Experimental Study On Bodily Form Optimization Of The Shaft Spillway

There is a problem of high dam and large discharge and narrow river valley and difficulty in disposing discharge & energy dissipation in the course of development of hydraulic engineering in west china. But the traditional used energy dissipation scheme often causes a series of insurmountable difficulties, such as fogging, cavitations demolition, and bank scouring .High dam projects always need build some large-scale diversion tunnel. Nevertheless, the investments of diversion tunnel are huge but they belong to temporary building and then more and more experts and doctors study and pay attention to the permanent utilization of diversion tunnel. So the researches of energy dissipater of flood discharge tunnel have important meaning on science and theoretic and practical applied cost and also can bring definite economic value.This text is on the basic of shaft spillway project of JINPING hydraulic power station which is planned to build and study the hydraulic characteristic of shaft spillway that has energy dissipation structure. With associating comparison of test and theoretical analysis, research and discuss the disciplinarian of hydraulic characteristic caused by the series change of body type parameter of inner-dissipater to optimize body type. In the test, four alterations of flip bucket altitude (contraction ratio) are taken, four alterations of pore diameter on upper part, eight series alterations of dissipation well's size, three alterations of altitude of the compression slope's exist port without changing the proportion of the compression slope. Through a series of researches of comparison test, refers to literature and theory study, by model test, acquire much innovative and engineering valuable result, no matter what extent and deepness, this study possess explore and auspicate.(1) In the experiment process, by observing the flow condition in different contraction ratio, allocating the change series of ring dam's flow condition and definition the range of adapted water head of ring dam. Through study the series change of exist altitude of entercompression slope of recession tunnel. Analyzes the change condition of each hydraulic parameter and get the logical design plan of oppression altitude.(2) Get the contraction ratio of inlet and some weir water head basic disciplinarian of leakage flow resulted of pore diameter change. Through test data fitting, gets the empirical computing formula of leakage flow with different contraction ratio and relational expression between Fr of vena contractor and flow coefficient of flood weir flow.(3) Comprehensive consider ting about flow condition, leakage flow and affecting factors in all directions, brings forward that it will be ideal condition in body type's design of actual engineering that contraction ratio should be 0.37.(4) With analyzing and generalizing the change law of vent speed of air hole and quantity of vent when pore diameter change under the same contraction ratio. Derives that the optimal design size of actual air hole's diameter should be d₀=1.35m.(5) Through study the comparison test of dissipation well's size, the ideal size of dissipation well should be: H₀=1.69 Do, D=1.4D₀.(6) Binding mockup test and theoretical derivation, the expression mathematical relationship of calculating system ratio of damping is build. when the total system ratio of damping is between 83% and 92%, the effect of this energy dissipation structure is good and it may act as extended body type in actual engineering when rebuild the diversion tunnel to permanent flood discharging tunnel.