Influence of the mounting conditions of air diffusion terminal units on their acoustic performances (Inter-Noise 2000)

Résumé et principaux résultats

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

The in situ acoustic performances of air diffusion terminal units sometimes differ greatly from those measured in the laboratory in accordance with the ISO 5135 standard. This stems from the fact that the standard assumes that the grilles (or diffusers) will have a very large air supply plenum, while in practice they are connected to a small plenum, which radically alters their acoustic power level performances. CETIAT has tested a grille equipped with a plenum whose dimensions could be varied: length of the plenum, branch connection diameter and position of the branch connection (rear or side). Each parameter could have two states representative of the true situation found in the field.
The purpose was firstly to determine the acoustic performances for each configuration and then to rank the importance of each parameter. These tests show that a grille's sound level can increase by approximately 15 dB(A) when a plenum is added, even though the latter is in its optimal configuration. The increase in sound level reaches 20 dB(A) between the plenum's two extreme configurations. These results confirm that the performances of grilles are radically modified by the type of plenum it is connected to. Regarding the
dimensions used in the tests, the analysis also shows that the most influential parameter is the position of the branch connections, followed by the branch connection diameter and finally, the length of the plenum.

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