Current research presents a comprehensive numerical study on the performance of riverbed intake systems equipped with non-circular cross section racks. Three types of bottom racks, such as rhombus bars, rounded-edge rectangle bars, and circular bars, were numerically modeled using Flow3D software with different geometric and hydraulic parameter, all in super critical approaching flow in clear water condition. Subsequently, changes in diverted discharge ratio (DDR) of bottom racks and factors affecting its intensity and manner of changes, were studied using model results. The study reveals that the RNG k-ε turbulence model accurately represents the flow field around the bottom racks. The results indicated that the DDR changes are directly related to rack length changes but is inversely related to the rack slope and upstream flow discharge. Also, rhombus bars outperform circular and rounded bars, with 23.34% and 35.92% higher flow diversion, respectively, attributed to the formation of more negative pressures between bars. The main focus of the present study was on accurate and complete estimation of the diverted discharge coefficient (C_d) for racks with different bar shapes—especially non-circular bars using the results of the constructed numerical model. Proposed relations for the diverted discharge coefficient (DDC), especially for non-circular bars, were rigorously validated and showed high accuracy in predicting DDC under diverse hydraulic and geometric conditions.

目前的研究对配备非圆形横截面机架的河床取水系统的性能进行了全面的数值研究。使用Flow3D软件对菱形杆、圆边矩形杆和圆形杆等三种类型的底架进行数值模拟，采用不同的几何和水力参数，均处于清水条件下的超临界逼近流动。随后，利用模型结果研究了底部机架分流率（DDR）的变化以及影响其强度和变化方式的因素。研究表明，RNG k-ε 湍流模型准确地表示了底部机架周围的流场。结果表明，DDR变化与机架长度变化直接相关，但与机架坡度和上游流量负相关。此外，菱形条的性能优于圆形条和圆形条，其导流率分别高出 23.34% 和 35.92%，这归因于条之间形成更多的负压。本研究的主要重点是利用所构建的数值模型的结果，准确、完整地估计不同棒材形状（尤其是非圆形棒材）的机架的分流系数（C _d ）。所提出的分流流量系数 (DDC) 关系，特别是非圆形杆件，经过严格验证，并在不同水力和几何条件下预测 DDC 时表现出较高的准确性。