Flow Field Analysis And Performance Prediction Of T-type Model With Ultra-low Specific Speed

At present,in the fields of petrochemical industry,iron industry and steel industry,hydraulic turbine is used to recycle high residual pressure liquid to achieve the purpose of energy saving and emission reduction.However,the commonly used reverse pump mode of hydraulic turbine has many disadvantages,such as too many stages,large size,low efficiency,narrow efficient working range,poor stability,etc.;although the new mode – T-type turbine can solve the above problems,due to the complex structure of the flow channel,parameter optimization is needed to achieve the optimal performance,fine parameter adjustment to adapt to requirements of different design water head,fast performance,etc.;fast prediction to reduce a lot of model design time.Therefore,in this paper,the parameters optimization,parameters refinement and performance fast prediction of ultra-low specific speed turbine model are studied.(1)Based on the theory of orthogonal experimental design,the geometric influence factors of the head and efficiency of the ultra-low specific speed turbine mode hydraulic turbine are studied by the range analysis method.It is concluded that the angle of the inlet is the biggest influence factor of the efficiency,and the diameter of the runner inlet is the biggest influence factor of the head.Based on this,two ultra-low specific speed turbine mode hydraulic turbine models with the best efficiency and head are established The CFD fluid simulation software is used to calculate the flow field of the optimal scheme of water head and efficiency,and to analyze the external and internal characteristics.(2)Runner is an important flow passage part of the hydraulic turbine.Among the parameters of the runner blade inlet setting angle,runner inlet diameter,runner outlet diameter,runner inlet width,runner blade number,etc.,the runner blade inlet setting angle has the greatest impact on efficiency,and the runner inlet diameter has the greatest impact on water head.Therefore,the runner blade inlet setting angle is 100°,110°,120° The hydraulic turbine model of ultra-low specific speed turbine mode adopts three different parameters of runner inlet diameter 490 mm,500mm and 510 mm to establish the model of ultra-low specific speed turbine mode hydraulic turbine respectively.By comparing the numerical simulation results,the effects of runner blade inlet angle and runner inlet diameter on the efficiency and head of ultra-low specific speed turbine mode hydraulic turbine are obtained.(3)The flow passage structure and the parameter model matrix of the flow passage components of the ultra-low specific speed hydraulic turbine are constructed by the orthogonal experimental method,and the CFD numerical calculation is carried out to obtain the basic data for prediction.Combined with the rapidity of the local search of BP algorithm and the global convergence of GA algorithm,the GA-BP neural network is established to optimize the initial weight and threshold of BP network to improve the convergence speed,prediction ability and prediction ability of the network Accuracy,to achieve ultra-low specific speed turbine mode hydraulic turbine performance fast prediction.