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Silica Aerogel Granules Optimization

Classification Size range Median Density Distribution Aspect ratio [Pg.115]

The two-microphone impedance tube determines the ratio of absorption coefficient and complex reflection coefficient based on the transfer function between the two microphones. The integrated PULSE software that calculates the various data ensures that the sum of the two coefficients shall always conform to unity. The plots in Fig. 7.5b show that AG2 and AGS have the best absorption coefficients of 0.52 and 0.48, respectively, compared to the other sizes when measured at 15 mm thickness. The absorption coefficients lowered to 0.32 and 0.29, respectively, when the thickness is reduced to 10 mm as shown in Fig. 7.5a. Naturally it can be seen that mixed granules, AGMX, for which 70 % of the composition come from the two sizes mentioned, has an absorption coefficient that is close to both the 1.2 and 1.7 mm sizes. The porous ply shows negligible absorption similar to air. Table 7.2 lists the absorption coefficients abstracted from Fig. 7.5 at the center and maximum frequency. [Pg.117]

The absorption coefficient values at low frequencies from 50 to 200 Hz show erratic response for all the granule sizes. One possible reason is that the superpositions of incident and reflected waves at very low frequencies create a region of maximum particle velocity. This usually occurs at V wavelength and it is common practice among acoustics engineers who design noise attenuation panels. [Pg.117]


In the previous chapter, the optimized mechanical properties are achieved when 0.56 %wt. SDS was added to the GSA composites. The GSA-SDS composites of various aerogel granule sizes are fabricated with 0.56 %wt. SDS for gelatin to silica aerogel granules mass fraction ratios of 0.2 0.8 and 0.4 0.6 respectively. The effects of the granule size on the thermal conductivity are investigated for the temperature profile described in Sect. 6.1 is shown in Fig. 6.9. [Pg.92]


See other pages where Silica Aerogel Granules Optimization is mentioned: [Pg.115]    [Pg.119]    [Pg.115]    [Pg.119]    [Pg.69]    [Pg.78]    [Pg.118]    [Pg.625]   


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