The use of acoustic measurement method for the registration of the vortex structure of flows in channels of complicated geometry

Аuthors

Mitrofanova O. V.^{1, 2*}, Pozdeeva I. G.^{1, 2**}

1. ,
2. National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoe shosse, Moscow, 115409, Russia

*e-mail: omitr@yandex.ru
**e-mail: pozdeeva_irina@mail.ru

Abstract

The results presented in this paper are obtained in the course of the program of experimental studies aimed at studying the mechanisms of generation of acoustic oscillations in vortex and swirl flows and determining the relationship of the vortex structure of flows with acoustic phenomena. For this purpose, the designs of two experimental facilities, working areas, vortex generators, as well as methods of experimental measurements of frequency characteristics of acoustic oscillations due to the generation of large-scale vortices in channels of complex shape in water and air media were developed. Measurements of the frequency of acoustic oscillations and visualization of the vortex structure of the flow make it possible to identify the conditions for the development of resonant phenomena in working models simulating the elements of the equipment of the thermal-hydraulic path of power plants. The instrument complex and broadband sensors for registration of acoustic signals during generation of local vortices in channels of complex shape have been developed. The tests determined the operating frequency range, non-uniformity of amplitude-frequency characteristics, and dynamic range of signal amplitude measurement. A measurement scheme is proposed to determine the parameters of quasi-stationary vortex structures. Methodological issues related to the allocation of signals against the background of noise due to the turbulent flow regime are solved. Theoretical analysis using the approximation of acoustic flow and the theory of screw flows and a comparison of experimental and calculated results are the justification of the proposed physical model of the flow, predicting the appearance of acoustic resonances due to the topology of the vortex flow.

Keywords:

fluid dynamics, vortex structures, swirl flow, acoustic oscillations, experimental measurements, amplitude­frequency characteristic, acoustic cavitation, resonance effects, physical mathematical modeling

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