Some features of spray breakup in effervescent atomizers
Some features of spray breakup in effervescent atomizers
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DOI：
10.1007/s00348-010-0929-6
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发表时间：
2011-02
影响因子：
2.4
通讯作者：
H. Gadgil;B. N. Raghunandan
中科院分区：
文献类型：
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作者：
H. Gadgil;B. N. Raghunandan
以水为模拟气体，空气为雾化气体，对泡沫式雾化器中低GLR(气液质量比)值下的近孔喷雾破碎进行了实验研究。从可视化的角度，将近孔喷雾结构分为三种模式：离散气泡爆炸、连续气泡爆炸和环形锥形喷雾。喷雾的破裂是用气泡离喷口的平均破裂距离来量化的。参数研究表明，气泡的平均爆裂距离主要取决于空气流量、射流直径和混合气速度。在给定的气流速度下，与混合气速度相比，射流直径对气泡破裂距离的影响占主导地位。气泡的平均爆裂距离由一个由上述所有参数组成的无量纲两相流数决定。发现气泡爆裂的位置在空间上是高度不稳定的，这受喷嘴内部流动动力学的影响。结果表明，射流破碎长度的不稳定是由于孔口内单相流和两相流的间歇性产生而导致气泡不同程度膨胀的结果。
The near orifice spray breakup at low GLR (gas to liquid ratio by mass) values in an effervescent atomizer is studied experimentally using water as a simulant and air as atomizing gas. From the visualizations, the near orifice spray structures are classified into three modes: discrete bubble explosions, continuous bubble explosions and annular conical spray. The breakup of the spray is quantified in terms of the mean bubble bursting distance from the orifice. The parametric study indicates that the mean bubble bursting distance mainly depends on airflow rate, jet diameter and mixture velocity. It is also observed that the jet diameter has a dominant effect on the bubble bursting distance when compared to mixture velocity at a given airflow rate. The mean bubble bursting distance is shown to be governed by a nondimensional two-phase flow number consisting of all the aforementioned parameters. The location of bubble bursting is found to be highly unsteady spatially, which is influenced by flow dynamics inside the injector. It is proposed that this unsteadiness in jet breakup length is a consequence of varying degree of bubble expansion caused due to the intermittent occurrence of single phase and two-phase flow inside the orifice.