METHOD AND DEVICE FOR DETERMINING CRITICAL BUFFETING LOADS ON A STRUCTURE OF AN AIRCRAFT

• US 20100312497A1
• Filed: 05/27/2010
• Published: 12/09/2010
• Est. Priority Date: 06/03/2009
• Status: Active Grant

• Current Assignee: Airbus Operations (European Aeronautic Defence and Space Company EADS NV)
• Original Assignee: Airbus Operations (European Aeronautic Defence and Space Company EADS NV)
• Inventors: Despre-Flachard, Carole, Soumillon, Stephane, Havas, Juliane, Jenaro Rabadan, Guillermo
• Granted Patent: US 8,255,174 B2
• Time in Patent Office: Days
• US Class Current: 702/42
• CPC Class Codes: G01M 9/04 Details
• CPC Class Codes: G01M 9/06 Measuring arrangements specially adapted for aerodynamic testing
• CPC Class Codes: G01M 9/08 Aerodynamic models

Abstract

A method and device for determining critical buffeting loads on a structure of an aircraft is disclosed. The device (1) comprises means (2, UC) implementing a semi-empirical method for determining the critical loads generated by some buffeting on the structure of the airplane.

Claims

1. A method for determining critical loads generated by buffeting on a structure (S) of an airplane (A), said method comprising:

a) conducting trials in a blowing unit on an airplane model, said trials comprising;

simulating conditions for which some flow burble occurs on at least one part of a surface of the airplane (A); and

carrying out, for such conditions, measurements using stationary pressure sensors, instationary pressure sensors and accelerometers arranged on said model;

b) using at least some of such measurements, the flow burble areas are determined on said structure (S) of the airplane (A);

c) implementing an aerodynamic model for determining, using the measurements from steps a), in the flow burble areas as determined from step b), a pressure field resulting in the structure (S) buffeting;

d) integrating the determined pressure field so as to obtain the overall stresses and moments generated by buffeting;

e) calculating, using such overall stresses and moments, the stresses that the structure (S) is to bear, such stresses comprising aerodynamic stresses caused by buffeting, induced aerodynamic stresses, inertia stresses and damping stresses; and

f) determining the critical loads due to buffeting using the stresses as calculated in step e).

2. A method according to claim 1, wherein in step b), flow burble areas are determined, additionally using data obtained from simulations.

3. A method according to claim 1, wherein in step c), additional instationary pressure signals are determined using an interpolated amplitude of pressure signals as obtained from step a), and a cross-correlated random phase.

4. A method according to claim 3, wherein in step c), said additional instationary pressure signals are determined using analytical functions illustrating space correlations between the signals.

5. A method according to claim 4, wherein said additional instationary pressure signals are defined at the intersections of a predetermined grid (G) being associated with said structure (S).

6. A method according to claim 1, wherein in step c), the additional instationary pressure signals are converted from particular conditions relating to trials in a blowing unit into flight conditions.

7. A method according to claim 1, wherein in step d), first of all, the pressure field is integrated according to the chord of said structure (S), then the result being obtained is integrated according to the span of the structure (S), so as to obtain said overall stresses and moments.

8. A method according to claim 1, wherein in step e), a model of finished elements and an aerodynamic model are used, taking into consideration the effects of the aerodynamics as induced by the structure (S) vibration.

9. A method according to claim 1, wherein, for determining the critical loads generated by some buffeting on a structure representing an elevator unit (S) of the airplane, in step f):

the same excitation is applied both on the right and on the left of the airplane;

a scan is implemented with a constant phase shift; and

a time delay is introduced in the signals.

10. A device for determining the critical loads generated by some buffeting on a structure (S) of an airplane (A), said device (1) comprising:

first means (2) for conducting trials in a blowing unit on a model of an airplane, said trials comprising simulating conditions for which some flow burble occurs on at least one part of a surface of the airplane (A), and carrying out, for such conditions, measurements using stationary pressure sensors, instationary pressure sensors and accelerometers being arranged on said model; and

second means (4) for determining, using at least some of such measurements, flow burble areas on said structure (S) of the airplane (A);

third means (5) for carrying out an aerodynamic modelling so as to determine, using the measurements as implemented during trials in a blowing unit, in the flow burble areas as determined by said second means (4), a pressure field, generating some buffeting of the structure (S);

fourth means (7) for integrating the thus determined pressure field so as to obtain the overall stresses and moments generated by the buffeting;

fifth means (9) for calculating, by means of such overall stresses and moments, the stresses the structure (S) is to bear, such stresses comprising aerodynamic stresses generated by buffeting, induced aerodynamic stresses, inertia stresses and damping stresses; and

sixth means (11) for determining the critical loads generated by buffeting using the stresses as calculated by said fifth means (9).