Prediction of train interior noise due to the HVAC system

In recent years, the significance of acoustic comfort in rail vehicles has grown considerably, owing to its direct impact on passenger well-being. As a consequence, interior noise levels are progressively becoming more restrictive. Meeting these requirements is a key challenge for rolling stock manufacturers. The predominant source in stationary condition is the HVAC (Heating, Ventilation, and Air Conditioning) system. To effectively assess and potentially reduce the noise generated by the HVAC system, the availability of tools and methodologies for predicting the propagation of noise through the air ducts and interior noise levels in the passenger compartment during the design phase is crucial. This paper presents a simulation methodology for predicting interior noise levels by evaluating various alternatives within a commercial software. Input data for the simulations encompass the geometry and materials of the supply and return ducts, along with the acoustic power of each outlet measured at the source. This data is associated with the nominal operating mode of the HVAC system. Finally, the paper establishes a correlation between the simulation results and in-situ measurements conducted on the completed train, with the HVAC equipment operating under nominal conditions.