Investigation of Jet Noise Reduction in the Hybrid Rocket Nozzle

Abstract

This project presents an attempt to use the hybrid rocket motor for missile applications. The gas released with high pressure causes noise above 130 db. According to recent studies, loud noise above 120 dB has a strong vibrational energy that leads to a negative influence on electronic equipment with a high degree of integration. In this study, a basic fire-extinguishing nozzle with absorbent was selected as the reference model and numerical analysis was conducted using the commercial software, ANSYS FLUENT ver. 18.1 and comparing with materials of aluminums and titanium in nozzle section.  The calculation results show that the jet noise is with obvious directivity. The total sound pressure levels are obviously much higher in 10°to 30°direction than that in other direction. Results show that the vibrational energy of the noise was reduced by minimizing the turbulence kinetic energy. Pressure and velocity distributions were calculated and graphically depicted with various absorbent configurations.