河工模型试验模拟技术探讨

Approach to Modeling Techniques of River Model Test

在河工变态模型试验中,几何变态造成水流的流速场和动力场不完全相似,具体反映在糙率相似、起动切应力与起动流速不协调及时间变态等问题上。从动力调整的新视角来分析,在变态模型试验中,可将模型旋转改变比降,调整糙率,解决阻力相似和起动流速与起动切应力的不协调问题;动床模型时间变态会使模型中最基本的水力因素的相似性产生严重偏离,目前使用的任何校正措施都难以奏效。分析发现使用动力调整技术,可以改变模型水流的挟沙能力,进而影响冲淤变形时间比尺。提出了解决时间变态问题的一个新途径。

During the river distorted model tests,the flow velocity field and dynamic field caused by geometric distortion are not completely similar,specifically shown by roughness similarity,unbalanced priming shear stress and starting velocity and time distortion.Analyzing from new visual angle of dynamic regulation, it can change gradient,regulate roughness,solve resistance similarity and unbalanced priming shear stress and starting velocity through model rotation;the time distortion of movable-bed model will severely cause the most fundamental similarity hydraulic factors of the model deviation and no correction measures that used at present are effective.It finds out through analysis that dynamic regulation technique can change the sediment carrying capacity of the model and affect the time scale of scouring and silting deformation.It puts forward a new way for solving time distortion issue.