常规水力学模型试验中的缩尺效应问题

本文根据丹江口水利枢纽泄洪深孔的模型试验成果和原型观测资料,对常规水力学模型试验中的缩尺影响问题进行了分析研究。通过原、模型成果资料的对比分析表明:水流基本特性,诸如:水流边界上的压力特性,泄水建筑物的泄流能力等,可以通过按佛劳德相似准则设计的模型试验得以预见。而高速水流造成的水雾现象,模型上难以反映。其次,由于裂隙发育的岩基河床的构造特性在模型上难以模拟,因而坝下游河床冲刷坑的位置和冲刷坑形状无法通过模型试验预测。

Study on Scale Effect in Conventional Hydraulic Models

This paper presents the informations related to the model tests and the prototype observations of the Danjiangkou project high head bottom outlet. According to the findings , scale effect is as sessed. By comparing the model test results with the field data collected from the Danjiankou project high head bottom outlet , it can be demonstrated that in conventional hydraulic models, namely the scale model designed according to the Froude Similarity Criteria, the pressure characteristics of the wa ter flow on flow boundary , the discharge capacity and so on may be predicted by scale model tests. But the spary appearance caused by high velocity flow can not be replicated on scale models. Second ly,because of the structure characteristics of the rock and the fissures can not be simulated on scale model, so that location and shape of the scour pit also can not be predicted by scale model tests.