PROBLEMS OF VIBROACOUSTICS FOR NEW AIRPLAN GENERATION

摘要

Substantial noise redistribution has occurred in the aircraft of new generation. While jet noise has been reduced dramatically, the engine still remains the basic source of noise, which is a fan noise. In the forward hemisphere, beside the discrete components at fan blade frequency, long row of discrete components has been observed around the principal blade frequencies as result of Shockwave influence. This phenomenon is called "buzz-saw noise". Fan shaft frequency reduction is one of the necessary measures for Shockwaves control. Due to the decrease of frequency vibration spectrum shifts towards the low-frequency range. Such components will determine dynamical impact spectrum of power plant, transmitted through mounting to airframe construction. An airframe typically possesses dozens of oscillation modes in the low-frequency spectrum part. Interaction of some of them with the influence of power plant may generation of discrete low-frequency high-level noise components in cabin. Selecting power plant for airplanes of new generation, beside solving the problems of community noise, should include developing a high-performance system of vibroprotection of crew and passengers for the maintenance of comfortable conditions and flight safety.