Theoretical Analysis of the Transient Response of a Wing to Non-Stationary Buffet Loads (Analyse Theorique de la Reaction Transitoire d'une Aile Soumise au Buffeting Non-Stationnaire)
NATIONAL AERONAUTICAL ESTABLISHMENT OTTAWA (ONTARIO)
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A method for predicting the response of a wing to non-stationary buffet loads is presented. The wing is treated as a cantilever beam with known mass distribution. Using generalized co-ordinates, the vibration of the wing is governed by the second order mass-spring-damper oscillator equation. The buffet load on the wing is expressed as an integral of the sectional force, which is a function of the spanwise location and time. The non-stationary load is represented by the product of a deterministic time function and a statistically stationary random function. The time history of the applied load is segmented into a number of time intervals. Analytical expressions for the mean square response of the wing displacement are derived using a power spectral density for the random part of the applied load, similar to that used in the theory of isotropic turbulence. The effects of damping, ratio of the undamped natural frequency of the system to the half power frequency of the power spectral density, length of time segment, and duration of applied load on the response of the wing have been investigated for three examples of the load versus time histories.
- Fluid Mechanics