气泡雾化喷嘴射流及含气液丝破碎的仿真研究

Simulation Study on Breakup of Gas-Liquid Jet and Filament of Effervescent Atomizer

关键词:  气泡雾化喷嘴  含气射流  含气液丝  破碎  仿真

Key words:  Effervescent atomizer  Gas-liquid jet  Gas-liquid filament  Breakup  Simulation

摘要:

为探究气泡雾化喷嘴气液作用对雾化的影响机制，采用数值模拟方法对一个气泡雾化喷嘴的含气射流及含气液丝破碎形态进行了仿真研究。研究结果表明，建立的仿真模型可比较准确实现气泡雾化喷嘴含气射流及含气液丝破碎的模拟；气相膨胀对射流破碎以及破碎液丝和破碎液滴的形成具有显著促进作用；射流表面出现的气相膨胀凸起宽度和射流液柱断裂间距随瞬时通过喷孔气相体积的增加而增大，但增加到一定程度后，其影响变小；提高充液压力可加强气相膨胀扰动对射流破碎的作用，并促进破碎后液相的扩散；与一般不含气液丝破碎相比，含气液丝破碎时的形态变化更加复杂，在相同条件下含气液丝更易发生二次破碎；增大气泡直径、增加气泡压力以及提高气流速度均可明显缩短含气液丝的破碎时间，促进含气液丝破碎。

Abstract:

To reveal the influence mechanism of gas-liquid interaction of the effervescent atomizer on atomization， a numerical simulation method was used to investigate breakup shapes of gas-liquid jet and gas-liquid filament by using an effervescent atomizer. The results show that the simulation model can be used to accurately simulate the gas-liquid jet and gas-liquid filament breakup of effervescent atomizer. The gas expansion promotes the gas-liquid jet breakup， gas-liquid filament breakup and the droplet formation. The gas expansion bulge width on the jet surface and the fracture distance of jet liquid column increase with the increase of the instantaneous gas volume through the injection orifice， but the influence becomes smaller when the instantaneous gas volume increase to a certain extent. Increasing the pressure can enhance the influence of gas expansion disturbance on jet breakup， and promote the diffusion of liquid phase after breaking up. Comparing with the breakup of pure liquid filament， the shape variation of gas-liquid filament breakup is more complicated， and is more likely to occur secondary breakup under the same condition. By increasing the bubble diameter， bubble pressure and gas flow velocity， the breakup time of gas-liquid filament can be significantly shortened， which promote the gas-liquid filament breakup.