RU2485081C1 - Composition of paste-like rocket fuel for ramjet engines with afterburner chamber - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to rocket engineering and specifically production of paste-like fuel for ramjet engines an afterburner chamber. Disclosed is a composition which contains nanodispersed metal powders. The nanodispersed metal powders are boron powder or a mixture of powdered aluminium borides with 34-62% aluminium content, average particle size of 60-350 nm, which are obtained by re-condensation in a plasma arc reactor. The solvent used is decilin solvent of general formula C₁₀H₁₆, which is thickened with polyethylene in amount of 2-10%, with the following ratio of components, wt %: decilin 30-40, polyethylene 2.5-10; nanodispersed boron powder or mixture of aluminium borides containing 34-62% Al 15-35; ammonium perchlorate 15-35.

EFFECT: composition of said paste-like rocket fuel has a high rate of combustion, high combustion heat and efficiency.

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Description

The invention relates to rocketry, and in particular to the field of production of paste-like fuels for ramjet engines with ramjet.

The volumetric heat of combustion of known liquid rocket fuels used in ramjet engines and liquid rocket engines (LRE) does not exceed 9500 kcal / kg. To increase the energy intensity, components with a higher volumetric heat of combustion, for example, finely dispersed, are introduced into the liquid fuel. metal powders such as aluminum, boron, titanium, their alloys, etc. To prevent sedimentation of metal powder particles, the fuel is thickened, i.e. translate into a gel-like or pasty state while maintaining its thixotropic properties. Such fuel, like liquid, can be pumped through pipes, sprayed through nozzles, and it is also possible to refuel rockets at the start and it is relatively simple to adjust the thrust module. In addition, the use of pasty fuel can reduce evaporation losses and increase fire safety.

Known gel-like monofuel rocket obtained by dispersing aluminum with a particle size of up to 0.15 microns in a liquid oxidizing agent - nitrogen tetroxide (N ₂ O ₄ ). This fuel has a specific impulse close to 400 s (RF patent No. 2309140, IPC C06B 47/04, C06D 5/10, 2007).

The disadvantages of this rocket monofuel include high toxicity and chemical aggressiveness of the oxidizing agent - nitrogen tetroxide.

Flammable gel containing 36-40% of monomethylhydrazine as a liquid phase, up to 60% of powder of various energy-intensive metals and their hydrides with a particle size of metal powder of 6-10 microns and from 1 to 3% of a gelling agent, which is used dimethylurea or silicon dioxide, described in US patent No. 4039360, IPC C06B 47/08, 1977; US No. 5438824, IPC F02K 9/00, 1995; USA No. 5597947, IPC C10L 7/00, 1997. Sedimentation of metals does not occur even with a load of several hundred g.

The disadvantages of the known pasty combustibles include the large size of powders of various energy-intensive metals and their hydrides dispersed in combustible particles, which leads to a decrease in the burning rate and incomplete combustion.

In US patent No. 4090895, IPC СВВ 43/00, 1978, a paste-like (suspension) fuel is described, in which lower alcohols with the number of carbon atoms from 1 to 3 are used as the liquid phase. Fine powders of boron and aluminum are used as the high-energy component , aluminum borides, titanium, zirconium with a particle size of 0.1-10 microns, hydroxypropyl cellulose serves as a gelling agent.

In the examples given in the patent, gel-like compositions contain only amorphous boron, spherical aluminum, zirconium and zirconium boride with a particle size of 1-10 μm. The resulting gel-like fuel compositions are characterized by thermal stability, are stable during storage and by the action of gravity up to 100 g.

Known compositions are intended for use in a liquid engine, in which chlorine fluorides F ₃ Cl and F ₅ Cl are proposed as an oxidizing agent. The oxidizer: fuel ratio is 6: 1. The compositions are hypergolic. The need for a large amount of oxidizing agent in the fuel tanks of the LRE does not give any advantage compared to ramjet, where atmospheric air is used as the oxidizing agent. In addition, the proposed oxidizing agents are very aggressive and toxic.

For use in ramjet with an afterburner, solid fuel is proposed (US Pat. No. 6,736,912, IPC С06В 45/10, 2004) containing an organic matrix in which metal particles and particles of a fluorine-containing oxidizing agent are dispersed, capable of reacting with metal particles to form subfluorides. Moreover, the composition contains an oxidizing agent in an amount sufficient to maintain combustion, but not sufficient for the complete oxidation of combustible components. Products of incomplete combustion are ejected into the afterburner, into which heated air is introduced to completely burn the organic part and metals.

The disadvantages of the composition proposed in US Pat. US No. 6736912, adopted by us as a prototype, can be attributed to the relatively low heat of combustion, the low rate of combustion of the composition in the first combustion chamber, which makes it difficult to obtain supersonic flight speeds.

About the use in the ramjet with an afterburner of pasty combustible materials we have not found in the patent literature.

It should be noted that in the known compositions of gelled combustibles, a wide gamut of various metals is declared as energy-intensive components: Al, Sb, Be, B, Ca, Co, Cu, Au, Fe, Mg, Zr and others, as well as their alloys obtained by electric explosion conductive wire, it is indicated that the particle size does not exceed 1 μm. However, this method cannot be used to obtain powders of metals having the highest calorific value, for example, boron, aluminum borides, silicon, since it is impossible to make an electrically conductive wire from them.

The objective of the invention is to obtain a paste-like rocket fuel composition having a high combustion rate, high heat and completeness of combustion, used in ramjet engines with an afterburner.

To solve this problem, a paste-like rocket fuel composition for ramjet engines with an afterburner containing nanodispersed metal powders is proposed, characterized in that boron powder or a mixture of aluminum boride powders containing 34-62% aluminum is used as nanodispersed powders the average particle size of the powders is 60-350 nm, obtained by the method of condensation in a plasma electric arc reactor, and dissolve as the dispersion phase. l decylin general formula C ₁₀ H ₁₆ , thickened with polyethylene in an amount of 2-10%, in the following ratio of components, wt.%:

Decilin 30-40 Polyethylene 2,5-10 Nanodispersed powder boron or a mixture of borides aluminum containing 34-62% Al 15-35 Ammonium perchlorate 15-35

The high heat of combustion of the composition and the high burning rate of the composition are ensured by introducing nanodispersed powders of boron and aluminum borides into it, obtained by the method of condensation in a plasma electric arc reactor, which allows nanodispersed powders of elements that are not electrically conductive or from which the wire cannot be made.

As the liquid phase, a decylin solvent of the general formula C ₁₀ H ₁₆ having a high density and high volumetric heat of combustion was selected. To thicken the hydrocarbon, polyethylene is used in an amount of 2.5-10%. Ammonium perchlorate is introduced into the composition in an amount sufficient to maintain combustion, but not sufficient for complete combustion of combustible components. During combustion due to the interaction of nanodispersed metals with ammonium perchlorate, gasification and pyrolysis of the hydrocarbon part occurs, and the combustion products enriched in fuel, as well as unburned pasty fuel with thixotropic properties, enter the afterburner, where they are mixed with air from the atmosphere during flight rockets. In the afterburner, complete combustion of the fuel occurs.

Example.

The polyethylene granules are dissolved in decylin with heating and stirring. The resulting solution was transferred to a Werner-Pfleiderer-type twin-screw mixer and nanodispersed metal powder was added with stirring, then ammonium perchlorate was added. Then, for homogenization, the mixture was stirred for 1.5 hours at room temperature.

By the described method, all pasty combustibles were obtained. Combustibles are characterized by heat resistance, storage stability, delamination does not occur when accelerating to 100 g.

The composition, some physicochemical properties and combustion rates of the compositions are given in tables 1-4, which use the following notation: ASD-4 spherical aluminum powder with micron particles, n-Al - nanosized aluminum powder with an average particle size of 150 - 200 nm , n-B is a nanosized boron powder with an average particle size of 90-120 nm, BA is a mixture of nanosized aluminum boride powders with an average particle size of 120-150 nm, to you is amorphous boron powder, the numbers for BA indicate the aluminum content in the aluminum boride mixture, PHA - ammonium perchlorate, TP - deciline, thickened with polyethylene, L ₀ - the amount of air required for afterburning the fuel composition.

Table 1 The effect of metal on the burning rate of a composition containing: 50% TP, 30% PHA and 20% metal Composition Metal (average particle size) The density of the composition, g / cm ³ Calorific value, kcal / l Combustion rate, mm / s L ₀ , kg / kg P-8 ASD-4 (5-10 microns) 1.30 8590 1,1 7.4 P-9 n-Al (200 nm) 1.30 8590 1,2 7.4 P-4 BA-52 (110) 1.30 9380 4.0 7.95

The burning rate of the P-4 composition containing aluminum boride is more than three times higher than the burning rate of compositions containing micron and nanoscale aluminum powders. In addition, this composition is superior to compositions P-8 and P-9 in terms of calorific value and the amount of air required for complete combustion.

table 2 The effect of metal on the burning rate of a composition containing: 50% TP, 20% PHA and 30% metal Composition Metal (average particle size) The density of the composition, g / cm ³ Calorific value, kcal / l Combustion rate, mm / s L ₀ , kg / kg P-21 ASD-4 (5-10 microns) 1.33 9730 1,0 7.9 P-20 n-Al (200 nm) 1.33 9730 3.2 7.9 P-12 In am (5-7 microns) 1.30 12060 2,8 9.69 P-13-1 nV (90 nm) 1.30 12060 7.5 9.69 P-13-2 n-B (120 nm) 1.30 12060 7.4 9.69 P-14 n-Al / B am 50/50 1.31 10790 3.0 8.8 P-15 n-Al / n-B 50/50 1.31 10790 3.4 8.8 P-5 BA-52 (110 nm) 1.31 10780 6.2 8.72

In this series, compositions with nano-sized boron and aluminum boride also have a higher burning rate than compositions with their micron counterparts or even with mechanical mixtures of nano-aluminum and nano-boron.

As follows from Table 3, the mass ratio between the oxidizing agent and the metal also affects the burning rate; the ratio of the oxidizing agent to the metal, equal to 20 / 30-25 / 25, is most preferred.

Table 3 The effect of the ratio of PHA and BA-52 in the composition on its burning rate. The TP content in the composition is 50%. Composition Content% The density of the composition, g / cm ³ Calorific value, kcal / l Combustion rate, mm / s L ₀ , kg / kg PHA BA-52 P-7 fifteen 35 1.32 11530 4.4 10.07 P-5 twenty thirty 1.31 10780 6.2 8.72 P-2 25 25 1.30 10035 5.3 8.52 P-4 thirty twenty 1.30 9380 4.0 7.95 P-6 35 fifteen 1.28 8590 1.9 7.15

At the same time, the ratio between aluminum and boron in aluminum boride in compositions from BA-34 to BA-62 does not significantly affect the burning rate (Table 4). However, a further increase or decrease in the aluminum content leads to a decrease in the burning rate. Therefore, it is preferable to use aluminum borides with an aluminum content of 34 to 62%.

Table 4 The effect of aluminum content in a mixture of aluminum borides on the burning rate of a composition containing 50% TP, 25% PHA, 25% BA Composition The amount of aluminum in BA,% Combustion rate, mm / s P-BA-65 65 4.9 P-BA-62 62 5.2 P-BA-52 52 5.5 P-BA-43 43 5.7 P-BA-34 34 5.8 P-BA-30 thirty 5.1

The technology for the manufacture of pasty fuel and its sedimentation stability is also affected by the thickening of decylin with polyethylene. Table 5 shows the burning rates of pastes with different ratios of decylin and polyethylene.

From the data given in tables 1-5, it follows that, in comparison with the ASD-4 aluminum powders commonly used in rocket fuels and the currently widely studied nanoaluminum, nanodispersed aluminum boride and nanoboron powders are more efficient in burning rate, they have a high calorific value with a comparative a large value of L ₀ .

Claims (1)

A paste-like rocket fuel composition for ramjet engines with an afterburner containing nanodispersed metal powders, characterized in that boron powder or a mixture of aluminum boride powders containing 34-62% aluminum is used as nanodispersed powders, the average particle size of the powder is 60- 350 nm obtained by recondensation of the electric arc in a plasma reactor, in which a solvent is used as solvent detsilin general formula C ₁₀ H _16, the thickened with polyethylene in a lichestve 2-10% of the following component ratio, wt.%:
Decilin 30-40 Polyethylene 2,5-10 Nanodispersed powder boron or a mixture of borides aluminum containing 34-62% Al, 15-35 Ammonium perchlorate 15-35