Abstract

Propagation of Sonic Booms Through the Turbulent Boundary Layer of the Atmosphere

V.A.Gusev (Department of Acoustics, Faculty of Physics, Moscow State University, Moscow, Russia);

e-mail: vagusev@newmail.ru

The propagation of sonic booms through the turbulent atmosphere leads to the appearance of high-pressure outbursts which are dangerous for living beings and constructions located on the ground. A new analytical approach is developed to describe the sonic boom transmission through a layer of turbulence based on new nonlinear equation. The most intense fluctuations of atmospheric parameters are known to be concentrated near the ground in the boundary layer of the atmosphere, and the thickness of this layer is small compared with typical altitudes of aircraft flight. In this case the turbulent layer can be replaced by a random infinitesimally thin phase screen. Behind the phase screen the propagation of sonic boom inclined at the arbitrary angle is described by nonlinear evolution equation, where the diffraction processes are considered, so the focal region and other singular regions of geometrical acoustics may be described. The statistical characteristics of sonic boom wave are derived. Dependencies of the peak pressure and dispersion of pressure on phase fluctuation are considered. It is shown that in spite of decrease in the average peak pressure, the pressure dispersion increases with increase in the phase dispersion, so the probability of arbitrary large outbursts caused by atmosphere turbulence essentially differs from zero.

Section : 6