Aerodynamic noise analysis of 6MF-30 portable pneumatic extinguisher.

Portable pneumatic extinguisher is one of the most important equipment for forest fire-fighting in China. But the noise of portable pneumatic extinguisher may have serious physiological and psychological effects on operators. Simulation via FLUENT and noise test experiment were carried out to determine the position of noise source. In addition, several suggestions about noise reduction of portable pneumatic extinguisher were given. The results indicate that acoustic field could be computed via two-dimensional model when large eddy simulation and Flowcs-Williams/Hawkings equation are used; the muffler should be considered during noise simulation; the main aerodynamic noise sources are impeller and vortex tongue; air duct noise contributing to the total noise is minimal; it is suggested that increasing air director could reduce parotic noise caused by working machine.