Numerical Simulation Panel Vibrations of Aircraft When the Effect of Acoustic Pressure Oscillations
Keywords:
thin-walled shell, acoustic pulsations aerodynamic pulsations, vibration, power spectral density.Abstract
Investigation vibration characteristics of thin-walled shell when excitation of randompressure fields defined of wall pressure fluctuations in a turbulent boundary layer at flow regime of maximum dynamic pressure and fluctuations induced by the noise of a jet engine at the start. Is assumed that the noise from the jet engine is described a longitudinal acoustic wave propagating along the product's enclosure and diffuse acoustic field, in particular emerging as a result reflection of acoustic waves from the launch facility. As a thin-walled structure is considered streamlined panel fairing products made of a composite materials. In structure of the panel, except shell, included reinforcing circumferential ribs with two frames. The mathematical model presented for described external effects and algorithms for determining of a random vibration characteristics when exposed to fields random pressure. The calculation of the frequency response of the system is produced by the superposition of forms. The spatial correlation function of wall pressure fluctuations in turbulent boundary layer is determined according to the expression Corcos, in which the coefficients the damping of the spatial correlation function are corrected according to the model Efimtsov. The spectral density of wall pressure fluctuations in the turbulent boundary layer is determined according to the model Efimtsov. The levels sound of acoustic pressure caused by the noise of a jet engine at the start is determined by calculating of gas dynamics, and are given as the initial data. It shows the spectral characteristics of the vibration acceleration thin-walled structure depending on the frequency and distribution of the surface of the structure in a neighborhood of the central frequency at which there is maximum loading. It is assumed that the calculated levels of loads will be used as loading conditions during experimental testing of parts.
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