缓变弯道水力特性及泥沙输移数值模拟研究

发布时间：2018-04-04 20:27

本文选题：缓变曲线　切入点：三维水流泥沙数学模型　出处：《西安理工大学》2017年硕士论文

【摘要】：当水流通过弯道时,液体质点同时受到重力和离心惯性力的作用,在垂直于水流方向的横断面上存在二次流,与主流纵向速度叠加、构成螺旋流。螺旋流会引起弯道泥沙的横向输移,造成弯道凹岸冲刷、凸岸淤积的冲淤特性。因此弯道水流运动规律的研究对于河流开发、泥沙防护、河道演变等具有重要的意义。受到公路转弯处设置缓变曲线的启发,本文也在弯道中插入缓变曲线。在清水定床和清水冲刷两种工况下,通过MIKE 3软件的水动力(HD)模型和泥沙输移模型(ST),研究120°单曲线弯道、缓圆缓弯道、对称凸型弯道的水力特性和冲淤特性,并分析不同缓变因子A (缓圆缓弯道和对称凸型弯道)对弯道水流的改善效果。研究结果表明:(1)插有缓变曲线的弯道能够显著降低弯道水面超高,减小弯道水面横比降,并改善弯道水面扭曲度,其中缓圆缓弯道改善水面形态最为有效。(2)插有缓变曲线弯道的凹岸近底流速均小于单曲线弯道,凸岸的弯道进口附近及过弯顶断面后插入缓变曲线弯道的近底流速较单曲线弯道明显减小,表明插入缓变曲线后的弯道能够减少近底水流流速;在凹岸侧,插有缓变曲线的弯道冲刷比单曲线弯道要小,在凸岸侧淤积也显著减小;说明插入缓变曲线后的弯道能明显减小水流冲淤作用,减小河道冲刷,滞后顶冲点位置,缩短凹岸冲刷长度。(3)分析不同弯道的水力要素及冲淤特性可以得出,三种弯道在改善水面形态、减小冲刷程度的效果上作用大小依次为:缓圆缓弯道对称凸型弯道单曲线弯道。(4)弯道中插入缓变曲线后的改善效果不仅取决于插入缓变曲线的长度,而且与弯道曲率有关,弯道缓和因子越大,改善效果越好。
[Abstract]:When the water flows through the corners, a liquid particle by both gravity and centrifugal force, there are two flow in the cross section perpendicular to the flow direction, and the mainstream superposition of longitudinal velocity, a spiral flow. The spiral flow will cause the lateral transport of river sand, causing the concave bank erosion, erosion and deposition characteristics of convex deposition. Therefore, the study on bend flow in river sediment development, protection, is of great significance. Inspired by the river evolution curve slow setting road corner, this also in the corners into the slow curve. In fixed bed and water scouring water under two different conditions, the water power of the MIKE 3 software (HD) and sediment transport model (ST), on the 120 degree single curve, slow slow circular curve, the hydraulic characteristics of symmetric convex curved and sedimentation characteristics, and the analysis of different factor A (slow slow slow bends round and symmetrical convex corners) The effect of bend flow. The results show that: (1) inserted transition curve curve can significantly reduce the bend surface high, reduce the bend of the transverse gradient of the water surface, and improve the water bend distortion, the slow circle gentle curve improve the surface morphology is the most effective. (2) inserted with slowly varying curve the near bottom velocity is less than single concave curve, the near bottom velocity curve near the inlet and the top section of convex corner insert slow curve with single curve was significantly reduced, showed that the insert slow curve curve can reduce the flow velocity near the bottom; in the concave side, inserted with slowly varying curve curve scour is smaller than the single curve, the convex side deposition also significantly decreased; that slow curve bend insertion can significantly reduce water erosion, reduce river erosion, lagging behind the top spot position, shorten the length of concave bank. (3) analysis of different curve The hydraulic elements and characteristics of erosion and deposition can be drawn, three corners in improving the surface morphology, reduce the extent of erosion on the effect of effect size is as follows: the slow circle gentle curve symmetric convex curved single curve. The curve (4) inserted in the slow curve after improvement not only depends on the length of the curve is inserted into the slow, but also related to the bend curvature curve, relaxation factor is bigger, better effect.

【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV133;TV143

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