Numerical investigation of low-pressure turbine flow control (Invited)

The low-pressure turbine is an important element of modern jet engines. Any performance improvement will lead to net savings in aircraft operating expenses. Experiments showed that separation from low-pressure turbine blades can be controlled by steady and pulsed vortex generator jets and plasma actuators. This paper summarizes numerical simulations that were carried out at the computational fluid dynamics laboratory at the University of Arizona. A two-pronged approach was taken. i) The entire low-pressure turbine blade was studied using a versatile but computationally less efficient multi block code. ii) Separation bubbles under low-pressure turbine conditions on a flat and a curved plate were investigated with a high-order-accurate research code. The first approach allows for simulations of the uncontrolled flow and for investigating active flow control techniques for the entire blade. The grid resolution especially near the actuators is, however, not sufficient for these simulations to be true direct numerical simulations. For the second approach all length scales down to the dissipative length scales were resolved. These well resolved high-fidelity simulations allow in-detail investigations of the relevant physical mechanisms associated with separation control by steady and pulsed vortex generator jets.