Radiation of higher order modes from circular ducts with flow

This work aims to predict the transfer function of a given modal content inside a circular duct with a bellmouth inlet in the presence of a mean flow. The transfer function is the relation in amplitude and phase between a given mode inside the duct and an observer located in the far-field. The numerical solution is obtained by finite element simulation in which the mean flow is input data. Verification is provided by comparison to the analytical solution of an unbaffled circular duct with uniform flow. Influence from various parameters such as the geometry and mean Mach number on the radiated pressure field is investigated. The analytical solution is a good approximation for finding the radiated principal lobe, and the inlet geometry is found to be more important than other parameters such as mean flow when static inlet configuration is studied.

Automated summary

This work aims to predict the transfer function of a given modal content inside a circular duct with a bellmouth inlet in the presence of a mean flow. The transfer function represents the relation between amplitude and phase of a given mode inside the duct and an observer located in the far-field. A numerical solution is obtained through finite element simulation with the mean flow as input data. Verification is done by comparing with the analytical solution of an unbaffled circular duct with uniform flow. The study investigates the influence of various parameters such as geometry and mean Mach number on the radiated pressure field. The analytical solution serves as a good approximation for determining the radiated principal lobe, and the inlet geometry is found to be more significant than other parameters when studying static inlet configuration.