水工定床模型相似度的研究

Study on similarity grade of immovable riverbed hydraulic model

对水工定床模型相似性的分析可量化为模型相似度的比较。模型系统与原型系统之间的相似在于二者之间有若干个相似元。各相似元的相似值等于特征值比例系数和相应的特征权数的乘积。相似元的相似值总和为二者之间的相似度 ,即二者之间相似性的度量。水工定床模型系统与原型系统之间的相似性由十个相似元构成。根据这一理论 ,本文分析了模型的几何变形对流速、压强和相应场产生的变态效应 ,并以算例分析了变态率和几何比尺对水工定床模型相似度的影响。结果表明相似度量化评估有利于提高模型的相似性 ,水工定床模型宜多采用大比尺。

The concept of similarity grade is proposed to quantitatively assess the similitude of hydraulic models.Similitude relationship between model and prototype is based on a series of similarity elements,which is equal to the product of characteristic ratio and corresponding characteristic weight.The sum of all similarity elements is the similarity grade representing the degree of similitude.The similarity between prototype and immovable hydraulic model consists of 10 elements.According to this principle,the effect of geometric distortion on velocity and pressure in distorted model are analyzed.Calculation examples are given.It is concluded that the quantitative evaluation of similarity grade results in enhancing simitilude, and models with larger scale should be advocated.