Synthetic jets have been utilized for various active flow control applications including control of boundary layer transformation/detachment, lift enhancement and drag reduction, heat transfer enhancement by cooling of microprocessors in electronic industry and mixing augmentation. Numerical examination is performed to address the effects of excitation voltages and actuation frequency on the characterization of synthetic jet fluidics. The present study also explores the heat transfer improvement by a synthetic jet actuator having two cylindrical orifices arranged at the top of cavity opposite to heated thin stainless steel foil. The diameter of each orifice of the synthetic jet actuator is 2 mm with the spacing being 4 mm. The excitation voltages for actuation are taken as 20 V, 30 V, and 55 V. The computation is carried out by using Commercial software COMSOL 5.3a Multiphysics for solving three dimensional incompressible unsteady Reynolds-averaged Navier-Stokes equations with an established Shear- Stress-Transport (SST) k- turbulence model coupled with piezoelectric and ALE Moving Mesh technique describing the diaphragm movement. The qualities of the extracted results from the present study are authenticated by grid density, time and domain independence studies and are validated with the existing experimental data. Results show that the radial and axial velocities at the orifice exit of synthetic jet actuator tend to approach maximum at 55 V and the average heat transfer coefficient due to double cylindrical orifice is 32 % higher to that of a single orifice synthetic jet actuator with constant cavity volume thereby leading to better performance.