| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 102 === Effects of inlet channel angle on the gas feeding dynamics in pulsed
detonation cycle in a micro pulsed detonation engine were investigated in the
study. Stoichiometric of ethylene/oxygen were used and high-speed
cinematography were applied to observe the flame propagation in mixing
section and inlet manifolds upstream of the ignition spot. Laser shadowgraph
was also utilized to analyze the shock propagations in the manifolds.
It can be found that both of 60° and 90° were typical detonation wave, and a
low-speed detonation mode in 30° case. By using a gas chromatography(GC)
to measure the mixing status in different angle cases. The equivalent ratio
decreased with inlet angle increase. It can be seen that with the smaller inlet
angle, there were an intense shock wave propagating back into the inlet
manifolds. With 90° inlet angle, the shock wave could only propagate until
the cross section, and the expansion resulted in the dissipation of the shock. A
dynamic pressure sensor was installed on the oxygen feeding channel to
quantify the pressure evolutions in the inlet manifold. The results showed that
the shut-off duration for the 30° to 90° inlet was about 306, 219 and 299 us
respectively. And reduce to 281, 266 and 270 us by increasing supply
pressure. Comparison of single shot and continuous operating of 70 Hz, there
were the slowest reaction wave velocity in the inlet section. A cavity design
has been apply in the manifold. It can be seen that the shock wave in oxygen
manifold were not obvious in cavity case. And the value of peak pressure
were 0.45 MPa in original design but there were only 0.12 MPa in cavity case.
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