Phase difference effects on synthetic jet array flow: A proper orthogonal decomposition study

In the present work, a proper orthogonal decomposition (POD) analysis is conducted for a synthetic jet array (SJ array) to qualitatively and quantitatively investigate the influence of jet vectoring resulting from the phase difference (& empty;) between the actuators on the distribution of kinetic energy (KE) among the vortices and their oscillating behavior across various modes. Here, the POD analysis is conducted for the SJ array operated at Strouhal number St=0.086 with different phase differences for a fixed Reynolds number Re=300. The simulated cases were run in OpenFOAM software, utilizing a two-dimensional, incompressible solver, and k-omega shear stress transport turbulence model. It has been observed that increased jet vectoring enhances vortex interactions, leading to the formation of smaller secondary vortical structures and a redistribution of KE toward higher modes. Furthermore, we observed that at phase differences of 60 degrees and 90 degrees (where maximum vectoring occurs), the energy within the synthetic jet array disperses evenly across various modes, indicating enhanced vortex interactions and leading to more complex flow dynamics. In contrast, at a phase difference of 180 degrees, the jets exhibit continued interactive behavior, reflecting intricate flow patterns despite being completely out of phase with one another. The study also reveals that larger phase differences result in more complex flow behavior, requiring 324 modes to capture the actual flow at & empty;=180 degrees, compared to 295 modes at & empty;=0 degrees. This study highlights the critical role of jet vectoring in controlling the distribution of kinetic energy and the oscillation patterns of vortices, which are essential for optimizing the synthetic jet array and enhancing practical applications, such as targeted cooling efficiency and improved mixing processes in aerodynamics and thermal management systems.