Design and output characteristic of siren incentive system

An experimental system with siren was designed for combustion instability study and flame transfer function (FTF) measurement. The factors influencing siren output characteristics were studied, and system resonance mode was analyzed by experimental and numerical method. The researched factors included pressure drop of measurement section, valve opening and pulsation frequency. The results indicate that siren incentive system output average speed is decided by pressure drop of measurement section. The mass flow pulsation through siren unsteady path m' affects the amplitude of oscillating velocity u'. The greater m' is, the greater u'/ū becomes. In the experiment, the maximum value of u'/ū exceeded 4%. Besides, the frequency of pressure oscillation affects u' though affecting siren actuator outlet pressure fluctuation distribution. The occurrence of system resonance leads to obvious increasing value of u'/ū. When frequency comes to 270 Hz which is close to the resonant frequency, the siren outlet pressure fluctuation reaches the maximum value.