跌坎下的B型水跃

跌坎下的B型水跃(中文1600字,英文1100字)
Willi H.Hager,1 M.ASCE
引言
水跃是最常见的消能方式之一。最简单的形式，是矩形、棱柱水平明渠，这中类型已被广泛运用近两个世纪，但对其水流特性不是很了解。
每当利用水跃消能时，必须控制所有可能的流动条件下稳定性。这是所谓的消力池，水跃发生在某特定的区域。众多类型的消力池已提出过[例如，Peterka（5）]。其设计通常根据于水力模型中的复杂流动现象的研究。本试验用一个简单的几何模型，水跃发生在一个棱柱形、矩形的的明渠的底板上。虽然第一次观测可追溯到1930年（1），但有价值和重要的水力特性并没有完全发现。因此，一个基本的水力方程被用来分析水跃区域的非静亚力的分布。
传统方法
根据下游较远的弗劳德数，突扩可能导致四种不同的流态类型。这些分别如下：：（1）小亚临界;（2）分向超临界;（3）超亚临界;（4）超临界流状态。在本实验，仅考虑第三种类型，水跃发生。
B-JUMP AT ABRUPT CHANNEL DROPS
BY Willi H. Hager,1 M. ASCE
INTRODUCTION
Hydraulic jumps are one of the most frequently used energy dissipators. Its simplest form, the plane hydraulic jump occurs in rectangular, prismatic, and almost horizontal channels; this type has been extensively studied for almost two centuries, yet, its internal flow behavior cannot be fully described. Whenever using hydraulic jumps as a kinetic energy dissipator, one has to control carefully its stability under all possible flow conditions. This may be achieved by so-called stilling basins, by which the jump is forced to appear at a particular location. Numerous types of stilling basins have been proposed [see, e.g., Peterka (5)]. Their design relies usually in hydraulic models by which the complex flow behavior can be studied. The present investigation deals with a simple geometrical configuration, the hydraulic jump in a prismatic, rectangular channel having an abrupt drop of the channel bottom. Although first observations date back to 1930(1), interesting and important features have not been thoroughly considered. Therefore, an elementary hydraulic approach will be developed by accounting for the nonhydrostatic pressure distribution at the drop section.