Contact Analysis of Steam Turbine Blades With Fin Heaves

For rotating blades with fin heaves used in steam turbines, large deflection and contact effects must be taken into account. By using 3-D finite element model and the augmented Lagrangian formulation, contact pressure between fin heaves is analyzed. Contact friction considered, the relation curve of the contact pressure vs. rotating speed is obtained and intrinsic frequencies of blades at 3 000 r/min are calculated. Calculating results show that two neighbored fin heaves become to contact at rotating speed of 400 r/min. After this, contact pressure increases steadily as the rotating speed increases. However, as the speed reaches 1 825 r/min, increasing of the contact pressure becomes to slow down apparently. At 3 000 r/min, the contact pressure reaches its maximum of 700 MPa and the contact area is about 1/4 of the design contact area.