Physical characteristics of detonation noise from multi-tube pulse detonation engine

An experimental system of multi-tube pulse detonation engine with single tube to four tubes is set up to study the formation of detonation noise and acoustic characteristics of multi-tube pulse detonation engine.The physical parameters of multi-tube detonation noise,including waveform,attenuation of sound pressure,radiation characteristics,duration and acoustic spectrum characteristics are obtained.The results show that the peak sound pressure of detonation noise attenuates faster in the area near the tube exit,and the attenuation speed in the area far away from the tube exit is inversely proportional to the radius distance.With the increase of the number of detonation tubes,the peak sound pressure level of detonation noise at each directivity angle increases gradually.In the far-fiekl region,the directivity of the detonation noise is M-shaped.As the number of detonation tubes increases,the A and B durations of detonation noise increase.The acoustic spectrum of detonation noise is a broadband signal,and the acoustic energy mainly concentrates in the range of middle and low frequency.The dominant spectrum peak and sound pressure level of the acoustic spectrum vary with the increase of the number of detonation tubes.The results are of great significance for studying the propagation of acoustic wave in detonation process and will be useful for application of pulse detonation engine in aircraft power systems.