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Experimental and Numerical Characterization of a Liquid Jet Injected into Air Crossflow with Acoustic Forcing
Flow, Turbulence and Combustion ( IF 2.4 ) Pub Date : 2020-05-04 , DOI: 10.1007/s10494-020-00126-0
Anthony Desclaux , Swann Thuillet , Davide Zuzio , Jean-Mathieu Senoner , Delphine Sebbane , Virginel Bodoc , Pierre Gajan

The current work presents a study on spray dynamics in aeronautical injectors. More particularly, the experimental characterization of a liquid jet in an oscillating gaseous cross flow (LJIOGCF) atomization is presented and compared to numerical simulations. The experimental setup consists of a water jet transversally injected into an oscillating subsonic air flow at ambient conditions. In a first step, a cross-comparison is performed in order to validate the numerical model and the tools used to quantitatively analyze the experimental data in the case of steady air flows. In a second step, the air flow is submitted to longitudinal acoustic waves using a pneumatic loudspeaker. A detailed database, representative of the actual dynamics of LJIOGCF configurations, is obtained using both experiments and numerical simulations. Visualizations with a back lighting approach are employed to characterize the liquid jet close to the injection location while phase doppler anemometry is used to determine the characteristics of the crossflow and the spray in terms of droplet size, velocity and concentration. Phase-averaging is performed to characterize the response of the liquid jet, the air velocity field and the spray oscillations during the excitation cycle. The numerical simulation relies on a multi-scale large eddy simulation approach. This method couples a multi-fluid solver for the liquid jet main body with a dispersed phase solver for the atomized spray. The acoustic perturbation is imposed as a fluctuating air inflow condition. The experimental results show that the acoustic forcing induces a flapping motion of the liquid jet. As a consequence, velocity and concentration waves travelling downstream the liquid jet appear. Coupling phenomena between the crossflow, the atomization of the liquid jet and the transport of droplets are observed, revealing different wave transport velocities. It further appears that spray dynamics are both driven by liquid column and crossflow oscillations. The numerical simulation is able to capture the global flapping dynamics of the liquid jet’s main body. More quantitative comparisons show a very good agreement between simulation and experiments regarding the jet trajectories over the entire excitation cycle. Numerical droplet average velocities are also in good agreement with experiments. Finally, the numerical simulation partly reproduces the coupling between acoustics and spray dynamics observed in the experiments.

中文翻译:

液体射流注入带有声强迫的空气错流的实验和数值表征

目前的工作是对航空喷油器喷雾动力学的研究。更具体地说,介绍了振荡气体交叉流 (LJIOGCF) 雾化中液体射流的实验表征,并与数值模拟进行了比较。实验装置包括在环境条件下横向注入振荡亚音速气流中的水射流。第一步,进行交叉比较以验证数值模型和用于在稳定气流情况下对实验数据进行定量分析的工具。在第二步中,使用气动扬声器使气流受到纵向声波的影响。使用实验和数值模拟获得了代表 LJIOGCF 配置实际动力学的详细数据库。使用背光方法的可视化来表征靠近注射位置的液体射流,而相位多普勒风速测量法用于确定交叉流和喷雾在液滴尺寸、速度和浓度方面的特征。执行相位平均来表征液体射流的响应、空气速度场和激发周期中的喷雾振荡。数值模拟依赖于多尺度大涡模拟方法。该方法将用于液体喷射主体的多流体求解器与用于雾化喷雾的分散相求解器耦合。声扰动是作为波动的空气流入条件施加的。实验结果表明,声强迫引起液体射流的拍打运动。作为结果,出现在液体射流下游传播的速度波和浓度波。观察到横流、液体射流的雾化和液滴传输之间的耦合现象,揭示了不同的波传输速度。进一步看来,喷雾动力学是由液柱和横流振荡驱动的。数值模拟能够捕捉液体射流主体的全局扑动动力学。更多的定量比较表明模拟和实验之间关于整个激发周期的射流轨迹非常一致。数值液滴平均速度也与实验非常吻合。最后,数值模拟部分再现了实验中观察到的声学和喷雾动力学之间的耦合。
更新日期:2020-05-04
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