For many years the analysis of dynamic signals obtained from aero engine mounted transducers has been performed either by
using real time spectrum analysers within the test facility, or
by making high quality tape recordings during engine tests and
analysing the data via an off-line main frame computer.
Although real time analysers produce the information where it
is most needed, they provide no history of events and the
results are operator dependent. Analysis from tape recordings
enables information extraction algorithms to be performed and
tables and graphs of notable events to be printed. However
much of this information could be more effectively utilised if
produced within the test facility and in real time. This
thesis describes the design and development of a real time data
acquisition, signal processing and information extraction
system ideally suited for engine health and performance
monitoring within test facilities.
The thesis begins with a detailed description of the problems
encountered in dynamic signal analysis in the field of aero
engine performance testing, and with an overview of digital
signal processing and the latest technology signal processing
micro processors that have made this project possible. It then
describes the problems encountered and the subsequent solutions
found during the design and development of the hardware and
software needed for the·high bandwidth data acquisition and
fast signal processing algorithms.
The fast Fourier transform has been used for very many years in
the field of spectrum analysis, ... however this technique has
limitations which are overcome by some of the more modern
spectrum estimation techniques. This thesis makes an assessment
of some of these techniques, noting particularly their
performance on aero engine type signals. The results of these
tests are recorded and the possible use of the techniques in
aero engine analysis is discussed.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.