Power plants – Reaction motor – Interrelated reaction motors
Patent
1990-05-23
1992-08-11
Bertsch, Richard A.
Power plants
Reaction motor
Interrelated reaction motors
60 3931, 244 55, F02K 302
Patent
active
051368390
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a ducted fan turbine engine, by which is meant a gas turbine engine in which a portion of the net energy is used to drive a ducted fan. The invention is particularly concerned with the outer discharge nozzle of a ducted fan turbine engine.
In the operation of a ducted fan turbine engine, air enters the engine core where it is mixed with fuel which is ignited to rotate a turbine at the rear region of the engine. Rotation of the turbine rotates a fan in the forward region of the engine thereby directing by-pass air to flow rearwardly over the outside of the engine core. The main air stream in the engine core leaves the engine through an inner discharge nozzle, and the by-pass air leaves the engine through an outer discharge nozzle surrounding the inner nozzle.
The outer discharge nozzle is required to withstand the operational pressure conditions, inertia, acoustic fatigue, and creep or other temperature/strength/time-related forms of degradation. The outer nozzle is also required to be constructed to facilitate engine removal.
In order to meet the above-mentioned operational requirements, conventional outer discharge nozzles have been constructed of heat-resistant, high strength/stiffness materials such as titanium, steel and Inconels, and these outer nozzles have either been permanently attached to the engine turbine case, or supported off the aft end of the by-pass duct fixed structure.
The above-mentioned materials are considerably more expensive than for example aluminium alloys both to obtain and to work. In addition, these materials are relatively heavy, which means that outer discharge nozzles constructed of these materials are correspondingly heavy and require suitably robust mounting supports.
In a conventional ducted fan turbine engine, the outer nozzle is supported on the inner or primary nozzle by several struts or vanes extending between the two nozzles. Because of the considerable differences in operational temperature between the inner and outer nozzles, and also because of the internal burst pressure effects, the supporting vanes or struts are subjected to high stresses which cause deformation of both the nozzles. These stresses and deformations have to be allowed for in the design of the engine.
When removing from an aircraft a ducted fan turbine engine equipped with a conventional outer nozzle, either the outer nozzle is removed first from the aircraft to be followed by removal of the remainder of the engine, or the engine including the outer nozzle is removed in one operation. With both these removal techniques, the outer nozzle adds considerably to the complexity of the operation because of its weight and size. It will be appreciated that the outer nozzle is also vulnerable to being damaged during or after its removal from the remainder of the engine.
It is an aim of the invention to alleviate the above-mentioned disadvantages, and according to one aspect of the invention there is provided a ducted fan turbine engine comprising an inner assembly including an inner discharge nozzle, and an outer assembly having a nacelle and an outer discharge nozzle surrounding the inner discharge nozzle, wherein the inner and outer discharge nozzles are separate from one another.
According to another aspect of the invention there is provided a ducted fan turbine engine comprising an inner assembly including an inner discharge nozzle, and an outer assembly having a nacelle and an outer discharge nozzle surrounding the inner discharge nozzle, wherein the outer discharge nozzle is mounted on an aircraft for movement between a forward operational position adjacent the nacelle, and a rearward park position to clear the inner assembly during removal thereof from the aircraft.
The outer discharge nozzle may be movable relative to the aircraft by means of rollers running on guide rails. In the construction in which the guide rails are mounted on the outer discharge nozzle, means may be provided to secure the guide rails to the aircraft to retain the outer discharge nozzle in its
REFERENCES:
patent: 4037809 (1977-07-01), Legrand
patent: 4122672 (1978-10-01), Lowrie
patent: 4790137 (1988-12-01), Quin
Bertsch Richard A.
Kocharov Michael I.
Short Brothers PLC
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