流体自控振荡的机理及其对水环境维护的有益功能

从真实流体所具粘滞耗散特性出发,以数学解析法严谨地论证了淹没射流因沿程能量通量渐减,加以其动量通量沿程守恒,故其质量通量必然沿程递增,从而衍生出射流卷吸及附壁效应,于是,在专门设计的腔体中就会发生流控振荡现象.发生流控振荡的腔体的两个出口会交替地输出两股非共面动量通量射束并在其后形成顺流螺旋涡,在绕水平轴旋涡的流场中,重于水的沙粒将获得附加的悬浮功增量,而轻于水的气泡或藻菌团的上浮行动将受阻碍.前者会加大河流的挟沙能力,后者的影响将导致水藻所赖以滋长的光合能量锐减而枯萎,从而改善水质.

Mechanism of fluidic oscillation and its potential utility in water environment engineering

Through mathematical derivation, it is verified that the submerged jet should entrain ambient fluid as a consequence of the combination of momentum flux conservation and energy dissipation of the very jet itself. As a result, jet entrainment as well as the wall attachment phenomena would occur in a confined fluid field, bounded by side walls, so called as "Coanda effect". Thus, the transition from a state of steady jet to a state of fluidic bistable oscillation might get its way,in the specially designed cavity of apparatus. The streamwise vortex, induced by two unparallel momentum flux vectors, would give the sand a suspension work increment, so as to enlarge the sediment transporting capacity of the river flow; as well as suppress the growth rate of algae, owing to the decrease of photosynthesis energy supplying to algae.