Abstract

The Difference Frequency Doppler Tomography of Bubble Streams

I.Didenkulov (Institute of Applied Physics RAS, Nizhny Novgorod, Russia); L.M.Kustov, A.I.Martyanov, N.V.Pronchatov-Rubtsov (Nizhny Novgorod State University, Nizhny Novgorod, Russia); S.W.Yoon (Sung Kyun Kwan University, Suwon, Republic of Korea)

e-mail: din@hydro.appl.sci-nnov.ru

In the present paper a method of bubble diagnostics based on the difference frequency scattering is considered. It is described the specific Doppler effect for the difference frequency scattering. This allows one to detect bubbles and measure their velocities. For low-density bubble populations such measurements can be done in the approximation of given primary waves. For dense bubble streams it is necessary to take into account attenuation of primary waves at bubbles inside the jet. The nonlinear acoustic Doppler tomography method for measurement of the velocity distribution across the stream of liquid is described. It is based on measurement of Doppler frequency spectrum of the difference frequency acoustic wave scattered from the bubble stream and it comparison with the model spectrum. Numerical model was developed in the approach of the axially symmetric bubble concentration distribution in the cross section of the jet. Experimental measurements were done in a water tank with a submerged cavitation water jet. The results of the work demonstrate the possibility of remote nonlinear acoustic Doppler tomography of bubble streams, which can find different applications. This work was supported by the RFBR grants 01-02-17653 and 01-02-16938.

Section : 4