Piano Key Weir (PKW) is a special type of overflow weir which provides an improved discharge capacity with its increased crest length. Increased discharge capacity makes this weir an attractive alternative in the rehabilitation of existing spillways. After the introduction of this new weir type, many experimental and numerical studies are conducted to understand the effect of the numerous geometrical parameters on the discharge capacity. However, empirical discharge formulas suggested by different researchers are not conforming to a unique expression mostly due to dependence on the experimental conditions from which they are derived. A numerical approach is used in the present study to investigate the dependence of discharge capacity of a PKW unit on several geometric parameters. Numerical models are developed and three-dimensional velocity fields are computed using FLOW-3D® software. Discharge efficiency of a PKW over an equivalent linear sharp-crested weir is evaluated within the practical range of parameters from 145 numerical solutions for 29 different PKW models. Numerically obtained data is used to form dimensionless expressions for the weir height and length as function of discharge efficiency which are proposed to facilitate an iterative numerical solution to meet the design requirements of a given project. This approach allows cost optimization while dimensioning the PKW for the required hydraulic capacity. The design procedure based on iterative numerical solutions is described and exemplified.

钢琴键堰 (PKW) 是一种特殊类型的溢流堰，它通过增加顶部长度来提供改进的排放能力。增加的排放能力使该堰成为修复现有溢洪道的有吸引力的替代方案。在引入这种新的堰型后，进行了许多实验和数值研究，以了解众多几何参数对泄流能力的影响。然而，不同研究人员提出的经验放电公式并不符合唯一的表达式，这主要是由于依赖于它们所源自的实验条件。本研究中使用数值方法来研究 PKW 单元的放电容量对几个几何参数的依赖性。开发了数值模型，并使用 FLOW-3D® 软件计算了三维速度场。PKW 在等效线性尖顶堰上的排放效率在实际参数范围内评估，来自 29 个不同 PKW 模型的 145 个数值解。数值获得的数据用于形成堰高和长度随排放效率的函数的无量纲表达式，这些表达式旨在促进迭代数值解以满足给定项目的设计要求。这种方法可以优化成本，同时为所需的液压能力确定 PKW 的尺寸。描述和举例说明了基于迭代数值解的设计过程。PKW 在等效线性尖顶堰上的排放效率在实际参数范围内评估，来自 29 个不同 PKW 模型的 145 个数值解。数值获得的数据用于形成堰高和长度随排放效率的函数的无量纲表达式，这些表达式旨在促进迭代数值解以满足给定项目的设计要求。这种方法可以优化成本，同时为所需的液压能力确定 PKW 的尺寸。描述和举例说明了基于迭代数值解的设计过程。数值获得的数据用于形成堰高和长度随排放效率的函数的无量纲表达式，这些表达式旨在促进迭代数值解以满足给定项目的设计要求。这种方法可以优化成本，同时为所需的液压能力确定 PKW 的尺寸。描述和举例说明了基于迭代数值解的设计过程。