基于PDPA的双流体撞击式喷嘴雾化特性研究

使用自主搭建的一套基于相位多普勒粒子分析仪(PDPA)的开放式雾化试验台,开展了不同工况下双流体雾化流场的测试试验,研究了气体流量和水流量对雾化特性(包括喷雾锥角、有效射程以及雾滴粒径、速度、个数的分布)的影响。结果表明:随着气体流量的增大以及水流量的减小,喷雾锥角呈增大趋势,雾滴的索特平均直径(SMD)、速度以及个数均呈减小趋势,而有效射程随着气体流量以及水流量的增大而增大;随着轴向距离的增大,雾滴的SMD、速度以及个数均呈现增大的分布规律;随着径向距离的增大,雾滴的SMD呈增大的分布规律,而雾滴速度以及个数呈现先增大后减小的分布规律。气体流量和水流量对喷嘴出口与振动头之间区域的湍流程度、对冲现象有明显影响,进而显著影响雾化特性。当气体流量为0.8 m3/h、水流量为35 L/h时,与优化前(气体流量为0.95 m3/h、水流量为40 L/h)相比,SMD减小了21.50%,有效射程、雾滴速度、雾滴个数分别增加了10.26%、39.08%、61.54%,喷嘴雾化能耗降低的同时综合雾化效果得到了提升。

Atomizing Characteristics of Twin-fluid Impact Nozzle Based on PDPA

In order to improve the atomizing performance and decrease the consumption, the effect of air flow and water flow on the atomizing characteristics of twin-fluid impact nozzle was researched, the twin-fluid atomizing flow field was tested under different working conditions by an open atomizing test bench which was based on phase Doppler particle analyzer (PDPA). The atomizing characteristics which included spray cone angle, atomizing range, droplets diameter distribution, droplets velocity distribution and droplets numbers distribution were analyzed systematically according to the test results. It could be concluded from the test results, with the increase of air flow and decrease of water flow, the spray cone angle was increased remarkably, the droplets Sauter mean diameter (SMD), droplets velocity and droplets numbers were decreased, but the atomizing range showed an increasing trend with the increase of air flow and water flow. The distributions of droplets SMD, droplets velocity and droplets numbers were increased along the axial direction. Moreover, the distribution of droplets SMD was increased while the droplets velocity and droplets numbers were increased firstly and then decreased along the radial direction. Furthermore, the turbulence and hedging in the region between the nozzle exit and vibrating head were affected obviously by the air flow and water flow, and then the atomizing characteristics was markedly influenced. The air flow and water flow were decreased by 15.79% and 12.50%, respectively, after optimization when they were 0.8m3/h and 35L/h, meanwhile, the SMD was decreased by 21.50%, the atomizing range was increased by 10.26%, the droplets velocity and droplets numbers were increased by 39.08% and 61.54%, and it can be concluded that the atomizing performance was improved and the consumption of the nozzle was decreased.