Numerical investigation of the flow and thermal behavior of impinging single and multi-orifice synthetic jets with different waveforms

Abstract

The present article reports the thermal and flow characteristics of single and multi-orifice circular synthetic jet for different waveform shapes through numerical investigation. Present study reports the effect of various parameters such as the pitch ratios (PR = 1.3, 2.1, and 2.8), surface to nozzle distance (z/d = 1–15), and different excitation frequency (f = 50–150Hz) on the thermal performance. The synthetic jet with triangular wave pattern provides higher thermal performance than sinusoidal and rectangular wave patterns for both single and multi-orifice jets. At PR of 1.3, the maximum value of the average Nusselt number for multi-orifice synthetic jet is found to be 17.5% and 39.6% higher compared to PR of 2.1 and 2.8, respectively. At PR of 1.3, f = 150Hz with triangular wave pattern, multi-orifice synthetic jet exhibits 29.8% higher heat transfer compared to single orifice synthetic jet. Present study investigates the flow behavior such as flow interaction between the multi-orifice synthetic jet, jet mass flow rate, and jet half-width for its possible effect on heat transfer rate. The interaction and merging of the adjacent jets are found to be delayed with the increase in the separation distance between the orifice.