Investigating Effect of Geometric Differences on Fluid Behavior in Synthetic Jets

Abstract

A synthetic jet is a flow that is created by an actuator vibrating at a specific frequency and amplitude. In this study the velocities and propagation of synthetic jets have been measured using both circular and single-wave orifice geometries. Axial velocity measurements in the direction of flow have been taken using the PCE 423 model hot wire anemometer. Also flow visualization has been performed using TiO2 surface oil visualization to determine velocity distributions in the radial direction. The measurements have been conducted at different H/D values, representing the ratio between the axial distance (H) and the orifice diameter (D). The excitation frequency has been varied between 4 Hz and 5 Hz with a sinusoidal signal type. The results have shown that circular orifice geometry have higher velocities in the axial direction. However, When the axial velocity was measured at 4 Hz, it has been observed that the single wave geometry provided results close to a circle at H/D = 13 and 14 values, and at 5 Hz for H/D = 12 and 13 values. This suggests that the geometric shape is not very important at high H/D ratios. In addition, the axial velocity values for a single wave orifice geometry show almost the close results for both excitation frequency values. The flow visualization results have indicated that the single-wave orifice geometry with H/D=12 ratio perform better and provides a more accurate and well-distributed velocity field. In conclusion, the findings of this study suggest that synthetic jets could be potentially useful for industrial applications, especially in heat transfer applications with their extended flow field implications.