Publisher
Florida Atlantic University
Description
For aerospace and naval applications where low radiated noise levels are a
requirement, rotor noise generated by inflow turbulence is of great interest. Inflow
turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have
a significant impact on the noise source levels. This thesis studies the distortion of
subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur
when a rotor is embedded in a turbulent boundary layer. The analysis is based on Rapid
Distortion Theory (RDT), which describes the linear evolution of turbulent eddies as they
are stretched by a mean flow distortion. Providing that the gust does not distort the mean
flow streamlines the solution for a mean flow with shear is found to be the same as the
solution for a mean potential flow with the addition of a potential flow gust. By
investigating the inflow distortion of small-scale turbulence for various simple flows and
rotor inflows with weak shear, it is shown that RDT can be applied to incompressible
shear flows to determine the flow distortion. It is also shown that RDT can be applied to more complex flows modeled by the Reynolds Averaged Navier Stokes (RANS)
equations.