Effect of turbulence intensities and passive flow control on LP turbine

Abstract

Flow controlling of boundary layers separation of low-pressure (LP) turbine blade is still a high leverage area for advent of high lift and ultra-high lift LP turbines. At cruising conditions, the Reynolds number in the LP turbine reduces (due to the decrease in air density) to the critical value that flow starts to separate from the blade suction surface. In the present study, cascade T106A is used to control the laminar separation bubble on the suction side of the blade. Fluent® commercial CFD code with gamma theta transition model has been employed to study the boundary layer separation at various different turbulent intensities. Numerical results are validated with the available experimental data and are in good agreement. An optimize dimple is used to control the boundary layer separation at low and intermediate turbulent intensities. Normalized loss coefficient is reduced to about 5% with the help of optimal dimple size and location, which increase the LP turbine efficiency. C p plots and boundary layers profiles are made for flow visualization.