The acoustic properties of pyrotechnic whistle devices with the whistle composition consisting of 30% potassium benzoate and 70% potassium perchlorate have been investigated by advanced measurement technologies in the study. The effects of the loading density and the chimney length on the whistling were examined firstly. The experiment results show that the pyrotechnic whistle composition burns with a loud whistling sound when the loading density is larger than a certain value called critical density and the chimney length is longer than a minimum. The critical density and the minimum chimney length for the whistle composition were obtained. Then the relationship between the whistling and the behaviors of the flame was investigated. It is found that although the flame exited from the tube mouth exhibits the marked difference between non-whistling and whistling, the flame front propagates at a constant rate even when the composition transitions from non-whistling to whistling.
whistle, acoustics, pyrotechnics, oscillating burning, combustion