Power plants – Reaction motor – Motive fluid from diverse generators alternatively ejected...
Patent
1998-06-10
2000-09-12
Thorpe, Timothy S.
Power plants
Reaction motor
Motive fluid from diverse generators alternatively ejected...
60251, 602701, F02K 328, F02K 710
Patent
active
061160199
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to ramjets, and to aerial vehicles, such as missiles or the like, propelled by ramjets of this kind. It deals more specifically with a shut-off system for an orifice letting air into the combustion chamber of a ramjet.
It is known that ramjets essentially consist of a combustion chamber, ending in a jet pipe, and into which liquid or gaseous fuel (which may be generated from a solid fuel) and combustion air are introduced. This combustion air is introduced into the said combustion chamber through at least one orifice in the wall of the said combustion chamber and collecting air (or receiving it via an air intake duct) when the said ramjet (or the aerial vehicle carrying it) is moving with respect to the surrounding air.
Thus, for a ramjet to operate, the said ramjet needs first of all to be brought up to speed with respect to the said surrounding air.
To achieve this, it is common practice, in an initial operating phase which corresponds to the said ramjet being brought up to speed, to have this ramjet operate like a rocket, thanks to a consumable auxiliary motor housed in the said combustion chamber, and then, when the said ramjet has reached a predetermined speed and the said auxiliary motor has been completely consumed, there is a change to actual ramjet operation, with fuel and combustion air injected into the combustion chamber.
Such dual-mode operation (rocket mode, followed by ramjet mode) means that it is necessary to provide a shut-off system in order, on the one hand, to close off the said air-inlet orifice during rocket operation, in order to prevent leaks, through the said orifice, of the gases generated by the said consumable auxiliary motor and, on the other hand, to open the said air-inlet orifice for operation in actual ramjet mode.
Three types of shut-off systems are known: ejection of which takes place under the action of the difference in pressures applied respectively to the two faces of the said shutter, that is to say, on one side, the pressure of the air collected and, on the other, the pressure of the gases from the said auxiliary motor inside the said combustion chamber. It will be noted that the ejection of such a shutter takes place via the combustion chamber, which means that there may be resulting damage to the thermal protective layer generally provided on the walls of the said chamber and/or of the jet pipe. Furthermore, such natural ejection assumes a sufficient pressure difference, which means that shut-off systems of this first type are restricted to ramjets intended to operate at low or medium altitude; This thus avoids the drawbacks of the systems of the first type, but it is necessary to provide a particularly sophisticated control system, preventing any inadvertent opening of the flap which could cause premature firing of the said consumable auxiliary motor and thus damage the carrier (aeroplane for example) of a missile equipped with the said ramjet; chamber itself, which is cut to the shape of the said orifice at the end of rocket operation. It goes without saying that the cutting device used for this (generally of the pyrotechnic type) has to exhibit the same safety as that imposed on the system for controlling the pivoting flap of a system of the second type and that such a system of the third type has the drawback of a system of the first type, as regards the ejection, through the combustion chamber, of the cut-out pieces of wall.
The object of the present invention is to overcome the drawbacks recalled hereinabove and this invention relates to a system for shutting off the air-inlet orifice of a ramjet, allowing the latter: consumable auxiliary motor without having to resort to an external control system; and
To this end, according to the invention, the shut-off system for an orifice for introducing combustion air into the combustion chamber of a ramjet, the said ramjet being capable, in an initial phase of operation corresponding to the said ramjet getting up to speed, of operating as a rocket thanks to a consumable auxiliary motor
REFERENCES:
patent: 3115008 (1963-12-01), Cohen et al.
patent: 4028886 (1977-06-01), Hackett
Japanese Patent Abstracts, 03057867, Mar. 13, 1991.
Japanese Patent Abstracts, 04259647, Sep. 16, 1992.
Japanese Patent Abstracts, 04148047, May 21, 1992.
Japanese Patent Abstracts, 04148051, May 21, 1992.
Japanese Patent Abstracts, 04148048, May 21, 1992.
Hallais Michel
Protat Vincent
Gartenberg Ehud
Societe Nationale Industrielle et Aerospatiale
Thorpe Timothy S.
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