Method of Calculating Unsteady Force Acting on Rotor Blade or Stator Blade, Method of Designing Turbine and Method of Manufacturing Turbine

A method of calculating an unsteady force acting on a rotor blade or a stator blade in a turbine stage including the stator blade and the rotor blade, comprising:

• obtaining unsteady forces acting on the rotor blade or the stator blade with respect to a plurality of values by varying a value of a factor by the viscous flow solution using models of the stator blade and the rotor blade for which blade basic shapes have been determined;
• obtaining exciting forces by potential field interaction acting on the rotor blade or the stator blade with respect to the plurality of values by the inviscid flow solution using the models;
• obtaining exciting forces by wake interaction acting on the rotor blade or the stator blade with respect to the plurality of values from a difference between a result of the viscous flow solution and a result of the inviscid flow solution;
• mathematically expressing the exciting forces by the potential field interaction and the exciting forces by the wake interaction based on the obtained exciting forces by the potential field interaction and exciting forces by the wake interaction with respect to the plurality of values;
• and
• predicting the unsteady force acting on the rotor blade or the stator blade when the factor is an arbitrary value based on the mathematically-expressed exciting forces by the potential field interaction and exciting forces by the wake interaction.