Spray painting robots equipped with air spray guns have been widely used in the painting industry. In view of the low efficiency of single-nozzle air spray guns when spraying large targets, a new double-nozzle air spray gun structure was designed in this paper based on the Coanda effect of double jets. Firstly, a 3-D physical model of the double-nozzle air spray gun was built in Solidworks, in which unstructured grids were generated for the computational domain by ICEM. Secondly, the spray painting process was numerically modeled with the help of the computational fluid dynamics (CFD) software ANSYS-Fluent 16.0. The two-phase spray flow was calculated by coupling a discrete phase model (DPM) and the Taylor analogy breakup (TAB) method. The TAB model was applied to predict the secondary break-up. The DPM model was applied to predict the droplet trajectories. The geometry of an air spray gun has a significant influence on the spray flow field characteristics. The influence of the air spray gun geometry on the interference spray flow field characteristics and coating film thickness distribution were investigated by changing the values of the distance between the centers of the two paint holes (L) and the angle between the axes of the two paint holes (θ). Numerical results show that the smaller L and θ are, the stronger the interference effect between the two jets, while the more concentrated the paint is in the central region of the target surface, the easier it is for overspray to occur. With increasing L and θ, the interference effect gradually decreased and the extension distance of the coating film along the x-axis gradually increased. However, if L and θ are too large, the interference effect will become too weak and the shape of the coating film will become a concave, with more paint on both side regions and less paint in the central region, which will cause an uneven coating film. From the simulation results, it can be concluded that a more uniform coating film can be obtained when L = 30 mm and θ = 10°. The effective coating width of the double-nozzle air spray gun was increased by 85.7% compared with the single-nozzle air spray gun, which improved the spraying efficiency.

中文翻译：

---

双喷嘴空气喷枪的设计及干涉喷雾流场的数值研究

配备有空气喷枪的喷涂机器人已被广泛应用于喷涂行业。鉴于单喷嘴气喷枪在喷射大目标时效率低下，本文基于双喷嘴的柯恩达效应设计了一种新型的双喷嘴气喷枪结构。首先，在Solidworks中建立了双喷嘴空气喷枪的3-D物理模型，其中ICEM为计算域生成了非结构化网格。其次，借助计算流体动力学（CFD）软件ANSYS-Fluent 16.0对喷涂过程进行了数值建模。通过耦合离散相模型（DPM）和泰勒类比破裂（TAB）方法来计算两相喷雾流量。TAB模型用于预测二次破裂。DPM模型用于预测液滴轨迹。空气喷枪的几何形状对喷雾流场特性有重大影响。通过改变两个喷漆孔中心之间的距离值来研究喷枪几何形状对干涉喷流场特性和涂膜厚度分布的影响（L）和两个喷漆孔的轴线之间的夹角（θ）。数值结果表明，L和θ越小，两个喷嘴之间的干涉效果越强，而涂料在目标表面中心区域的浓度越高，越容易发生过喷。随着L和θ的增加，干涉效应逐渐减小，涂膜沿x的延伸距离轴逐渐增加。然而，如果L和θ太大，则干涉效果将变得太弱并且涂膜的形状将变为凹形，在两侧区域上的涂料更多，而在中央区域中的涂料更少，这将导致涂层不均匀。电影。从模拟结果可以得出结论，当L＝ 30mm和θ＝ 10°时，可以获得更均匀的涂膜。双喷嘴气喷枪的有效涂层宽度比单喷嘴气喷枪的有效涂层宽度增加了85.7％，提高了喷涂效率。