For the simulation of bubbly flows, knowledge of the lift force as an interaction between gas bubbles and a surrounding shear field is of great importance. The sign of the lift coefficient $C_L$ changes with increasing bubble size, i.e. with more pronounced bubble deformation. Beside this, impurities in terms of surface-active components are well-known to change the complete hydrodynamic behavior of a bubble even if the amount is very small. In the present work, the lift coefficient of single ellipsoidal bubbles is determined with a recently developed method, which is suitable to overcome difficulties connected to low viscous systems. In order to investigate the influence of impurities on the lift force, we conducted experiments with single bubbles of different sizes in purified, deionized and tap water. Overall, the determined lift coefficients show no difference between deionized and tap water but reveal differences to results obtained with purified water. As no significant differences in shape and velocity are found between the different water qualities, it remains unclear how the impurities cause the observed differences. For the deionized and tap water results that are more relevant in practice, a new correlation is proposed to account for the observed differences in comparison to data from the literature. It can be used to calculate $C_L$ of ellipsoidal bubbles in the investigated size range.

为了模拟气泡流动，了解作为气泡和周围剪切场之间相互作用的升力非常重要。升力系数的符号$C_{\mathrm{大号}}$随着气泡尺寸的增加（即气泡变形更加明显）而变化。除此之外，众所周知，就表面活性成分而言，即使其量很小，杂质也会改变气泡的完全流体力学行为。在目前的工作中，采用最新开发的方法确定单个椭圆形气泡的升力系数，该系数适合克服与低粘度系统有关的难题。为了研究杂质对提升力的影响，我们在净化水，去离子水和自来水中用不同大小的单个气泡进行了实验。总体而言，确定的升力系数显示去离子水和自来水之间没有差异，但揭示了与纯净水获得的结果的差异。由于在不同水质之间没有发现形状和速度的显着差异，因此尚不清楚杂质如何引起观察到的差异。对于在实践中更相关的去离子水和自来水结果，提出了一种新的相关性，以解决与文献数据相比所观察到的差异。它可以用来计算$C_{\mathrm{大号}}$ 在研究的尺寸范围内的椭圆形气泡。