Power plants – Reaction motor – Liquid oxidizer
Reexamination Certificate
1999-12-23
2001-11-13
Thorpe, Timothy S. (Department: 3746)
Power plants
Reaction motor
Liquid oxidizer
Reexamination Certificate
active
06314719
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to ignition systems and more particularly an ignition system for a propulsion producing engine that uses optical means for initiating the exothermic chemical reaction associated with so-called green fuels.
2. Description of the Related Art
Chemical hypergolic additives have long been used to initiate exothermic chemical reactions. These “hypergols” are highly reactive and highly toxic. In order to be deemed a non-toxic fuel, a small amount of hypergol can be added to the fuel directly. In such instance, there is sufficient hypergol to allow for the initiation of the reaction. Yet, its presence in a non-toxic fuel is of sufficient dilution that the fuel still qualifies as non-toxic. In summary, the fuel is maintained in a “green” classification by adding enough hypergol to the fuel to make it self-initiating in the presence of the oxidizer, but in such small quantities that its dilution in the fuel technically qualifies the mixture as non-toxic.
However, the presence of the hypergol in the fuel means that its performance is reduced. That is, once the mixture has begun to react, the hypergol's role is no longer necessary and it becomes, in essence, a contaminant, potentially reducing the propulsion performance. In practical terms, there is no long term storage data regarding whether this fuel hypergol mixture will remain viable in the long term.
U.S. Pat. No. 4,702,808, issued to J. H. Lemelson, entitled “Chemical Reaction Apparatus and Method” discloses rocket engine ignition in which propellants are ignited by an intense radiant energy, such as a light beam generated by a laser mounted in a housing. A beam of intense light is directed to the interior volume and caused to intersect fuel fed through inlets to effect ignition. There is no discussion in this patent of the photo-chemical interaction of the oxidizer and the fuel.
U.S. Pat. No. 5,727,368, issued to E. J. Wernimont, entitled “Hybrid Motor System with a Consumable Catalytic Bed a Composition of the Catalytic Bed and a Method of Using”, discloses a method, device, and composition for achieving ignition and sustained combustion using a solid consumable catalytic bed. The consumable catalytic bed (CCB) accomplishes this by decomposition of an injected fuel. Initially, this reaction is catalytic or hypergolic in nature eventually becoming entirely thermal as the CCB is consumed in the reaction generated. The patent is directed to a hydrogen peroxide hybrid rocket.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore a principal object of the present invention to provide an ignition system for an engine, which is particularly applicable for use with a hydrogen peroxide oxidizer.
Another object is to use an optical system as a means for disassociating the oxidizer.
These and other objects are achieved by the present invention, which in its broadest aspects, includes an optical source capable of producing light having physical characteristics sufficient for optically driven chemical disassociation of a hydrogen peroxide oxidizer; and, an optical delivery system for providing optical delivery of light from the optical source to a combustion chamber. The ignition system is used for a propulsion producing engine having a combustion chamber for the introduction of a fuel and a hydrogen peroxide oxidizer. The initiation of combustion is produced by the non-linear, optical interaction of the produced light with a fuel and the oxidizer present in the combustion chamber, thereby leading to molecular disassociation of the oxidizer such that there is initiation of combustion.
The use of optically induced ignition in a rocket engine has a number of advantages over standard ignition systems. The use of hypergolic chemical additives is being gradually phased out due to the danger of handling extremely toxic liquids. Additionally, the hypergols have long delay times (>1 millisecond) in their ability to initiate combustion. Solid state pyrotechnics work well, but can only be used once, prohibiting their use in circumstances where a re-light may be necessary. The standard source for most engines is an electrical discharge. The device which produces the requisite energetic discharge is large, heavy and must be located within the reaction chamber making remote operation impossible. Additionally, the discharge requires that the chemicals be in a fuel rich mixture to start the reaction. The resulting transient produces a huge shock acoustic shock wave. Engines must be built to specifications, not to survive steady state operation, but to survive the start transient. Optical ignition can start at almost any mixture ratio, offering the ability to reduce or eliminate the start transient. This leads to lighter weight engines.
These and other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
REFERENCES:
patent: 4702808 (1987-10-01), Lemelson
patent: 5367869 (1994-11-01), DeFreitas
patent: 5497612 (1996-03-01), Few
patent: 5727368 (1998-03-01), Wernimont
patent: 5876195 (1999-03-01), Early
Hunt Jeffrey H.
Lander Herbert R.
Gartenberg Ehud
Ginsberg Lawrence N.
The Boeing Company
Thorpe Timothy S.
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