台阶式溢洪道掺气特性的试验研究

通过试验研究了台阶式溢洪道上的掺气现象以及掺气区域的划分，试验表明，台阶式溢洪道沿程掺气可以分为非掺气区、掺气发展区和掺气充分发展区等三个区域；断面掺气分为台阶影响的含气区、楔形清水区、水中气泡区和空中水滴区。试验还测量了台阶式溢洪道上的断面掺气浓度及其沿程分布，计算了断面含水率，提出了初始掺气点的计算方法。与光滑溢洪道相比较，台阶式溢洪道具有初始掺气点前移，掺气发生早，发展快，掺气浓度大等特点。

Experimental Investigation on the Characteristic of Air Entrainment on the Stepped Spillways

The air entrainment is the key point of the air erode and the security of the operation on the stepped spillways. The phenomenon and the division method of air entrainment on the stepped spillways have been studied by experimental mthod. The along-road air entrainment on the stepped spillways can be divided into 3 regions which are the non-entrainment region, the development region and the air sufficient region. The sectional air entrainment can be divided into 4 regions which are the bottom air entrainment zone, cuniform pure water zone, bubble zone and drip zone. The along-road distribution of the sectional air entrainment thickness has also been studied in the experiment. The sectional water containing index has been calculated. The calculating method of the initial air entrainment point on the stepped spillways has been declared. Compared with that of the slippery spillways, the initial air entrainment point of the stepped spillways moves forward. The air entrainment of the stepped spillways occur earlier, develope quickly. And the thickness of air entrainment is large.