Numerical Simulation on the Effect of Tip Clearance on the Last Stage Low Pressure Steam Turbine

To maximize turbine performance, it is crucial to broaden a deeper comprehension of the flow structure at tip region of the rotor blade and its consequence. The purpose of this study is to examine the impact of tip clearance flow in a low-pressure steam turbine. The research focused on the final stage of the low-pressure steam turbine blade of a typical steam power plant operating at 3000 rpm (50 Hz). Steady-state compressible numerical simulation and blade stress analysis was performed to analyze the flow characteristic and blade stress level on the last stage blade under three operating load conditions. Two variations of rotor blades are adopted. The results found that the torque in both models increased with an increase in loads resulting in increasing turbine output. However, the torque generated by tip clearance model is smaller than torque in the model without tip clearance. It can be implied that the turbine performance is reduced as a result of the presence of tip clearance flow corresponding to tip leakage loss. The blade stress analysis shows that the stress level exceeds on rotor blade in model tip clearance is higher compared to model no-tip clearance under 100% and 120% load.