Piano key weirs are a new type of weir designed to enhance the discharge capacity of dams. The present study is aimed at experimentally evaluating the hydraulic characteristics of a D-type triangular piano key weir. The purpose of these experiments was to study the flow regime, the stage-discharge relationship, and the effect of h/P ratio on the discharge coefficient. The results indicated that the discharge coefficient in D-type triangular piano key weirs was higher than that of rectangular ones, and it varied in the range of \(0.48 < C_{d} < 1.6\) and \(0.6 <\) (with and without a downstream ramp, respectively). Moreover, under similar laboratory conditions, the results showed that the discharge coefficient of the piano key weir is higher than that of the linear weir. The increase in the discharge coefficient of the piano key weirs, compared to linear weirs, can be up to three times in low heads. Finally, to predict the discharge coefficient of the piano key weirs, an equation was proposed for two cases, i.e., with a downstream ramp and without a downstream ramp.

钢琴键堰是一种新型堰，旨在增强大坝的泄水能力。本研究旨在通过实验评估D型三角钢琴键堰的水力特性。这些实验的目的是研究流态，阶段-排放关系以及h / P比对排放系数的影响。结果表明，D型三角钢琴键堰的排放系数高于矩形堰，且在\（0.48 <C_ {d} <1.6 \）和\（0.6 <\）的范围内变化。（分别带有和不带有下游坡道）。此外，在相似的实验室条件下，结果表明，钢琴键堰的放电系数高于线性堰的放电系数。与线性堰相比，钢琴键堰的排放系数的增加在低扬程中可高达三倍。最后，为了预测钢琴键堰的放电系数，提出了两种情况下的方程，即具有下游斜面而没有下游斜面的情况。