• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.474-478
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• 2010

Hybrid rocket combustion experiments using liquefying diaphragm made by blended liquefying fuel with 10 wt% of LDPE were performed. Results of experiments were compared to the those of pure paraffin. In case of using liquefying diaphragm, regression rate of rear fuel grain, characteristic velocity and specific impulse highly increased due to the induced turbulent intensity and heat transfer. The serious combustion instability was not observed in analysis of combustion instability. These results can imply that the liquefying diaphragm is efficient to improve low combustion efficiency in hybrid rocket using liquefying fuel.

• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.147-153
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• 1998

The strain characteristics of a fiber optic Fabry-Perot pressure sensor with high sensitivity using a $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$ (N/O/N) diaphragm is experimentally investigated. A 600 nm thick N/O/N diaphragm was fabricated by silicon anisotropic etching technology in 44 wt% KOH solution. An interferometric fiber optic pressure sensor has been manufactured by using a fiber optic Fabry-Perot intereferometer and a N/O/N diaphragm. The 2 cm length fiber optic Fabry-Perot interferometers in the continuous length of single mode fiber were produced with two pieces of single mode fiber coated with $TiO_{2}$ dielectric film utilizing the fusion splicing technique. The one end of the fiber optic Fabry-Perot interferometer was bonded to a N/O/N diaphragm. and the other end was connected to an optical setup through a 3 dB coupler. For the N/O/N diaphragm sized $2{\times}2\;mm^{2}$ and $8{\times}8\;mm^{2}$, the pressure sensitivity was measured 0.11 rad/kPa and 1.57 rad/kPa, respectively, and both of the nonlinearities were less than 0.2% FS.