Figure 1 Studied duct containing a porous material.
Related Figures (13)
Fig. 5. Representation of a duct containing two samples. Fig. 3. Flow chart illustrating the measure of acoustic properties. Fig. 4. Representation of a duct containing a single sample. Fig. 7. Real and imaginary of the coefficients of the transfer matrix for duct containing one rock wool specimen. Fig. 8. Real and imaginary of the coefficients of the transfer matrix for duct containing two rock wool specimen. This section describes the procedure used to measure matrices and acoustic indicators of the duct with rock wool material. These measurements were made in the Sound and Vibration laboratory in the University of Cairo at Ain Shams using SIDLAB platform in Fig. 9. Module and magnitude of the transmission coefficients for duct containing one rock wool specimen. Fig. 10. Module and magnitude of the transmission coefficients for duct containing two rock wool specimens. As the sample is symmetric, the matrix then contains only two unknowns instead of four. SIDLAB calculation code, which is In this section, we present the experimental results obtained with the reference sections: coefficients of the transfer matrix, Fig. 11. Module and magnitude of the reflection coefficient for duct containing one rock wool specimen. Fig. 12. Module and magnitude of the reflection coefficients for duct containing two rock wool. For test the developed method, the coefficients of the experi- mental transfer matrix were compared with those calculated For the coefficients of the transfer matrix presented in Figs. 7 and 8 and the exception of certain frequencies, the concordance of the real and the imaginary part of these coefficients between Fig. 13. The transmission loss (a) for duct containing one rock wool specimen (b) for duct containing two rock wool specimen. Fig. 15. Effect of the length of the sample in the conduit.
