Boundary Layer Control on a Low Pressure Turbine Blade by Means of Pulsed Blowing

Abstract

The current work investigates the performance benefits of pulsed blowing with frequencies up to 10 kHz on a highly loaded low pressure turbine (LPT) blade. The influence of blowing position and frequency on the boundary layer and losses are investigated. Pressure profile distribution measurements and midspan wake traverses are used to assess the effects on the boundary layer under a wide range of Reynolds numbers from 50,000 to 200,000 at a cascade exit Mach number of 0.6 under steady as well as periodically unsteady inflow conditions. Highfrequency blowing at sufficient amplitudes is achieved with the use of fluidic oscillators. The integral loss coefficient calculated from wake traverses is used to assess the optimum pressure ratio driving the fluidic oscillators. The results show that pulsed blowing with fluidic oscillators can significantly reduce the profile losses of the highly loaded LPT blade T161 with a moderate amount of air used in a wide range of Reynolds numbers under both steady and unsteady inflow conditions.