Forced Cooling on a Heated Wall with Impinging Flow Configuration Using Synthetic Jet Actuator Under Combined Wave Excitation

Abstract

This research investigated the forced cooling characterization of an impinging synthetic jet under combined wave excitation. The synthetic jet cooling used an air flowing in a vertical direction into the heated wall. The synthetic jet actuator used two oscilating membranes to push and pull the air from and to the cavity. The main purpose of this synthetic jet was to create vortices pair to come out from nozzle which will accelerate the heat transfer process occurring at the impinged wall. This heat transfer enhancement principles became the basis to simulate an alternative cooling system to substitute the conventional fan cooling in electronic devices application due to its advantage for having a small form factor and low noise. The investigation combined computational and experimental works. The model was simulated to examine the distribution of heat flow on the impinged walls using variation of turbulence model i.e. standard k–epsilon, realizable k–epsilon, standard k–omega and k–omega SST (Shear Stress Transport). Meshing order was elements tri and type pave and the number of grid was 4473 mesh faces to ensure detail discretization and more accurate calculation results. In the experiment the variation of sine and square wave signals were generated with sweep function generators to oscillate the membrane. The frequency of sine wave excitation for the first membrane was kept constant at 80 Hz, meanwhile the second membrane was excitated with varied square wave signals at 80 Hz, 120 Hz, and 160 Hz. Furthermore the velocity amplitude was 0.002 m/s. Some results indicate significant influence of the excitation, and combined waveform to the rate of heat transfer obtained.