RU2378523C1 - Solid propellant rocket engine - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention is related to the field of rocket engineering, namely to solid propellant rocket engines and charges of solid propellant rocket engines of various purpose. Solid propellant rocket engine comprises body, front and nozzle bottoms, charge of solid propellant with slots, arch of which increases towards nozzle bottom of engine. Charge is made of three serially arranged sections: at the first and second sections thickness of burning arch increases, the third section is arranged with permanent thickness of burning arch. Values of burning arch thicknesses at each of sections are defined by ratios that are defended by the present invention. At the second and third sections there are slots arranged with triangular and rectangular profiles, which are combined into two symmetrically arranged groups with even location of slots in each of groups. Ratio of angles between slots of rectangular and triangular profiles makes 0.2…0.5. Height of rectangular profile slots makes 0.1…0.3 of required thickness of burning arch. Angle of incline of triangular profile slots tops to axis of engine makes 30…60°.

EFFECT: invention makes it possible to increase volume filling of engine chamber with fuel, to provide for increased level of traction at initial stage of engine operation, to reduce degressive burning down sections of fuel, and also to reduce gradient of traction growth as engine reaches mode.

3 cl, 3 dwg

Description

The invention relates to the field of rocket technology, namely to solid propellant rocket engines (solid propellant rocket engines) and to solid rocket propellant charges for various purposes, and can be used in the development of solid propellant rocket motors with charges bonded to the engine body.

One of the main tasks in creating solid propellant rocket constructions is to increase their energy characteristics due to the maximum volumetric filling of the engine chamber with solid rocket fuel. For the efficient use of the engine’s energy capabilities, the nature of the draft diagram must be neutral, and the degrading-burning fuel residues should be minimal.

In some cases, in addition to the requirements set forth above, it is necessary to have an increased level of traction at the initial stage of engine operation; in others, it is necessary to increase the time for the engine to reach operating mode.

Classical channel-slotted construction of charges (see books by Abugov D.I., Bobyleva V.M. Theory and calculation of solid propellant rocket engines. - M.: Mashinostroenie, 1987, p. 84, 85; Fakhrutdinov I.Kh., Kotelnikov A .V. Design and engineering of solid propellant rocket engines. - M.: Mashinostroenie, 1987, p. 53) with slots of a rectangular or close profile make it possible to ensure a neutral character of the thrust diagram with a minimum value of degrading-burning fuel residues and a high level of volumetric filling fuel chamber engine.

The disadvantages of such designs are:

- the inability to obtain a neutral character of the traction diagram with a small elongation of the charge (the ratio of the length L to the outer diameter D of the charge);

- the inability to obtain an increased level of traction in the initial section with a neutral character of the main section of the diagram.

Known charge of rocket solid fuel according to patent RU No. 2221158, decl. 02/03/2003, publ. 01/10/2004, comprising a housing, a fuel block firmly fastened to it with a round channel and a slotted part, in which the channel is made with a ratio of diameters in the slotted and round part of 1.10 ... 1.13, the tops of the slots are located on a conical surface with a half-angle of opening 5 ... 8 °, which is simultaneously transitional from one section of the channel to another, and the opening angle of the slits is 10 ... 12 °.

This design of the charge is not optimal both from the point of view of volumetric filling of the engine chamber with fuel, and from the point of view of the stress-strain state (VAT) of the charge:

- the charge channel along the entire length of the gap part is made with a diameter increased by 10 ... 13%, that is, the charge arch in the gap part is smaller than in the rest of the charge section;

- the gap is made of a triangular profile with an inclination angle of 10 ... 12 °. It is known that from the point of view of VAT, the optimal angle of inclination is 30 ... 60 °.

The closest in technical essence and the achieved technical result to the claimed invention is a rocket engine according to patent RU No. 2298110, F02K 9/18, decl. 2005113460106, publ. November 20, 2006, adopted as a prototype. It contains a housing, a front and a nozzle bottom, a solid fuel charge having slots from the front bottom side, the charge arch increases towards the engine nozzle bottom due to the transition of the cylindrical channel into a cone tapering towards the nozzle bottom, and the slots are arranged in symmetrical pairs.

The objective of the prototype is to increase the volumetric filling of the combustion chamber and the use of fuel for thermal protection of the engine housing while providing a neutral diagram of engine thrust.

However, this design can only be applied in engines in which the effect of erosive combustion of fuel is manifested quite strongly, in addition, for the occurrence of erosive combustion, a sufficiently high gas flow rate in the chamber is required, which reduces the residence time of the combustion products in the chamber, leading to incomplete combustion fuel and, as a consequence, increase the loss of specific impulse of thrust, that is, to non-optimal use of fuel energy.

The objective of the proposed technical solution is to increase the volumetric filling of the combustion chamber of engines in which the effect of erosive combustion of fuel is practically not manifested, as well as to obtain a traction diagram that is of increased importance in the initial part of the work and neutral in nature with a minimum mass of degrading burning fuel residues.

The problem is achieved in that the charge is made of three sections. In the first portion the thickness of the burning fuel is increased from a set (0.9 ... 0.99) _of e to the desired value _of e is determined by the time of the engine, the second portion of the burning arch thickness increases from f _o to (1,1 ... 1, 3) е _о , and the third section is made with a constant thickness of the burning arch (1.1 ... 1.3) е _о . A coating of a polymer material with a constant or decreasing thickness towards the nozzle bottom can be applied to the channel of the first charge site. On the second and third sections of the charge, slots of a triangular and rectangular profile are made, combined into two symmetrically located groups with a uniform arrangement of slots in each of the groups. The angle between adjacent slots of a rectangular profile is less than between the slots of a triangular profile, the ratio of angles is 0.2 ... 0.5. The height of the slots of the rectangular profile is less than the height of the slots of the triangular profile and is equal to (0.1 ... 0.3) e _о , and the slots of the triangular profile are made with an angle of inclination of the vertex to the axis of the engine 30 ... 60 °. Between slots of a triangular profile, slots of a rectangular profile can be made.

The combination of structural elements, their relative position and the ratio of their geometric dimensions allow:

- increase the volumetric filling of the engine chamber with fuel, since the charge channel is made in series with a cone tapering towards the nozzle bottom and a cylinder connected with a cone tapering to the nozzle bottom;

- to ensure the operation of the engine with a high level of traction in the initial section due to the fact that the slots are made in two different configurations and heights and are combined into two symmetrically located groups in which the angle between adjacent slots of a rectangular profile is smaller than between the slots of a triangular profile;

- to minimize the degrading-burning fuel residues due to the execution of slots of a rectangular profile between the slots of a triangular profile in combination with the choice of the angle of inclination of the generatrix of the channel in the first portion of the charge;

- to reduce the gradient of the increase in thrust when the engine enters the mode due to the application of the first portion of the coating charge on the channel of the polymer material with a constant or decreasing thickness towards the nozzle bottom.

The invention is illustrated by drawings.

Figure 1 - General view of a rocket engine of solid fuel, where

1 - housing; 2 - front bottom; 3 - nozzle bottom; 4 - charge of solid fuel; 5 - slots of a triangular profile; 6 - coating of a polymeric material; α is the angle of inclination of the top of the slit 5 to the axis of the engine; e _about - the required thickness of the burning fuel vault is determined by the engine operating time.

Figure 2 is a cross section of the engine at the location of the slots, where 5 are slots of a triangular profile; 7 - slots of a rectangular profile; β is the angle between adjacent slots of a triangular profile; γ is the angle between adjacent slots of a rectangular profile, combined into groups.

Figure 3 is a view of a slit of a rectangular profile, where e _about - the required thickness of the burning fuel vault, is determined by the operating time of the engine; 7 - a slit of a rectangular profile; and - the height of the slit of a rectangular profile.

The operation of the engine, made in accordance with the invention, is as follows. At the moment the engine is turned on, the surface of the slots 5.7 and the channel between the slots light up, the temperature in the engine chamber rises to the temperature of the fuel combustion products, resulting in a gradual heating of the surface of the polymer coating 6. This heating occurs unevenly along the length of the channel, since nozzle bottom 3, where the combustion of fuel occurs, the temperature of the combustion products is higher than that of the front bottom 2. As a result of this, the surface of the channel is gradually opened and tanned, and consequently, a gradual increase in traction until the entire coated channel surface ignites. Increasing or decreasing the thickness of the coating, as well as making it variable in length, the gradient of change in traction at the initial stage of work is regulated. Since charge 4 has two types of gaps, grouped in a certain way, this gives the following effect. Slots of a rectangular profile 7 having a height a quickly degenerate, which leads to a decrease in the combustion surface and the engine switches to the main lower thrust level, the neutral character of which is achieved due to the fact that the vertices of the slots 5 of the triangular profile gradually reach the engine body 1, as a result of which the surface of the slots decreases gradually and compensates for the progressive nature of the change in the surface of the channel, the progressiveness of the channel surface is also regulated at the end of the engine’s cone angle channel section of the first part of the charge. A part of the slots of the rectangular profile 7 located between the slots of the triangular profile 5 minimizes the degrading-burning fuel residues. The height and length of the slots, the angle of inclination of the apex of the slots 5, the ratio of the thickness of the fuel vault in all three sections of the charge, the thickness of the coating 6 are determined by calculation in each case, depending on the requirements of the engine, and can be refined during experimental testing.

The performance of the engine, made in accordance with the invention, is confirmed by fire bench tests in the experimental conditions of FSUE NIIPM.

Claims (3)

1. A rocket engine of solid fuel, comprising a housing, front and nozzle bottoms, a charge of solid fuel with slots, the arch of which increases towards the nozzle bottom of the engine, characterized in that the charge is made of three successive sections: in the first section, the thickness of the burning arch increases from (0.9 ... 0.99) e _о to е _о , in the second section, the thickness of the burning arch increases from e _o to (1.1 ... 1.3) е _о , the third section is made with a constant thickness of the burning arch (1, 1 ... 1.3) _of e, and the second and third portions are slots triangular and rectangular profiles, which are combined into two symmetrically located groups with a uniform arrangement of slots in each of the groups, and the ratio of the angles between the slots of the rectangular and triangular profiles is 0.2 ... 0.5, the height of the slots of the rectangular profile (0.1 ... 0.3 ) e _о , and the angle of inclination of the vertices of the slots of the triangular profile to the axis of the engine is 30 ... 60 °. 2. The solid propellant rocket motor according to claim 1, characterized in that between the slots of the triangular profile there are slots of the rectangular profile. 3. The solid propellant rocket motor according to claim 1, characterized in that the channel of the first charge portion is coated with a polymer material with a thickness that is constant or decreasing towards the nozzle bottom.

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