A designer friendly approach to simulating HVAC noise

Heating, ventilation, and air-conditioning (HVAC) ducts typically run into a few tens of meters especially in commercial and occasionally in residential accommodations. The flow path should be minimally obtrusive for the performance. That being the case any acoustic energy from mechanical components like compressors, booster fans, and others can easily reach the occupants causing acoustic discomfort. This is even more critical with large ships where you find multitude of these components to move air across the different sections. Front loading the design of the ducting through simulation is an obvious cost-effective approach. Building and solving finite- or boundary-element models could be computationally expensive. As such, empirical models based on standards such as ASME and SNAME have been in use. The models have spread-sheet look and feel, with manual editing for various dimensions of the ducting sections. This is potentially error-prone and time consuming, especially for large systems such as ships and submarines. A few weeks to months for a section of the ship is not un-common. In this paper the authors continue to rely on rules from these standards and propose a methodology that exploits automation and ray-tracing techniques, to reduce model build and analysis time to a few hours.