ABSTRACT
The hybrid propulsion has the superiority of safety (Non-explosive), simplicity (high
reliability), low environmental pollution and available technology over traditional solid
and liquid propulsion, all these benefits have a tendency to low cost and laboratory
work. Classical hybrid rocket motor (HRM), however have suffered from slow fuel
regression rate, relatively poor combustion efficiency and still in search of safety
ignition system.
The direct goal of the paper is to realize a functioning test, evaluating the
performance of a designed Small-Scale Hybrid Rocket Motor (SSHRM) and
prepared for laboratory firing tests. Moreover, the objective is extended to examine
different types of ignition methods (pyrotechnic charge, fuse wire, heat wire and
finally hot oxidizer method by using heat exchanger), which are proposed as very
safe ignition method and finally recognize phenomena of re-start operation. Various
fuel grains with different configuration of Polyethylene (PE), metalized PE (PE+AL)
and Polymethyle-methacrylate (PMMA) were developed and it is decided to use the
commercial gaseous oxygen, for its availability and low cost.
A SSHRM has been designed, manufactured and tested at various conditions with
high level of safety. Ignition by hot air has been proved to be a very attractive ignition
method for SSHRM, for its higher safety, higher reliability and acceptable delay time.
Adding Al powder to PE fuel proved to have more smooth fuel grain surface with less
plume soot, higher regression rate and combustion efficiency, less combustion
instability, ignition delay time and nozzle life compared with pure PE combustion.
Finally; the re-start operation was demonstrated several times and can be carried out
more easily with hot air ignition method.