RU2230052C2 - Method of production of the mixed solid propellant charges - Google Patents

Abstract

FIELD: production of mixed solid propellant charges for rocket equipment. SUBSTANCE: the invention presents a method of production of the mixed solid rocket propellant charges. The invention is dealt with fields of production of rocket equipment, namely with manufacture of the mixed rocket solid propellant charges. The method provides for preparation of an oxidizing agent, preparation of a mixture of a binder with a metal combustible and additives, and also a mixture of a hardener, preparation of tanks of rocket engines, preparation of combustible mass by stirring, polymerization, pressing-out and by a non-destructive test. At manufacturing of a charge they previously determine optimal particle size of a faction of oxidizing agent with an average mass particle size being in an interval of 0.5-15 microns at which the minimum unconfined volume of a mixture of dispersible propellant components is achieved, at a share of the fraction mass in the composition of the oxidizing agent ensuring the required burning rate of the charge. Usage of the invention allows to decrease a viscosity of the combustible mass, that promotes the more qualitative production of the charges. EFFECT: the invention allows to decrease viscosity of the combustible mass and to increase quality of production of the charges. 3 tbl

Description

The invention relates to the field of production of rocket technology, namely the manufacture of mixed solid fuel (CTT) charges, which can be equipped with rocket engines, for example, multiple launch rocket systems.

A known method of manufacturing charges CTT [1, p.96-98], [2], including the stage (phase):

- grinding of oxidizing agent and metal fuel;

- preparation of a fuel binder in the form of a liquid-viscous system;

- mixing of all components in the mixer with subsequent deaeration (evacuation) of the fuel mass;

- preparation of buildings with the application of a protective-fixing (armoring) composition, installation of a channel forming tooling, with a release coating;

- molding (casting) of the charge;

- polymerization;

- pressing out (extracting the channel forming tooling);

- flaw detection.

The disadvantage of this method is the inability to achieve a uniform distribution of metal fuel in the fuel volume, which can lead to heterogeneity of ballistic, physico-mechanical and other characteristics of different parts of the charge.

Also known is “A method of manufacturing mixed solid fuel charges” [3], adopted by the authors as a prototype, in which the aforementioned drawback is eliminated by introducing the operation of preliminary mixing of metallic fuel (usually aluminum) with a polymer binder. This method includes the following stages (phases):

- preparation of an oxidizing agent;

- preparation of a mixture of binder components with metallic combustible aluminum and other additives;

- preparation of a mixture of hardener components;

- preparation of engine housings;

- cooking fuel mass;

- charge shaping;

- polymerization;

- extrusion;

- flaw detection.

The disadvantages of this method include the impossibility of guaranteed obtaining the required rheological properties of the fuel mass, providing high-quality charge production.

The present invention is to develop a method of manufacturing charges CTT, providing a minimum level of viscosity of the fuel mass in the manufacture of the charge.

The problem is solved as follows. In the known method for the manufacture of mixed solid fuel charges, including the preparation of an oxidizing agent with grinding, fractionation and mixing in a certain ratio of various fractions, preparation of a binder mixture with metallic fuel and technological additives, as well as a mixture of components, hardener, preparation of fuel mass, preparation of engine bodies with further molding, polymerization, extrusion, and flaw detection, while a fine fraction is prepared during grinding and fractionation of the oxidizing agent a weight average particle size of which is selected from the range of 0.5-15 microns, reaching the minimum providing the free volume of dispersed fuel components at a weight fraction of fines in the composition of the oxidant, fuel which provides the desired combustion rate.

So, a significant difference of the proposed method for the manufacture of CTT charges is that at the stage of preparation of the oxidizing agent before grinding, the required mass average particle size of the fine fraction of the oxidizing agent is determined. Moreover, it should be such that with a mass fraction of a fine fraction in the composition of the oxidizing agent that provides the required rate of charge burning, the “free volume” (total volume unoccupied by particles) of the mixture of all dispersed fuel components (oxidizing agent, metallic fuel and additives) is minimal. Since it is precisely with the minimum “free volume” of the mixture of dispersed components that the minimum viscosity of the fuel mass is achieved.

The mass average particle size of the fine fraction is advisable to assign from the interval of 0.5-15.0 microns. When the particle size is less than 0.5 microns, the manufacturing cost sharply increases, and the stability of the fuel characteristics, in particular, the burning rate, also decreases. When the particle size of the fine fraction of the oxidizing agent is more than 15 μm, it becomes problematic to ensure a minimum “free volume" of the mixture of dispersed components.

To ensure the above requirements, it is necessary to prepare (grind and fractionate) a number of samples of a fine fraction of an oxidizing agent with mass-average particle sizes from the interval 0.5-15.0 μm. Grinding is performed, for example, in a grinding-vacuum plant. After that, samples of mixtures of dispersed fuel components with such a fraction of the fine fraction in the oxidizer composition are prepared at which the required fuel burning rate is ensured. Next, determine the “free volume" of these mixtures. The “free volume" can be determined, for example, by measuring the volume of liquid filling the free space between the particles of the mixture of dispersed components after its compaction. The mass-average particle size of the fine fraction of the oxidizer of the sample, on which the minimum value of the “free volume” of the mixture of dispersed components is obtained, is taken as optimal for the manufacture of the fine fraction of the oxidizing agent of the fuel itself.

Thus, the proposed method of manufacturing a charge of CTT includes the following stages:

- preparation of an oxidizing agent, including the operations of drying, grinding, fractionation and mixing in a certain ratio of the fraction; the fine fraction of the oxidizer is prepared with a mass-average particle size selected from the interval of 0.5-15 microns so that it achieves the minimum "free volume" of the mixture of dispersed fuel components for a given mass fraction of the fine fraction in the mixture of oxidizer, determined by the required fuel burning rate charge;

- preparation of a binder mixture with metallic combustible aluminum and additives;

- preparation of a mixture of hardener components;

- preparation of engine housings, including the application of a protective and fixing composition to its internal walls and the installation of technological equipment for forming the channel;

- preparation of the fuel mass, including dosing, mixing all the components in the mixer, followed by evacuation;

- molding (pouring into the engine housing);

- polymerization;

- Pressing (extraction of technological equipment for forming channels and charge);

- flaw detection;

In some cases, in order to ensure the accuracy of maintaining the fractional composition of the oxidizing agent (exclusion of refraction during loading and unloading), it is advisable not to pre-mix the fractions obtained in the preparation phase of the oxidizing agent, but to introduce them into the fuel composition at the fuel mass preparation phase, loading fractionally into the mixer .

According to the proposed method, samples of CTT charges were manufactured and tested. The task was to create a CTT charge, where the fuel has a burning rate of (25.0 ± 0.2) mm / s at 20 ° C and a pressure of 100 kgf / cm ² (10 MPa), with a minimum viscosity of the fuel mass. The fuel of the charge samples included 65% of an oxidizing agent, ammonium perchlorate, 9% of a polymeric binder, 18% of metallic fuel-aluminum, 8% of a catalyst and processing aids. Ammonium perchlorate fractions with a weight average particle size of 0.5 were prepared as a fine fraction; 4 and 15 microns.

The results of the manufacture and testing of test samples are presented in table. 1-3. The "free volume" of mixtures of dispersed components was determined by measuring the volume of inert liquid remaining between the particles after compaction of the mixture by centrifugation. The value of “free volume” is given in relative units (the ratio of the total volume unoccupied by particles, ie, “voids”, to the volume occupied by the mixture of dispersed components).

As follows from the data in Table 1, it was not possible to achieve the required rate of charge fuel combustion using a fine fraction of an oxidizer with a mass-average particle size of 15 μm at any of its mass fraction in the oxidizer mixture. The data in Tables 2 and 3 show that the task of ensuring a burning rate of (25.0 ± 0.2) mm / s is solved using small fractions of the oxidizing agent: with an average particle size of 4 μm, with its mass fraction in the composition of the oxidizing agent 20%, and with a mass-average size of 15 μm with its mass fraction in the composition of the oxidizing agent 35%. Moreover, in the first case (Table 2, sample 3), the mixture of dispersed fuel components has a "free volume" of 0.125 units, and the viscosity of the fuel mass is 160 Pa · s. In the second case (Table 3, sample 6), the “free volume" is 0.209 units, and the viscosity of the fuel mass is 600 Pa · s. As a result, it is proposed to use the first option for the manufacture of a charge (Table 1, sample 3): a fine fraction is prepared with a mass average size of 4 μm, and its mass fraction in the composition of the oxidizer is taken to be 20%.

Thus, in the described example, the manufacture of a charge according to the proposed method allowed to lower the viscosity of the fuel mass from 600 to 160 Pa · s, which contributes to a better manufacture of charges.

Sources of information

1. Grigoriev A.I. Solid rocket fuels. M .: Chemistry, 1969, 116 p.

2. Fakhrutdinov I.Kh., Kotelnikov A.V. Design and engineering of solid propellant rocket engines. M.: Mechanical Engineering, 1987.p. 43-45.

3. RF patent No. 2170721.

Claims (1)

A method of manufacturing mixed solid fuel charges, including the preparation of an oxidizing agent with grinding, fractionation and mixing in a certain ratio of various fractions, preparation of a binder mixture with metallic fuel and technological additives, as well as a mixture of hardener components, preparation of fuel mass, preparation of engine bodies with further molding, polymerization , by pressing and flaw detection, characterized in that when grinding and fractioning the oxidizing agent, a fine fraction is prepared with a mass-average particle size that is selected from an interval of 0.5-15 μm, which ensures the achievement of a minimum free volume of a mixture of dispersed fuel components, with a mass fraction of fine fractions in the oxidizer composition providing the required fuel burning rate.

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