Investigation of Turbine S₂ Stream Surface Direct Problem Aerodynamic Optimization Design

The final process of the turbine aerodynamic optimization design is the 3D aerodynamic optimization design of multi-stage turbine, while the 3D calculation is very complex in space and time and many problems should be concerned during the process. It is hard to get a good result within a short time if there were no suitable quasi-3D calculation result which is taken as the original parameters. Therefore, it is necessary to set up an excellent layered optimization design system which combines the classic design process and modern design concepts together.The author represented the development and history of the turbine aerodynamic design system and the aerodynamic optimization design including: 1D aerodynamic design system, quasi-3D aerodynamic design system, 3D aerodynamic design system, 1D aerodynamic optimization design, quasi-3D aerodynamic optimization design, 3D aerodynamic optimization design. Then the history and present state of S2 stream surface and loss model were introduced in details. At last the author introduced the S2 stream surface aerodynamic optimization system applied in the dissertation including: profile modeling, calculation of S2 stream surface, loss model, optimization methods and software.Considering the design parameters, objective function and constraint conditions, the author testified the effects of different loss models to the optimization result applying the S2 calculation program. The results revealed that different loss models affected the result heavily, while the total loss was reduced and isentropic efficiency was raised in different degrees. Also the result demonstrated the importance of the loss model to the S2 optimization calculation.The author compared the predicting results ofЦИАМloss model with 10 sets of profiles experimental data, then found the weakness, finally revised the origin model. The error of the new model predicting the profile loss decreased from 37.56% to 22.59% and the total loss from 38.31% to 30.95%.Applying the S2 optimization design system of this dissertation, the author designed the S2 stream surface of two low pressure turbines. The isentropic efficiency of the four stages turbine applying the originalЦИАМloss model increased from 90.40% to 91.25%, and the revised one increased from 90.81% to 91.59%. The isentropic efficiency of the three stages turbine increased from 89.50% to 91.22%.