加长型环形水槽水流特性的数值模拟

Numerical simulation of flow characteristics in elongated annular flume

由直槽及半环形水槽组成的加长型环形水槽被用来研究水流的三维水力特性.水流由位于水面的运动固体盖拖曳而产生运动.采用ADV测速仪对水流动力学特性进行物理观测,并采用美国Fluent公司的标准化CFD计算软件对水流进行了三维数值模拟.研究表明,在弯段有明显的二次流,水槽外侧流速大于内侧,且由于对流作用,弯段下游的直段水槽内水流也呈类似分布,但随着流程的增加,流速沿横向分布趋于均匀.与单一环形水槽相比,加长型环形水槽由于直段内水流结构相对简单,可以更好地用于泥沙动力学研究.

A complex annular flume, consisting of 2 straight flumes and 2 semicircular flumes, is built for invastigation of the hydrodynamic characteristics of water flow driven by a moving lid on the water surface. The CFD software developed by Fluent Inc. is used for simulation of 3D hydrodynamic characteristics of water flow in the flume, and the simulated result is in good agreement with that observed by ADV. The research shows that in the curved section of the flume, there exists a strong secondary flow, and the velocity tends to increase significantly in the radial direction from the inside to the outside, and that in the straight section near the outlet of the curved section, the velocity distribution has the same characteristics as that in the curved section due to the effect of convection, but, with the increase of flow distance, the velocity in the transversal direction tends to be uniform. Owing to the simple flow structure in the straight section near the outlet of the curved section, the elongated flume can be effectively used for investigation of the interaction between sediment motion and water hydrodynamics as compared with the simple annular flume.