star-shaped, cylindrical and conical.

Also known is the charge of a rocket engine (patent for the invention of the Russian Federation No. 2274757, IPC F02K 9/18, publication date 20.04.2006) on a mixed metallized solid fuel, containing a housing, a protective and fastening layer, a slotted part of the charge channel from the front end, passing into the cylindrical part of the charge channel, while the slotted part of the channel has a combustion surface equal to 1.2-1.4 from the combustion surface of the cylindrical part of the charge channel.

There is a solid propellant rocket engine (patent for the invention of the Russian Federation No. 2298110, IPC F02K 9/18, publication date 11/20/2006), which contains a body, front and nozzle bottoms, as well as a solid fuel charge having slots from the front bottom of the engine . The charge of solid fuel is fastened to the body with a protective-fastening layer. The charge vault increases towards the nozzle bottom of the engine due to the transition of the cylindrical channel from the side of the front bottom into a cone tapering towards the nozzle bottom. The slots are arranged in symmetrical pairs with the ratio of the angles between slots of one pair and between adjacent slots of adjacent pairs of 0.1-0.4. The height of the slots is 0.3-0.7 of the value of the full burning arch of the charge. The length of the slots is 0.05-0.25 of the total body length. The design of this rocket engine is taken as a prototype.

These inventions have some common technical solutions: they are all single-chamber engines containing a combined (channel-slotted) charge bonded to the body with a protective and fastening layer, while the slotted (or star-shaped) part of the charge channel is located on the side of the front bottom. This design of the charge makes it possible to ensure stable operation of solid propellant rocket motors, increase the volumetric filling of its combustion chamber with fuel, protect its body from thermal effects and ensure a neutral thrust diagram. However, they also have a common drawback - single-mode, i.e. the inability to provide a large, more than 5, thrust difference in the initial and subsequent periods of operation.

The aim of the invention is to eliminate this disadvantage, namely, to ensure dual-mode operation of solid propellant rocket motors: starting and marching modes, while improving manufacturability and ensuring the reliability of its operation.

This goal is achieved in that the dual-mode solid propellant rocket engine contains a housing, a front bottom with an igniter, a rear bottom with a gas duct and a nozzle block, and a solid propellant charge with an internal cylindrical channel having slots from the front bottom and fastened to the body with a protective fastening layer, while the length of the slots is 0.4-0.7 of the total length of the solid fuel charge, and the ratio of the burning area of the slotted part of the channel is 5-8 to the burning area of the cylindrical part of the channel.

The essence of the invention is illustrated by a diagram of the longitudinal section of the engine shown in Fig. 1 and the calculated diagram of its thrust shown in Fig. 2.

The proposed dual-mode solid propellant rocket engine (Fig. 1) consists of a body 1, a front bottom 2 with an igniter 3, a rear bottom 4 with a gas duct 5 and a nozzle block 6, a solid fuel charge 7, fastened to the body 1 with a protective and fastening layer 8. The charge 7 has channel-slotted shape, while the slotted part is located in the front of the engine, the length of the slots is 0.4-0.7 of the total length of the charge 7, the inner channel has a cylindrical shape and has a diameter D, greater than the diameter of the critical section of the nozzle d (D> d). To achieve a large difference in thrust between the starting and marching modes of operation, the ratio of the burning area of the slotted part of the channel should lie in the range of 5-8 to the burning area of the cylindrical part of the channel, for which the number, location along the circumference and height of the slots are selected by calculation.

The operation of a dual-mode solid propellant rocket motor, made in accordance with the present invention, is carried out as follows. After actuation of the ignition device 3, the resulting gases ignite the charge of solid fuel 7, initially through the slots, and then through the inner channel and the rear conical end, thereby forming a relatively large charge burning area, providing high thrust in the starting mode of operation (part of the graph 1 in Fig. 2). After burning out part of the charge in the zone of slots, combustion continues along the surface of the cylindrical channel, the conical front and rear ends, while the cylindrical channel flares up and increases simultaneously with a decrease in its length due to the charge burning out from the ends, thereby ensuring a relatively constant burning area and, accordingly, a neutral thrust diagram in the marching mode of operation (part of graph 2 in Fig. 2). In this mode, in the zone of the slotted part of the charge, free from burnt fuel, a stagnant zone is formed, the same zone is formed between the conical rear end of the charge and the conical part of the nozzle bottom. The stagnant zones have a lower temperature and gas outflow rate relative to the main flow, which makes it possible to reduce the thermal and erosive effect on the protective-fastening layer and ensure reliable engine operation.

The operability of the proposed dual-mode solid-propellant rocket engine is substantiated by computational studies and confirmed by firing bench tests.

Thus, the proposed technical solution allows achieving the set goal, namely, ensuring the dual-mode operation of solid propellant rocket motors: starting and marching modes, while improving the manufacturability and ensuring the reliability of its operation.

Claims (1)

A dual-mode solid propellant rocket engine, comprising a body, a front bottom with an igniter, a rear bottom with a gas duct and a nozzle block, and a solid fuel charge with an internal cylindrical channel, having slots from the side of the front bottom and fastened to the body with a protective and fastening layer, characterized in that the length of the slots is 0.4-0.7 of the total length of the solid fuel charge, the ratio of the burning area of the slotted part of the channel is 5-8 to the burning area of the cylindrical part of the channel.

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