Separation control using plasma actuators: Steady flow in low pressure turbines

A Dielectric Barrier Discharge plasma actuator is operated in flow over the suction surface of a Pack-B Low Pressure Turbine (LPT) airfoil at a Reynolds number of 50,000 (based on exit velocity and suction surface length) and inlet free-stream turbulence intensity of 2.5%. Measurements of total pressure using a glass total-pressure tube are taken. Corrections for streamline displacement due to shear and wall effects are made, and comparisons with previous hot-wire measurements are used to validate data. Measurements from previous work have shown that separation control is possible without stream-wise momentum addition, by adding disturbances that cause transition in the separated shear layer. The present results are from measurements taken using a glass dielectric, with a conventional two-electrode geometry, and a new three-electrode geometry. The region of high momentum flow produced due to the presence of the actuator is found to be above the shear layer, and not at the wall. The near-suction-surface total pressure field in the trailing part of the airfoil passage and its wall-normal gradient are used to demonstrate effective prevention of flow separation using the plasma actuator.