Application of side weirs with high effective length is necessary to discharge excessive flows, to control the flow in water conveyance systems, and irrigation and drainage systems. Most of the studies on the side weirs have been conducted on the straight channels and linear weirs. The flow pattern on the outer arc of the curved channels and its suitability for side weir can be used and combined with the piano key weirs. So far, no comparison has been made on rectangular piano key side weirs (RPKSW) at a 120° Section of a 180° Curved Channel. In this study, an experimental study was performed on A-, B-, C-, and D-type RPKSW at a bend angle of 120 degrees. The results showed that the specific energy at two ends of the RPKSWs was the same, with a slight difference of 3.4% for A-Type, 1.3% for B-Type, 1.1% for C-Type, and 1.8% for D-Type weirs. The discharge coefficients of the studied weirs were also investigated, and it was concluded that B-Type weir has better performance than other weirs. On average, the discharge coefficient of B-Type weir was 9.9%, 21.2%, and 24.1% higher than that of A-Type, C-Type, and D-Type weir, respectively. It was shown that the ratio of P/h1 is the main parameter affecting the weir discharge coefficient. Finally, an empirical equation was proposed for each weir. The proposed equation has MAE = 0.028 for A-Type weir, MAE = 0.041 for B-Type weir, MAE = 0.049 for C-Type weir, and MAE = 0.053 for D-Type weir.

必须使用有效长度较长的侧围堰，以排出过多的水流，以控制输水系统，灌溉和排水系统中的水流。关于侧围堰的大多数研究都是在直线通道和线性围堰上进行的。可以使用弯曲通道外弧上的流型及其对侧堰的适用性，并与钢琴键堰组合使用。到目前为止，还没有对180°弯曲通道的120°截面上的矩形钢琴键侧堰（RPKSW）进行比较。在这项研究中，以120度弯曲角度对A型，B型，C型和D型RPKSW进行了实验研究。结果显示，RPKSW的两端的比能相同，A型，B型为1.3％，C型为1.1％，D型为1.8％略有差异，为3.4％。堰。还研究了所研究堰的排放系数，得出的结论是B型堰比其他堰具有更好的性能。平均而言，B型堰的排放系数分别比A型，C型和D型堰高9.9％，21.2％和24.1％。结果表明，P / h1比是影响堰溢流系数的主要参数。最后，为每个堰提出了经验方程。拟议方程的A型堰的MAE = 0.028，B型堰的MAE = 0.041，C型堰的MAE = 0.049，D型堰的MAE = 0.053。C型和D型堰。结果表明，P / h1比是影响堰溢流系数的主要参数。最后，为每个堰提出了经验方程。拟议方程的A型堰的MAE = 0.028，B型堰的MAE = 0.041，C型堰的MAE = 0.049，D型堰的MAE = 0.053。C型和D型堰。结果表明，P / h1比是影响堰溢流系数的主要参数。最后，为每个堰提出了经验方程。拟议方程的A型堰的MAE = 0.028，B型堰的MAE = 0.041，C型堰的MAE = 0.049，D型堰的MAE = 0.053。