LP Turbine Laminar Separation With Actuated Transition: DNS, Experiment and Fluidic Oscillator CFD

Abstract

Laminar separation bubbles form on the back surfaces of aero-engine LP turbine blades. In recent years significant weight and cost reductions and performance improvements have been achieved through a better understanding of the behavior of such separation bubbles. A project is underway at the Universita¨t Stuttgart to study a possible technique to suppress laminar separation bubbles using actuated transition. This paper reports on DNS results with and without actuation for different frequencies, amplitudes and Reynolds numbers, revealing the nature of the transitional process. Early results from an experimental simulation are included. In addition numerical simulations of fluidic oscillators which are capable to provide the required frequencies at a size which would fit into an LP turbine are presented.