Effect of filling fraction in the noise characteristic of pulse detonation engine

The experiment system of gas-liquid two-phase pulse detonation engine, where filling fraction could be regulated accurately, was set up to investigate the detonation noise characteristic with different filling fractions. The experiment was carried out in 800 mm and 3000 mm at four angles. The results show that as the filling fraction increasing, there are increases in amplitudes of impact noise and jet noise at all angles, without an increase in the amplitude ratio of jet noise and impact noise. A significant increase in amplitude of impact noise and jet noise are observed at the turning point from deflagration stage to detonation stage. The amplitude of impact noise and jet noise are slow increase in deflagration stage, but significant increase in detonation stage. With increased distance, the enhancement of filling fraction in impact noise and jet noise are shown down and the decay rate of jet noise is slower than impact noise. With increased filling fraction, the detonation noise directivity becomes obviously at short distance, but ambiguously at long distance.