Study On Fish-Friendly Evaluation Of Kaplan Turbine

The dam not only blocks the routes of migration fish,but also breaks the complete water ecosystem into discontinuous environmental units,destroys the whole life history of fish,cuts off the gene exchange between populations.Therefore,the development of the traditional fishery industry and the protection of the ecological diversity of rare fish species are affected.As the turbine passage of the fish passing through the dam,it is possible to solve the above problems theoretically.How to evaluate the "fish-friendly" performance of the turbine has become a key link.On the basis of collecting a large number of references and engineering data,this paper takes the four major Chinese carps,the typical economic fish species in the Yangtze River Basin and ZZ500 turbine,the Kaplan turbine in Gezhouba hydropower project are selected as the research objects.Based on the distribution characteristics of hydrodynamic factors in turbine under different operating conditions and the experimental results of single hydrodynamic factor of "four major Chinese carps",an evaluation model for the damage possibility of the fish passing through the turbine is established to evaluate the effect of turbine operating conditions on the "fish-friendly" performance.The main contents and conclusions of this paper are as follows:1)Study on distribution characteristics of hydrodynamic factor in full channel of Kaplan turbine under typical conditions.The geometric model,mesh model and numerical calculation model of ZZ500 Kaplan turbine are constructed.Through the design and calculation of full working conditions,the key hydrodynamic factors such as velocity,velocity gradient,pressure,pressure gradient are obtained under the whole channel and all conditions of full head,flow rate,output,corresponding efficiency,guide vane opening and blade angle.The abrupt change of pressure exists at the back surface of blades,and the abrupt change of shear force mainly occurs near the blade.The draft tube is the main negative pressure area.The runner chamber and draft tube are the most likely damage areas for fish.2)Study on the correlation between fish-passing capacity and hydrodynamic factors in Kaplan turbine.The key hydrodynamic damage factors affecting fish passing through the channel safely are identified as flow velocity,velocity gradient,pressure and pressure gradient.The damage threshold is obtained by the threshold experiment of key hydrodynamic factors.Through the design and calculation of damage method programming language,the volume ratio of fish damage area in Kaplan turbine is obtained.When the volume ratio of Kaplan turbine is the maximum,the turbine is in the condition of maximum water head,maximum negative blade angle and minimum guide vane opening.3)Establishment of the "fish-friendly" performance evaluation model for Kaplan turbine.Based on the volume ratio of the damaged area of the turbine channel,the relationship model between the operation parameters of the turbine and the volume ratio of the damaged area is constructed by BP neural network,and the performance evaluation model of the Kaplan turbine is obtained.