| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系 === 85 === Hydrazine/Shell 405 thruster is a simple, steady, and
repeatable system.It has been used on attitude control and
orbital transfer systems forspacecraft. Because the starting
characteristic of the thruster affectsthe effectiveness of
thruster''s pulse operation, this thesis researchfocused on
the change of the response time of the thruster(ignition delay)
by variating the temperature of the feed propellant. The ideal
and steady-state performance of the thruster based on the
chamber pressure andtemperature measurements are also
calculated. Hydrazine was heated by a thermostatically control
system to keep thetemperature of the feed propellant at
steps of 30, 40, 50, 60℃. Inreaction chamber, a peizo-
electric pressure transducer was used to observethedynamic
pressures at the starting period. The voltage .vs. time
signalfrom the piezo-electric pressure transducer was adopted
to define theignition delay and compared to the static
chamber pressure traces. Inaddition, a series of experiments
with different configurations of thecylindrical catalyst bed
were performed to observe the changes of chamberpressure,
temperature, and the extent of ammonia dissociation (x).
Thesedata were used to estimate the thrust and specific impulse
of the thruster.The results showed :(a) With a constant
catalytic bed load, increasing the diameter of the bed
shortened the ignition delay. The delay time of the 15mm bed
diameter was 16% longer than that of the 20mm''s.(b) A higher
propellant feed temperature showed a shorter ignition delay.
The delay time decreased about 80% at 60℃than that at 30℃.(c)
When the propellant temperature was increased from 30℃ to 60℃,
the extent of ammonia dissociation (x) was increased about
3∼5%. The values of x in the present experimental
configurations were ranged in 0.52∼0.58.(d) Increasing the
propellant feed temperature decreased the chamber
pressure and temperature slightly, as a result, the calculated
thrust and specific impulse were also decreased. The
calculated values decreases about 4% at 60℃than that at
30℃.
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