Numerical Modeling of Pulsed Electrical Discharges for High-Speed Flow Control.

摘要

This report describes work carried out on numerical modeling of flow control devices based on pulsed electrical discharges. Given the lack of flow control options in the high-speed regime, there is strong interest in developing such devices for control of laminar-turbulent transition, turbulence, engine unstart, and inlet shock train stability. Pulsed electrical discharge actuators offer the features of rapid actuation, low profile, and low mean power consumption. Under this project, work was carried out on improving both the physical models used to represent the actuators and the accuracy of the numerical schemes used to implement them. Initial work focused on demonstrating the use of high-order, compact difference methods for discharge modeling. These were initially demonstrated on canonical problems in one and two dimensions, and later on more complex problems. Subsequent work compared different physical models for pulsed discharges: one-moment (drift-diffusion with local equilibrium with the electric field), two-moment (drift-diffusion with energy equation), and five-moment (continuity, momentum, and energy equations for each species). The results were found to be sensitive to the model used for the electrons. Later stages of the project involved collaboration with The Ohio State University (OSU). Reduced chemical kinetic models for air were developed, and the importance of rapid thermalization reactions in pulsed discharges was explored. Three-dimensional fluid dynamics computations were carried out to investigate flow physics and control in a Mach 5 cylinder flow experiment carried out at OSU.