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Nonlinear propagation of the sonic boom wave through the atmosphere turbulent layer

Enflo B. O., Rudenko O. V.

Hydroacoustics

1999

Vol. 2

263--266

A new analytical approach to the statistical theory of sonic boom propagation through randomly inhomogeneous media is developed on the base of nonlinear evolution equations. The turbulent atmosphere layer is modelled by a random phase screen. A new Burqers' type equation is derived for arbitrary speeds of supersonic aircrafts using nonlinear geometrical acoustics approximation. The average peak pressure, squared pressure and dispersion of fluctuations are calculated, as well as statistical distributions for peak pressure and its outbursts. It is shown that in spite of decrease in the main characteristics of the N-wave, the fluctuations can increase and lead to the appearance of undesirable outbursts.

Sound beams with shockwave pulses

Enflo B. O.

Hydroacoustics

1997

Vol. 1

75--78

The beam equation for a sound beam in a diffusive medium, called the KZK (Khokhlov-Zabolotskaya-Kuznetsov) equation, has a class of solutions, which are power series in the transverse variable with the terms given by a solution of a generalized Burgers' equation. A free parameter in this generalized Burgers' equation can be chosen so that the equation describes an N-wave which does not decay. If the beam source has the form of a spherical cap, then a beam with a preserved shock can be prepared. This is done by satisfying an inequality containing the spherical radius, the N-wave pulse duration, the N-wave pulse amplitude and the sound velocity in the fluid.