Patent Publication Number: US-2022213839-A1

Title: Fire wall and method for opening same

Description:
TECHNICAL FIELD 
     The present disclosure relates to the field of turbomachines, and particularly a firewall for an auxiliary arm of a turbomachine. 
     What is meant here by “turbomachine” is an assembly comprising, from upstream to downstream in a flow direction of a working fluid, a compressor, a combustion chamber, and a turbine connected mechanically by a rotating shaft to the compressor. Among turbomachines are therefore counted gas turbines, turbojets, turbofans, turboprops and turbine engines. 
     PRIOR ART 
     This disclosure relates in particular to turbofans, without however being limited to them. In fact, to allow the routing of fluids, such as fuel, lubricant or hydraulic fluid, as well as electricity, turbofans typically comprise auxiliary arms extending radially in the air stream of the fan, and receiving, within a tubular structure, bundles of ducts and/or electrical cables. One example of such auxiliary arms was disclosed in the publication of European patent application EP 1 741 879 A1. 
     In order to prevent the propagation of possible fires within said auxiliary arms, firewalls can be placed there transversely, with through openings for the passage of ducts and electrical cables extending inside the auxiliary arm. To ensure the sealing of the firewall, the ducts and/or electrical cables can be tightly received in these through openings, for example in sealing blocks attached to the firewall and in which these through openings are formed. 
     This arrangement had however the disadvantage of normally requiring the dismantling of the sealing blocks, to allow the extraction by passage through the firewall of even a single duct and/or cable for its inspection, its maintenance, its repair or its replacement. Moreover, a duct or a cable had to be disconnected at one of its two ends at least to allow it to be extracted by passage through and opening of the firewall, which during operation is occupied by a sealing block, once the sealing block which surrounds this duct or cable is dismantled. This extending the duration of the dismantling in situations for which it is desirable to dismantle the auxiliary arm assembly. The dismantling of the auxiliary arm necessitated disconnecting all the ducts and/or cable in order to free them from the firewall. 
     DISCLOSURE OF THE INVENTION 
     The present disclosure has the purpose of solving this disadvantage by proposing a firewall facilitating access to each duct and/or electrical cable passing through it. 
     To this end, a firewall for a turbomachine auxiliary arm according to the present disclosure can comprise one or more through openings in a thickness direction of the firewall, a fixed portion, and a first removable portion extending, in a width direction, orthogonal to said thickness direction, from at least one adjacent opening among the through openings, to a first outer edge of the firewall. 
     Due to this arrangement, by separating the first removable from the fixed portion, it is possible to gain access directly from the outside to a duct or electrical cable received in said adjacent opening, even to extract it individually from it. It is therefore not necessary to pass a duct or an electrical cable through an opening of the firewall to extract it. Moreover, the ducts and/or cables generally have sufficient flexibility or pliability to be removed from the firewall without having to disconnect their ends, which allows withdrawing the auxiliary arm by moving it in the downstream direction of the turbomachine while leaving in place the ducts and/or cables. The fact of not having to disconnect the ducts and/or cables contributes a substantial time saving for an operation of dismantling and withdrawal of the auxiliary arm. 
     To receive several ducts and/or electrical cables, the firewall can comprise one or two rows of said through openings, each extending in a length direction, orthogonal to said thickness and width directions. 
     If the firewall comprises a first row and a second row of said through openings passing through said rows, the fixed portion of the firewall can extend in the length direction between them, the first removable portion can extend from the first row to the first outer edge and a second removable portion of the firewall can extend from the second row to a second outer edge of the firewall, opposite to the first outer edge. 
     Alternatively, however, said first removable portion can extend from the first row to the first outer edge and the second removable portion of the firewall extend between the first and second rows. In this second case, in order to ensure good sealing of the firewall, the second removable portion can overlap an adjacent surface of the fixed portion and the first removable portion can overlap an adjacent surface of the second removable portion. Moreover, the first and second removable portions can comprise jaws connected by one or more bolts, so as to releasably attach the first removable portion to the second removable portion. 
     In order to ensure good sealing of the firewall, the first removable portion can overlap an adjacent surface of the fixed portion. 
     In order to increase the stiffness of the firewall, but also to ensure good sealing between the firewall and each through opening, the first removable portion can comprise an inner stiffener, protruding in the thickness direction, located on a perimeter of the at least one adjacent opening among the through openings. 
     Also in order to increase the stiffness of the firewall while ensuring its sealing, the first removable portion can have, on the first outer edge, an outer stiffener, protruding in the thickness direction, which overlaps a fitting of an adjacent stiffener of the fixed portion of the firewall. 
     To releasably attach the first removable portion to the fixed portion, the first removable portion and the fixed portion can comprise jaws connected by one or more bolts. 
     This disclosure also relates to a turbomachine auxiliary arm, which can comprises a tubular structure, one or more ducts and/or electrical cables inside the tubular structure and the firewall mentioned above, and in which the ducts and/or electrical cables can pass through the firewall by the through openings, as well as a turbomachine which can comprise at least one auxiliary arm of this type, which can extend radially between the two axial shrouds, particularly for passing through an air stream of a fan of the turbomachine. 
     Finally, this disclosure also relates to a method for opening the firewall mentioned above, comprising a step of dismantling the first removable portion to allow access to one or more ducts and/or electrical cables received in the through openings. 
     The invention will be better understood and its advantages will appear more clearly upon reading the detailed description that follows, of an embodiment shown by way of a non-limiting example. The description refers to the appended drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an aircraft equipped with turbofans. 
         FIG. 2  is a schematic view of one of the turbofans of the aircraft of  FIG. 1 , which auxiliary arms passing radially through the air stream of the fan. 
         FIG. 3  is an exploded view of a first embodiment of a firewall intended for one of the auxiliary arms of  FIG. 2 . 
         FIG. 4A  is a first perspective view of the firewall of  FIG. 3 . 
         FIG. 4B  is a second perspective view of the firewall of  FIG. 3 . 
         FIG. 5  is a schematic view of a second embodiment of a firewall intended for one of the auxiliary arms of  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     As illustrated in  FIG. 1 , an aircraft  10  can be equipped with turbomachines, particularly in the form of turbofans  100 . As illustrated in  FIG. 2 , these turbofans  100  can comprise a fan  101  and an engine core  102 , with respective coaxial casings  103 ,  104 . To retain the concentricity of the casings  103 , 104 , these can be connected by structural arms  105  extending radially through the air stream of the fan  101 . 
     In order to allow the routing of fluids and or of electricity between the casing  103  of the fan and the casing  104  of the engine core  102 , the turbofan  100  can also include auxiliary arms  106  extending radially, through the air stream of the fan  101 , of an inner shroud  107  integrated with the casing  104  of the engine core  102 , to an outer shroud  108  integrated with the casing  103  of the fan  101 . These auxiliary arms  106  can be adjacent to the structural arms  105 , directly downstream of them in the flow direction of the air in the air stream of the fan  101 . 
     Each of the auxiliary arms  105  can comprise a tubular structure  109  and a bundle  110  of ducts and/or cables  111  extending inside this tubular structure  108 . Although the auxiliary arms  105  illustrated have tubular structures  108  with an essentially rectangular cross section, other forms of transverse section are also conceivable. In order to allow access to the inside of the tubular structure  108 , this can comprise outer walls  113  which can be dismantled. In order to avoid the propagation of fire inside, each auxiliary arm  105  can also comprise at least one firewall  112 , which can be arranged transversely inside the tubular structure  108 . 
     As illustrated in  FIGS. 3, 4A and 4B , in at least a first embodiment, the firewall  112  can comprise a fixed portion  120  and two removable portions  130 ,  140 . The fixed portion  120  can be integral with the tubular structure  108  of the auxiliary arm  105 , while each of the removable portions  130 ,  140  can be releasably connected to the fixed portion  120  by bolts (not illustrated). At least one of these bolts can be oriented in the width direction Y of the firewall  112  to connect the jaws  121 ,  131 ,  141  protruding in the thickness direction Z of the firewall  112 , respectively on the fixed portion  120 , the first removable portion  130  and the second removable portion  140  of the firewall  112 . Other bolts can be oriented in the the thickness direction Z of the firewall  112  to connect, respectively, the first removable portion  130  and the second removable portion  140  to the fixed portion  120 . To allow the passage of these other bolts, the fixed portion  120  can have openings  122  aligned with corresponding openings  132 ,  142  in the respective overlap zones  133 ,  143 . These overlap zones  133 ,  143  in which the fixed portion  120  can overlap, in the thickness direction Z, with the first and second removable portions  130 ,  140  respectively, allow also ensuring good sealing of the firewall  112 . 
     As also illustrated in  FIGS. 4A and 4B , the firewall  112  can have one or more through openings  180  to allow the passage of the ducts and/or electrical cables  111  of the bundle  110 . If the firewall  112  can comprise a plurality of through openings  180  of this type, these can be arranged in one or more rows  181 ,  182 . Each of these rows  181 ,  182  can extend in the length direction X of the firewall  112 . In order to ensure good sealing of the firewall  112  around each duct or electrical cable  110 , these through openings  180  can be dimensioned so that each duct or electrical cable  111  is tightly surrounded there, and their perimeter have a noticeable excess thickness which can form the stiffeners  124 ,  134 ,  144  protruding in the thickness direction Z on, respectively, the fixed portion  120 , the first and second removable portions  130 ,  140 . 
     As also illustrated in  FIGS. 4A and 4B , the first removable portion  130  can extend from the first row  181  of through openings  180  to a first outer edge  190  of the firewall  112 , while the second removable portion  140  can extend from the second row  182  of through openings  180  to a second outer edge  200  of the firewall  112 , on a side opposite to the first outer edge  190 . Thus, in a method for opening the firewall  112 , the first removable portion  130  can be dismantled to allow access to the ducts and/or electrical cables  111  received in the first row  181  of through openings  180 , in order to allow their individual inspection, maintenance repair and or replacement, while the second removable portion  140  can be dismantled to allow access to the ducts and/or electrical cables  111  received in the second row  182  of through openings  180 , in order to allow their individual inspection, maintenance, repair and or replacement. 
     The stiffener  124  of the fixed portion  120  can extend until the outer edges  190 ,  200  of the firewall  112 , and have at this location fittings  125  allowing the superposition of outer stiffeners  135 ,  145 , also protruding in the thickness direction Z over the adjacent ends of the stiffener  124 . This overlap, which can have a clearance d, for example, of 1 mm in the width direction Y, also allows ensure good sealing of the firewall  112  with the outer edges  190 ,  200  in contact with the walls of the tubular structure  108 . 
     As in the alternative embodiments illustrated schematically in  FIG. 5 , it is also conceivable that the second removable portion  140  extends rather between the two rows  181 , 182  of through openings  180 , and that the fixed portion  120  comprises a segment interposed between the second row  182  and the second outer edge  200  of the firewall  112 . In order to connect them releasably, the first and second removable portions  130  can comprise jaws connected by one or more bolts. To ensure good sealing between the removable portions  130 ,  140  and between the second removable portion  140  and the fixed portion, the second removable portion  140  can overlap an adjacent surface of the fixed portion  120  and the first removable portion  130  overlap an adjacent surface of the second removable portion  140 . 
     In the second embodiment, the first removable portion  130  can be individually dismantled to allow access to the ducts and/or the electrical cables  111  received in the first row  181  of through openings  180 , in order to allow their individual inspection, maintenance, repair and or replacement, while the two removable portions  130 ,  140  can be dismantled to allow access to the ducts and/or the electrical cables  111  receive in the second row  182  of through openings  180 , in order to allow their individual inspection, maintenance, repair and/or replacement. 
     Although the present invention has been described by referring to specific examples, it is clear that different modifications and changes can be applied to these examples without departing from the general scope of the invention as defined by the claims. Consequently, the description and the drawings can be considered in an illustrative, rather than a restrictive sense.