Hybrid rocket combustion

Fineman, S., Some Analytical Considerations of the Hybrid Rocket Combustion Problem, M. S. E. Thesis, Department of Aeronautical Engineering, Princeton University, Princeton,... 

Hybrid rockets are intermediate between solid rockets and hquid rockets in terms of the nature of the combination of solid fuel and hquid oxidizer. Since the fuel and oxidizer components of a Hquid rocket are physically separated, two mechanical systems are needed to feed these components into the combustion chamber. On the other hand, a hybrid rocket uses a polymeric inert material as a fuel and a Hquid oxidizer, and so only one mechanical system is needed to feed this Hquid oxidizer into the combusHon chamber. 

In order to improve the combustion performance of hybrid rockets, a new concept of a hybrid rocket is proposed the gas-hybrid rocket.l ] Fig. 14.23 shows a schemafic drawing of a gas-hybrid rocket composed of a combustion chamber, a gas generator, a Hquid oxidizer tank, and oxidizer feeding pipes and a valve. UnHke conventional hybrid rockets, the gas-hybrid rocket is a two-stage combusHon sys-... 

Though the pyrolants used in gas-hybrid rockets burn in a similar manner as rocket propellants, their chemical compositions are fuel-rich. The pyrolants burn incompletely and the combustion temperature is below about 1000 K. When an atomized oxidizer is mixed with the fuel-rich gas in the secondary combustor, the mixture reacts to generate high-temperature combustion products. The combushon performance designated by specific impulse, is dependent on the combinahon of pyrolant and oxidizer. 

Kuwahara, T, Mitsuno, M., Odajima, H., Kubozuka, S., and Kubota, N., Combustion Characteristics of Gas-Hybrid Rockets, AlAA-94-2880, New York (1994). 

Q3) V. Lindner, pp 716-17 in Kirk Othmer s Encycl, Vol 8(1965) (Burning rate detn of rocket proplnts by strand burning method ) R ) R.J. Zabelka, "Combustion of Several Hybrid Rocket Fuels , UnivMicrofilms, Ann Arbor, Michigan, Order No 65-2668, 247 pp. Dissertation Abstract 26(4), 2091-92(1965) (Engl) CA 64, 3273 (1966) K2) F. Solimosi... 

Hybrid Rocket Propellants. A special proplnt combination of unlike materials, particularly of unlike physical characteristics. Typical hybrid proplnt combinations are a solid fuel (or oxidizer) in combination with a liquid oxidizer (or fuel) in tjiat order. Sometimes a grain of solid fuel is encased in the combustion chamber of a rocket engine and burned in combination with liq oxygen. Similarly, a liq fuel may be injected into a combustion chamber in contact with a solid oxidizer. Another example is the use of concentrated hydrogen peroxide and a hydrocarbon fuel. In this case, the hydrogen peroxide is converted by decompn into a hot gas contg oxygen. The fuel is injected downstream of the first reaction, mixed with the hot oxidizer-rich gas, and burns (Ref 1)... 

This system is very rarely used though it has certain advantages it has not found much favor with missile designers the world over. The use of hybrid propellants extends the range but poses additional engineering and combustion related problems. Figure 4.4 shows a simple hybrid rocket motor. 

Apart from the above applications, hydrazine hydrate is also used in preparing organic derivatives, like hydrazones and hydrazides such as carbohydrazide (CH), oxalyl dihydrazide (ODH), malonic acid dihydra-zide (MDH), tetra formal tris azine (TFTA) and so on, from the corresponding ketones and aldehydes. Hydrazones have been investigated as solid fuels in hybrid rockets [40]. The hydrazides have been exploited as combustible fuels with metal nitrate oxidizers in the preparation of nanocrystalline oxide materials [41]. 

In a solid-propellant rocket motor, the propellant is contained within the wall of the combustion chamber, as shown in Fig. 1. This contrasts with liquid systems, where both the fuel and oxidizing components are stored in tanks external to the combustion chamber and are pumped or pressure-fed to the combustor. In hybrid systems, one component, usually the fuel, is contained in the combustion chamber, while the other component is fed to the chamber from a separate storage tank, as in liquid systems. The solid-propellant motor also has an ignition system located at one end to initiate operation of the rocket. The supersonic nozzle affects the conversion of... 

Hybrids is the name given in rocket technology to systems in which a solid fuel in the form of a case-bonded charge with a central perforation is reacted with a liquid oxidant. Hybrids with solid oxidant and liquid fuel also exist. Hybrids can be thrust-controlled during combustion and can even be re-ignited if hypergolic components are incorporated in the formulation of the fuel charge. 

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