METHOD FOR CREATING A CONNECTING ELEMENT POSITIONED BETWEEN TWO COMPONENTS OF A STRUCTURE, CONNECTING ELEMENT AND BYPASS TURBOJET ENGINE COMPRISING SUCH A CONNECTING ELEMENT
A method for creating a connecting element, arranged between two components of a structure, or a turbojet engine structure, which is subjected to compressive and/or tensile loadings and which includes a hollow shaft immersed, at least partially, in a stream of air flowing between the two components, the method including: dimensioning a width of the main cross section associated with the shaft of the connecting element in a direction orthogonal to the longitudinal axis of the shaft according to desired mechanical strength and desired mass, and according to characteristics of the airstream; and working an external surface of the shaft of the connecting element, at least over part of this surface, to give it a surface finish with an arithmetic mean roughness at least equal to 20 microns, to reduce drag of the connecting element thus dimensioned by comparison with a smooth connecting element of the same diameter.
1 - 11 . (canceled)
12 . A method for producing a connecting element arranged between two components of a structure, or of a turbojet engine, which is subjected to forces of compression and/or traction and which includes a longitudinal hollow shaft immersed at least partially in an air stream flowing between the two components having a Reynolds number greater than 10 4 , the method comprising:
dimensioning a width of maximum cross section associated with the shaft of the connecting element, in a direction at right angles to the longitudinal axis of the shaft, as a function of desired mechanical resistance and mass and characteristics of the air stream; and
machining an external surface of the shaft of the connecting element over at least one part, to apply thereto a surface state of which average arithmetical roughness Ra is at least equal to 20 micrometers, to reduce drag of the connecting element thus dimensioned relative to drag produced by a smooth shaft.
13 . The method as claimed in claim 12 , wherein a degree of the roughness is selected to be between 10 −4 and 10 −1 for a Reynolds number ranging between 4×10 4 and 3×10 5 .
14 . A connecting element configured to be arranged between two components of a structure, or of a turbojet engine, the connecting element being subjected to forces of compression and/or traction and including a hollow longitudinal shaft, immersed at least partially in an air stream flowing between the two components having a Reynolds number greater than 10 4 ,
wherein
a width of maximum cross section associated with the shaft of the connecting element in a direction at right angles to the longitudinal axis of the shaft is at least equal to 20 millimeters; and
at least one part, or an entirety, of an external surface of the shaft of the connecting element has an average arithmetical roughness at least equal to 20 micrometers.
15 . The connecting element as claimed in claim 14 , wherein the external surface of the shaft belongs, at least partially, to one of:
an abrasive surface;
a cellular surface;
a surface including microballs;
a longitudinally grooved surface;
a surface including longitudinal facets.
16 . The connecting element as claimed in claim 14 , wherein a ratio of the width of the maximum cross section associated with the shaft in the direction at right angles to the longitudinal axis of the shaft on an aerodynamic chord of the shaft ranges from 0.25 to 1.05.
17 . The connecting element as claimed in claim 16 , wherein the cross section of the shaft is circular or elliptical.
18 . The connecting element as claimed in claim 14 , wherein the shaft of the connecting element is tubular and has a lateral wall thickness at least equal to 0.8 mm and at most equal to 5 mm.
19 . The connecting element as claimed in claim 14 , wherein the width of the maximum cross section associated with the shaft in the direction at right angles to the longitudinal axis of the shaft is equal to 40 millimeters, and wherein the external surface of the shaft has, at least partially, an average arithmetical roughness equal to 70 micrometers.
20 . The connecting element as claimed in claim 14 , wherein the width of the maximum cross section associated with the shaft in the direction at right angles to the longitudinal axis of the shaft is equal to 30 millimeters, and wherein the external surface of the shaft has, at least partially, an average arithmetical roughness Ra equal to 100 micrometers.
21 . The connecting element as claimed in claim 14 , in a form of a connecting rod which comprises fastening means, or a ball joint, at each of its longitudinal ends.
22 . A bypass turbojet engine comprising:
a hot stream generator extending along a longitudinal axis and comprising an exhaust casing of the hot stream in a vicinity of its downstream end;
a bypass fan driven in rotation by the hot stream generator;
a nacelle that surrounds at least partially the hot stream generator and the bypass fan and that defines an outer bypass duct;
a supporting ring of the nacelle and of the rear suspension which is borne by connecting elements fastened to the exhaust casing and immersed, at least partially, into the bypass stream of the outer duct;
wherein the connecting elements are of the type according to claim 14 .