Modernisation of the last stage in the low- pressure cylinder of a steam turbine using CFD and optimisation techniques

The results of gas dynamic improvement of the last stage in the low-pressure cylinder of a steam turbine are presented. The turbine stage performance and the 3D flow patterns were obtained with the CFD solver FlowER. Stage modernisation was carried out in two ways. First, stage blade sections were renovated, and then the 3D blade shape was optimised using the CFD and optimisation techniques. The optimised stage has stator blades with a compound lean at the hub and a compound sweep at the tip. The efficiency of the improved stage is higher by roughly 2 percent at nominal flow conditions and is up to 10 percent for low flow rate conditions as compared to that of the original stage.