(Commenced: 01-Jan-2007,Concluded: 12-Dec-2007)
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The
aim of this project was to develop a valveless pulsejet engine and thrust
measurement stand. The primary design specifications of the engine were to
produce 3kg of thrust and to weigh no more than 2kg. The
engine development was divided into two phases. The first phase involved the
development of an experimental engine which incorporated adjustable intake
and exhaust lengths to allow for optimisation. Engine design was possible
through the use of existing designs and isentropic fluid behaviour software.
The second phase involved the design and fabrication of an engine based upon
the optimisation results and a simulation program. This software used the
method of characteristics to provide an accurate prediction of the
performance of a simulated engine, taking into account the heat input through
the combustion process. A
test site leased from the Federal Government near RAAF Edinburgh was used for
the testing program. Sixty three static firings were completed over a period
of six days. Measurement of thrust and specific fuel consumption, as well as
video footage, was used to assess engine performance. The findings of which
are outlined in the report. The
first phase of testing produced a maximum thrust of 2.392kg, 20.3% less than
the desired 3kg but consistent with the results of the theoretical model.
Testing revealed the engine attained a maximum thrust at a total engine
length of 1035mm. Self sustaining combustion was achieved for eleven other
intake and exhaust combinations. This contradicted the findings of the
literature review which suggested self sustaining operation was highly
dependant on engine geometry. The
second phase of testing was unable to obtain self sustaining operation.
Resonance was achieved on five of the thirteen tests, but the engine failed
to operate unassisted. The reason for this is unknown. The omission of flares
from this design and the larger exhaust and intake tubes are thought to have
contributed to lower intensity pressure waves within the engine. These
pressure waves are critical to engine operation. This
project succeeded in designing, building and operating a pulsejet engine,
while simultaneously developing a software program to model pulsejet
operation. Further research in both these areas is required if a UAV is to be
developed. Project DeliverablesImage Galleries: |
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