通过模型试验，研究了起旋器出口面积收缩率对水 平旋流泄洪洞水力特性的影响。研究发现面积收缩率对流态、泄流量、壁面压强和空腔内的 气体压强均有较大的影响。面积收缩率较大时，流态变化复杂，泄流量和环流空腔内的负压 的变化减小，但空腔环流的空腔直径和泄洪洞的消能率增大。 

The influence of the area contraction ratio of rotary flow generator on the hydraulic characteristics of level rotary flow has been investigated by the hydraulic model test of an internal energy dissipation tunnel . The area contraction ratio has obvious influence on the flow pattern, discharg e, wall pressure and air pressure inside level rotary flow. For the larger area contraction ratio, the flow condition becomes more complicated, the discharge of the tunnel and the change of the negative pressure in the cavity pocket will be reduced, but the cavity diameter of the level rotary cavity flow and the dissip ation ratio of the system will be increased.