Separation Control in a Centrifugal Bend Using Plasma Actuators

An experiment and CFD simulation are presented to examine the use of plasma actuators to control flow separation in a 2-D channel with a 135$^{\circ}$ inside-bend that is intended to represent a centrifugal bend in a gas turbine engine. The design inlet conditions are $P=330$\,psia., $T=1100^{\circ}$F, and $M=0.24$. For these conditions, the flow separates on the inside radius of the bend. A CFD simulation was used to determine the location of the flow separation, and the conditions (location and voltage) of a plasma actuator that was needed to keep the flow attached. The plasma actuator body force model used in the simulation was updated to include the effect of high-pressure operation. An experiment was used to validate the simulation and to further investigate the effect of inlet pressure and Mach number on the flow separation control. This involved a transient high-pressure blow-down facility. The flow field is documented using an array of static pressure taps in the channel outside-radius side wall, and a rake of total pressure probes at the exit of the bend. The results as well as the pressure effect on the plasma actuators are presented.