Numerical analysis of the aerodynamic performance and excitation forces in a transonic turbine cascade with flat-tip and squealer-tip blades

The purpose of this paper is to numerically investigate the effect of blade tip clearance and its structure on the turbine aerodynamic performance and excitation force on blades in a transonic turbine cascade. Hence, circular cascades with flat-tip and squealer-tip blades and eight different tip clearances based on the SNECMA transonic turbine were established and the rotational effect was taking into consideration. The simulations were performed by solving the RANS equations and the SST turbulence model was used. The results show that tip clearance and tip structure have a significant influence on the turbine efficiency and excitation forces. Smaller tip clearance and squealer tip structure can reduce the tip leakage flow and leads to higher turbine efficiency. The tangential blade force varies nonlinearly with tip clearance since the leakage flow significantly changes the static pressure distributions on blade surfaces. Further, the excitation force factor was also calculated and illustrated.