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