Application of the Twisted and Sloped Blades in the Thermal-Power Co-Generation Turbine Unit
Cheng Daijing,Qi Mingxu
（School of Energy and Power Engineering,Xi'an Jiaotong University,Xi'an 710049,China)

Abstract: Two low-pressure stages of CC25 turbine unit are optimized.The twist-slope combined design method is adopted to improve the original blades.Keeping the desired aero-performance both in design and off-design cases, the inlet and outlet geometric parameters of the stages are adjusted based on the quasi-three-dimensional calculations, and thus the efficiency of the turbine unit is increased.Third-order B-spline method is used in the twisted blade design considering the inlet and outlet flow angles .Meanwhile,the static blades are also sloped to improve the flow performance.The results show that proper match of the attack angles between stator and rotor blades can decrease the attack loss. Sloped and twisted stator blades and twisted rotor blades can adjust the reaction distribution along the spanwise direction, decrease the second flow loss at tip and hub, and decrease the exit loss. The inner efficiency of the two low-pressure stages is raised by 6.6 percent after the optimization.
Keywords: optimization;B-spline;twisted;blade