Plasma-Based Flow-Control Strategies for Transitional Highly Loaded Low-Pressure Turbines

Abstract

Recent numerical simulations have indicated the potential of plasma-based active flow control for improving the efficiency of highly loaded low-pressure turbines. The configuration considered in the current and earlier simulations correspond to previous experiments and computations for the flow at a Reynolds number of 25,000 based on axial chord and inlet conditions. In this situation, massive separation occurs on the suction surface of each blade due to uncovered turning, causing blockage in the flow passage. It was numerically demonstrated that asymmetric dielectric-barrier-discharge actuators were able to mitigate separation, thereby decreasing turbine wake losses. The present investigation extends this work by investigating a number of plasma-based flow control strategies. These include the chordwise location of actuation, spanwise periodic arrays of actuators, multiple actuation in the streamwise direction, and spanwise-direct actuation. The effect of alternate plasma-force models is also considered. Solutions were obtained to the Navier–Stokes equations, which were augmented by source terms used to represent plasma-induced body forces imparted by an actuator on the fluid. The numerical method utilized a high-fidelity time-implicit scheme, employing domain decomposition to carry out calculations on a parallel computing platform. A high-order overset grid approach preserved spatial accuracy in locally refined embedded regions. Features of the flowfields are described, and resultant solutions are compared to each other, with a previously obtained control case, and with the base line situation where no control was enforced.