Numerical Analysis of Circular Synthetic Jet in Crossflow

摘要

The present paper reports results of numerical simulation of a circular synthetic jet in the presence of crossflow. The simulations are carried out for compressible, laminar flow with crossflow velocities of 30 m/s and 80 m/s. For a crossflow velocity of 30 m/s, the velocity ratio is 1.4375 for 600 Hz and 1.2 for 1100 Hz. For a crossflow velocity of 80 m/s, the velocity ratio is 0.55 for 600 Hz and 0.4375 for 1100 Hz. Flow fields and vortical structures at the orifice exit and inside the cavity are studied for different positions of the flexible diaphragm during the suction and ejection stroke of the diaphragm at different frequencies. Three aspects are studied in the current research: the effect downstream of the synthetic jet, the role of the orifice region throughout the entire cycle and the effect of the crossflow on the pressure inside the cavity. Analysing these effects gives an insight into the flow field characteristics for the circular synthetic jet in crossflow. It is observed that the flow field characteristics inside and outside the circular synthetic jet vary widely for the case when the vortex structure formed at the orifice exit escapes the boundary layer or stays within the boundary layer. The results show significant difference in flow characteristics for VR ＞ 1 and VR ＜ 1. It is observed that for VR ＜ 1, the frequency of vibration has very less effect downstream of the circular synthetic jet.