The last three stages of a low-pressure steam turbine are optimized with the response surface method simultaneously considering the influences of aerodynamic losses and wetness losses. The stagger angles and stacking lines of the last three stages are chosen as the design variables. Adjusting the stagger angles
the pressure distribution
consequently the supercooling distribution
among the multi-stage turbine are changed. As a result
both the non-equilibrium thermodynamic loss and the water droplet diameter are reduced. The wetness losses in the last three stages decrease by 20.71%. The strategy for adjusting stagger angles to reduce the wetness losses is concluded. The optimization of stacking lines improves the radial reaction distribution
reduces the boundary layer separation and secondary losses to heighten aerodynamic effects. Meanwhile the optimization of stacking lines also leads to changes of supercooling and outlet velocity in a turbine stage resulting in decrease in the primary and secondary water droplet sizes. The aerodynamic loss is reduced by 0.52%
and the wetness loss is further reduced by 9.48%.
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references
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