An experimental approach to the effective elastic bulk modulus of porous fibrous materials at intermediate flow regimes

摘要

In this work is accomplished a study of the complex elastic bulk modulus. This parameter has a complex imaginary part much less than his real part and because of this in phenomenological approximations is tended to employ the modulus. When the materials are rigid the problem is tended to simplify supposing than this equivalent fluid have an isothermal behaviour in low frequency and adiabatic in high frequency. So that this parameter is reduced to a constant function related with the static pressure of the air. But in practical situations the frequencies are intermediate and a review of these simplifications must be made. Because of this in this work the thermodynamic behaviour of the equivalent fluid has been checked experimentally, at intermediate frequencies and flow regimes. With this the elastic bulk modulus is adapted for the analysis of real rigid samples in any frequency.