METHOD AND DEVICE FOR ANALYZING THE ACTUAL SHAPE OF AN AERODYNAMIC SURFACE OF A PART.

Abstract

The invention relates to a method and device for analyzing the profile of an actual shape of a part's surface. To this end, the device determines and divides into subsections the deviation between the actual shape and the theoretical shape. Then, for each subsection, a sinusoidal wave characterized by an amplitude b and a half-wavelength a is identified. When b is less than a predetermined value bmin or when a is less than a predetermined value amin, the device stops the analysis; otherwise, a new iteration of the analysis is performed, considering the identified sinusoidal wave as a new profile of a theoretical shape of the surface. At the end of the analysis phase, an alert message is generated if the values ​​b and / or b / a do not meet a manufacturing tolerance criterion. It is thus possible to identify differences between the actual shape and the theoretical shape, taking into account complex wave profiles.Figure to be published with the abbreviation: Fig. 3.

Description

Title of the invention: METHOD AND DEVICE FOR ANALYZING AN ACTUAL SHAPE OF AN AERODYNAMIC SURFACE OF A PART. Technical field

[0001] The present invention relates to a method and a device for analyzing the actual shape, i.e. manufactured or deformed under application of a load, of an aerodynamic surface of a part subjected to a flow of flow that is desired to be laminar, such as for example a part of an aircraft. In particular, the method and the device according to the invention relate to the identification of differences between the shape of the actual surface of such a part and its theoretical shape. STATE OF PRIOR ART

[0002] The increase in fuel prices and the need to reduce the environmental impact of airline operations have led to the discovery of new technologies to address these issues.

[0003] Among these new technologies, aircraft parts (for example: wings, empennages, engine air intakes, etc.) with natural laminar flow (NLF) make it possible to reduce fuel consumption and greenhouse gas emissions in commercial aviation. Indeed, maintaining a laminar flow instead of a turbulent flow on an aerodynamic surface makes it possible to considerably reduce the coefficient of friction of this surface and therefore to optimize the performance of an aircraft.

[0004] Obtaining a natural laminar flow is in particular conditioned by the shape of the aerodynamic surface of an aircraft part, such as an engine air intake. The theoretical shape (i.e., as provided during the design) of the surface of the NLF type engine air intake has a curvature that evolves in all directions (longitudinal and azimuthal), which in particular makes it possible to obtain such a natural laminar flow. Furthermore, the surface of the engine air intake must be kept smooth (i.e., having any roughness contained within a predefined tolerance margin) and free from defects (for example: insect residues, steps, holes, undulations, etc.) to maintain a natural laminar flow.

[0005] The following explanation regarding aircraft parts is given for illustrative purposes and is applicable to the manufacture or design of other types of parts subject to a desired laminar flow pattern.

[0006] It should be noted that the shape of the actual surface of a part subjected to a desired laminar flow (e.g. aircraft part as described previously), i.e. manufactured or deformed after application of a load, may present differences from its theoretical form. For example, ripples may form on the surface of the part during manufacture or when the surface in question is subjected to a load. [Fig.l] illustrates, for example, in a schematic manner different ripple geometries that can form on the surface of an aircraft part during manufacture or after application of a load. In [Fig.l], at a given location of the part, three examples of 2D sections of the surface are shown. A first example section presents a ripple denoted Cl, a second example section presents a ripple C2 and a third example section presents a ripple C3. Each ripple, or wave, is characterized by an amplitude denoted b and a half-wavelength denoted a.Ripple Cl is then represented in dotted lines, for reference, on ripples C2 and C3. Although these three ripples Cl, C2 and C3 have different geometries, they have identical amplitude b and half-wavelength a values. It is the differences in geometry, or profile, of these ripples that will play an important role in maintaining, or not, a natural laminar flow. In other words, if the profile of ripple Cl is conducive to maintaining a natural laminar flow, ripples C2 and C3 have profiles that, on the contrary, can introduce a risk for maintaining such a laminar flow. It should be noted that the geometry of ripples can be much more complex than what is presented above in connection with [Fig.l].

[0007] It is therefore desirable to analyze the actual shape of the surface of a part subjected to a desired laminar flow, such as a part of an aircraft, in particular by comparing it to its theoretical shape, in order to identify differences which may be the cause of a change from natural laminar flow to turbulent flow. For this, there are various tools for making this comparison, such as for example tools based on a 3D scan of the actual shape of the surface of the part modeled by CAD tools ("Computer Aided Design").

[0008] Using a 3D scan of the actual surface (i.e., manufactured, or deformed after application of a load) allows a multitude of waves of different shapes, sizes and wavelengths to be observed, when this scan is compared to the theoretical shape of this surface. However, 3D scanning tools can introduce noise into the measurements, which can accentuate the differences between the actual shape and the theoretical shape.

[0009] The use of CAD tools allows for a more in-depth analysis of the differences between the actual shape of the surface and its theoretical shape.

[0010] However, when the theoretical shape of the surface is curved, the curvature of the theoretical shape may create a bias in understanding the waviness of the surface. real. Thus, it is necessary to assess the gap between the real form and the theoretical form.

[0011] However, the actual and theoretical shapes are not necessarily in the same geometric reference frame, which can complicate the evaluation of the difference between the actual shape and the theoretical shape. In order to correct this difference in reference frame, a "best-fit" can be achieved with these CAD tools by minimizing the distance between the two shapes (or two sections of the aircraft part in a 2D environment). However, this type of operation can distort the understanding of the differences between the actual shape and the theoretical shape, in particular at the start and end points of the analyzed 2D section.

[0012] Consequently, the perception of the ripple may be affected by a misunderstanding of the wavelengths and amplitudes involved.

[0013] Furthermore, the preceding techniques have other limitations. Indeed, they do not allow the differences between the curvatures of the actual surface and the curvatures of the theoretical surface to be identified and quantified in order to be able to control the deviations, in particular during the manufacture of the aircraft. In particular, it is not possible to define geometric characteristics of the surface undulations that may be found on the actual surface of the part, in order to be able to evaluate their criticality on the laminarity of the flow, for example via a comparison with quantifiable criteria (for example: manufacturing tolerance criterion).

[0014] However, there are criteria for NLF type surfaces which take into account in particular the characteristics of the undulations which can cause a transition from a laminar flow to a turbulent flow by different mechanisms in the boundary layer (i.e., interface zone between a body and the surrounding fluid during a relative movement between the two).

[0015] For example, Carmichael's research in the late 1950s led to the definition of a so-called "Carmichael" criterion on the permissible undulation for maintaining laminar flow.

[0016] This criterion applies in particular to undulations, or waves, of the sinusoidal type, for which the maximum value of the b / a ratio compatible with a laminar flow is given by the following semi-empirical formula: - for simple waves, the admissible wave gradient is:

[0017] with:

[0018] b the Fonde amplitude;

[0019] at half wavelength;

[0020] (p the scanning angle;

[0021] Rec the Reynolds number based on the chord noted c. - for multiple waves (i.e., superposition of several waves on each other) others), a multiplicative factor less than 1 can be applied to the previous equation, depending on the application considered.

[0022] The use of the Carmichael criterion, however, has certain limitations: - the analysis may be distorted if the manufactured part is curved by design (for example, the NLF type engine air intake); - the different profiles, or shapes, of waves for given identical a and b values ​​(see for example [Fig.l] above) are not perceived.

[0023] [Fig.2] schematically illustrates an example of a profile, or geometry, of a multiple wave. Some multiple wave geometries can lead to a biased conclusion when the Carmichael criterion is used. In this example, a small PO wave sits on a longer LO wave. If the Carmichael criterion presented above is applied, then: - if b = 0.35 mm for a = 750 mm, then Fonde is compatible with a laminar flow because bmax = 0.38 mm for a multiple wave; - if b = 0.07 mm for a = 50 mm, then Fonde is compatible with a laminar flow because bmax = 0.10 mm for a multiple wave; - if b = 0.42 mm for a = 750 mm then Fonde is not compatible with a laminar flow because bmax = 0.38 mm for a multiple wave.

[0024] Thus, depending on the Fonde geometry taken into account for the calculation of the Carmichael criterion, Fonde may or may not be compatible with a laminar flow. It is therefore not possible to precisely determine values ​​of amplitude b and half-wavelength a allowing the use of the Carmichael criterion for undulations with complex profiles.

[0025] It is then desirable to overcome these drawbacks of the state of the art. In particular, there is a need for a technique for analyzing the undulations of the actual shape (manufactured or deformed under load) of an aerodynamic surface of an aircraft part, in particular an engine air intake, by comparing it in particular with its theoretical shape. It is particularly desirable to provide a solution that makes it possible to evaluate whether the actual shape of the surface complies with tolerances (e.g., manufacturing tolerances) that guarantee that the flow of the stream (e.g., air flow) will remain laminar. Presentation of the invention

[0026] A method for analyzing a profile of a real shape of a 2D section of an aerodynamic surface of a part is proposed here, implemented by an analysis device. The method comprises: adapting a geometric reference system to match leading and trailing edges of the profile of the real shape to the leading and trailing edges of a profile of a theoretical shape of the 2D section of the aerodynamic surface of the part. The method further comprises an analysis phase comprising the steps following: determine a deviation between the profile of the actual shape and the profile of the theoretical shape of the 2D section, divide the deviation into subsections, each subsection being defined by a part of the deviation comprising a start and an end corresponding to points for which a value of the deviation is zero, then for each subsection: (i) identify a maximum sine wave in line with the part of the deviation defining the subsection to within a predefined margin, this maximum sine wave being characterized by a wave amplitude value b and a half-wavelength value a, (ii) when the wave amplitude value b is less than a predetermined minimum amplitude value bmin or when the half-wavelength value a is less than a predetermined minimum half-wavelength value amin, then stop the analysis phase for the subsection, otherwise,when the wave amplitude value b is greater than the predetermined minimum amplitude value bmin and the half-wavelength value a is greater than the predetermined minimum half-wavelength value amin, then performing a new iteration of the analysis phase by considering the identified maximum sinusoidal background as a new 2D section of a theoretical shape of the aerodynamic surface. At the end of the analysis phase, the method comprises: generating an alert message if the wave amplitude values ​​b and / or wave gradient b / a of the maximum sinusoidal wave or if at least one wave amplitude value b and / or wave gradient b / a of a set of maximum sinusoidal waves are greater than a manufacturing tolerance criterion.

[0027] It is thus possible to identify differences, or deviations, between the actual shape of the aerodynamic surface of a part subjected to a desired laminar flow, such as an aircraft part, with the theoretical shape of this surface, taking into account complex undulation profiles. In particular, it is possible to eliminate a potential bias that may be introduced by a different geometric reference frame between the actual shape of the surface and its theoretical shape and to analyze complex and arbitrary surface deviations, such as may be encountered during a manufacturing process of an aircraft part. Furthermore, it is possible to identify the different scales of undulation, from long wavelengths to short wavelengths, and evaluate their geometric characteristics, one undulation independently of the others.It is thus also possible to determine whether the deviation is acceptable, or not, for a given objective (e.g. maintaining a natural laminar flow), according to a manufacturing tolerance criterion.

[0028] According to a particular embodiment, the alert message informs an operator about the presence of a defect in the actual shape of the aerodynamic surface of the part, this alert message comprising a type of defect and / or a location of the defect in the actual shape of the aerodynamic surface of the part.

[0029] According to a particular embodiment, the alert message further comprises at least one proposal for corrective action for the fault.

[0030] According to a particular embodiment, the maximum sinusoidal wave comprises: a start and an end identical to the start and the end of the subsection, a wavelength 2a corresponding to a length of the subsection and the amplitude b defining a maximum amplitude corresponding to an amplitude of the deviation of the subsection, to within the predefined margin.

[0031] According to a particular embodiment, the tolerance criterion is based on a Carmichael criterion for maintaining a natural laminar flow at the level of the aerodynamic surface of the part.

[0032] A method for repairing an aerodynamic surface of a part is proposed here, comprising: analyzing a profile of a real shape of a 2D section of the aerodynamic surface of the part by executing an analysis method as described previously and implemented by an analysis device, repairing the aerodynamic surface of the part by an operator if an alert message is generated by executing the analysis method as described previously.

[0033] A device is proposed here for analyzing a profile of a real shape of a 2D section of an aerodynamic surface of a part comprising electronic circuitry configured to implement: adapting a geometric reference frame to match leading and trailing edges of the profile of the real shape to the leading and trailing edges of a profile of a theoretical shape of the 2D section of the aerodynamic surface of the part. The electronic circuitry is further configured to implement an analysis phase comprising the following steps: determining a deviation between the profile of the real shape and the profile of the theoretical shape of the 2D section, dividing the deviation into subsections, each subsection being defined by a part of the deviation comprising a start and an end corresponding to points for which a value of the deviation is zero,then for each subsection: (i) identify a sine wave in line with the part of the deviation defining the subsection, to within a predefined margin, said maximum sine wave being characterized by a wave amplitude value b and a half-wavelength value a, (ii) when the wave amplitude value b is less than a predetermined minimum amplitude value bmin or when the half-wavelength value a is less than a predetermined minimum half-wavelength value amin, then stop the analysis phase for the subsection, otherwise, when the wave amplitude value b is greater than the predetermined minimum amplitude value b min and the half-wavelength value a is greater than the predetermined minimum half-wavelength value amin, then perform a new iteration of the analysis phase by considering the identified maximum sine wave as a new , 2D section of a theoretical shape of the aerodynamic surface. At the end of the analysis phase, the electronic circuitry is configured to implement: generate an alert message if the b-wave amplitude and / or b / a-wave gradient values ​​of the maximum sine wave or if at least one b-wave amplitude and / or b / a-wave gradient value of a set of maximum sine waves are greater than a manufacturing tolerance criterion.

[0034] Also provided is a computer program product, comprising instructions causing a processor to execute the method mentioned above according to any one of its embodiments, when said instructions are executed by the processor. Also provided is a storage medium, storing such instructions. Brief description of the drawings

[0035] The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of at least one exemplary embodiment, said description being made in relation to the attached drawings, among which:

[0036] [Fig-1] schematically illustrates different corrugation geometries that can form on the surface of an aircraft part during its manufacture or after application of a load;

[0037] [Fig.2] schematically illustrates an example of geometry of a multiple wave;

[0038] [Fig.3] illustrates in diagrammatic form an algorithm for analyzing the profile of the real surface of a section of a part of an aircraft according to one embodiment;

[0039] [Fig.4] schematically illustrates examples of results obtained for certain steps of the algorithm described in connection with [Fig.3];

[0040] [Fig.5] schematically illustrates an example of modeling of a result obtained for a subsection of a section of a real surface of an aircraft part after implementation of the algorithm described in connection with [Fig.3]; and

[0041] [Fig.6] schematically illustrates an example of hardware architecture of an analysis device according to one embodiment.

[0042] DETAILED DESCRIPTION OF EMBODIMENTS

[0043] It is proposed here to analyze the actual shape of the aerodynamic surface of a part subjected to a desired laminar flow, such as for example an aircraft part, and in particular an engine air intake, by comparing it to its theoretical shape. In particular, it is proposed here to identify and quantify the differences, or deviations, between the shape of the theoretical surface of the part and that of the actual surface, to determine the compatibility of the undulations that may form on the surface of the actual part with the maintenance of a laminar flow. More specifically, the profile of the on The actual surface shape is compared to the theoretical surface shape profile to assess whether the actual part surface shape meets manufacturing tolerances that ensure the flow will remain laminar. If manufacturing tolerances are not met, then the process and device can identify the position and extent of defects in order to define corrective actions. In an example, these corrective actions are: removing dents (e.g. by manual or robotic sanding of the part), replacing the part, reshaping the part, etc.

[0044] Hereinafter, the terms "actual surface" and "actual surface shape" designate the surface, respectively the surface shape, of an aircraft part after manufacture or after deformation linked to the application of a load on the part.

[0045] The terms “profile” and “geometry” designate the shape of the surface and in particular the shape of the undulations present on the actual aerodynamic surface of the part. These terms are interchangeable.

[0046] [Fig. 3] illustrates in diagrammatic form an algorithm for analyzing the profile of the actual surface of a section of a part, in particular of an aircraft, according to one embodiment. The algorithm applies in particular, but is not limited to, the analysis of the actual shape of the surface of an NLF type engine air intake of an aircraft. Thus, the term "part" designates any part subjected to a flow of flow that is desired to be laminar, and therefore in particular aircraft parts such as: an NLF type engine air intake, or any other type of part of an aircraft, such as for example a wing of an aircraft.

[0047] The algorithm described below takes as input data concerning the aerodynamic shape of the theoretical surface of the analyzed part (e.g., engine air intake), and a set of data concerning the real, i.e. manufactured, shape of this same part or of a model of a part deformed under load. The data concerning the real shape of the surface of the manufactured part are for example obtained via 3D scan of the part. The data concerning the theoretical shape of the surface of the part are for example obtained via CAD. The data concerning the real shape of the part deformed under the application of a load are for example obtained via a finite element model (FEM). This data is for example data on dimensions, shape (e.g.: curvature), surface undulations, etc.

[0048] The algorithm applies, for example, to a “2D section” of a 3D geometry of the part to be analyzed, i.e. to a set of points representative of this part, located in a plane. In another example, the algorithm applies to a so-called “non-planar” 2D section (i.e., resulting from the intersection between the real surface to be analyzed and a selected non-planar, i.e. curved, surface), to follow the natural direction of air flow over the surface of the part.

[0049] Thus, the term “analyzed section” refers to a 2D section extracted for example from a 3D scan of the manufactured part (for example in the form of a point cloud) or from an FEM result of a part deformed by a load.

[0050] The algorithm described below is implemented by a surface profile analysis device DISP 600 (also called DISP 600 analysis device) presented below in connection with [Fig. 6]. This DISP 600 analysis device is for example a computer.

[0051] [Fig.4] schematically illustrates an example of a result obtained for certain steps of the algorithm described in connection with [Fig.3] for a section to be analyzed of the part. [Fig.4] firstly schematically illustrates an example of a 2D section of the real surface, denoted SR, of a part of the part, and of a 2D section, denoted ST, of the theoretical surface of this same part.

[0052] During a step 301, the analysis device DISP 600 adjusts a geometric reference frame in a relative manner between the shape of the real surface and the shape of the theoretical surface of the 2D section of the part. This adjustment makes it possible to match the leading and trailing edges of the 2D section of the real surface SR (i.e., manufactured or deformed under load) to the leading and trailing edges of the 2D section of the theoretical surface ST of the part to be analyzed. This action of adjusting the reference frame of the 2D sections of the real surface and the theoretical surface may, for example, require the application of a translation and / or a rotation of the data of the section of the part to be analyzed.It is thus possible to correct any difference in geometric reference and to visualize the gaps, or deviations, between the profile of the theoretical surface ST of the section and the profile of the real surface SR of the section to be analyzed (also called subsequently real section SR). In addition, given that each point of the 2D section to be analyzed corresponds to a point located on the surface of the part, it is also possible to determine the position, or location, of the gaps at the level of the real surface of the part. If necessary, it is thus possible to locate defects on the real surface of the part.

[0053] The analysis device DISP 600 then implements a phase of analysis of the real section SR or, where appropriate, of a subsection of the real section SR. This analysis phase comprises the steps 302 to 306 described below.

[0054] During step 302, the analysis device DISP 600 calculates, for each point of the 2D section of the real surface SR, the curvilinear distance (i.e., deviation from the 2D section of the theoretical surface ST for this same point) between the real surface SR of the section to be analyzed and the theoretical surface ST of this same section. The analysis device DISP 600 thus determines a deviation comprising a set of distance deviations between the profile of the real surface and the profile of the theoretical surface of the section to be analyzed. In one example, this deviation is then represented in the form curve showing all the distance differences between the real surface SR of the section to be analyzed and its theoretical surface ST as a function of the curvilinear distance on the theoretical surface ST (see [Fig.4]) of this section.

[0055] During step 303, the analysis device DISP 600 divides, or fragments, the deviation of the real surface SR of the section to be analyzed into several parts thus defining a set of subsections defined by the points where the value of the deviation is zero (i.e., points of the 2D section of the surface at which there is no difference, or no deviations, between the real surface SR and the theoretical surface ST). In the example linked to [Fig. 4], the graphical representation of the deviation is divided into 4 subsections noted #1 to #4. Each subsection therefore comprises a start point and an end point corresponding to points of the real surface SR of the section to be analyzed whose value of the deviation is zero compared to the theoretical surface ST of the section to be analyzed.

[0056] During step 304, for a given subsection (for example, subsection #3), the analysis device DISP 600 identifies the most important sinusoidal (or sine) wave, called the maximum sine wave. This maximum sine wave is in line with the deviation of the analyzed subsection (i.e., subsection #3), that is to say that the amplitude of the maximum sine wave is close to the amplitude of the deviation of the subsection over the entire subsection, as described below. This maximum sine wave has a start point and an end point identical to the start and end points of the analyzed subsection.Furthermore, this maximum sine wave includes a wavelength denoted 2a defining the length of the analyzed subsection (a being therefore the half-wavelength of the maximum sine wave) and an amplitude denoted b defining the maximum amplitude of the sinusoidal wave in an interval of values ​​framing the amplitude of the deviation of the analyzed subsection. In other words, the value of the amplitude of the maximum sine wave is included in an interval of values ​​framing the value of the amplitude of the deviation of the subsection over the entire subsection (i.e., the limits of the interval are defined such that: upper limit is equal to the value of a predefined threshold plus the value of the amplitude of the deviation of the subsection over the entire subsection and lower limit is equal to the value of the amplitude of the deviation of the subsection over the entire subsection less the value of the predefined threshold).This range of values ​​therefore defines a predefined margin taken into account for the definition of the maximum amplitude of the sine wave. The maximum amplitude of the sine wave is therefore in line with the amplitude of the deviation of the subsection over the entire subsection, using this predefined margin.

[0057] During step 305, the analysis device DISP 600 stops the analysis phase if the half-wavelength a or the amplitude b of the identified sine wave reaches values ​​below respective predefined thresholds amin and bmin.

[0058] During step 306, on the contrary, if the values ​​of half-wavelength a and wave amplitude b are, respectively, greater than the predefined thresholds amin and bmin, the analysis device DISP 600 determines that the maximum sinusoidal wave identified in step 304 is a new 2D section of a theoretical surface of the part. The analysis device DISP 600 then reiterates the analysis phase by repeating steps 302 and following, in a loop, until the conditions for stopping the analysis phase are met. More specifically, the analysis device DISP 600 determines that the maximum sinusoidal wave identified in step 304, then called the “mother” sinusoidal wave, is a 2D section of a theoretical shape of the surface.The DISP 600 analysis device then determines (step 302) one or more deviations between this new 2D section of the theoretical surface and a part of the deviation forming the previously analyzed subsection (for example subsection #3). The DISP 600 analysis device divides this subsection, called “mother” subsection, into new subsections (step 303), called “daughter” subsections (for example subsections #3.1 and #3.2). The DISP 600 analysis device identifies, for each “daughter” subsection (step 304), a maximum sine wave. The analysis device DISP 600 then repeats steps 305 or 306 depending on the result of the comparison of the half-wavelength a and wave amplitude b values ​​of the maximum sine waves identified for each “daughter” subsection (e.g., values ​​a' and b' of the maximum sine wave of subsection #3.1 and the values ​​a” and b” of the maximum sine wave of subsection #3.2) respectively to the predefined amin and bmin values. .

[0059] These repetitions of the analysis phase, or cascade analysis, are thus carried out for all the “mother” subsections (for example subsections #1 to #4) and their “daughter” subsections if necessary.

[0060] Thus, at the end of the algorithm, for an analyzed “mother” subsection, the analysis device DISP 600 identifies, from the potential “daughter” subsections, a series, or set, of sinusoidal waves accumulated on top of each other.

[0061] [Fig.5] schematically illustrates an example of a result obtained after implementation of the algorithm described in connection with [Fig.3] for a given subsection of a 2D section of an aircraft part.

[0062] More particularly, [Fig.5] represents in graphic form the deviation of the 2D section of the real surface analyzed at a subsection #n as a function of the curvilinear distance on its theoretical surface. This subsection #n has a particularly complex profile, with several undulations on top of each other and / or following each other. When the analysis device DISP 600 finishes the analysis phase (i.e., steps 302 to 305 or 306) of this subsection #n, the deviation between the

[0063]

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[0068] real form of subsection #n and the theoretical form of this section is decomposed into a series of sinusoidal waves including: - a “mother” sine wave noted Sinus 1 for the mother subsection #n, - “daughter” sine waves noted Sinus 1.1, Sinus 1.2 for the sub- girls sections #n. 1 and #n.2, - a “granddaughter” sine wave noted Sinus 1.2.1 resulting from a new iteration of the analysis phase carried out from the “daughter” subsection #n.2 and which are accumulated on top of each other, for each subsection and their potential “daughter” subsections. Thus, for each maximum sine wave identified for a “mother” subsection and its potential “daughter” subsections, the following characteristics are known: - position on the subsection and therefore on the analyzed 2D section; - half wavelength a; - amplitude b (can be positive or negative). During a step 307, these half-wavelength characteristics a and amplitude b of each “mother” subsection and its potential “daughter” subsections can then be compared to a manufacturing tolerance criterion. This tolerance criterion can be defined for example by: - a maximum value of wave amplitude b for a given half-wavelength value a (e.g. Carmichael criterion), - a minimum value of half-wavelength a for a given wave amplitude value b, - a maximum value of the gradient b / a for a given half-wavelength a, - a combination of these tolerance criteria, to determine whether the quality of the actual surface shape of the part is acceptable for a given purpose. This objective is, for example, a goal of maintaining laminar flow for an aircraft engine air intake. In this case, the manufacturing tolerance criterion is, for example, based on the Carmichael criterion described above. It is thus possible to ensure a link to existing ripple acceptance criteria, such as the Carmichael criterion, by means of the parameters a (half-wavelength) and b (amplitude) of the individual maximum sine waves. In another exemplary embodiment, the manufacturing tolerance criterion is based on the Carmichael criterion for the so-called “mother” subsections, while a different manufacturing tolerance criterion (eg, a maximum value of the b / a gradient for a given half-wavelength a) is applicable to the so-called "daughter" subsections.

[0069] Thus, for each subsection of the 2D section of the real surface SR to be analyzed, one or more maximum sinusoidal waves are identified. For each maximum sinusoidal wave identified, the pair a (half-wavelength) and b (amplitude) is compared to the manufacturing tolerance criterion (for example, Carmichael criterion). Thus, when a subsection can be characterized by a set of sinusoidal waves, then if at least one pair a (half-wavelength) and b (amplitude) characterizing a sinusoidal wave of the subsection does not meet the manufacturing tolerance criterion, then it is the entire subsection that does not meet this manufacturing tolerance criterion.

[0070] In one example, when the manufacturing tolerance criterion is based on the Carmichael criterion, for maintaining natural laminar flow, then the manufacturing tolerance criterion is a maximum wave amplitude value bmcu for a given half-wavelength value a.

[0071] It should be noted that the position of the non-conformity, or the failure to meet the manufacturing tolerance criterion, is important to identify the part of the part on which the flow laminarity is compromised.

[0072] Indeed, from this manufacturing tolerance criterion, the DISP 600 analysis device can identify and locate a defect (i.e., corresponding to a deviation of the actual shape compared to the theoretical shape) on the surface of the air inlet when the values ​​of b are greater than the authorized tolerance criterion. In the example above, the manufacturing tolerance criterion is based on the Carmichael criterion, so if b > b^ for a given then the maintenance of the natural laminar flow is compromised and it is necessary to implement actions to repair the identified defect.

[0073] For this, the analysis device DISP 600 generates an alert message intended for a human-machine interface (for example graphic and / or sound) used by an operator / technician. This alert message comprises, in a particular embodiment, information on the type of defect (e.g., holes, bumps, etc.) and / or information on the location of the defect, for example. Alternatively, this alert message further comprises at least one proposal for corrective actions that can be carried out by the operator / technician in order to repair the defect.

[0074] It is then possible for the operator / technician to apply the necessary actions to repair this defect at the level of the part, and in particular the engine air intake.

[0075] In other words, the analysis method as described above makes it possible to implement a method for repairing an aircraft part, in particular an engine air intake. In particular, thanks to the generation of an alert message including in particular a proposal for corrective actions, a technician / operator can carry out these actions for the repair of the aircraft part.

[0076] [Fig. 6] schematically illustrates an example of hardware architecture of the analysis device DISP 600, which then comprises, connected by a communication bus 610: a processor or CPU (“Central Processing Unit” in English) 601; a RAM (“Random Access Memory” in English) 602; a ROM (“Read Only Memory” in English) 603, for example a Flash memory; a data storage device, such as a hard disk HDD (“Hard Disk Drive” in English), or a storage media reader, such as an SD (“Secure Digital” in English) card reader 604; at least one communication interface 605 allowing the analysis device DISP 600 to interact with different systems for measuring the shape of an aerodynamic surface, such as the shape of a surface of an engine air intake of an aircraft.

[0077] The processor 601 is capable of executing instructions loaded into the RAM 602 from the ROM 603, from an external memory (not shown), from a storage medium, such as an SD card, or from a communication network (not shown). When the analysis device DISP 600 is powered on, the processor 601 is capable of reading instructions from the RAM 602 and executing them. These instructions form a computer program causing the processor 601 to implement the behaviors, steps and algorithm described herein.

[0078] All or part of the behaviors, steps and the algorithm described herein may thus be implemented in software form by executing a set of instructions by a programmable machine, such as a DSP (Digital Signal Processor) or a microcontroller, or be implemented in hardware form by a machine or a dedicated component (chip) or a set of components (chipset), such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specified Integrated Circuit). Generally speaking, the analysis device DISP 600 comprises electronic circuitry arranged and configured to implement the behaviors, steps and the algorithm described herein.

Claims

Claims

1. Method for analyzing a profile of a real shape of a 2D section of an aerodynamic surface of a part implemented by an analysis device (600), said method comprising: - adapting a geometric reference system (301) to match leading and trailing edges of the profile of the real shape (SR) to the leading and trailing edges of a profile of a theoretical shape (ST) of the 2D section of the aerodynamic surface of the part, the method further comprising an analysis phase comprising the following steps: - determine a deviation (302) between the profile of the real shape (SR) and the profile of the theoretical shape (ST) of the 2D section, - divide (303) the deviation into subsections, each subsection being defined by a part of the deviation comprising a start and an end corresponding to points for which a value of the deviation is zero, then for each subsection:(i) identifying (304) a maximum sine wave in line with the part of the deviation defining the subsection, to within a predefined margin, said maximum sine wave being characterized by a wave amplitude value b and a half-wavelength value a, (ii) when the wave amplitude value b is less than a predetermined minimum amplitude value bmin or when the half-wavelength value a is less than a predetermined minimum half-wavelength value amin, then stopping (305) said analysis phase for said subsection, otherwise, when the wave amplitude value b is greater than the predetermined minimum amplitude value bmin and the half-wavelength value a is greater than the predetermined minimum half-wavelength value amin (306),then perform a new iteration of the analysis phase by considering the identified maximum sine wave as a new 2D section of a theoretical shape of the aerodynamic surface, - at the end of the analysis phase, generate an alert message if the values ​​of wave amplitude b and / or wave gradient b / a of the maximum sine wave or if at least one value of wave amplitude b and / or wave gradient b / a of a set of maximum sine waves are greater than a manufacturing tolerance criterion.,

2. The method of claim 1, wherein the alert message informs an operator of the presence of a defect in the actual shape of the aerodynamic surface of the part, said alert message comprising a type of defect and / or a location of the defect in the actual shape of the aerodynamic surface of the part.

3. Method according to claim 2, in which the alert message further comprises at least one proposal for corrective action for said fault.

4. Method according to one of claims 1 to 3, in which the maximum sine wave comprises: - a start and an end identical to the start and the end of the subsection, - a wavelength 2a corresponding to a length of the subsection and - the amplitude b defining a maximum amplitude corresponding to an amplitude of the deviation of the subsection, to the predefined margin.

5. The method of claims 1 to 4, wherein the tolerance criterion is based on a Carmichael criterion for maintaining natural laminar flow at the aerodynamic surface of the part.

6. Method for repairing an aerodynamic surface of a part comprising: - analyzing a profile of a real shape of a 2D section of the aerodynamic surface of the part by executing an analysis method according to one of claims 1 to 5 and implemented by an analysis device (600), - repairing the aerodynamic surface of the part by an operator if an alert message is generated by executing the analysis method according to one of claims 1 to 5.

7. Device (600) for analyzing a profile of a real shape of a 2D section of an aerodynamic surface of a part comprising electronic circuitry configured to implement: - adapt a geometric reference frame (301) to match leading and trailing edges of the profile of the real shape (SR) to the leading and trailing edges of a profile of a theoretical shape (ST) of the 2D section of the aerodynamic surface of the part, the electronic circuitry is further configured to implement an analysis phase comprising the following steps: - determine a deviation (302) between the profile of the real shape (SR) and the profile of the theoretical shape (ST) of the 2D section, - divide (303) the deviation into subsections, each subsection being

8.

9. defined by a part of the deviation comprising a start and an end corresponding to points for which a value of the deviation is zero, then for each subsection: (i) identifying (304) a maximum sine wave in line with the part of the deviation defining the subsection, to within a predefined margin, said maximum sine wave being characterized by a wave amplitude value b and a half-wavelength value a, (ii) when the wave amplitude value b is less than a predetermined minimum amplitude value bmin or when the half-wavelength value a is less than a predetermined minimum half-wavelength value amin, then stopping (305) said analysis phase for said subsection, otherwise, when the wave amplitude value b is greater than the predetermined minimum amplitude value bmin and the half-wavelength value a is greater than the predetermined minimum half-wavelength value amin (306),then perform a new iteration of the analysis phase considering the maximum sine wave identified as a new 2D section of a theoretical shape of the aerodynamic surface, - at the end of the analysis phase, generating an alert message if the values ​​of wave amplitude b and / or wave gradient b / a of the maximum sine wave or if at least one value of wave amplitude b and / or wave gradient b / a of a set of maximum sine waves are greater than a manufacturing tolerance criterion. Computer program product, comprising instructions causing the execution, by a processor, of the method according to any one of claims 1 to 5, when said instructions are executed by the processor. Storage medium, storing a computer program comprising instructions causing the execution, by a processor, of the method according to any one of claims 1 to 5, when said instructions are read and executed by the processor.

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