Acoustic Radiation Study of Wind-Induced Aerodynamic Noise From a Large Cruise Ship Chimney Based on the CAS-RTM Method

The cruise ship’s chimney, situated at the highest position of the top deck, is susceptible to aerodynamic noise induced by the sea’s wind field, thus affecting the comfort of passengers on the open deck. This study conducted real measurements on wind-induced aerodynamic noise from a large cruise ship chimney. Based on offshore wind conditions, CFD simulations were conducted to derive the surface pulsation pressure, which in turn was input to the acoustic boundary elements and translated into a compact sound source. Then, employing the Compact Acoustic Source combined with the Ray Tracing Method (CAS-RTM), the acoustic radiation impact of the aerodynamic sound source on the open deck was predicted and analyzed. The predicted outcomes were validated through comparison with measured results, and finally, the aerodynamic shapes of the chimney were optimized. The results highlighted the effectiveness of the CAS-RTM method in obtaining a directional aerodynamic noise source and realizing sound propagation in an open acoustic environment. The directivity of the aerodynamic noise source primarily manifests on the left and right sides of the chimney, with radiated sound pressure exhibiting an increase and then decrease with rising frequency, peaking at 315 Hz. Both aerodynamic optimization schemes enhanced flow separation and vortex shedding while mitigating pulsation pressure distribution. Optimization I demonstrated the largest reduction of 3.172 dB, mainly at position 1 on the front side of the chimney. Conversely, Optimization II exhibited the greatest reduction, measuring 4.414 dB, at position 6 on the rear side of the chimney. This study can provide some instructive insights for the prediction and control of aerodynamic noise from cruise ship chimneys.