Experiment Research Of Water Flow Characteristics Of Spiilway Discharge Under Different Curve Conditions And Arrangement Plan Of Guide Walls

The spillway is the most important part of reservoir pivotal project, and the drain slot is the connection part between control part (weir or brake) and energy dissipation impingement facility. In actual engineering, due to the limitations of topography and geology, we often have to set curves in the drain slot. Because of the circulation characteristics of curve, when the rapids get through the curves, the flow regime deteriorates. Therefore in order to eliminate the adverse effect of curve stream, setting the guide wall is one of the engineering measures. In this paper, base on the model test, we made a research of water flow characteristics of multiple combinations curve, the content and conclusions are as follows:(1) The analysis of water flow characteristics of curve after it has been set guide wall.The water flow characteristics of spillway curve with guide wall are basically consistent with the condition without guide wall. The water flow (both vertically and horizontally) of spillway curve is still uneven, the wave crest and valley of cut bank and convex bank appear alternately. There is an obvious diamond wave spreading to the down stream. The bottom slope and axis radius have an obvious influence on the vertical change of depth of water of cut bank,the bigger the bottom slope,the smaller the depth of water of cut bank; the bigger the axis radius,the smaller the depth of water of cut bank.The depth of water of every transverse section of curve has apparent change, the depth of water of cut bank is bigger than convex bank, forming an obvious surface transverse slope. The horizontal water flow have local indicates high and lower, thus it is asymmetrical. There is an influence of bottom slope and axis radius on the cross section difference:the bigger the bottom slope,the bigger the difference between every cross section, the smaller the axis radius,the bigger the difference between every cross section. Hence reducing the bottom slope and increasing the axis radius can minimize the waterhead of fracture surface of curve exit, making the down stream water flow well-distributed. After we set the guide wall, it divides the water flow of curve into left and right sink.When there is a small flow (the water level below the guide wall),the transverse slope is smaller, and the waterhead of the guide wall is big, the right depth of water of the guide wall apparently higher than that of left;on the contrary when there is a big flow(the water level is above the guide wall) the transverse slope is relatively obvious,and the right and left water level of guide wall is roughly horizontal.(2) The analysis of improved result of water flow after we have set the guide wall.Different flow, bottom slope of chute,axis radius of curve, number of guide walls exert great influence on improved results of curve water flow. We introduced the lowing rate of surface difference of cross section and flow uniformity to evaluate the improved results. Therefore the result indicates that the smaller the flow, the better improved results of water flow brought by the guide wall,that is to say,when the guide wall dividing the water flow completely,there will be best improved results of water cross-section waterhead brought by the guide wall; the same is true with the bottom slope; while the bigger the axis radius the better results of water cross-section waterhead; and the more guide walls,the better improved results of water flow brought by guide walls. After we set the guide walls, the vertical change of velocity is more stable, and the more guide walls, more stable it will become.ght sink.