Experimental Research On The Sound Level Changes Generated By Potassium Nitrate In Second Bang Powder Of Double-bang Firecracker

Experimental method was used in this dissertation.The sound level change generated by potassium nitrate in second bang powder of double-bang firecracker was studied.Potassium nitrate,aluminum powder,aluminum-magnesium alloy powder and sulfur were contained in it. Fifteen formulas of second bang powder were gotten though changing the weight of potassium perchlorate which was sensitive to display effect and other components being unchanged.And this corresponds,oxygen balance of formulas were also changed.MP302 dual-channel acoustic analysis was used in this experiment to measure sound level of different formulas and distribution of spectrum.Not only the relationship between sound level of second bang powder and its oxygen balance was quantitatively studied,but also the spectrum characteristic of different formulas on the base of experimental data.The display effect requirement of powder can be reached when the mass fraction of potassium perchlorate was from 30.30%to 74.16%.Relevantly with this the range of oxygen balance of powder was from -0.108 g·g^-1 to +0.247g·g^-1.The frequency distribution was from 100 to 20000Hz,which was in the people's auditory sensation area.Distribution of spectrum frequency had typical noise characteristic. The distribution of sound level in each frequency was uniform and there was no obvious peak value.Though calculating coefficient of variation of different formulas,its stability of display effect was variant.Mathematical optimization model of second bang powder was established on the base of mixture ratio determined by the experiment.The lowest cost was as goal of the model and minimum and maximum levels of mass fraction were as restraint condition.The optimal mixture ratio of second bang powder was calculated by MATLAB6.5.The mass fraction of potassium nitrate,aluminum powder,aluminum-magnesium alloy powder and sulfur was separate 30%,30%,12%,16%and 12%.It was an initial attempt that mathematics optimization was used in the aspect of formula adjustment of fireworks and crackers.The main innovation of this dissertation was that the change law between the sound level and oxygen balance of second bang powder was studied quantitatively and sound distribution of the spectrum of it.