Hypergolic Liquid Or Gel Fuel Mixtures

Abstract

Hypergolic liquid or gel fuel mixtures utilized in bipropellant propulsion systems are disclosed as replacements for fuels containing toxic mono-methylhydrazine. The fuel mixtures include one or more amine azides mixed with one or more tertiary diamine, tri-amine or tetra-amine compounds. The fuel mixtures include N,N,N′,N′-tetramethylethylenediamine (TMEDA) mixed with 2-N,N-dimethylaminoethylazide (DMAZ), TMEDA mixed with tris(2-azidoethyl)amine (TAEA), and TMEDA mixed with one or more cyclic amine azides. Each hypergolic fuel mixture provides a reduced ignition delay for combining with an oxidant in fuel propellant systems. The fuel mixtures have advantages in reduced ignition delay times compared to ignition delay times for each unmixed component, providing a synergistic effect which was not predictable from review of each component's composition. Additional fuel mixtures include various tertiary diamine, tertiary tri-amine or tetra-amine compounds combined with one or more amine azides or imidic amide compounds, to provide clean burning, high performing, and non-toxic fuels.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Not Applicable.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to the inventors and / or the assignee of any royalties thereon.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]The present invention relates to fuel mixtures utilized in hypergolic propulsion systems. More specifically, the invention relates to hypergolic fuel mixtures of tertiary amines and amine azides, or amines and imidic amides.[0005]2. Description of the Related Art[0006]A liquid or gel bipropellant rocket propulsion system consists of gas generators, oxidizer and fuel propellant tanks, plumbing, oxidizer and fuel valves, and an engine. The bipropellant rocket propulsion unit begins operation when the gas generators have been initiated and the gases from the gas generator pressurize oxidizer and f...

AI Technical Summary

Benefits of technology

[0013]Additional combinations of chemical compounds to form a hypergolic fuel mixture include numerous cyclic amidine (also identified as imidic amide) compounds, such as 1,5-diazabicyclo(4.3.0)non-5-ene (hereinafter, DBN), mixed with a hypergolic tertiary diamine such as TMEDA, or a 1,8-Diazabicyclo(5.4.1) undec-7-ene (hereinafter, DBU), mixed with a hypergolic tertiary diamine such as TMEDA. A monocyclic analog of bi-cyclic DBN but having the non-nitrogen containing cyclic structure opened along with isomers thereof, are additional compounds utilized to form a hypergolic fuel mixture when mixed with a hypergolic tertiary diamine such as TMEDA. Compounds containing one or more tertiary tri-amine structures, such as N,N,N′,N″,N″-pentamethyldiethylenetriamine (hereinafter, PMDETA), and compounds containing tetra-amine, such as hexamethyl-triethylene-tetra-amine (HMETA), or larger amine structures, when mixed with amine azide or imidic amide compounds, are also capable of providing favorable short ignition delay values to serve as hypergolic fuel mixtures with minimal toxicity and lacking suspicion as a human carcinogen.

Problems solved by technology

A short ignition delay characteristic is important since a long ignition delay of approximately 25 millisecond or longer causes fuel and oxidizer to accumulate in the combustion chamber, so that when ignition does take place an overpressurization can occur with creation of a “hard start.” Overpressurization in the combustion chamber can be severe enough to destroy the rocket motor and negate achievement of the mission objective.

A main drawback of MMH is the high toxicity of the compound.

Classified as a suspected human carcinogen, MMH requires exceptional safety precautions during handling which makes fueling of rocket motors both time consuming and expensive.

The '143 patent did not disclose alternative oxidizer compounds which may provide similar or improved performance when combined with DMAZ, BAZ or PYAZ.

A limitation of the compounds disclosed in the '143 patent included, for each of the three hydrocarbon moieties attached to the tertiary amine, that at least one but no more than two moieties contained an azide group.

A further limitation of the '143 patent includes the tertiary amine azide molecule can have no more than seven carbon atoms for the compound to remain hypergolic, allowing the tertiary amine azides to produce adequate specific impulse or density specific impulse results when mixed with IRFNA.

The '504 patent does not disclose alternative tertiary amine azide compounds which may provide similar or improved performance when used instead of, or in combination with DMAZ, BAZ or PYAZ.

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