| In this paper, the experimental studies on flip bucket with tongue-type were done systematically. The application and development of ski-jump energy dissipaters are also reviewed. Some experimental results were obtained and discussed. The principal content and achievement are concluded as followed:Compared with normal flip bucket, water's time-average pressure in plunge pools down from flip buckets with tongue-types was decreased notably. With discharging, the nappe's widths increase distinctly. For the tongue type diffusers disperse water discharge, the unit discharge in plunge pool decreases.When the discharge is small, the time-average pressure in plunge pool resulting from large-size flip buckets with tongue-type is almost as the same as small ones. However, as discharge increasing, the time-average pressure caused from the large diffuser is superior over the smaller.When pours dive into plunge pool, the incident shape of the flow down from spherical flip bucket and from tongue-type flip bucket are all segmental arc. If they have the same curvature and jet-trajectory angle, the nappe's dispersion ratios are quite equal. However distributions of the unit discharge are heterogeneity, and the time-average pressure in plunge pool caused by the former is great than the later.Based on experiments and dimensional analysis, the formula of the transversal diffusion width is obtained. It includes, e.g., the radius curvature and jet-trajectory angle of flip buckets with tongue-type, the Froude number of the outlet section and the hydraulic head between upstream and downstream. Using such a formula, the nappe's widths can be worked out. The inlet width is a factor when flip buckets with tongue-type are estimated on the inlet in plunge pools. Furthermore inlet shapes and homogeneity of the nappe are also important. As inlet shapes and homogeneity are similar, the effect is good as the transversal width is sufficient. As transversal widths and homogeneity of the nappe are similar, the curved shape is superior to the linear. As transversal widths and shapes of the inlet are similar, the homogeneity of the nappe's thickness becomes the key factor.The jet-trajectory angles of tongue-type flip buckets should be not too large. In this paper, the upper limit exists in . Once the value precedes this limit, the effect of the tongue-type flip buckets decreases apparently.Based on experimental data and analysis of the formula on hand, the formula of the farthest jet-trajectory length in flip buckets with tongue-type is obtained. It is similar to the one in normal flip buckets. Some of it's factors are also introduced. Furthermore, the nearest jet-trajectory length is made. As a result nappe's pattern can be determined.Compared with shock tests in plunge pools, the same results are obtained through movable-bed model tests. As the discharge's scale is not too big, the scour depths are similar caused by different sizes tongue-type flip buckets. Moreover the shock tests reflect the fine differences among the different flip buckets. With the size of the flip buckets with tongue-type becoming small, the sour depths increase ordered. |
