Precision Air Flow Control via EHD Actuator: A Co-simulation and Control Design Case Study

TL;DR

This work tackles precise outflow regulation in a DBD plasma actuator-based amplifier that uses electrohydrodynamic ($F_{ehd}$) body forces to generate a Coanda-attached jet and amplify the main flow, quantified by outlet rate $Q_o$. A co-simulation framework couples COMSOL Multiphysics CFD with Simulink to model discharge via a two-species model and feed the time-averaged $F_{ehd}$ into the Navier–Stokes equations. Two control strategies, ADRC and PID, are evaluated for tracking performance and disturbance rejection using input $V_{ap}$ and measured $Q_o$, with ADRC showing superior performance. Results reveal how geometry parameters (e.g., inner radius $r_1$ and nozzle divergence angle $oldsymbol{lpha}$) modulate vortex formation and Coanda attachment, affecting amplification and response times. The study lays a computational foundation for experimental validation and informs design choices for safe, high-flow EHD actuators in internal-flow applications.

Abstract

A Dielectric Barrier Discharge (DBD) plasma actuator for controlling airflow is proposed. It consists of diverging and converging nozzles, two concentric cylinders and an actuator mounted in-between the two cylinders. The actuator employs electrohydrodynamic (EHD) body force to induce an air jet within the air gap between the two cylinders, effectively creating a suction area while passing through the diverging nozzle, due to the Coanda effect. While merging with the air stream inside the inner cylinder, the Coanda jet effectively enhances amplification of the airflow. The outflow rate is measured by a velocity sensor at the outlet and controlled by the plasma actuator. The control strategy is based on the Active Disturbance Rejection Control (ADRC) and compared to the baseline PID controller. The actuator was modelled by seamlessly linking two modeling platforms for a co-simulation study. The CFD simulation of the plasma and airflow was carried out in the COMSOL multi-physics commercial software, and the control was implemented in the Simulink. The DBD plasma model was based on the two-species model of discharge, and the electric body force, calculated from the plasma simulation, was used in the Navier-Stokes equation for the turbulent flow simulation. The plasma-air flow system was analyzed using the input (the actuator voltage) and output (the outlet flow rate) data for the control design. Finally, the performance of the system of air flow control device was tested and discussed in the co-simulation process.

Figures (10)

• Figure 1: The airflow control device(gray) and the DBD plasma actuator (black) shown inside the computational domain. The empty space indicates the airflow region.
• Figure 2: Structure of the $2^{nd}$ order ADRC.
• Figure 3: The unstructured triangular mesh and hybrid mesh employed for the discharge and air flow computations on the left and right columns, respectively. Near the actuator area, the grids were refined, shown in the second row.
• Figure 4: The electric field in Vm^-1 and the electric field lines when the supply voltage is equal zero (\ref{['p1']}), or reaches its maximum value (\ref{['p2']}). The average electric body force $F_{ehd}$ (\ref{['p3']}), and its magnified version in Nm^-3 (\ref{['p4']}).
• Figure 5: Vortex formation following the activation of the actuator at times: $t=0.005$ (\ref{['v1']}), and $t=0.015$ (\ref{['v2']}). Velocities are in ms^-1.