Accurate airborne noise source levels for Navy standard fan coil assemblies and fan coil units

摘要

Highly accurate measurements of the airborne noise source levels for Navy standard fan coil assemblies (FCA's) and fan coil units (FCU's) used in the design and construction of heating ventilation and air conditioning (HVAC) systems aboard ships have recently been performed. The methods used to measure sound pressure levels and derive sound power levels are similar to the procedures defined in reference [1], with a few modifications. As a result of the measurements, accurate sound power levels radiated from the inlet air openings, the discharge air openings, and the casings of Navy standard FCA's and FCU's are now available to assist acousticians in the design of appropriate noise mitigation measures for shipboard HVAC systems. Measurements reveal that the total sound power levels for Navy standard FCA's and FCU's are significantly higher than previously stated in test reports for equipment items of identical configurations. This paper describes the previous and the recommended equipment arrangements, sound pressure measurement procedures, and sound power derivation procedures that can be applied to define noise source characteristics for FCA's and FCU's. Results obtained using the recommended procedures including measured sound pressure levels and derivations of inlet, discharge, casing, and total sound power levels for Navy standard FCA's and FCU's are presented.