突扩式跌坎消力池掺气特性试验

采用模型试验对突扩式跌坎消力池内水流的掺气浓度进行了量测，研究了来流条件、突扩比、水流流态对掺气特性的影响。结果表明：突扩式跌坎消力池掺气水流典型流态为水跃流叠加在射流之上，跃首被射流分裂成两部分，气泡跃移区在泄槽延长线范围内，长度较无突扩跌坎消力池有所减小，气泡悬移区长度有所增加，临底长度有所减小，突扩处为清水回流区，携带部分气泡；无突扩跌坎消力池底板掺气浓度呈降峰形曲线分布，各纵向断面沿程掺气浓度分布均匀；突扩式跌坎消力池底板掺气浓度呈升峰形曲线分布，掺气浓度在消力池底板1/4中线处最大，1/2中线处次之，靠近边墙处最小；在同一水力条件下，突扩式跌坎消力池底板掺气浓度较无突扩跌坎消力池有显著降低，且消力池底板掺气浓度不随突扩比的增大而减小。

Experimental research on aeration characteristics of a stilling pool with drop sill and sudden expansion

Based on the model test, the aeration concentration of the water flow in a stilling pool with drop sill and sudden expansion was measured, and the influence of incoming flow conditions, sudden expansion ratio, and flow state on the aeration characteristics was studied. The results show that the typical flow pattern of the aerated water flow in a sudden-expansion slumping stilling pool is a hydraulic jump superimposed on the jet of which the head is split into two parts. The bubble zone is within the extension of the chute and the length is reduced compared with the stilling pool without sudden expansion. The length of the drip zone is increased, but its length near the bottom is reduced. A pure water recirculation zone containing bubbles occurs at the sudden expansion. The aeration concentration of the bottom plate of the stilling pool without sudden expansion shows a peak-decreasing curve distribution, and the aeration concentration of each longitudinal section is evenly distributed. The aeration concentration of the bottom plate of the stilling pool with sudden expansion shows a peak-rising curve distribution, with the highest aeration concentration at the 1/4 midline of the floor, the second highest concentration at the 1/2 midline of the floor, and the lowest concentration near the side walls. Under the same hydraulic conditions, the aeration concentration at the bottom of the sudden expansion stilling pool is significantly lower than that without sudden expansion, and the aeration concentration does not decrease with the increase of the sudden expansion ratio.