dc.description.abstract |
In-service performance deterioration of gas turbine engines
can be identified, at the engine module level, in terms of
reductions in the component mass flow and the efficiency.
Continued operation of a deteriorated gas turbine is (i)
uneconomical and (ii) unsafe. Timely identification of the
faults and ensuing maintenance could prevent both. Gas Path
Analysis is a technique to establish the current performance
level of the gas turbines and identify the faulty modules.
Computer models can predict the off_design performance of gas
turbines by aero-thermo-dynamically matching the engine
components. This thesis describes the development of DETEM
(DEeteriorated Turbine Engine Model), a generalised computer
program, developed to model degraded gas turbine engines and
analyse faults.
The program has an integrated graphics module and creates
windows on the VDU terminal,for displaying the program output
and accepting the user input. This enables the user to compare
the results of two different types of runs at the same time.
The program incorporates sensor models that modify the output,
with noise and in bias, based on the sensor characteristics,
thus simulating a real engine. It is possible to simulate the
engine performance at design point, off-design and under
transient conditions. The runs could be for a "clean" and a
deteriorated engine.
Three techniques, iterative, fault coefficient matrix, and
a statistical best-estimation technique, have been used to
analyse the engine performance and identify the fault.
Analysis of two and three shaft turbo-shaft engines and two
spool turbo-fan and turbo-jet engines have been worked out in
the thesis. Effects of reducing the number of measurements and
measuring different engine parameters, on the accuracy of the
fault identification, have been studied.
The program is considered to have a potential for the
generation of fault trees for rule-based expert system
applied to gas turbine diagnostics. Because of the controlled
output to the screen, a direct comparison of two different
runs side by side, on the same screen, makes the program a
good teaching aid for gas turbine diagnostics. |
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