Properties of acoustic resonance in double-actuator ultra-sonic gas nozzle: numerical study

The ultra-sonic gas atomization(USGA) nozzle is an important apparatus in the metal liquid air-blast atomization process.It can generate oscillating supersonic gas efflux,which is proved to be effective to enforce the atomization and produce narrow-band particle distributions.A double-actuator ultra-sonic gas nozzle is proposed in the present paper by joining up two active signals at the ends of the resonance tubes.Numerical simulations are adopted to study the effects of the flow development on the acoustic resonant properties inside the Hartmann resonance cavity with/without actuators.Comparisons show that the strength and the onset process of oscillation are enhanced remarkably with the actuators.The multiple oscillating amplitude peaks are found on the response curves,and two kinds of typical behaviors,i.e.,the Hartmann mode and the global mode,are discussed for the corresponding frequencies.The results for two driving actuators are also investigated.When the amplitudes,the frequencies,or the phase difference of the input signals of the actuators are changed,the oscillating amplitudes of gas efflux can be altered effectively.     

双激励超音速气体雾化喷嘴共振特性的数值研究

超音速气体雾化(ultra-sonic gas atomization,USGA) 喷嘴是实现喷射雾化的重要装置,它能够产生脉动的超音速气流,获得较小的平均粒径和集中的粒径分布.在USGA喷嘴的共振管端部引入了主动的激励信号,组成双激励式超音速气体雾化器,并对超音速气体雾化器内部Hartmann腔体气体流场在无激励/有激励情况下所产生的气体振动特性进行了数值研究.结果表明在主动激励器的作用下,超音速气体雾化器内气流的振动效果如振幅和起振特性等都得到了有效的加强.研究发现超音速气体雾化器存在多个气体受激振动的共振频率,其对应于两类不同的共振模式,“Hartmann模式”和“全局模式”.双激励器信号的频率、激励幅度及相位差改变都能够有效地改变超音速气流的振动特性.研究同时阐明了Hartmann共振管和二次共振管在USGA喷嘴腔体内产生气体脉动时的联动特点.