依托某工程泄洪洞出口消能工体型优化试验，对常规挑坎、平面扩散型和纵向扩散型消能工（窄缝挑坎）的挑坎水舌特性进行了对比研究，其中重点对窄缝挑坎消能工鼻坎体型对水舌运动轨迹、水舌形态、入水范围的控导作用进行了初步探讨。研究结果表明：通过侧墙非对称偏向、出口局部偏转等措施实现挑坎水舌运动方向的控导效果，适应下游河道边界特殊需要，较好地解决了工程消能难题，可为同类型工程提供参考，但鼻坎体型、尺寸等参数与水舌运动轨迹的定量关系仍有待进一步深入系统研究。

To optimize the energy dissipation at the outlet of flood-discharge tunnel, characteristics of the nappes of common flip bucket and narrow-slot flip bucket(including  planar-diffusion and longitudinal diffusion energy dissipator) were systematically investigated. The controlling and diverting effect of narrow-slot bucket type on the movement locus and pattern of nappe and the contact area of jet flow into water were discussed in emphasis. Results showed that problems of energy dissipation can be well addressed  by asymmetric side-wall and partial deflection of the outlet to control and divert the nappe direction and subsequently adapt to the complex downstream channel boundary. The research could be a reference for similar projects, yet the quantitative relation between the nappe movement locus and the bucket type and size are to be studied in depth.