射流掺气对冲刷的影响

Influence of aeration on scouring

通过对射流掺气与不掺气时基岩冲刷的对比试验 ,研究了掺气对射流冲刷的影响。试验结果表明 :掺气总是使冲坑减小 ,冲坑深度随掺气浓度的增加而递减的规律可表示为幂函数关系。当入射流速和水舌厚度相同时 ,随着下游水垫深度的增加 ,掺气对射流冲刷能力的减弱程度也增加 ;当水舌厚度和水垫深度相同时 ,对不同的入射流速 ,在本次试验范围内 ,掺气对射流冲刷能力的减弱程度是相同的。掺气对冲坑形态并没有实质性的影响 ,冲坑的宽深比随冲坑深度的减小而增大 ,无论造成冲坑深度减小的原因是掺气、降低流速还是减少入射水舌厚度 。

The influence of aeration on scouring is studied experimentally in laboratory. The result shows that aeration of jet mitigates the scouring and the effect of air concentration on scouring depth obeys the exponential law. Aeration will not influence the shape of scouring pit. The ratio between the length and the depth of scouring pit will decrease with the increase of the scouring depth, in spite of the variations of air concentration and jet thickness. It follows a linear relationship.