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Researchers Submit Patent Application, "Aircraft Nacelle Comprising a Reinforced Connection between an Air Intake and a Means of Propulsion", for...

June 19, 2014



Researchers Submit Patent Application, "Aircraft Nacelle Comprising a Reinforced Connection between an Air Intake and a Means of Propulsion", for Approval

By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Porte, Alain (Colomiers, FR); Dida, Stephane (Fontenilles, FR), filed on November 20, 2013, was made available online on June 5, 2014.

The patent's assignee is Airbus Operations Sas.

News editors obtained the following quote from the background information supplied by the inventors: "An aircraft propulsion assembly comprises a nacelle wherein is arranged, substantially concentrically, a means of propulsion connected to the rest of the aircraft by means of a pylon.

"As shown in FIG. 1, the nacelle comprises, at the front, an air intake 10 by means of which an air flow can be channelled towards the means of propulsion 12, wherein a first portion of the inflowing air, termed the primary flow, passes through the means of propulsion in order to participate in combustion, and the second portion of the air flow, termed the secondary flow, is driven by a fan and flows in an annular duct delimited by the inner wall of the nacelle and the outer wall of the means of propulsion.

"For the remainder of the description, the longitudinal direction corresponds to the direction of the axis of rotation of the fan of the means of propulsion.

"The air intake 10 comprises a lip 14; that surface of the lip which is in contact with the aerodynamic flows extends, inside the nacelle, in the form of an inner duct 16 of substantially circular section and, outside the nacelle, in the form of an outer wall 18 of substantially circular section. The means of propulsion comprises a duct 20 which may be arranged in the continuation of the inner duct 16.

"As shown in FIG. 2, the air intake 10 is connected to the means of propulsion 12 by a connection which comprises, at the level of the means of propulsion, a first annular flange 22 secured to a second annular flange 24 of a panel which delimits the duct 16 or of an interposed part 26, termed bracket, connected to the panel which delimits the duct 16. The two flanges 22 and 24 are clamped against one another, at the level of a junction plane 28 which is substantially perpendicular to the longitudinal direction, and are held in that position by connecting elements 30, for example bolts or rivets, which pass through the flanges 22, 24 and extend parallel to the longitudinal direction.

"In terms of structure, the air intake 10 comprises a first frame, termed the forward frame 32, which connects the inner duct 16 and the outer wall 18 delimiting, with the lip 14, an annular duct 34 and a second frame, termed the rear frame 36, which connects the inner duct 16 and the outer wall 18 close to the junction plane 28.

"The rear frame, for its part, transmits bending, rotational or other forces which act on the air intake such as, for example, the weight of the air intake and the forces produced by the aerodynamic flows.

"According to one embodiment, the rear frame 36 is connected to the duct 16 either directly or via an interposed part or bracket 38 (shown in detail in FIG. 2) one leg of which is connected to the duct 16, the other leg being connected to the rear frame 36.

"The rear frame 36 is connected to the outer wall 18 either directly or via a bracket 40 (shown in FIG. 1) having a T-shaped cross section, wherein the rear frame 36 is connected at the level of the foot of the T-shaped bracket, and wherein the head of the T presses against the inner face of the outer wall 18.

"In accordance with one embodiment shown in the document FR-2.904.604, the rear frame comprises a first metal ring, in particular made of titanium, which extends around the entire periphery and which is connected to the inner duct 16, and a second ring whose outer peripheral edge is connected to the outer wall 18. The first ring comprises, at the level of its outer peripheral edge, a region overlapping the inner peripheral edge of the second ring. The two rings are connected by any appropriate means at the level of this overlapping region.

"In the event of fan blades failing, the duct 20 of the means of propulsion tends to undergo substantial deformation as it is designed to absorb, by deformation, the energy of the broken blades. At the level of the air intake, the inner duct 16 is made of a composite material and its mechanical properties are more limited than those of the duct 20 of the means of propulsion, in particular in terms of bending strength.

"In addition, in order to limit the risks of the panel or panels, which form the inner duct 16 of the air intake, coming loose, it is expedient to limit the propagation of the deformations from the duct 20 of the means of propulsion towards the inner duct 16 of the air intake.

"A first solution consists in designing a rear frame and/or a connection between the air intake and the means of propulsion which may deform so as to absorb a portion of the energy and thus limit the propagation of the deformations towards the inner duct 16 of the air intake.

"Another solution consists in limiting the deformations of the inner duct 16 of the air intake by stiffening it in the connection region between the inner duct 16 of the air intake and the duct of the means of propulsion. Solutions have been developed for increasing the stiffness of the rear frame or of the connection between the air intake and the means of propulsion.

"In order to stiffen the connection between the air intake and the means of propulsion, one solution consists in increasing the thickness of the flanges, increasing the number of connecting elements or increasing the size of the latter. However, this solution is not satisfactory as it increases the on-board mass.

"In order to stiffen the rear frame, the document FR-2.960.856 proposes a reinforced rear frame comprising a first metal ring whose inner edge is connected to the inner wall of the air intake and a second ring whose outer edge is connected to the outer wall of the air intake, the two rings being connected to each other. According to one feature of this rear frame, the second ring comprises at least one angular sector made of composite material having at least one hollow shape and the first ring comprises a rib extending over the entire periphery of said ring.

"Whichever region is stiffened (rear frame or connection between the air intake and the means of propulsion), there is a risk of deformation by torsion between the annular flange of the air intake and the rest of the inner duct, it being possible for a bending movement, along an axis tangential to the inner duct, to appear between the annular flange and the rest of the duct when the duct of the means of propulsion undergoes deformation.

"Another drawback is that the rear frames of the prior art are not entirely satisfactory in terms of axial (in the longitudinal direction) and radial stiffness. BRIEF SUMMARY OF THE INVENTION

"Thus, the present invention aims to remedy the drawbacks of the prior art.

"To that end, the an embodiment of the invention is an aircraft nacelle comprising: an air intake, connected to a means of propulsion, which defines a longitudinal direction, an outer wall, an inner duct comprising an annular flange connected, by means of connecting elements, to the means of propulsion, a forward frame and a rear frame which connects the outer wall and the inner duct, said nacelle being characterized in that the rear frame comprises a first ring and a second ring, in longitudinal planes, said rings comprising a first connection to the outer wall, the first ring comprising a second connection with the annular flange, the second ring comprising a third connection with the inner duct, which third connection is remote from the second connection.

"That the second and third connections are remote from one another makes it possible to limit the risk of the connection between the air intake and the means of propulsion becoming deformed by limiting bending phenomena between the annular flange and the rest of the inner duct.

"The rear frame preferably comprises a reinforcing element which connects the two rings and maintains the separation between them in the longitudinal direction, said reinforcing element being remote from the outer wall and from the inner duct.

"The presence of the reinforcing element makes it possible to stiffen the two rings and to increase the axial and radial rigidity of the rear frame as well as the strength of the connection between the air intake and the means of propulsion with respect to circumferential forces.

BRIEF DESCRIPTION OF THE DRAWINGS

"Other features and advantages will become apparent from the following purely exemplary description of the invention with regard to the appended drawings, in which:

"FIG. 1 is a cutaway of the lower, forward portion of an aircraft nacelle according to the prior art,

"FIG. 2 is a cutaway showing, in detail, a connection between an air intake and a means of propulsion according to the prior art,

"FIG. 3A is a longitudinal cutaway showing, in detail, a rear frame according to a first embodiment of the invention,

"FIG. 3B is a longitudinal cutaway showing, in detail, a rear frame according to a second embodiment of the invention,

"FIG. 4A is a longitudinal cutaway showing, in detail, a rear frame according to a third embodiment of the invention,

"FIG. 4B is a longitudinal cutaway showing, in detail, a rear frame according to a fourth embodiment of the invention,

"FIG. 5 is a longitudinal cutaway showing, in detail, a rear frame according to a fifth embodiment of the invention,

"FIG. 6 is a longitudinal cutaway showing, in detail, a rear frame according to a sixth embodiment of the invention, and

"FIG. 7 is a longitudinal cutaway showing, in detail, a rear frame according to a seventh embodiment of the invention."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Thus, the present invention aims to remedy the drawbacks of the prior art.

"To that end, the an embodiment of the invention is an aircraft nacelle comprising: an air intake, connected to a means of propulsion, which defines a longitudinal direction, an outer wall, an inner duct comprising an annular flange connected, by means of connecting elements, to the means of propulsion, a forward frame and a rear frame which connects the outer wall and the inner duct, said nacelle being characterized in that the rear frame comprises a first ring and a second ring, in longitudinal planes, said rings comprising a first connection to the outer wall, the first ring comprising a second connection with the annular flange, the second ring comprising a third connection with the inner duct, which third connection is remote from the second connection.

"That the second and third connections are remote from one another makes it possible to limit the risk of the connection between the air intake and the means of propulsion becoming deformed by limiting bending phenomena between the annular flange and the rest of the inner duct.

"The rear frame preferably comprises a reinforcing element which connects the two rings and maintains the separation between them in the longitudinal direction, said reinforcing element being remote from the outer wall and from the inner duct.

"The presence of the reinforcing element makes it possible to stiffen the two rings and to increase the axial and radial rigidity of the rear frame as well as the strength of the connection between the air intake and the means of propulsion with respect to circumferential forces.

BRIEF DESCRIPTION OF THE DRAWINGS

"Other features and advantages will become apparent from the following purely exemplary description of the invention with regard to the appended drawings, in which:

"FIG. 1 is a cutaway of the lower, forward portion of an aircraft nacelle according to the prior art,

"FIG. 2 is a cutaway showing, in detail, a connection between an air intake and a means of propulsion according to the prior art,

"FIG. 3A is a longitudinal cutaway showing, in detail, a rear frame according to a first embodiment of the invention,

"FIG. 3B is a longitudinal cutaway showing, in detail, a rear frame according to a second embodiment of the invention,

"FIG. 4A is a longitudinal cutaway showing, in detail, a rear frame according to a third embodiment of the invention,

"FIG. 4B is a longitudinal cutaway showing, in detail, a rear frame according to a fourth embodiment of the invention,

"FIG. 5 is a longitudinal cutaway showing, in detail, a rear frame according to a fifth embodiment of the invention,

"FIG. 6 is a longitudinal cutaway showing, in detail, a rear frame according to a sixth embodiment of the invention, and

"FIG. 7 is a longitudinal cutaway showing, in detail, a rear frame according to a seventh embodiment of the invention."

For additional information on this patent application, see: Porte, Alain; Dida, Stephane. Aircraft Nacelle Comprising a Reinforced Connection between an Air Intake and a Means of Propulsion. Filed November 20, 2013 and posted June 5, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=2883&p=58&f=G&l=50&d=PG01&S1=20140529.PD.&OS=PD/20140529&RS=PD/20140529

Keywords for this news article include: Airbus Operations Sas.

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Source: Politics & Government Week


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