Abstract

In this study, laboratory experiments are conducted to assess the effects of a set of novel ring-type collars and prevalent spiral threading around a circular pier on scouring in a clear-water flow regime in non-cohesive bed materials. Also, numerical simulations are conducted to reveal the flow field in the scour hole around a pier with spiral threading. Various angles and spacings of the ring collars are considered to find the best configuration. Moreover, four test scenarios of spiral threading with different elevation levels are considered to investigate the optimum upper bound of spiral threading elevation. Results show that the ring collars (Angle = 45˚, relative spacing = 4/3 of pier diameter) are the best configuration and reduce the scour depth by 29% according to the scour depth around a plain pier. This configuration of ring collars reduces maximum scour depth three times better than the best configuration of single spiral threading (suggested by previous research). Furthermore, the ring collars reduce the scour rate while the spiral threading has no considerable effect on the scour rate. The spiral threading under the initial bed level plays a major role in reducing local scour.

摘要

在这项研究中，进行了实验室实验，以评估一组新型环形套环和围绕圆形码头的普遍螺旋螺纹对非粘性床材料中清水流态冲刷的影响。此外，还进行了数值模拟，以揭示具有螺旋螺纹的码头周围冲刷孔中的流场。考虑环圈的各种角度和间距以找到最佳配置。此外，考虑了四种不同高度水平的螺旋螺纹测试场景，以研究螺旋螺纹高度的最佳上限。结果表明，环圈（角度 = 45˚，相对间距 = 墩直径的 4/3）是最佳配置，根据普通墩周围的冲刷深度，冲刷深度减少了 29%。与单螺旋螺纹的最佳配置相比，这种环圈配置可将最大冲刷深度降低三倍（先前的研究建议）。此外，环圈降低了冲刷速度，而螺旋螺纹对冲刷速度没有显着影响。初始床面下的螺旋螺纹在减少局部冲刷方面起着重要作用。