掺气水流掺气浓度缩尺影响的估计

Estimation of scale effect of air entrainment in model test of aerated flow

根据紊动扩散理论和相似理论导出了掺气水流试验的9个模型相似律。研究表明,若要求掺气水流的掺气浓度原、模型相似,并按重力相似律引伸,则掺气气泡的上浮速度应和水流流速一样满足重力相似律。在模型采用和原型相同的介质,即水和空气进行试验时,由于气泡上浮速度不相似,引起掺气浓度巨大的缩尺影响,本文首次对这种影响进行定量估计。研究表明,模型的比尺λL应足够大,以减小掺气浓度的缩尺影响。

Based on the diffusion theory of turbulence and similarity theory the similarity laws of air entrainment for model test of aerated flow are deduced. It is found that the bubble buoyancy velocity in model must obey the similarity law of gravity. In model test using the same media as in prototype the scale effect is remarkable. The analysis shows that for reducing the scale effect the length scale for water flow model test must be large enough.