Numerical simulation of the 3-D unsteady flow in the last stage of the steam turbine

Air cooling steam turbine uses air as working fluid, and it works in variable-operating condition. It is important for the design of air cooling steam turbine and the performance and stability of turbine to study unsteady flow mechanism in design and off-design state. The flow of turbine in design and off-design state was simulated by the method of numerical simulation of 3-D viscous flow, and the flow mechanism in design and off-design state was studied. The results show that rotor-stator interaction causes unsteady flow in design state, and the rotor-stator interaction in off-design state is weak, the unsteady phenomena is not obvious in off-design state.