Characterisation of the acoustic power level of a range of rectangular diffusers using a reduced number of tests (Inter-Noise 2000)

Résumé et principaux résultats

Inter-Noise 2000, Nice (France), Août 2000

Since the sound level requirements are increasingly strict, the characterisation of the acoustic performances of complete product ranges has become essential for the manufacturers. This is particularly true for ranges of air diffusion terminal units composed of a large number of different types and sizes and for which it would be prohibitively expensive to carry out exhaustive laboratory tests. CETIAT has studied the possibility of carrying out a reduced number of test in order to characterise a complete range of rectangular diffusers. The acoustic power level was measured on a grille model available in 7 different sizes, from 200x200 mm to 600x300 mm (4 flow rates for each one). Then, the regression relation was determined between the global dB(A) level and the air flow and the area of the grill. This relation gave an average error of 1 dB(A) with 82% of the deviations lower than 1.5 dB(A). The next step was to determine how many initial tests were necessary to determine the acoustic performances of the rest of the range with an acceptable error. The regression coefficients were calculated for all the possible combinations of 3 grilles (respectively 4), then the error committed on the other 4 grilles (respectively 3) was calculated.
These results show that 3 different sizes are sufficient to establish the regression coefficients for a given type of grille. In addition, if the 3 grilles used in the test are chosen intelligently so as to cover the different sizes and shapes (section and ratio of dimensions), the deviations observed over the rest of the range were among the smallest.

Commissions

Ventilation des bâtiments résidentiels et tertiaires

Thème

Ventilation et qualité de l'air

Mots-clés

Acoustique, Bouches et diffuseurs, Conditionnement d'air, Ventilation

Auteurs

BESSAC François