Understanding and reducing air entrainment in liquid metals is important for improving casting filling systems and liquid metal transfer processes. Air entrainment generates oxide inclusions that reduce the mechanical performance of metals. This paper presents air entrainment measurements for a jet of liquid aluminum alloy A356 plunging into a pool. Measurements are performed in argon and air atmospheres and for a range of jet fall heights. The volume ratio of entrained gas to liquid aluminum poured is measured to be equal to 0.43 for an average jet impact velocity of about 3.8 m/s in the argon atmosphere. This ratio is of a similar magnitude as for water under the same jet parameters. For the corresponding experiment in air, the measured volumetric ratio is only 0.16. It is found that nearly 50 pct of the volume of oxygen entrained is consumed by oxidation, but this alone does not account for the difference between the measurements in inert and oxidizing atmospheres. Instead, the ratio for air is so low because during some portion of the experiment no air was entrained. The onset velocity for gas entrainment for a plunging jet of liquid A356 is found to be 3.9 m/s in an air atmosphere and 3.4 m/s in argon, with the difference attributed to the stabilizing effect of the oxide film on the jet surface in air. These are about three times greater than the onset velocity previously measured for water.

中文翻译：

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铝合金浇注过程中空气夹带的测量

了解和减少液态金属中的空气夹带对于改进铸件填充系统和液态金属转移过程非常重要。空气夹带会产生氧化物夹杂物，降低金属的机械性能。本文介绍了对坠入水池的液态铝合金 A356 射流的空气夹带测量。测量是在氩气和空气气氛中进行的，并针对一系列喷射落差高度进行。对于氩气气氛中约 3.8 m/s 的平均射流冲击速度，测量到的夹带气体与浇注的液态铝的体积比等于 0.43。在相同的射流参数下，该比率与水的大小相似。在空气中进行相应的实验，测得的体积比仅为0.16。发现所夹带的氧气体积中有近 50% 被氧化消耗，但这并不能解释惰性和氧化气氛中测量值之间的差异。相反，空气的比例如此之低，因为在实验的某些部分没有夹带空气。发现液体 A356 的俯冲射流的气体夹带起始速度在空气中为 3.9 m/s，在氩气中为 3.4 m/s，差异归因于氧化膜在射流表面的稳定作用。空气。这些大约是之前为水测量的起始速度的三倍。空气的比例如此之低是因为在实验的某些部分没有夹带空气。发现液体 A356 的俯冲射流的气体夹带起始速度在空气中为 3.9 m/s，在氩气中为 3.4 m/s，差异归因于氧化膜在射流表面的稳定作用。空气。这些大约是之前为水测量的起始速度的三倍。空气的比例如此之低是因为在实验的某些部分没有夹带空气。发现液体 A356 的俯冲射流的气体夹带起始速度在空气气氛中为 3.9 m/s，在氩气中为 3.4 m/s，差异归因于氧化膜在射流表面的稳定作用空气。这些大约是之前为水测量的起始速度的三倍。