垂直射流冲刷砂床的喷嘴间距试验研究

Experimental study on nozzle distance of sand bed scour by impinging water jets

疏浚工程中常利用射流进行河道清淤和冲砂施工。为探究喷嘴间距对射流冲刷的影响,开展了一系列不同靶距、速度和间距的双喷嘴冲刷粗砂、中砂砂床试验,分析了冲刷坑形、冲坑深度和冲坑截面积的变化特性,得到了各工况下的最优喷嘴间距L_B和不利喷嘴间距L_N。结果表明,对于同一粒径砂床,改变靶距和速度冲刷时的L_B和L_N值变化较小,而与粗砂砂床相比,冲刷中砂砂床时的L_B和L_N值均有所增加。研究成果可供疏浚工程中射流系统设计作为参考。

Water jets are often utilized to desilt and scour sandy deposition on river bed in dredging practice. The effects of the nozzle distance to the scour by water jets were studied. Experiments of scouring on coarse and medium sand beds by two water jets were conducted with impinging height, jet velocity at nozzle, and the nozzle distance variation. The profile, the maximum depth, and the sectional area of the scour holes with the nozzle distance are analyzed. An optimal nozzle distance LN and a negative nozzle distance LN are obtained in a series of tests with the same impinging height and jet velocity. The results reveal that, both LB and LN have small changes when the impinging height and the jet velocity vary at the same particle diameter of sand. Values of LB and LN increase when the scoured particles turn from coarse sands to medium sands.