Simulation of HVAC flow noise sources with an exit vent as an example

The control of flow noise is an important design aspect nowadays in the HVAC industry. However, acoustic design has largely been based on trial and error, which leaves the physical mechanisms responsible for the noise problems unexplained. Thus, a method is needed to analyse these mechanisms. The standard flow-modelling software used in industry misses the link between the flow and the far-field sound pressure. In the automotive and aviation industry, acoustic solver software products have been introduced to cover this gap. In this paper, a trade-off solution is proposed based on using standard flow simulation software to simulate the transient acoustic source field. This approach can be used to tackle some basic questions like where the noise is generated, which of the alternative geometrical variations is likely to produce least noise, or whether there could be distinct tones present at some frequencies. Source field analysis is also a useful intermediate phase prior to implementing an acoustic solver.