Large-Eddy Simulation of a Flow Generated by a Piston-driven Synthetic Jet Actuator

We study the characteristics of a compressible flow generated by a piston-driven synthetic jet actuator by employing large-eddy simulation with OpenFOAM. The actuator consists of a piston and a cylinder with a square orifice on top and produces a compressible synthetic jet with the piston movement. Comparison with experimental data demonstrates that the numerical model constructed with OpenFOAM is useful to examine the performance of the actuator. As the piston frequency increases, the maximum pressure inside the cylinder increases while the minimum pressure decreases. The fluid temperature inside the cylinder also varies similarly to the pressure. The maximum jet Mach number is well represented as a function of the maximum pressure. The phase-averaged velocity field of the synthetic jet confirms that the blowing and suction phases do not perfectly match with the piston movement. The root-mean-square velocity defined with the phase average also shows that a high turbulence level is observed in the region where the flow is decelerated at the furthest location of the jet in the blowing phase