Power plants – Reaction motor – With thrust direction modifying means
Reexamination Certificate
1998-08-25
2001-02-27
Freay, Charles G. (Department: 3746)
Power plants
Reaction motor
With thrust direction modifying means
C060S228000, C239S265310, C239S265410
Reexamination Certificate
active
06192671
ABSTRACT:
FIELD OF THE INVENTION
The scope of the present invention is a divergent petal arrangement in convergent-divergent nozzles with thrust vectoring capability.
BACKGROUND OF THE INVENTION
Many of the existing military aircraft are equipped with convergent divergent nozzles. These can optimize the thrust for different flying conditions by varying the nozzle throat and exit area.
The manoeuvering capability of the aircraft together with the flying envelope can be enhanced by providing the aircraft with the capability of vectoring the thrust by introducing a component perpendicular to the engine axis. Thrust vectoring can be achieved with a change in the geometry of the divergent nozzle section with the convergent section remaining axisymmetric.
One of the possible arrangements for the divergent sections consists of a number of master petals positioned circumferentially around a conical section. Slave petals are positioned closing the gaps between each two of the master petals on the internal side of the conical surface. Engine gas pressure pushes the slave petals against the master petals providing adequate sealing.
The position of the slave petals between master petals must avoid disengagement or circumstance in which the sides of a master and slave petal cross allowing a gas exit. Slave petals must also be capable to deflect through flexion and/or torsion to adapt their sides to the gas side surfaces of the master petals, guaranteeing proper sealing.
The position of the master divergent petals can be determined by an actuation system consisting of hydraulic actuators, an actuation ring and different struts that connect each of the master divergent petals to the actuation ring. For a given position of the actuators and throat area the opening and vectoring degree of the divergent section is determined.
The slave petals are positioned radially by the engine gas pressure and the reaction against the master petals. The circumferential and axial position of each petal is determined by a centering mechanism that can be connected to the convergent section and the adjacent master petals. The mentioned mechanism must guarantee a centered position for both axisymmetric and vectored configurations. The system must also be compatible with the torsion and flexion of the slave petal.
Hangers must avoid the displacement of the slave petal away from the master petals when the gas pressure is less than the outer cavity pressure on the air side of the petal. This condition is encountered for large divergence angles at determined points of the flying envelope.
SUMMARY OF THE INVENTION
The present invention consists of a centering mechanism for divergent slave petals which reduces the numbers of parts compared to other known solutions. The mechanism also avoids the need of one of the hangers to withstand the forces that result from pressure acting on the air side of the petal. The mechanism is also capable of withstanding axial forces and therefore allows the removal of the joint between convergent and divergent slave petals.
The present invention consists of a support element joint on the air side of the slave divergent petal to which two centering bars are attached, preferably by spherical joints to accommodate the changes in angle. Each of the centering bars has two grooves that extend from their central position to the sides.
The master divergent petals have two sled elements on each side. Two sleds on opposite sides of the petal are forward sleds, characterized by being located closer to the throat area than the rear sleds, which stand nearer to the nozzle exit area. Each of the sled elements slides through a groove on one of the centering bars.
The centering bars join the left sleds of the master divergent petal located at the right of the slave divergent petal with the right sleds of the master divergent petal located at the left of the mentioned slave petal. The bars cross each other such that each of the two joins a front sled of one master petal with the rear sled of the other petal. The position of the support of the slave divergent petal is determined by the crossing of the two centering bars.
If the pressure difference on the sides of the slave divergent petal results on a net force towards the gas side of the petal, one of the two centering bars contacts the air side of the adjacent master petals limiting the displacement of the slave petal and holding it at an adequate position.
In a different axial position to the one of the support of the centering bars and preferably close to the exit area, there is a second support element joined to the slave divergent petal on the air side. A hanger element with two grooves that extend from its center to the sides, is joined preferably by a spherical joint, to the second support element. A stop element, which is allowed to move freely though the interior of one of the grooves in the hanger, is attached to the master petals, in a similar way to the sleds. The stop elements only contact the sides of the grooves when achieving a limit offset from the centered position.
The purpose of the described hanger element is to limit the displacement towards the gas side when the pressure on the air side of the slave divergent petal is higher than the pressure on its gas side and to limit the offset from the centered position at the corresponding axial location, avoiding any disengagement for maximum opening of the nozzle and collision of the slave petals for minimum opening of the nozzle.
These main advantages and other features and benefits will be more easily understood in the following description together with the appended drawings, in which the arrangement of the centering mechanism according to the principles of the invention, has been represented over the divergent petals as a non limiting example.
REFERENCES:
patent: 5232158 (1993-08-01), Barcza
patent: 5269467 (1993-12-01), Williams et al.
patent: 5484105 (1996-01-01), Ausdenmoore et al.
patent: 5485959 (1996-01-01), Wood et al.
patent: 5680755 (1997-10-01), Hauer et al.
patent: 595 753 A1 (1994-05-01), None
patent: 687 810 A2 (1995-12-01), None
Darby & Darby
Freay Charles G.
Industria de Turbo Propulsores S.A.
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