弯道水流对下游回水响应特征试验研究

Experimental study of bend flow response to downstream backwater

弯道水面横比降及断面环流是弯道水流的显著特性。通过U形弯道水流壅水试验,对弯道水面横向比降、横向流速分布、环流强度、紊动能及纵向流速沿程的变化进行了试验研究。结果显示,随着下游回水的抬高,弯道水面横比降、横向流速分布、环流强度、紊动能及纵向流速将发生明显的改变。为深入探讨下游回水对弯道水流结构的影响提供了科学依据。

The transverse water surface slope and secondary flow are main hydraulic features of bend flows,which are the result of the interaction between the gravity and the centrifugal force in bend flows.The hydrodynamic characteristics of bend flows such as the water surface slope,the longitudinal velocity,the transverse circulation,the turbulence kinetic energy and the intensity of secondary flow vary with the water depth in downstream.A series of flume experiments were conducted in a U-shape bend to study these hydrodynamic characteristics.Results show that the water surface slope,the longitudinal velocity,the turbulence kinetic energy and the intensity of secondary flow generally decrease with the increase of downstream water depths.The decline appears to be uneven in different sections of the bend.The results are favorable to further study on the effect of backwater to the structure of bend flows.