Study of the noise reduction in hot air balloon burners

Abstract

The noise produced by an ULTRAMAGIC MK-32 hot air balloon burner has been ana-lysed and studied. Furthermore, different possibilities for its reduction have been designed,which are: incorporation of chevrons, glass wool shielding, incorporation of ejectors, an-nular mixer and swirl burner transformation. However, only the first three have beenmanufactured and tested, in different versions and configurations. The results of thesetests showed that some particular versions of chevrons and ejectors provide significantreduction of the noise emitted at particular frequency ranges but generating incrementsin other ranges. For reducing this worsenings but keeping the good improvements in thenoise emission, the annular mixer solution has been suggested.