Hydraulic Performance Research And Optimization Of Hydraulic Turbine

As an important pressure-reducing device in the production of liquefied natural gas,FLNG hydraulic turbine can not only reduce pressure during the process of producing liquefied natural gas,but also increase the production of liquefied natural gas.Based on the multi-stage hydraulic turbine model,the numerical simulation method is used to optimize the hydraulic turbine impeller in order to obtain a more efficient model.Firstly,the hydraulic turbine flow field model was established,and the internal flow field numerical simulation and hydraulic performance calculation were carried out.The results show that the original model of the hydraulic turbine has low efficiency,local pressure is too high at the joint between the vane and the impeller,and the vortex is close to the blade area.Secondly,the sensitivity analysis of the parameters of the hydraulic turbine blade is carried out,and the influence of the blade inlet width,the blade thickness and the blade inlet angle on its efficiency is discussed.The results show that with the increase of the blade exit width,the efficiency increases gradually;as the blade thickness increases,the efficiency decreases gradually;as the blade inlet angle increases,the efficiency fluctuates.Thirdly,the power loss of the hydraulic turbine is selected as the optimization target,the parameter optimization design scheme is determined,the fitness function is obtained,and the genetic algorithm is used for optimization.Through comparison and analysis of the model before and after optimization,it is found that the head and output of the model are improved,and the efficiency is improved from 65.31% to 68.66%.From the internal flow field analysis,the pressure field distribution of the optimized model is more uniform,and the vortex on the surface of the blade is improved.Finally,based on the optimization results of the blade parameters of the hydraulic turbine,the axial flow path of the impeller is further optimized.Based on the Bezier curve,the orthogonal decomposition method is used to analyze the influence of the variation of the axial flow path on the performance of the hydraulic turbine..The results show that the primary and secondary order affecting the efficiency of the hydraulic turbine is: the curvature of the front cover > the curvature of the rear cover > the degree of inclination of the front cover > the degree of inclination of the rear cover.The comparative analysis of the models before and after optimization shows that the efficiency of the optimized model has been significantly improved,the efficiency is 71.23%,which is 2.57% higher than the blade parameter optimization.