Problems encountered in the prediction of flow-generated noise in hvac air distribution systems

In order to attain a satisfactory indoor environmental quality, the design of a HVAC air distribution system is not only determined by thermal requirements but also the acoustical requirements. Current design guides such as CIBSE guide and ASHRAE handbook have provided the design method for predicting the flow-generated noise in a HVAC air distribution system. However, these guides are based on the experimental works of a number of investigators who worked on a limited range of in-duct components and a limited range of duct sizes. Moreover, these guides are applied to an isolated element in a HVAC air distribution system. It is known that they underestimate the levels off low-generated noise in practical systems. In this paper, problems encountered in the prediction off low-generated noise will be discussed. Recent development of prediction methods for flow-generated noise will also be introduced.