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The propagation of intense acoustic beams at large Reynolds numbers having a complex temporal and spatial structure is studied experimentally. An experimental setup based on the automatic measuring system of Precision Acoustics (Ultrasound Measurement System Control Center) is described. The experimental technique used makes it possible to investigate the propagation of beams at large acoustic Reynolds numbers. The absolute accuracy of the displacement of the receiving system in the volume under study is 6 μm. The installation uses PVDF-membrane hydrophones, which allow to correctly carry out absolute measurements in the frequency range up to 100 MHz. The results of the following cycles of experiments are discussed. . Degenerate parametric interaction in intense acoustic beams. It is shown that at large times the field has a universal structure, determined only by the period of the wave. Degenerate parametric interaction of an intense acoustic pump beam and a weak signal beam on a subharmonic. It is shown that the use of the energy of higher odd harmonics makes it possible to substantially increase the amplification efficiency of a weak signal. Evolution of noise quasimonochromatic beams at large Reynolds numbers. It is shown that the nonlinear interaction in the propagation of the noise signal leads to the appearance of new harmonics whose width increases with the number of the harmonic and at high frequencies a continuous power spectrum is formed. Diffraction of a nonlinear beam on a flat screen and a circular hole. It is shown that, because of the different diffraction divergence of the beam harmonics, a significant distortion of the wave profile occurs. This work was supported by a grant from the Russian Science Foundation № 14-12-00882.
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