Abstract:
The low-pressure turbine blades of aero-engines play a vital role at cruising altitudes, where the density of the atmosphere becomes low. This phenomenon is observed particularly at the boundary layer of low pressure turbine blades in the range of low Reynolds number. At this stage, flow reversal occurs in the boundary layer on the suction side of low pressure turbine blades. This is because of increasing adverse pressure gradient, and the turbofan engine’s efficiency is lost by consumption of more fuel. Therefore, design of the blades should be optimized to control the flow separation behavior for minimizing pressure losses. Flow separation is controlled by using dimples, on the suction side. Six different geometrical dimples were engraved at 85% Cax of the suction side of low pressure turbine blade. They were rectangular, triangular, oval, half hexagonal, circular and square in shapes. T-106A low pressure turbine blade profile has been used for analyzing boundary layer behavior. Gamma Theta transition model was used to control boundary layer separation at Reynolds number 91000 with low turbulent intensity. Square dimple with diameter 2.00 mm produces the least amount of pressure losses, about 8.00 % in controlling flow separation behavior at the range of low Reynolds number. Specific transition patterns from laminar to turbulent phase of the suction side in the boundary layer have been observed.
