Abstract:
The present disclosure relates to a self-mounted cascade for a thrust reverser of an airplane jet engine nacelle. The cascade includes an upstream portion and an opposite downstream portion, along with respective connection means so that two adjacent cascades are directly connected to one another only in the respective downstream portions by downstream connection means thereof. The downstream portion corresponds to an area extending from a downstream side edge over a length less than or equal to N times the length of the last cavity located along said downstream side edge, where N is less than 3. The present disclosure is of use in the field of airplane jet engine nacelles.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/FR2011/051259 filed on Jun. 1, 2011, which claims the benefit of FR 10/54473, filed on Jun. 8, 2010. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a self-mounted cascade for a thrust reverser of an airplane turbojet engine nacelle. 
     It also relates to a cascade assembly and an airplane turbojet engine nacelle comprising such an assembly. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     An airplane is moved by several turbojet engines each housed in a nacelle also housing a set of related actuating devices connected to its operation and performing various functions when the turbojet engine is running or stopped. These related actuating devices in particular include a mechanical thrust reversal system. 
     As illustrated in  FIG. 1 , a nacelle generally has a tubular structure comprising an air intake  2  upstream of the turbojet engine, a middle structure  3  designed to surround a fan of the turbojet engine, a downstream section  4  housing thrust reverser means (also called thrust reverser) and designed to surround the combustion chamber of the turbojet engine, and generally ends with a jet nozzle  5  whereof the outlet is situated downstream of the turbojet engine. 
     Modern nacelles are designed to house a dual flow turbojet engine capable of generating, via the rotating fan blades, a hot air flow (also called primary flow) coming from the combustion chamber of the turbojet engine, and a cold air flow (secondary flow) that circulates outside the turbojet engine through an annular channel  6 , also called a duct, formed between a fairing  7  of the turbojet engine and an inner wall  8  of the nacelle. The two flows of air are ejected from the turbojet engine through the rear of the nacelle. The two flows of air are ejected from the turbojet engine through the rear of the nacelle. 
     The role of a thrust reverse device is, during landing of an airplane, to improve the braking capacity thereof by reorienting at least part of the thrust generated by the turbojet engine forward. In that phase, the reverser obstructs the cold air flow, and orients that flow toward the front of the nacelle, thereby generating a counter-thrust that is added to the braking of the wheels of the airplane. 
     The means implemented to perform this reorientation of the cold flow vary depending on the type of reverser. However, in all cases, the structure of a reverser comprises moving parts that can be moved between a deployed (or “reverse jet”) position, in which they open a passage in the nacelle designed for the diverted flow on the one hand, and a retracted (or “direct jet”) position, in which they close that passage on the other hand. 
       FIGS. 2 and 3  illustrate a traditional cascade vane thrust reverser  40 , also known as a cascade reverser, in which the reorientation of the air flow is done by cascade vanes  41 , the cowl  42  being slidingly mounted along the axis A of the nacelle so as to expose or cover said vanes  41 . Complementary blocking doors  43 , also called reverser flaps, activated by the sliding of the cowling, generally allow closing of the annular cold air flow (secondary flow) channel  6  downstream of the vanes  41  so as to optimize the reorientation of that air flow. 
     This type of cascade thrust reverser  40  is arranged downstream of the fan case  30  of a dual flow turbojet engine, and its associated fan cowl  31 . This reverser  40  has at least one moving cowl  42  having an outer panel  420  and an inner panel  421  (or inner diaphragm) designed to delimit, in a direct jet position of the turbojet engine ( FIG. 2 ), an outer wall of the annular channel  6  in which the secondary flow flows, the reverser  40  having at least one reverser flap  43  hingedly mounted on the inner wall  421  of the moving cowl  42  and actuated by at least one connecting rod  45  during the movement of the moving cowl  42  in the downstream direction, such that, in a thrust reversal or reverse jet position ( FIG. 3 ), each blocking door  43  has an area extending in the annular channel  6  so as to deflect at least part of the secondary flow outside said annular channel  6 . 
     This thrust reverser  40  has a plurality of cascade vanes  41 , fastened between the front peripheral frame  46  and a stationary rear peripheral frame  47  that generally join the outer panel  420  and the inner panel  421  of the moving cowl  42  between them. During operation, the reorientation of the secondary flow, in the reverse jet position, is done by said cascade vanes  41 , the moving cowl  42  primarily having a sliding function aiming to expose or cover said cascade vanes  41 , the translation of the moving cowl  42  being done along a longitudinal axis substantially parallel to the axis A of the nacelle  1 . A housing  48  is provided in the moving cowl  42  and makes it possible to house the cascade vanes  41  when the thrust reverser  40  is not actuated, i.e. in the direct jet position, as shown in  FIG. 2 . 
     The sliding of the moving cowl  42  between its direct jet and reverse jet positions is ensured by cylinders (not shown) distributed on the periphery of the nacelle. Traditionally, these cylinders are fastened upstream on a stationary part of the nacelle, such as the upstream front support frame  46  of the cascade vanes  41 , and downstream inside the moving cowl  42 , by means of adapted fittings. 
     More specifically, the actuating rods of said cylinders pass through the downstream rear support frame  47  of the cascade vanes  41  to cooperate with the moving cowl  42 . This necessarily means that the upstream rear support frame  47  of the cascade vanes  41  has a certain radial bulk. Furthermore, the vanes  41 , in reverse mode or reverse jet position, undergo major aerodynamic loads that tend to cause the downstream portions of the vanes  41  fastened on the peripheral groove frame  47  to emerge outward. The height (or thickness) of the rear frame  47  is advantageously larger than that of the vanes  41  so as to provide the best possible inertia for the vane assembly  41 . 
     In standard thrust reverser structures  40 , the thickness of the aerodynamic lines is sufficient to have an adapted inertia of the vane assembly  41  and to be able to pass through the rear frame  47  using the cylinder rod to reach the fastener of the moving cowl  42  downstream of the rear frame  47 . To return to the current inertia, the structure of the rear frame  47  is festooned at the opening, increasing the height of the rear frame proportionately. 
     However, in modern nacelles, where efforts are made to reduce aerodynamic losses due to wet surfaces, the lines are increasingly close together, and it is in particular therefore important to be able to reduce the radial thickness of the rear frame, or even to be able to completely eliminate the rear frame. In fact, it is often more possible to house the rear frame having openings in the moving cowl, the total thickness of the cowl no longer being sufficient to house the entire architecture of the thrust reverser in the nacelle. 
     To respond to this problem of eliminating the rear frame in cascade thrust reversers, it is known, in particular from patent applications EP 1 852 595 A2 and EP 1 515 035 A2, to use a self-mounted cascade assembly, also called self-mounted cascades, i.e. an assembly of cascades only fastened to each other and to the front frame, with no rear frame. 
       FIGS. 4 to 6  illustrate one known example of a self-mounted cascade assembly  51 . As illustrated in  FIG. 4 , the thrust reversers  50  with self-mounted cascades  51  have an assembly of several self-mounted cascades  51  that makes it possible to achieve a flexible arrangement of the driving of the reverser layers. The self-mounted cascades  51  are distributed on the periphery of the downstream portion of a peripheral front frame  56  and may form an assembly that may contain up to twelve cascades per half-side of the reverser  50 , such as for example for self-mounted cascades  51  per half-side in the example of  FIG. 4 . 
     The multiplicity of the self-mounted cascades  51  allows very flexible driving of the reverser layers and makes it possible to use a specific blading configuration in several positions, this ultimately making it possible to control the overall cost of producing the reverser function using cascade vanes. 
     As shown in  FIG. 5 , which illustrates a detail of  FIG. 4 , each self-mounted cascade  51  is provided with a plurality of cells and has two opposite openwork front surfaces, in this case an upper front surface  510  situated toward the outside across from the outer panel  420  of the moving cowl  42 , and a lower front surface  511  situated toward the inside across from the inner wall  421  of the moving cowl  42 . 
     As shown in  FIG. 6 , which illustrates an assembly of two self-mounted cascades  51 , each self-mounted cascade  51  has an upstream portion  512  (sometimes called front portion) fastened on the front frame  56  and an opposite downstream portion  513  (sometimes called rear portion) that is free, i.e. that is not fastened to a rear frame. Furthermore, each self-mounted cascade  51  has two opposite side edges extending over the entire width of the self-mounted cascade  51 , i.e. an upstream side edge  514  situated in the upstream portion  512  and a downstream side edge  515  situated in the downstream portion  513 ; the side edges  514 ,  515  of the self-mounted cascades  51  form the circumferential, or peripheral, edges of the cascade assembly  51  situated in the thrust reverser  50 , extending in a bowed manner around the axis A of the nacelle. 
     Each self-mounted cascade  51  also has two opposite transverse edges  516  extending over the entire length of the self-mounted cascade  51 ; the transverse edges  516  of the self-mounted cascades  51  form junction edges between the self-mounted cascades  51  of the cascade assembly situated in the thrust reverser  50 , said transverse edges  516  extending substantially parallel to the axis A of the nacelle. 
     To be assembled to one another, each self-mounted cascade  51  has two strips of material  517 , substantially parallel to the front surfaces  510 ,  511 , positioned on the two transverse edges  516  and extending over substantially the entire length of the self-mounted cascade  51 . In this way, the adjacent strips of material  517  of two adjacent self-mounted cascades  51  overlap one another and are fastened to one another by fastening screws  518 . In this way, in this assembly, the self-mounted cascades  51  are fastened to one another over substantially the entire length thereof. 
     The main drawback of this type of assembly is that it has solid strips of material  517  at successive intervals, between the cascades  51  over substantially the entire length of the cascades  51 , thereby limiting the deflection function of the cold air flow by limiting the surface area of the openwork surfaces. 
     Since the cross-section of the self-mounted cascades  51  should be substantially equal to the section of the annular channel  6 , in other words the cold air duct, it is important for the loss of cross-section due to this connection of the self-mounted cascades  51  to one another to be offset by an increased length of said self-mounted cascades  51 . 
     However, the Applicant has noted in practice that excessively long self-mounted cascades  51  do not efficiently deflect the cold air flow in their downstream portions  513 . In fact, the longer the self-mounted cascade  51 , the less air effectively passes through all of the cells (or blades) of the cascade, with the result that the efficiency of the deflection (and therefore breaking) is reduced during thrust reversal. 
     Thus, the management of the layers of the reversal flow is more delicate to manage with an assembly of several self-mounted cascades  51 ; the flexibility obtained by using several individual cascades assembled to one another is lost with this increased length, and each self-mounted cascade  51  cannot be reused on another peripheral sector of the thrust reverser  50 . Ultimately, the cost of this assembly of self-mounted cascades  51  then becomes higher than that of using individual cascades. 
     SUMMARY 
     The present disclosure provides a self-mounted cascade, and an assembly of such self-mounted cascades, that makes it possible to limit the passage cross-section loss and the length of the self-mounted cascade, in other words to assemble cascade vanes without adding a rear frame and while minimizing the passage cross-section loss so as to minimize the length of the cascades. 
     The present disclosure also provides a self-mounted cascade that makes it possible to assemble approximately a dozen cascades per half-side of the thrust reverser so as to be able to optimize the output direction of the reversal flow, in other words to allow very flexible driving of the reverser layers and thereby make it possible to use a specific blading configuration in several positions, in particular with the aim of limiting the overall cost of the cascade assembly and the reverser function. 
     To that end, it proposes a self-mounted cascade vane for a cascade thrust reverser for an airplane turbojet engine nacelle, said cascade vane being provided with a plurality of cells with two opposite openwork front surfaces, having, on the one hand:
         two opposite side edges extending over the width of the cascade, i.e. an upstream side edge situated in an upstream portion and a downstream side edge situated in a downstream portion;   two opposite transverse edges extending over the length of the cascade, i.e. a first transverse edge and a second transverse edge;       

     and, on the other hand, having:
         upstream fastening means formed on the upstream side edge and designed to fasten the cascade on a stationary structure of the nacelle, such as a front frame structure; and   first and second connecting means formed on the first and second transverse edges, respectively, to connect the cascade to two adjacent cascades situated on the thrust reverser;       

     the cascade being remarkable in that the first and second connecting means, called first and second downstream connecting means, are arranged only on the downstream portion of the cascade, said downstream portion corresponding to an area extending from the downstream side edge over a length smaller than or equal to N times the length of the last cell situated along said downstream side edge, where N is less than 3 and preferably less than or equal to 1. 
     Thus, the present disclosure proposes only connecting the self-mounted cascades to one another directly in their respective downstream portions, in other words over a connecting link not taking up more than three rows of cells, and not over substantially the entire length of the cascades, as already known from the state of the art. Of course, the self-mounted cascades are connected to one another in their upstream portions via the stationary structure of the nacelle. 
     In this way, a cascade assembly according to the invention will have, at the interface between the cascades, connecting means between the cascades only in the downstream portion, over at most three rows of cells, thereby limiting the negative impact of those connecting means on the deflection of the secondary flow. Each cascade therefore does not have any connecting means with one or more adjacent cascades in the upstream portion thereof and in the central portion thereof (situated between the upstream portion and the downstream portion which extends over the entire length of the cascade decreased by at most three rows of cells), such that the cascade assembly will generally have an openwork and continuous surface in the upstream portion and central portion thereof, with no solid surface. Only the downstream portion of the assembly will have a solid surface, due to the presence of the downstream connecting means between the cascades. In this way, this cascade makes it possible to minimize the passage cross-section loss while making it possible to minimize the length of the cascade. 
     According to the present disclosure, the downstream connecting means are positioned only in the downstream portion of the cascade and therefore do not extend into the central portion and upstream portion of the cascade. 
     The downstream portion of the cascade corresponds to an area extending along the downstream side edge of the cascade and extending at most at a distance from said downstream side edge smaller than or equal to N times the length of the last cell situated along said downstream side edge, where N is less than 3 and preferably less than or equal to 1. In other words, the first and second downstream connecting means extend lengthwise, from the downstream side edge, over at most the last three rows of cells situated on the side of the downstream side edge, and preferably over at most the last row of cells. 
     In this way, the downstream connecting means do not extend further than the last three rows of cells situated in the downstream portion of the cascade, or preferably no further than the last row of cells situated in the downstream portion of the cascade, thereby having a low impact on the overall surface area of openwork surfaces of the assembly and therefore the deflection function. It is also possible to consider the downstream connecting means extending lengthwise (along the length over the cascade) over less than one cell, in other words extending lengthwise over only a portion of the last cell, and not the entirety thereof. 
     Within the meaning of the present disclosure, the length corresponds to a dimension considered in the longitudinal direction of the cascade, said longitudinal direction being parallel to the axis A of the nacelle situated on the thrust reverser and extending from the upstream side edge as far as the downstream side edge of the cascade. 
     Within the meaning of the present disclosure, the downstream side edge of the cascade extends over the width of the cascade, in the downstream portion, and partially defines the downstream circumferential or peripheral edge of the cascade assembly extending in a bowed manner around the axis of the nacelle, situated in the thrust reverser; this downstream circumferential or peripheral edge of the cascade assembly being free and not supported by a rear frame, since the cascades are of the self-mounted type. 
     Likewise, within the meaning of the present disclosure, the upstream side edge of the cascade extends over the width of the cascade, in the upstream portion of the side of the upstream stationary support structure of the cascade, and partially defines the upstream circumferential or peripheral edge of the cascade assembly extending in a bowed manner around the axis of the nacelle, situated in the thrust reverser. 
     Within the meaning of the present disclosure, the width corresponds to a dimension considered in the lateral direction of the cascade, this lateral direction being substantially normal to the longitudinal direction of the cascade and the axis A of the nacelle situated on the thrust reverser and extending between the two transverse edges of the upstream side edge as far as the downstream side edge of the cascade. 
     The connecting means may assume the form of connecting tabs that extend in the downstream portion of the cascade, and more specifically in the downstream corners of the cascade, so as to overlap the connecting pads of the adjacent cascades. 
     Different alternatives may potentially be considered alone or in combination: tabs superimposed like tiles, situated at least partially overlapping the last downstream cell of the cascade and/or situated in the extension of the downstream edge of the cascade. 
     According to a first feature, at least one of the first and second downstream connecting means is positioned partially withdrawn from the concerned transverse edge. 
     This feature is advantageous so that the downstream connection between two cascades is done withdrawn from the junction plane between the two adjacent transverse edges of the two cascades, to ultimately obtain two cascades joined edge to edge with said two substantially joined transverse edges, so that the cells of one cascade are extended with no discontinuity by the cells of the other cascade on either side of said junction plane between the two transverse edges. 
     Advantageously, one of the first and second downstream connecting means is positioned partially withdrawn relative to the concerned transverse edge toward the inside of the cascade, and the other of the first and second downstream connecting means is positioned partially withdrawn relative to the concerned transverse edge toward the outside of the cascade. 
     In this way, a first downstream connecting means of a cascade cooperates with a second downstream connecting means of another cascade, and such cooperation is done withdrawn from the junction plane between the two adjacent transverse edges of the two cascades, since the outer (or protruding) withdrawn connecting means may cooperate with the other downstream connecting means that is inwardly withdrawn relative thereto. 
     In one advantageous form, one of the first and second downstream connecting means has at least one passage opening for a fastening member situated withdrawn relative to the concerned transverse edge toward the inside of the cascade, while the other of the first and second downstream connecting means has at least one passage opening for a fastening member situated withdrawn relative to the concerned transverse edge toward the outside of the cascade. 
     In this way, a first downstream connecting means of one cascade cooperates with a second downstream connecting means of another cascade, and this cooperation is done withdrawn from the junction plane between the two adjacent transverse edges of the two cascades, since the inner withdrawn opening may coincide with the other inner withdrawn opening for the passage of a fastening member in those two openings. 
     According to one possibility the present disclosure, the first downstream connecting means has at least one first connecting tab and the second downstream connecting means has at least one second connecting tab. 
     In this way, the connection between two adjacent cascades will be done by overlapping and cooperation of at least one first connecting tab of a cascade with at least one second connecting tab of the other cascade. 
     In this way, a cascade may be assembled with two adjacent cascades using the first and second connecting tabs. Likewise, a peripheral cascade may be assembled to a structural element of the thrust reverser framing the cascade assembly, for example such as a beam situated in the upper portion of the nacelle (at 12 o&#39;clock), and which would have a complementary connecting tab for receiving one of the connecting tabs of the peripheral cascade adjacent to that structural element. 
     In a first form, the first downstream connecting means has at least one first front connecting tab and the second downstream connecting means has at least one second front connecting tab, each front connecting tab extending substantially parallel to the openwork front surfaces of the cascade. 
     In this way, said first front connecting tab is designed to overlap a second front connecting tab of an adjacent cascade so as to make it possible to connect the two cascades. 
     Each front connecting tab is preferably provided with at least one passage opening for a fastening member, and potentially with at least one passage opening for a centering member. 
     According to one feature, the first front connecting tab is arranged in a first downstream corner of the cascade and is situated at least partially overlapping a cell situated in said first downstream corner, and the second front connecting tab is arranged in a second downstream corner of the cascade, opposite the first downstream corner, and is situated at least partially overlapping a cell situated in said second downstream corner. 
     Within the meaning of the present disclosure, “downstream corner of the cascade” refers to the protruding corner space formed in the downstream portion by two edges of the cascade, in this case the downstream side edge and one of the two transverse edges of the cascade. 
     Within the meaning of the present disclosure, as a reminder, “transverse edges of the cascade” refers to the opposite edges that extend over the length of the cascade and that form the junction edges between the cascades of the cascade assembly situated in the thrust reverser, said transverse edges extending substantially parallel to the axis of the nacelle. 
     In this first form, the present disclosure also relates to the following features:
         the second front connecting tab is offset relative to the first front connecting tab, in a direction substantially normal to the openwork front surfaces of the cascade, so as to overlap a first front connecting tab of an identical adjacent cascade, and in that case the cascade assembly may have only identical cascades according to the invention; or alternatively   the second front connecting tab is substantially coplanar with the first front connecting tab, so as to overlap a first front connecting tab of an adjacent cascade, and in that case the cascade assembly has first cascades connected to second cascades alternating between first and second cascades.       

     According to one possibility of the present disclosure, the first front connecting tab is level with one of the two openwork front surfaces of the cascade, preferably the upper front surface of the cascade designed to be situated toward the outside situated on the thrust reverser, while the second front connecting tab is withdrawn relative to said front surface of the cascade in a direction substantially normal to the openwork front surfaces of the cascade. 
     According to another possibility of the invention, the first front support tab and the second front support tab are withdrawn relative to the two openwork front surfaces of the cascade in a direction substantially normal to the openwork front surfaces of the cascade. 
     In a second form (which may be considered alone or in combination with the first embodiment), the first downstream connecting means has at least one first side connecting tab and the second downstream connecting means has at least one second side connecting tab, each side connecting tab extending substantially parallel to the downstream side edge. 
     Each side connecting tab is preferably provided with at least one passage opening for a fastening member, and potentially with at least one passage opening for a centering member. 
     In this way, said first side connecting tab is designed to overlap a second side connecting tab of an adjacent cascade so as to allow the connection between the two cascades. 
     According to a first possibility, the second side connecting tab is offset relative to the first side connecting tab, in a direction substantially normal to the downstream side edge of the cascade, so as to overlap a first side connecting tab of a similar adjacent cascade. 
     According to a second possibility, the second side connecting tab is coplanar with the first side connecting tab, so as to overlap a first side connecting tab of a separate adjacent cascade. 
     According to another feature, the first side connecting tab and/or the second side connecting tab has:
         an upper wall substantially parallel to and coplanar with an upper front surface of the cascade, so as to bear against an upper edge of the complementary front tab with which said tab will cooperate to provide the connection; and/or   a lower wall substantially parallel to and coplanar with a lower front surface of the cascade, so as to bear against a lower edge of the complementary front tab with which said tab will cooperate to provide the connection.       

     The present disclosure also relates to a cascade assembly for a cascade thrust reverser, having at least one first, second, and third successive cascades according to the invention, in which:
         the first cascade is connected to the second cascade by complementary cooperation between the first downstream connecting means formed on the first transverse edge of the first cascade and the second downstream connecting means formed on the second transverse edge of the second cascade, the first transverse edge of the first cascade being substantially joined with the second transverse edge of the second cascade outside the area where said downstream connecting means are formed; and   the second cascade is connected to the third cascade by complementary cooperation between the first downstream connecting means formed on the first transverse edge of the second cascade and the second downstream connecting means formed on the second transverse edge of the third cascade, the first transverse edge of the second cascade being substantially joined to the second transverse edge of the third cascade outside the area where said downstream connecting means are formed.       

     The present disclosure also relates to an airplane turbojet engine nacelle having a cascade thrust reverser equipped with at least one assembly according to the invention, where the cascades of the assembly are fastened in the upstream portions thereof, with their respective upstream fastening means, on a stationary structure of the nacelle such as a front frame structure, and where the cascades of the assembly are directly connected to one another only in their respective downstream portions by their downstream connecting means. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings. 
       Other features and advantages of the present disclosure will appear upon reading the following detailed description of three non-limiting example embodiments, done in reference to the appended figures, in which: 
         FIG. 1 , already discussed, is a longitudinal cross-sectional view of a already discussed, is a longitudinal cross-sectional view of an airplane turbojet engine nacelle; 
         FIGS. 2 and 3 , already discussed, are partial longitudinal cross-sectional diagrammatic views of a traditional cascade thrust reverser, in the reverse jet and direct jet positions, respectively; 
         FIG. 4 , already discussed, is a diagrammatic transverse cross-sectional view of a known thrust reverser equipped with a self-mounted cascade assembly; 
         FIG. 5 , already discussed, is an enlarged view of zone V of  FIG. 4 ; 
         FIG. 6 , already discussed, is a diagrammatic perspective view of two self-mounted cascades equipping the thrust reverser illustrated in  FIG. 4 ; 
         FIG. 7  is a diagrammatic perspective view of two cascades according to a first form and assembled to one another; 
         FIG. 8  is a diagrammatic and partial perspective view of two cascades according to the first form before being assembled to one another; 
         FIG. 9 a    is a diagrammatic cross-sectional view along line AA′ of the two cascades of  FIG. 8  once they are assembled to one another; 
         FIG. 9 b    is a diagrammatic cross-sectional view, identical to that of  FIG. 9 a   , of two assembled cascades according to the first form; 
         FIG. 9 c    is a diagrammatic cross-sectional view, identical to that of  FIG. 9 a   , of two assembled cascades according to the first form; 
         FIG. 10 a    is a partial diagrammatic perspective view of two cascades according to a second embodiment before they are assembled to one another; 
         FIG. 10 b    is a partial diagrammatic perspective view of the two cascades of  FIG. 10 a    once they are assembled to one another; 
         FIG. 11  is a partial diagrammatic perspective view of two cascades according to the second embodiment and assembled to one another; and 
         FIG. 12  is a diagrammatic side view of two assembled cascades according to a third embodiment resulting from the combination of the first and second embodiments. 
     
    
    
     In all of these figures, identical or similar references designate identical or similar members or sets of members. 
     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. 
       FIGS. 7 to 9  illustrate assemblies of self-mounted cascades  61  according to a first embodiment of the invention. 
     Each cascade  61  is provided with a plurality of cells and has two opposite openwork front surfaces, in this case an upper front surface  610  and a lower front surface  611  visible in  FIGS. 9 a    to  9   c.    
     Each cascade  61  has an upstream portion  612  designed to be fastened on a front frame (not shown) and a free opposite downstream portion  613 , i.e. not fastened to a rear frame. 
     Furthermore, each cascade  61  has two opposite side edges extending over the entire width LA of the cascade  61 , i.e. an upstream side edge  614  situated in the upstream portion  612  and a downstream side edge  615  situated in the downstream portion  613 ; the side edges  614 ,  615  of the cascades  61  forming the circumferential, or peripheral, edges of the cascade assembly  61  situated in the thrust reverser, and extending in a bowed manner around the axis of the nacelle. 
     To fasten the upstream portion  612  of the cascade  61  on the front frame, said upstream portion  612  has a fastening wall  632  on the front frame, said fastening wall  632  extending parallel to the front surfaces  610 ,  611  protruding from the upstream side edge  614 , along the first row of cells. This fastening wall  632  thus forms a cornice that will bear against the front frame so as to be able to be fastened thereon. 
     The downstream portion  613  of the cascade  61  corresponds to an area extending along the downstream side edge  615  of the cascade  61  and extending at most at a distance from said downstream side edge  615  smaller than the length of the last three rows of cells (in this case, smaller than the length of the last row of cells) situated along said downstream side edge  615 . 
     Each cascade  61  also has two opposite transverse edges  616  extending over the entire length LO of the cascade  61 ; the transverse edges  616  of the cascades  61  form a junction edge between the cascade  61  of the cascade assembly situated in the thrust reverser, said transverse edges  616  extending substantially parallel to the axis of the nacelle. 
     To assemble these two cascades  61 , one of the cascades  61  (that on the left in  FIG. 7  or on the right in  FIGS. 8 and 9 ) has a first front connecting tab  617  positioned in the downstream portion  613 , provided with a passage opening for a fastening member and potentially with a passage opening for a centering member, and which extends substantially coplanar to the openwork front surfaces  610 ,  611  of the cascade  61 . This first front connecting tab  617  does not extend lengthwise any further than the last row cells situated in the downstream portion  613  of the cascade  61 . 
     More specifically, said first front connecting tab  617  is positioned in a first downstream corner  618  of the cascade  61 , in the downstream portion  613  of the cascade  61 , and is situated at least partially overlapping the last cell  619  situated in said first downstream corner  618 . It should be noted that the opposite overlap may also be applied. 
     To assemble these two cascades  61 , the other cascade  61  (that on the right in  FIG. 7  or the left to  FIGS. 8 and 9 ) has a second front connecting tab  620  positioned in the downstream portion  613 , provided with a passage opening for a fastening member and potentially with the passage opening for a centering member, which extends substantially coplanar to the openwork front surfaces  610 ,  611  of the cascade  61 . The second front connecting tab  620  does not extend lengthwise any further than the last row of cells situated in the downstream portion  613  of the cascade  61 . 
     More specifically, this second front connecting tab  620  is positioned in a second downstream corner  621  of the cascade  61 , opposite the first downstream corner  618  of that same cascade  61 , and is situated at least partially overlapping the last cell  622  situated in said second downstream corner  621 . 
     The second front connecting tab  620  of the cascade  61  on the left is offset relative to the first front connecting tab  617  of the cascade  61  on the right, in a direction substantially normal to the openwork front surfaces  610 ,  611  of the cascades  61 , so as to overlap one another, so as to have the openings formed in said front connecting tabs  617 ,  620  coincide to engage the fastening and centering members that will finalize the assembly between the two cascades  61 . The assembly is therefore done by positioning the front connecting tabs  617 ,  620  one over the other. 
     In  FIG. 7 , one can see that the openings of the first front connecting tab  617  are situated withdrawn relative to the concerned transverse edge  616  toward the outside of the cascade, while the openings of the second front connecting tab  620  are situated withdrawn relative to the concerned transverse edge  616  toward the inside of the cascade  61 , to allow those two transverse edges  616  to be substantially joined. The same is true in  FIG. 8 , with openings withdrawn relative to the concerned transverse edges. 
     The front connecting tabs  617 ,  620  exceed the transverse edges  616  to allow the adjacent transverse edges  616  of two adjacent cascades  61  to be positioned substantially one against the other, with assembly clearance. More specifically, the front connecting tabs  617 ,  620  overhang the concerned transverse edges by approximately half their width (dimension considered in the direction of the width LA of the cascade  61 ). In other words, it will be noted that:
         the first front connecting tab  617  has a withdrawn portion relative to the concerned transverse edge  616  toward the inside of the cascade  61  (in this case, the portion situated in the last corner cell  619 ), and a portion withdrawn relative to the concerned transverse edge  616  toward the outside of the cascade  61  (in this case, its free end, which exceeds or protrudes outside the transverse edge  616 ); and   the second front connecting tab  620  has a withdrawn portion relative to the concerned transverse edge  616  toward the inside of the cascade  61  (in this case, the portion situated in the last corner cell  622 ), and a withdrawn portion relative to the concerned transverse edge  616  toward the outside of the cascade  61  (in this case, its free edge, which exceeds or protrudes outside the transverse edge  616 ).       

     The or each cascade  61  (on the left in  FIG. 7 ) may have both a first front connecting tab  617  and a second front connecting tab  620  of the same type as those described above so as to make it possible to assemble the cascade  61  with two identical or similar adjacent cascades. Within a same cascade  61 , the second front connecting tab  620  of the cascade  61  may be is offset relative to the first front connecting tab  617  of that same cascade  61 , in a direction substantially normal to the openwork front surfaces  610 ,  611  of the cascade  61 , so that said second front connecting tab  620  can overlap a first front connecting tab  617  of an identical adjacent cascade  61 . 
     In one alternative not shown, within a same cascade, the second front connecting tab is substantially coplanar with the first front connecting tab, such that it is necessary for assembly to use different first and second cascades (at least in the localization of the front connecting tabs), alternating between first and second cascades. 
     In the examples of  FIGS. 7, 8 and 9   a , the first front connecting tab  617  is level with the upper front surface  610  of the cascade  61 , while the second front connecting tab  620  is withdrawn relative to the upper front surface  610  of the cascade  61 . 
     In the example of  FIG. 9 b   , the first front connecting tab  617  and the second front connecting tab  620  are withdrawn relative to the two openwork front surfaces  610 ,  611  of the cascade  61 . In this way, depending on the desired load distribution on the cascades, the front connecting tabs  617 ,  620  may be positioned differently in the thickness of the cascade. 
     In the example of  FIG. 9 c   , the first front connecting tab  617  and the second front connecting tab  620  are stair-stepped and each have, on the one hand, a base withdrawn from one of the front surfaces  610 ,  611  of the concerned cascade  61  and, on the other hand, a free end that is level with the other front surface  610 ,  611  of the adjacent cascade  61 . 
       FIGS. 10 and 11  illustrate self-mounted cascade assemblies  61  according to a second embodiment of the invention. These cascades  61  are of the same type as those described above for the first embodiment, with the exception of the downstream connecting means used to connect the downstream portions  613  of two adjacent cascades  61  to one another. 
     To assemble two cascades  61  to one another, one of the cascades  61  (on the left in  FIGS. 10 and 11 ) has a first side connecting tab  623  positioned in the downstream portion  613 , provided with passage openings for a fastening member and possibly with a passage opening for a center member, and which extends substantially orthogonally to the openwork front surfaces  610 ,  611  of the cascade  61 . This first side connecting tab  623  extends substantially parallel to the downstream side edge  615  of the cascade  61 , coplanar to that downstream side edge  615 . 
     More specifically, this first side connecting tab  623  is positioned in the first downstream corner  618  of the cascade  61  and is situated at least partially overlapping the last cell  619  situated at first downstream corner  618 . 
     To assemble these two cascades  61 , the other cascade  61  (on the right in  FIGS. 10 and 11 ) has a second side connecting tab  624  positioned in the downstream portion  613 , provided with a passage opening for a fastening member and potentially with a passage opening for a centering member, and which extends substantially orthogonally to the openwork front surfaces  610 ,  611  of the cascade  61 . This second side connecting tab  624  extends substantially parallel to the downstream side edge  615  of the cascade  61 , in an offset manner relative to said downstream side edge  615 . 
     More specifically, this second side connecting tab  624  is positioned in the second downstream corner  621  of the cascade  61 , opposite the first downstream corner  618  of that same cascade  61 , and is situated at least partially overlapping the last cell  622  situated in that second downstream corner  621 . 
     The second side connecting tab  624  of the right cascade  61  is offset relative to the first side connecting tab  623  of the cascade  61  on the left, in a direction substantially normal to the downstream side edges  615  of the cascades  61 , so as to overlap one another, so as to have the openings formed in said side connecting tabs  623 ,  624  coincide in order to engage the fastening and centering members that will finalize the assembly between the two cascades  61 . The assembly is therefore done by positioning the side connecting tabs  623 ,  624  one on the other. 
     It will be noted that the two openings of the first side connecting tab  623  are situated withdrawn relative to the concerned transverse edge  616  respectively toward the inside and the outside of the cascade  61 , and that the openings of the second side connecting tab  624  are situated withdrawn relative to the concerned transverse edge  616  toward the outside and toward the inside of the cascade  61 , respectively, to allow those two transverse edges  616  to be substantially joined. 
     The side connecting tabs  623 ,  624  exceed the transverse edges  616 , to allow the adjacent transverse edges  616  of two adjacent cascades  61  to be substantially one against the other, with assembly clearance. More specifically, the side connecting tabs  623 ,  624  overhang the concerned transverse edges  616  by approximately half their width (dimension considered in the direction of the width LA of the cascade  61 ). In other words, it will be noted that:
         the first side connecting tab  623  has a withdrawn portion relative to the concerned transverse edge  616  toward the inside of the cascade  61  (in this case, the portion situated in the last corner cell  619 ), and a portion withdrawn relative to the concerned transverse edge  616  toward the outside of the cascade  61  (in this case, its free end that exceeds or protrudes outside the transverse edge  616 ); and   the second side connecting tab  624  has a withdrawn portion relative to the concerned transverse edge  616  toward the inside of the cascade  61  (in this case, the portion situated in the last corner cell  622 ), and a portion withdrawn relative to the concerned transverse edge  616  toward the outside of the cascade  61  (in this case, its free end that exceeds or protrudes outside the transverse edge  616 ).       

     The or each cascade  61  may have both a first side connecting tab  623  and a second side connecting tab  624  of the same type as those described above so as to make it possible to assemble the cascade  61  with two identical or similar adjacent cascades. Within a same cascade  61 , the second side connecting tab  624  of the cascade  61  may be is offset relative to the downstream side edge  615 , while the first side connecting tab  623  of that same cascade  61  is substantially coplanar to said downstream side edge  615 , such that said second side connecting tab  624  can overlap a first side connecting tab  623  of an identical adjacent cascades  61 . 
     In an alternative that is not shown, within a same cascade, the first side connecting tab and the second side connecting tab are both coplanar, or then both offset, relative to the downstream side edge, such that it is necessary, for assembly, to use different first and second cascades (at least in the localization of the side connecting tabs), alternating between first and second cascades. 
     In an improvement illustrated in  FIG. 11 , the second side connecting tab  624  has an upper wall  625  that is substantially parallel to or coplanar with the upper front wall  610  of the cascade  61 , so as to bear against the upper edge of the first side connecting tab  623  of the adjacent cascade  61 , thereby strengthening the connection between the two cascades  61 . Alternatively or complementarily, the second side connecting tab  624  has a lower wall (not shown) substantially parallel to or coplanar with the lower front surface  611  of the cascade  61 , so as to bear against the lower edge of the first side connecting tab  623  of the adjacent cascade  61 . 
     In one alternative not shown, the first side connecting tab has an upper wall and/or a lower wall substantially parallel to and coplanar with the upper and lower front surfaces of the cascade, respectively, so as to bear against the upper and lower edges, respectively, of the second side connecting tab. 
       FIG. 12  shows a self-mounted cascade assembly  61  according to a third embodiment of the invention resulting from the combination of the first and second embodiments. In this third embodiment, the cascade  61  has both front connecting tabs  617 ,  620  and side connecting tabs  623 ,  624  to provide the connection between two adjacent cascades  61 ; these connecting tabs  617 ,  620 ,  623 ,  624  are in accordance with the preceding description. 
     Of course, the example forms described above are in no way limiting, and other improvements and details may be added to the cascade according to the present disclosure, without going beyond the scope of the invention, where other forms of downstream connecting means and/or connecting tabs may for example be used.