Patent ID: 12240618

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

FIG.1shows a wing1supporting a propulsion unit comprising a nacelle3. The nacelle3surrounds in particular a fan casing. A mast19, also called pylon, has one end fastened beneath the wing1, and an opposite end configured to support the propulsion unit.

FIG.2shows in detail a portion of a turbojet engine comprising a fan5and structural arms which may be formed by stream straightening vanes7surrounded by the fan casing20. In this example, vanes18of the fan5are fastened to a rotary hub6. The fan5allows the generation of the primary and secondary streams. The hub6is configured to be rotating about a longitudinal axis XX. An abradable coating12lines the internal surface of the fan casing20opposite the fan vanes18so as to make the fan casing20tight but also to inhibit wear of the fan5in case of contact between the fan vanes18and the fan casing20. The stream straightening vanes7allow straightening the secondary stream generated by the fan5. At least some of these stream straightening vanes7may have enough stiffness to provide a structural function in the connection between the fan casing20and other portions of the engine, in particular a fixed hub.

FIG.3shows a cross-sectional view of a portion of a nacelle17formed by a fan casing4according to the present disclosure. The nacelle17is delimited by an outer skin which is in contact with air outside the nacelle. The fan casing4has one single wall14which forms at least partially the outer skin of the nacelle17.

The wall14comprises enough stiffness to provide the structural function of the fan casing4of the nacelle17and fasten elements to the fan casing4.

An air inlet lip8is composed by a leading edge. The leading edge could be configured to receive a deicing means. The air inlet lip8may be integral with or attached to the nacelle17. Following the air inlet lip8, in the direction of the air flow through the nacelle17, is the air inlet flow path9. The air inlet flow path9comprises acoustic elements such as acoustic panels11so as to limit the noise diffused by the propulsion unit. The fan casing4is coincident with at least one portion of the outer skin of the nacelle17.

The fan casing4surrounds a fan5providing the secondary air stream. An abradable coating12lines the internal surface of the fan casing4opposite the fan vanes so as to make the fan casing4tight but also to inhibit wear of the fan5in case of contact between the fan vanes and the fan casing4. The fan casing4also supports acoustic elements such as acoustic panels11.

The acoustic panels11are fastened to the inner wall of the fan casing4, or to at least one inner removable cowl (not shown) of the nacelle17which seals at least one inner cavity (not shown) formed by the fan casing4. The acoustic panels11extend beyond the stream straightening vanes7up to a downstream end portion of the nacelle17, and form at least partially the inner skin of the cold air flow path. Over most of the inner wall of the fan casing4, the depth available to house the acoustic panels11is larger than that available in the nacelles of the prior art.

Opposite these stream straightening vanes7, a reinforcement13of the fan casing4of the nacelle17allows fastening to the fan casing4the straightening vanes7or any other arms having a structural function in the connection between the fan casing4and a fixed hub of the turbojet engine. The stream straightening vanes7may form structural arms having enough stiffness to provide the structural function. In one example, the bladed wheel that comprises the stream straightening vanes7may also comprise structural arms with a larger section, having, or not, a profile for straightening the stream.

The reinforcement13, which has W-shaped longitudinal section in the represented example, forms an outer cavity10directed towards the outside of the nacelle17. The outer cavity10is opposite the stream straightening vanes7.

The reinforcement13follows the wall14of the fan casing4of the nacelle17, and therefore the outer skin of the nacelle17, in the direction of the air flow through the nacelle17until arriving at the level of the outer cavity10. In other words, the reinforcement13delimits an outer cavity10with a longitudinal section substantially similar to a W. The W-shape opening onto the outside of the nacelle17.

Upon completion of the delimitation of the outer cavity10, the reinforcement13is again coincident with the outer skin of the nacelle17, in the direction of the air flow through the nacelle17. The reinforcement13has a structural function for the strength of the fan casing4of the nacelle17, and more particularly its wall14.

The outer cavity10allows accessing a portion13A,13B of the reinforcement13that accommodates fastening means of the stream straightening vanes or arms7or any other arm having a structural function. Indeed, the reinforcement13is configured for fastening of the fan casing4to arms at least part of which has enough stiffness to provide a structural connection between the fan casing4and other structural portions of the engine. These structural connecting arms may be totally formed by the stream straightening vanes7. The configuration of the reinforcement13to accommodate the fastening means of the arms7may consist in providing for orifices across the thickness of the reinforcement13, so as to accommodate fastening bolts of the arms. The arms7may comprise at their tips fastening areas7A also provided with orifices for accommodating the fastening bolts of the arms.

A cowl21, whether structural or non-structural, is configured to removably cover the outer cavity10so as to form the outer aerodynamic line of the nacelle17at the level of the outer cavity10.

When the removable cowl21does not cover the outer cavity10, an access is allowed for a user to access the fastening means of the stream straightening vanes7.

The reinforcement13does not necessarily project significantly towards the inside of the nacelle.

Alternatively, or in combination with a projection towards the inside of the nacelle17, the reinforcement13may be made by a local overthickness130of the wall14, which may form a substantially pronounced boss towards the inside of the nacelle17.

FIG.4shows a cross-sectional view of a portion of a nacelle17integrating a fan casing4according to another variant of the present disclosure. The nacelle17is also delimited by an outer skin. Similar to the nacelle ofFIG.3, the wall14has enough stiffness to provide the structural function of the fan casing4and to fasten therein elements for connection to other structural portions of the engine. The nacelle17is composed by the same elements as the nacelle17ofFIG.3.

In this example, a structural reinforcement131is introduced opposite the fan vanes. The reinforcement131comprises a cavity15directed towards the outside of the nacelle17. The cavity15has U-shaped longitudinal cross-section.

The reinforcement131of the fan casing4is directed locally towards the inside of the nacelle17in order to fasten the abradable material12on the fan casing4. The U-shape of the reinforcement131, in longitudinal section, confers additional stiffness on the fan casing4, at the level of the fan5. The outer cavity15may also accommodate an equipment of the propulsion unit.

A cowl22, whether structural or non-structural, is configured to cover the outer cavity15, like the cowl21of the outer cavity10, in a removable manner, to form the outer aerodynamic line of the nacelle17at the level of the outer cavity15and the outer cavity10.

The internal volume of each of the cavities is then accessible to an operator when the corresponding cowl21,22is removed.

Furthermore, at least one inner removable cowl23, covered by an acoustic panel11, is configured to cover at least one cavity16, configured to receive equipment of the propulsion unit. The cowl23, and a fortiori the at least one cavity16, is accessible through the air inlet of the nacelle17.

The present disclosure allows arranging a nacelle17in an improved manner in order to reduce the overall weight thereof by sharing the functions of the nacelle17and of the fan casing4. That is, the fan casing4and the nacelle17share the same wall14. In addition, the outer cavities10,15are integrated into the fan casing4to form structural reinforcements and form compartments that could receive equipment, and the outer aerodynamic line of the nacelle17is formed by the removable cowls21,22. The reinforcements13,131respectively forming the outer cavities10and15allow fastening and/or supporting elements such as the stream straightening vanes7and an abradable coating12, but also other parts while stiffening the fan casing4. This arrangement of the nacelle17also allows increasing the treated acoustic surfaces/volumes in order to increase the noise reduction capacity.

Of course, all simple modifications or combinations of elements derived from different variants of the present disclosure fall within the scope of the present disclosure.

Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.