Brujan Emil-Alexandru
Department of Hydraulics, University Politehnica Bucharest, 060042 Bucharest, Romania.
Ultrasonics. 2008 Sep;48(5):423-6. doi: 10.1016/j.ultras.2008.02.001. Epub 2008 Mar 4.
The role of extensional viscosity on the acoustic emission from laser-induced cavitation bubbles in polymer solutions and near a rigid boundary is investigated by acoustic measurements. The polymer solutions consist of a 0.5% polyacrylamide (PAM) aqueous solution with a strong elastic component and a 0.5% carboxymethylcellulose (CMC) aqueous solution with a weak elastic component. A reduction of the maximum amplitude of the shock wave pressure and a prolongation of the oscillation period of the bubble were found in the elastic PAM solution. It might be caused by an increased resistance to extensional flow which is conferred upon the liquid by the polymer additive. In both polymer solutions, however, the shock pressure decays proportionally to r(-1) with increasing distance r from the emission centre.
通过声学测量研究了拉伸粘度对聚合物溶液中以及刚性边界附近激光诱导空化气泡声发射的作用。聚合物溶液由具有强弹性成分的0.5%聚丙烯酰胺（PAM）水溶液和具有弱弹性成分的0.5%羧甲基纤维素（CMC）水溶液组成。在弹性PAM溶液中发现冲击波压力的最大振幅降低且气泡振荡周期延长。这可能是由于聚合物添加剂赋予液体的拉伸流动阻力增加所致。然而，在两种聚合物溶液中，随着距发射中心距离r的增加，冲击压力均与r(-1)成比例衰减。
