ESDU 11005:2011

$62.40

Prediction of Near-Field and Far-Field Harmonic Noise from Subsonic Propellers with Non-Axial Inflow

Published By	Publication Date	Number of Pages
ESDU	2011-07	NA

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Category: ESDU

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Description

ESDU 11005 introduces a computer program for estimating the
noise from an isolated single rotating propeller in uniform motion
or stationary in a lossless atmosphere without temperature
gradients or wind. Thickness noise and noise due to tangential and
axial loading are treated. The airflow need not be parallel to the
propeller axis. The observer may be stationary or on the aircraft
which may be climbing or descending. Noise due to non-linear
effects arises at tip relative Mach numbers exceeding 0.9 but is
neglected in the program. Input required includes the radial
distributions of chord, thickness, blade angle, coordinates of the
mid-chord line, relative Mach number, air angle, and the steady and
unsteady drag and lift coefficients. If unsteady lift and drag
coefficient distributions are not available, an option is provided
to have the lift distribution calculated within the program using
the method of ESDU 96027. The omission of the drag coefficient
distribution is thought to have a negligible effect on the noise
calculation in comparison with the lift coefficient distribution.
There is an option to output results in either reception
coordinates (based on the location of the propeller when the noise
reaches the observer) or emission coordinates (based on its
location when the noise was emitted). Details of the input and
output format are illustrated by a worked example.