Date of Award

2019

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

First Advisor

Dr. Michael Atkinson

Abstract

Historically, Dielectric Barrier Discharge (DBD) plasma actuators have shown to be an effective method to control adverse pressure gradient induced boundary layer separation. In this study, a numerical investigation was carried out to explore the effects of a DBD plasma actuator on a three-dimensional incompressible, separated flow. The well-validated National Aeronautics and Space Administration (NASA) wall-mounted hump configuration studied in the simulations, were run at a Reynolds Number of 936,000, based on chord length, and a freestream Mach number of 0.1. The baseline code, CALC-LES, developed by the Chalmers University of Technology was modified to include the effects of the plasma actuator [1], which were modeled as source terms in the momentum equations and were assumed to be steady and constant along the spanwise direction. A hybrid RANS-LES based Partially Averaged Navier-Stokes (PANS) model was used to compute the effects of fine-scale turbulence. The simulations were carried out for both a baseline (no control) and a plasma control case. Comparisons of time-averaged skin friction, coefficient of pressure, and velocity profiles showed good agreement with the experiment for the baseline case. The results with the plasma actuator turned on showed improved flow characteristics compared to the previous investigations by reducing the overall flow separation. A slight delay in the onset of flow separation and rapid flow reattachment was also observed. Several test cases with varied plasma actuator locations and applied voltage frequency were run to analyze and optimize the control performance of the plasma actuator. It was found that the plasma actuator placed at the location just downstream of the separation point showed improved results. In addition, the plasma actuator operated at a high frequency, i.e., 5KHz induces maximum plasma body force and hence completely removes the separated flow.

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