Preliminary Study Of Cavitation Characteristic And Preliminary Study On The Level Swiring Flow Spillway Tunnel

Chinese large-scale water resources and hydroelectric project mostly have the property of high head,large flow,narrow valley, large flow discharge and energy dissipation of high dam is the mutual technical problem of all kinds of projects. The horizontal vortex and rotary inner energy dissipating tunnel with an inlet shaft have the strong points of high energy dissipation ratio,simple construction,flexible arrangement,low engineering cost etc, that has value in biggish theoretical analysis and application to such study.To better develop the comparative study between atmospheric model and decompression model, and to further pertinency lucubrate study important problems of affecting project safety performance,model similarity rate relation, the paper makes concrete analysis and research to cavitation characteristics in seven key parts of GONGBOXIA gyrating flow spillway tunnel on different working conditions water level by means of sound pressure level difference and overall sound pressure, and compare analysis cavitation characteristics measurement result GONGBOXIA atmospheric model observation test and 1:40 atmospheric and vacuum model test.Flow pattern of level rotary flow inner energy dissipation discharge tunnel can disport to three areas by change law of swirl cavity diameter,cavity gas pressure and vent ventilation volume:free flow pattern,sucking flow pattern and submerged flow pattern. And contented similarity criterion is different between different flow patterns. In free flow pattern and submerged flow pattern, as long as flow movement meet the dynamic similar criterion can reach the similarity of spillway tunnel flow pattern; in sucking flow pattern, not only meet gravity similar criterion, but meet ventilation volume froude number fr of air hole section is same.On the basic assume conditions of flow analysis, proposing and defining the swirling flow characteristics of cavity swirling flow in horizontal rotary energy dissipation spillway:Swir. angleα,tangential velocity momentC,swirl strengthωand non-dimensional integrated swirl parameter AM,and establishing and derivedding the mathematical expression of these swirl characteristics. Another, from the average rotation angle of the swirl characteristics and comprehensive swirl characteristics, we get the further concrete similarity criterion to describe swirling flow characteristics of gyrating flow spillway tunnel.