Gates are important hydraulic structures and used for flow measurement, water delivery, and water level regulation in open channels and irrigation networks. In this study, the quarter-circular gate is introduced and investigated. The cross section of this gate consists of a quarter circular arc and the lip angle of the gate equals to zero. Discharge coefficient, variation of downstream flow depth, and velocity distribution at opening section of gate were experimentally measured. Using potential flow theory supported by dimensional analysis, equations for discharge coefficient and velocity distribution at gate opening section of quarter-circular gate were derived and then validated using experimental data. The mean percentage error (MPE) of obtained equation for discharge coefficient of quarter-circular gate was calculated as 2.24%, indicating the high precision of the proposed theory. Based on obtained results, downstream flow depth of quarter-circular gate is uniform. Also, velocity distribution at gate opening section is nearly uniform. Discharge coefficient of quarter-circular gate was averagely obtained 55% larger than that of sluice gate. It was also obtained larger than that of radial gate. Elimination of contraction section at downstream of gate opening, which is the main source for energy loss and therefore discharge capacity reduction, is the main reason for larger discharge coefficient of quarter-circular gate.

闸门是重要的水工结构，用于明渠和灌溉网络中的流量测量、输水和水位调节。在这项研究中，介绍和研究了四分之一圆门。该浇口的横截面由四分之一圆弧组成，浇口的唇角为零。实验测量了流量系数、下游水深变化和闸门开口段流速分布。应用量纲分析支持的势流理论，推导出四分之一圆闸门开口截面处的流量系数和速度分布方程，并利用实验数据进行验证。计算得到的四分之一圆闸门流量系数方程的平均百分比误差（MPE）为2.24%，表明所提出的理论的高精度。根据所得结果，四分之一圆闸门的下游流深是均匀的。此外，浇口开口部分的速度分布几乎是均匀的。四分之一圆闸门的流量系数平均比闸门大55%。它也获得了比弧形门更大的尺寸。闸口下游收缩段的消除是造成能量损失和放电容量降低的主要来源，是四分之一圆闸口放电系数较大的主要原因。四分之一圆闸门的流量系数平均比闸门大55%。它也获得了比弧形门更大的尺寸。闸口下游收缩段的消除是造成能量损失和放电容量降低的主要来源，是四分之一圆闸口放电系数较大的主要原因。四分之一圆闸门的流量系数平均比闸门大55%。它也获得了比弧形门更大的尺寸。闸口下游收缩段的消除是造成能量损失和放电容量降低的主要来源，是四分之一圆闸口放电系数较大的主要原因。