超声波雾化喷嘴共振腔对雾化特征的影响研究

Research on the influence of ultrasonic atomization nozzle resonance cavity on atomization characteristics

针对流体动力式超声波雾化喷嘴空间分布不均、噪声大的问题,采用数值模拟结合实验的方法,对喷嘴共振腔对雾化特征的影响进行了研究,计算获得共振腔的振荡特性,拍摄到了雾化近场特征,并测量了液滴的平均粒径及喷嘴噪声声压级。研究结果表明:对于目标喷嘴,吞吐模式与非吞吐模式下共振腔的压力振荡频率分别由喷嘴压力比和几何结构决定;吞吐模式下,共振腔深度增大导致压力振荡频率降低,容易导致喷嘴产生过大噪声,而过小的深度会导致腔口膨胀气流流速过低;共振腔内径对振荡频率影响较小,但内径过大会导致液滴空间分布不均及压力振幅下降;喷口到腔口的间隔距离影响声压级大小,喷嘴索特平均直径与声压级大小成反比。

Aiming at the problems of uneven spatial distribution and excessive noise of the hydrodynamic ultrasonic atomization nozzle,the influence of the resonant cavity of the ultrasonic atomization nozzle on the atomization characteristics was studied by numerical simulation combined with physical experiments,the oscillation characteristics of the resonance cavity were calculated,the near-field characteristics of atomization were photographed,as well as the average particle size of the droplets and the noise sound pressure level of the nozzle were measured.The results show that for the target nozzle,the pressure oscillation frequency of the resonator in huff and puff mode and non huff and puff mode is determined by the nozzle pressure ratio and geometry,respectively.In the huff and puff mode,the increase in the depth of the resonant cavity will lead to the decrease of the pressure oscillation frequency,which will easily lead to excessive noise of the nozzle,while the too small depth will lead to the low flow rate of the expansion airflow at the cavity opening.The inner diameter of the resonant cavity has little effect on the oscillation frequency,but it will lead the uneven droplet distribution and the lower pressure amplitude.The distance between the nozzle and the cavity affects the sound pressure level,and the average nozzle Sauter diameter is inversely proportional to the sound pressure level.