反拱水垫塘淹没冲击射流水力特性研究

Hydraulic characteristics of submerge impact jetininverted arch plunge cushion pool

【目的】系统研究高坝坝身泄洪水舌在空中的运动规律,以及下游反拱水垫塘流场内的流速分布、紊流结构及底板压强分布。【方法】以溪洛渡水电站工程为例,建立高拱坝及其下游水垫塘物理和数学模型,对工况1(坝身7表孔单独泄洪)和工况2(7表孔与8深孔联合泄洪)条件下反拱水垫塘内形成的淹没冲击射流的水力特性进行研究。【结果】工况1条件下,7表孔单独泄洪时的泄洪水舌不发生碰撞而分别交错射入水垫塘;工况2条件下,7表孔与8深孔联合泄洪时的泄洪水舌在空中发生碰撞后均匀落入水垫塘。2种工况下,反拱水垫塘内形成具有横向和纵向漩涡的淹没冲击射流为复杂的三维流动,塘内临底流速大小相当,最大时均临底流速约为24m/s;水垫塘底板压强在冲击区存在峰值区,且工况1较工况2小,沿纵向分别约为70和90m范围,但工况1最大底板时均压强较工况2大,分别为1 670和960kPa,前者约为后者的1.74倍。【结论】高坝坝身表孔、深孔联合泄洪较表孔单独泄洪具有更大的泄洪能力,在临底流速大小相当的情况下可明显降低底板压强,具有更好的安全性能。

【Objective】This study systematically investigated themovement rule of flood jet relief through dam,velocity distribution,turbulence structure,and base slab pressure in flow field of downstream arch invert cushion pool.【Method】Aphysical and mathematical model of high arch dam and arch invert cushion poolwas established using Xiluodu hydropower station as the engineering background.Then,thehydraulic characteristics of submerged impinging jetwere analyzed for condition 1（flood discharge by seven crest spills separated）and condition 2（flood discharge by eight lower outlets combined with seven crest outlets）.【Result】For condition 1,seven jets plunged into water cushion separately without crash energy,while jets of seven surface outlets and eight bottom outlets fell into plunge pool equably after impingingin condition 2.Submerge impact jets of transverse and lengthwise eddy in counter-arch plunge pool were three-dimensional complex flows with similar near-bed flow velocity and the maximum velocity of-24m/sin both conditions.Peak value scope of bottom pressure existedin impact zone of plunge pool.Scope of condition 1（-70m）was smaller than that of condition 2（-90m）while maximum averaged pressure of condition 1（1 670kPa）was 1.74 times of that of condition 2（960kPa）.【Conclusion】High dam flood discharge through crest and bottom outlets has greater capacity of flood discharge than through crest spillway andbottom pressure can begreatly reduced withthe same near-bed velocity.