Turbofan testing machine including a turbofan thrust measuring scale

Abstract

Turbofan testing machine comprising a turbofan thrust measuring scale One aspect of the invention relates to a fixed part (30) of a turbofan tested on a testing machine (2), comprising: A primary part (300) A secondary part (302) A primary flow duct (308), A hub (310) comprising: a cylindrical body (3100) fixed to a thrust measuring scale (24) of the testing machine, a hub arm (3102) extending from the cylindrical body (3100) and passing through the duct (308), an isolation baffle (312) of the hub arm located in the duct (308), placed between the cylindrical body (3100) and the secondary inner casing (302i), the isolation baffle surrounding the hub arm (3102) and being fixed to a fixed fairing (20) of the testing machine (2). Figure to be published with the abstract: Figure 3.

Description

Title of the invention: Turbofan testing machine comprising a turbofan thrust measuring scale TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of testing machines for aircraft turbofans and more precisely that of turbofan thrust measuring scales.

[0002] The present invention relates to a fixed turbofan part to be tested, a mounting method and an assembly comprising a testing machine and the fixed turbofan part. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Conventionally, a test machine is an installation in which engines and in particular turbojets are tested in operation, in particular during the development phase of the latter.

[0004] For example, a test machine can be used to determine the capacity of a fan of a dual-flow turbojet engine to produce counter-thrust.

[0005] [Fig.l] is a schematic representation of an axial section of an assembly 1 comprising a test machine 2 and a turbofan assembly 3 (also called turbofan assembly 3) tested on the test machine 2.

[0006] In particular, the testing machine 2 comprises a fixed fairing 20, a first thrust measuring scale 22 and a second thrust measuring scale 24.

[0007] The turbofan assembly 3 comprises a blower 32, also called a fan, mobile in rotation along the X axis, a turbofan shaft 31 and a fixed part 30 called fixed part 30 of turbofan in the suite.

[0008] The turbofan assembly 3 is mounted on the test machine 2.

[0009] In particular, the rotating blower 32 delivers an annular air flow having the following characteristics: axis of revolution the X axis, with a central annular part, called primary flow Fl, to supply air to parts of the engine such as a low pressure compressor - not shown in [Fig.l] - and an outer annular part, called secondary flow F2, which is ejected providing a significant fraction of the thrust.

[0010] The fixed part 30 of the turbofan comprises in particular a primary part 300, a secondary part 302, a nacelle 304 and a fixed internal structure 306 also called an IFS cowl (from the English "inner fixed structure").

[0011] The primary part 300 comprises a plurality of blades 301 also called primary flow fixed vanes or IGV (“Inlet Guide Vane”) having the role of straightening the primary flow F1 in the axis of the engine.

[0012] Furthermore, the primary portion 300 comprises a primary inner casing 300i and a primary outer casing 300e between which the plurality of blades included in the primary portion 300 extend axially.

[0013] The secondary part 302 comprises a plurality of blades 303 called secondary fixed flow vanes or OGV (“Outlet Guide Vane”) whose role is to straighten the secondary flow F2 in the axis of the engine.

[0014] In particular, the fixed internal structure 306 extends axially, along the X axis, from the secondary part 302. The fixed internal structure 306 comprises an external casing 306e which corresponds to a surface of revolution of the X axis.

[0015] The secondary part 302 comprises a secondary inner casing 302i, extending from the primary outer casing 300e, and a secondary outer casing 302e between which the plurality of blades included in the secondary part 302 extend axially.

[0016] The primary inner casing 300i and the primary outer casing 300e together form a first portion of a primary duct 308 of the primary portion 300. The primary inner casing 300i and the secondary inner casing 302i together form a second portion of the primary annular flow duct 308 extending from the first portion. In particular, the primary flow duct 308 forms a primary flow channel FL

[0017] Furthermore, the fixed part 30 of the turbofan comprises a hub 310, visible in [Fig.2], the hub 310 comprising a cylindrical body 3100, having the axis of revolution as the X axis, and a plurality of hub arms 3102 shown schematically, (equi)distributed around the cylindrical body 3100.

[0018] Each hub arm 3102 extends radially from the cylindrical body to an external fixing ring 3104, visible in [Fig.2], fixed to the secondary internal casing 302i.

[0019] In particular, each hub arm 3102 comprises a portion passing through the primary flow conduit 308.

[0020] With reference to the first balance 22, the latter is rotatable relative to the fixed fairing 2 and comprises a first part, not visible, mounted on the fan 32 and a second part, not visible, mounted on the turbofan shaft 31, so as to measure the forces applied to the fan.

[0021] The second scale 24 is fixed and comprises a part fixed to the fixed fairing 20, and a measuring part fixed to the hub 310.

[0022] Thus, the plurality of arms of the hub makes it possible to connect the measuring part of the second scale 24 to the assembly formed by the nacelle 304, the primary part 300, the secondary part 302 and the fixed internal structure 306.

[0023] When the primary flow Fl passes through the primary duct 308, the second balance 24 aims to measure only the aerodynamic forces applied to the nacelle 304, the primary part 300, secondary part 302 and fixed internal structure 306.

[0024] However, it has been found that there are measurement errors by the fixed scale.

[0025] The invention remedies this situation. Summary of the invention

[0026] The presence of the plurality of arms of the hub interferes with the primary flow and alters the measurement of the aerodynamic forces by the first balance. Thus, measurement errors related to the presence of the plurality of arms of the hub interfere with the primary flow have appeared.

[0027] The invention makes it possible to address this problem by isolating the aerodynamic forces applied to the plurality of hub arms from the forces applied to the nacelle, the primary part, the secondary part and the fixed internal structure.

[0028] The invention provides a solution to the problems mentioned above, by making it possible to integrate an isolation deflector on each hub arm and to fix each isolation deflector on the fixed fairing not weighed by the scale, the isolation deflectors making it possible to isolate the aerodynamic forces applied to the arms and to transmit them to the fixed fairing of a testing machine.

[0029] One aspect of the invention relates to a fixed part of a turbofan adapted to be tested on a test machine, comprising: • A primary part comprising a primary internal casing, • A secondary part comprising a secondary internal casing forming a primary flow duct with the primary internal casing, the primary flow duct defining a primary flow channel volume, • A hub comprising: • a cylindrical body to be attached to a scale of the testing machine and; • a hub arm extending radially from the cylindrical body to an outer attachment end secured to the secondary inner casing, the hub arm comprising a portion passing through the primary flow duct, • A hub arm isolation baffle located in the primary flow duct, movably interposed between the cylindrical body and the secondary internal casing, the isolation baffle comprising: • a fixing portion comprising a trailing edge of the deflector, suitable for fixing the deflector to a fixed fairing of the testing machine.

[0030] By "turbofan" we mean a double-flow turbojet.

[0031] Thanks to the invention, the aerodynamic forces applied by the primary flow to the plurality of arms of the hub are transmitted to the fairing via the isolation deflectors and no to the measuring part of the thrust measuring scale, the fixed fairings not being connected to the measuring part of the thrust measuring scale. Thus, the scale does not measure the aerodynamic forces applied to all elements of the fixed part of the turbofan except the hub arms.

[0032] In addition to the characteristics which have just been mentioned in the preceding paragraph, the fixed part according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations.

[0033] In one embodiment, the isolation deflector comprises an upstream portion comprising a leading edge of the isolation deflector, a lower surface wall and an upper surface wall each extending from the upstream portion to the attachment portion, the lower surface wall, the upper surface wall, the attachment portion and the upstream portion together defining an opening housing the through portion of the hub arm.

[0034] In one embodiment, the deflector is formed from: • A lower surface shell comprising the lower surface wall, a first portion of the fixing part and a first portion of the upstream part, • An extrados shell assembled with the intrados shell forming the deflector, comprising the extrados wall, and a second portion of the fixing part and a second portion of the upstream part.

[0035] In one embodiment, the isolation baffle comprises: • a first assembly hole passing through the intrados and extrados shell at the level of the fixing part and a first assembly pin in the first assembly hole, fixing the intrados shell to the extrados shell, a second assembly hole passing through the intrados and extrados shell at the level of the upstream part and a second assembly pin inserted in the second assembly hole, fixing the intrados shell to the extrados shell.

[0036] In one embodiment, each isolation baffle comprises a guide pin in the fixing portion, for being inserted into a groove in the fixed fairing of the testing machine.

[0037] In one embodiment, the fixed part according to the invention comprises a nacelle, and the secondary part comprises a secondary external casing fixed to the nacelle.

[0038] In one embodiment, the fixed portion comprises a fixed internal structure extending from the secondary portion.

[0039] Another aspect of the invention relates to a method, implemented by the fixed part of the turbomachine according to the invention, of mounting the isolation deflector on the hub arm, the method comprising: • Assembly of the intrados shell and the intrados shell around the hub arm, • Insertion of: • A first assembly pin in the first assembly hole included in the fixing part, • A second assembly pin in the second assembly hole included in the upstream part, to fix the intrados hull to the extrados hull.

[0040] Another aspect of the invention relates to an assembly comprising the fixed part of the turbofan according to the invention (with or without one or more of the different characteristics described above), and the fixed fairing, the fixing part being fixed to the fixed fairing.

[0041] According to one example, the assembly further comprises the test machine further comprising fixed fairing: • A thrust measuring scale for the forces applied to the fixed part of the turbofan, the thrust measuring scale being fixed to the fixed fairing and comprising a measuring part mounted on the hub of the fixed part of the turbofan and the fixed fairing. • Fixing means, inserted into the fixing hole of the isolation deflector to the fixed fairing.

[0042] In addition to the characteristics which have just been mentioned in the preceding paragraph, the assembly according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations.

[0043] In one embodiment, the fixing means comprises a screw.

[0044] In one embodiment, the fixed fairing comprises an outer casing and a casing internally forming together an extension of the primary flow channel.

[0045] In one embodiment, the isolation baffle is attached to one end of the outer casing of the fixed fairing.

[0046] In one embodiment, the turbofan assembly comprises a fan and a turbofan shaft.

[0047] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0048] Other advantages and characteristics of the invention will appear on reading the description which follows, illustrated by the figures in which:

[0049] [Fig.l] is an axial sectional view of an assembly comprising a test machine, a fixed turbofan part and a turbofan fan, according to the state of the art;

[0050] [Fig.2] is a front view of the hub of the fixed part of the turbofan of [Fig.l];

[0051] [Fig.3] is an axial sectional view of an assembly comprising a test machine, a fixed turbofan part and a turbofan fan, according to the invention;

[0052] [Fig.4] is a partial perspective view of a portion of the fixed fairing of the testing machine, on which an isolation baffle is fixed, and of the hub comprising an arm surrounded by the baffle;

[0053] [Fig.5] represents the insertion according to a partial perspective view of the deflector in the fixed fairing of the testing machine;

[0054] [Fig.6] is a perspective view of the hub including isolation baffles on each of its arms;

[0055] [Fig.7] is a perspective view of the assembly of an extrados shell and an intrados shell around an arm of the hub;

[0056] [Fig.8] represents the attachment according to a perspective view of the extrados shell to the intrados shell to obtain a deflector of the arm. DETAILED DESCRIPTION

[0057] An exemplary embodiment of an assembly comprising a test machine, and an assembly of a turbofan comprising a fixed part according to the invention is described in detail below, with reference to the appended drawings. This example illustrates the characteristics and advantages of the invention.

[0058] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0059] In the description, the terms "internal" and "external" are defined relative to the X axis, for example the term "internal casing" designates the casing closest to the X axis of rotation, as opposed to the term "external casing" which designates the casing furthest from the X axis.

[0060] [Fig. 3] represents an assembly 1' comprising a test machine 2' and a turbofan assembly 3' according to the invention.

[0061] The test machine 2' is identical to the test machine 2 shown in [Fig.l] of the prior art except that it further comprises fixing means explained below, on the fixed fairing 20. In an identical manner, it further comprises a first thrust measuring scale 22 and a second thrust measuring scale 24.

[0062] The turbofan assembly 3' is identical to the turbofan assembly 3 of [Fig.l] except with regard to the fixed part 30 according to the invention also called fixed turbofan part 30 in the following.

[0063] The turbofan assembly 3' is mounted on the test machine 2'.

[0064] In particular, the rotating fan 32 delivers the primary flow Fl, to supply air to parts of the turbofan engine - not shown in [Fig.3] - and the se- secondary F2, which is ejected providing a significant fraction of the thrust.

[0065] The first thrust measuring scale 22 and the second thrust measuring scale 24 are fixed on the test machine 2 and on different elements of the turbofan assembly 3 detailed in the rest of the writing.

[0066] The fixed part 30 of the turbofan, according to an example of a first aspect of the invention, notably comprises a primary part 300, a secondary part 302, a nacelle 304 and a fixed internal structure 306 also called an IFS cowl (from the English "inner fixed structure").

[0067] The primary part 300 has the role of straightening the primary flow F1 in the axis of the engine. The primary part 300 comprises a plurality of blades - also visible in [Fig.3] - also called primary flow fixed vanes or IGV ("Inlet Guide Vane").

[0068] Furthermore, the primary portion 300 comprises a primary inner casing 300i and a primary outer casing 300e between which the plurality of blades included in the primary portion 300 extend axially.

[0069] The secondary part 302 has the role of straightening the secondary flow F2 in the axis of the engine. The secondary part 302 comprises a plurality of blades - only three are shown - also called fixed secondary flow vanes or OGV ("Outlet Guide Vane").

[0070] In particular, the fixed internal structure 306 extends axially, along the X axis, from the secondary 302. The fixed internal structure 306 comprises an external casing 306e which corresponds to a surface of revolution of the X axis.

[0071] The secondary part 302 comprises a secondary internal casing 302i, merged with the primary external casing 300e, and a secondary external casing 302e between which the plurality of blades included in the secondary part 302 extend axially.

[0072] In particular, the nacelle 304 is mounted on the secondary external casing 302e.

[0073] The primary inner casing 300i and the secondary inner casing 302i jointly form an annular primary flow duct 308. In particular, the primary flow duct 308 forms a primary flow channel FL

[0074] In this example, the primary internal casing 300i comprises on the one hand a first upstream part in the form of a crown from which the blades of the primary part 300 extend, forming with the primary external casing 300e the rectifier duct and on the other hand a second downstream part in the form of a crown mounted coaxially against the first part, the second part being surrounded by the secondary internal casing 302i together forming the duct 308 following the rectifier duct.

[0075] Furthermore, the fixed turbofan part 30 comprises a hub 310, visible entirely or partially in [Fig.4], [Fig.5], [Fig.6], [Fig.7] and [Fig.8].

[0076] The hub 310 comprises a cylindrical body 3100, having as its axis of revolution the X axis, and a plurality of hub arms 3102 equally distributed around the cylindrical body 3100.

[0077] Each hub arm 3102 extends radially from the cylindrical body 3100 to an external fixing ring 3104, visible in [Fig.5] and in [Fig.6], fixed to the secondary internal casing 302i.

[0078] In particular, each hub arm 3102 comprises a portion passing through the primary flow conduit 308.

[0079] In a preferred embodiment, the through portion of each hub arm hub arm 3102 is a pad.

[0080] The fixed part 30 of the turbofan, according to a first aspect of the invention, further comprises a plurality of isolation deflectors 312 - only one is shown in [Fig. 3] - each isolation deflector 310 being placed on a hub arm 3102, so as to surround said hub arm 3102. In other words, on each hub arm 3102 is placed an isolation deflector 312. More particularly, when the fixed part 30 is not fixed to the fixed fairing 20 of the test machine 2', each deflector 3102 is interposed between the cylindrical body 3102 of the hub and the secondary internal casing 302i, so as to be movable while surrounding the arm. Thus each deflector separates a part of the primary flow channel into two paths (one path on the intrados side and the other path on the extrados side). Each path of the primary flow channel is therefore formed between two deflectors.

[0081] In particular, each isolation deflector 312 comprises a leading edge 312A and a trailing edge 312F, visible in: [Fig.4], [Fig.5], [Fig.6], [Fig.7] and [Fig.8], so as to deflect a portion of the primary flow F1 so that aerodynamic forces due to the portion of the primary F1 are not applied to the hub arm 3102 on which the isolation deflector 312 is placed. Indeed, each isolation deflector 312 separates a portion of the primary flow channel F1 that it receives into two separate paths.

[0082] As a result, the test machine 2 makes it possible to verify the capacity of the blower 32 to achieve counter-thrust without measurement errors linked to the force exerted by the air flow on the arms of the hub and thus verify the correct supply of the primary flow in this operating mode.

[0083] In particular, as seen in [Fig.4], [Fig.5], [Fig.7] and [Fig.8], the isolation deflector 312 comprises a fixing portion 3120 comprising the trailing edge 312F of the isolation deflector 312, a lower surface wall 312i, an upper surface wall 312e and an upstream portion 3122 comprising the leading edge 312A.

[0084] The intrados wall 312i and the extrados wall 312e each extend from the fixing part 3120 to the upstream part 3122. In particular, the intrados wall 312i and the extrados wall 312e together delimit an opening receiving the through part of the hub arm 3102.

[0085] Thus, each deflector 312 has an aerodynamic profile to deflect the primary flow Fl.

[0086] In one embodiment, each isolation deflector 312 is symmetrical and the intrados wall 312i and the extrados wall 312e thus have the same curvature.

[0087] A second aspect of the invention relates to an assembly comprising a turbofan testing machine and a turbofan assembly comprising the fixed turbofan part each isolation deflector 312 is fixed on the fixed fairing 20. Each isolation deflector 312 thus comprises a fixing hole 3124 included in the fixing part 3120, into which is inserted a fixing screw 200 passing through a fixing hole of the fixed fairing 20. Thus, each isolation deflector 312 is fixed to the fixed fairing 20 by means of the fixing hole 3124 and the fixing screw 200.

[0088] In particular, the fixed fairing 20 comprises an inner casing 20i and an outer casing 20e jointly forming an extension 201 of the primary flow duct 308, each isolation deflector 312 being included both in the primary flow duct 308 and in the extension 201 of the duct 308 and being fixed in the extension 201 of the duct 308.

[0089] In a preferred embodiment, each isolation baffle 312 is attached to the outer casing 20e of the fixed fairing 20. More particularly, each isolation baffle 312 is attached to one end of the outer casing 20e of the fixed fairing 20.

[0090] In particular, the end to which each isolation baffle 312 is fixed furthermore, the end to which each isolation baffle 312 is fixed comprises a fixing hole 202 for receiving the screw 200 for fixing the isolation baffle 312 to the external casing 20e of the fixed fairing 20.

[0091] In another embodiment, each isolation baffle 312 is attached to the inner casing 20i of the fixed fairing 20. More particularly, each isolation baffle 310 is attached to one end of the inner casing 20e of the fixed fairing 20. In particular, the end to which each isolation baffle 312 is attached corresponds to the end extending from the primary flow conduit 308.

[0092] With reference to the first balance 22, the latter is rotatable relative to the fixed fairing 2 and comprises a first part, not visible, mounted on the fan 32 and a second part, not visible, mounted on the turbofan shaft 31, so as to measure the forces applied to the fan.

[0093] The second scale 24 is fixed and comprises a part fixed to the fixed fairing 20, and a measuring part fixed to the hub 310.

[0094] Thus, the plurality of arms 3102 of the hub 310 makes it possible to connect the measuring part of the second scale 24 to the assembly formed by the nacelle 304, the primary part 300, the secondary part 302 and the fixed internal structure 306.

[0095] When the primary flow F1 passes through the primary duct 308, the second balance 24 aims to measure only the aerodynamic forces applied to the nacelle 304, the primary part 300, the secondary part 302 and the fixed internal structure 306. The arrangement of the plurality of isolation deflectors 312 on the plurality of arms 3102 of the hub and their attachment to the fixed fairing 20 - not measured by the balance - and not at the hub 310 advantageously makes it possible to avoid measuring the aerodynamic forces applied to the plurality of arms of the hub 3102.

[0096] [Fig.4] is a partial perspective view of a portion of the primary part 300, a portion of the fixed fairing 20, a portion of the cylindrical body 3100 of the hub and a hub arm 3102 and an isolation deflector 312 deposited on the hub arm 3102.

[0097] In particular, each isolation deflector 312 is formed of an intrados shell 3126 and an extrados shell 3128 assembled, visible in [Fig.7] and [Fig.8].

[0098] In particular, each isolation baffle 312 comprises a first assembly hole 3130 and a first assembly pin 3131, visible in [Fig.7], included in the fixing part 3120. The first assembly pin 3131 is inserted into the first assembly hole 3130.

[0099] Further, each isolation baffle 312 includes a second assembly hole 3132 and a second assembly pin 3133, visible in [Fig.7], included in the upstream portion 3122. The second assembly pin 3133 is inserted into the second assembly hole 3132.

[0100] The first 3131 and second 3133 assembly pins deform elastically (but could also deform plastically) in the assembly holes so as to be tightly mounted in the holes.

[0101] Thus, the first 3130 and second 3132 assembly holes and the first 3131 and second 3133 assembly pins make it possible to assemble the intrados shell 3126 and the extrados shell 3128.

[0102] The intrados shell 3126 comprises a first portion of the fixing part 3120, the intrados wall 312i, and a first portion of the upstream part 3122. In addition, the intrados shell 3126 comprises a first portion 41 of the fixing hole 3124, the first portion 41 being tapped.

[0103] The extrados shell 3128 comprises a second portion of the fixing part 3120, the extrados wall 312e, and a second portion of the upstream part 3122. In addition, the extrados shell 3128 comprises a second portion 43 of the fixing hole 3124.

[0104] In particular, the extrados shell 3128 is located between the external casing 20e of the fixed fairing 20 and between the intrados shell 3126.

[0105] [Fig.5] shows in a partial perspective view the insertion of an isolation deflector 312 under the end of the external casing 20e of the fixed fairing 20 intended to receive the isolation baffle 312. In particular, the end of the outer casing 20e comprises an imprint 203 of the fixing part 3120. In the embodiment of [Fig.5], the isolation baffle 312 comprises a guide pin 3012 to be inserted into a groove 204 located at the end of the outer casing 20e of the fixed fairing 20.

[0106] Advantageously, the guide pin 3012 inserted in the groove 204 makes it possible to guide the isolation deflector 312 so as to make the fixing hole 202 of the external casing 20e and the fixing hole 3122 of the isolation deflector 312 coincide in order to facilitate the insertion of the screw 200. In other words, the isolation deflector 312 being placed movably on the hub arm 3102, it is possible to have a clearance between the isolation deflector 312 and the hub arm 3102.

[0107] Thus, the insertion of the guide pin 3012 into the groove 204 makes it possible to eliminate this play of the isolation deflector 312 relative to the external casing 20e.

[0108] [Fig.6] shows the hub 310, the external fixing ring 3104 and the plurality of deflectors 312 surrounding the plurality of hub arms 3102, not visible in this figure.

[0109] Another aspect of the invention relates to a method of mounting an isolation baffle 312 on a hub arm 3102.

[0110] The method comprises a step of assembling the intrados shell 3126 and the intrados shell 3128 around the hub arm 3102, the step being visible in [Fig.7].

[0111] The method comprises an insertion step, visible in [Fig.8], of: • the first assembly pin 3131 in the first assembly hole 3130 included in the fixing part 3120, • the second assembly pin 3133 in the second assembly hole 3132 included in the upstream part 3122, the deflector being interposed in a movably manner around the arm between the cylindrical body 3100 and the secondary internal casing 302i

[0112] Another aspect of the invention relates to a method of mounting the deflector of the fixed part to the fairing, comprising a step of adjusting the fixing hole 3124 with the fixing hole of the fixed fairing 20 and a step of inserting a screw through the fixing hole of the fixed fairing 20, of the second portion 43 of the fixing hole 3120 passing through the extrados wall 312e and a step of screwing the screw into the thread of the first portion 41 of the fixing hole 3124 passing through the intrados shell 3126.

Claims

Claims

1. A fixed part (30) of a turbofan adapted to be tested on a test machine, comprising: - A primary part (300) comprising a primary inner casing (300i), - A secondary part (302) comprising a secondary inner casing (302i) forming a primary flow duct (308) with the primary inner casing (300i), the primary flow duct (308) defining a primary flow channel volume, - A hub (310) comprising: • a cylindrical body (3100) to be fixed to a thrust measuring scale of the test machine and;• a hub arm (3102) extending radially from the cylindrical body (3100) to an outer attachment end (3124) attached to the secondary inner casing (302i), the hub arm (3102) comprising a portion passing through the primary flow duct (308), - An isolation deflector (312) of the hub arm (3102) located in the primary flow duct (308), movably interposed between the cylindrical body (3100) and the secondary inner casing (302i), the isolation deflector (312) comprising: • an attachment portion (3120) comprising a trailing edge (312F) of the deflector (312), adapted to attach the deflector (312) to a fixed fairing (20) of the testing machine (2').;

2. Fixed part (30) according to the preceding claim in which the isolation deflector (312) comprises an upstream part (3122) comprising a leading edge (312A) of the isolation deflector (312), a lower surface wall (312i) and an upper surface wall (312e) each extending from the upstream part (3122) to the fixing part (3120), the lower surface wall (312i), the upper surface wall (312e), the fixing part (3120) and the upstream part (3122) together delimiting an opening housing the through part of the hub arm (3102).

3. Fixed part (30) according to the preceding claim in which the deflector is formed of: - An intrados shell (3126) comprising the intrados wall (312i), a first portion of the fixing part (3120) and a first portion of the upstream part (3122), - An extrados shell (3128) assembled with the intrados shell (3122) forming the deflector (312), comprising the extrados wall (312e), a second portion of the fixing part (3120) and a second portion of the upstream part (3122).

4. Fixed part (30) according to the preceding claim in which the isolation deflector (312) comprises: - a first assembly hole (3130) passing through the intrados (3126) and extrados (3128) shell at the fixing part (3120) and a first assembly pin (3131) in the first assembly hole (3130), fixing the intrados (3126) shell to the extrados (3128) shell, - a second assembly hole (3132) passing through the intrados (3126) and extrados (3128) shell at the upstream part (3122) and a second assembly pin (3133) inserted in the second assembly hole (3132), fixing the intrados (3126) shell to the extrados (3128) shell.

5. Fixed part (30) according to one of the preceding claims in which the isolation deflector (312) comprises a guide pin (3012) in the fixing part (3120) to be inserted into a groove (204) of the fixed fairing (20) of the testing machine (2).

6. Fixed part (30) according to one of the preceding claims comprising a nacelle (304), and in which the secondary part (302) comprises a secondary external casing (302e) fixed to the nacelle (304).

7. Fixed part (30) according to one of the preceding claims comprising a fixed internal structure (306) extending from the secondary part (302).

8. Assembly comprising the fixed part (30) according to one of claims 1 to 7, and the fixed fairing (20), the fixing part (3120) being fixed to the fixed fairing (20).

9. An assembly according to claim 8, comprising a turbofan testing machine (2') further comprising the fixed fairing (20): - A thrust measuring scale (24) of the forces applied to the fixed part (30) of the turbofan, the thrust measuring scale (24) being fixed to the fixed fairing (20) and comprising a measuring part mounted on the hub (310) of the fixed part (30) of the turbofan and the fixed fairing (20). - Fixing means, inserted into the fixing hole of the isolation deflector fixing the isolation deflector (312) to the fixed fairing (20).

10. Assembly according to one of claims 9 to 10 in which the fixed fairing (20) comprises an outer casing (20e) and an inner casing (20i) together forming an extension of the primary flow channel.

11. An assembly according to the preceding claim wherein the outer casing comprises a fixing hole through which the fixing means passes fixing the isolation baffle (312) to the outer casing of the fixed fairing.

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