Acoustic modelling of a propeller subject to non-uniform inflow

Understanding radiated noise from marine propellers is of interest from the point of view of mitigating sound pollution and avoiding detection. At the design stage this can be achieved using acoustic tools such as the Ffowcs Williams Hawkings (FW-H) acoustic analogy. However, these have not yet been widely adopted and thoroughly tested for realistic configurations in the marine context. The current work presents a systematic study of applying the porous FW-H method, coupled with a viscous RANS solver, to the INSEAN E779A propeller in a wake field, in both cavitating and non-cavitating conditions. The aim is to understand sensitivity of the analogy to the definition of the porous data surfaces and key simulation parameters, such as time step and grid resolution. These will in turn provide baseline guidelines to be used in subsequent work devoted to fully appended ship predictions. The results indicate that particular care must be taken to define the porous data surfaces in such a way so as to minimise the amount of upstream vorticity penetrating them while ensuring the effect of noise-generating flow features is aptly captured.