CFD Modelling of a Sweeping Jet Actuator

Abstract

A Sweeping Jet Actuator is a fluidic oscillator that produces a sweeping motion of the jet due to the internal flow dynamics. The effect of changing the Coanda surface shape of the classical Type I (Angled) and Type II (Curved) actuator on flow field was investigated in this work. Two different Coanda surface shapes were explored using 3D IDDES simulation. The resulting performance parameters, such as the oscillation frequency, external jet profile, jet spreading, and the overall pressure drop are analyzed and validated using the obtained experimental measurements of local time-resolved velocity measurements. The numerical simulations show a very good agreement with the experiments in terms of the external profile and oscillation frequency of the SWJ for all two modified Coanda surfaces, as well as for the reference geometry. The internal flow physics is studied using the phased averaged flow fields. The results show that the baseline and straight line Coanda surface profile in both the actuators produces a bifurcated jet. The curved Coanda surface profile produces a homogenous jet similar to the Type I actuator. It is found that the Type II actuators overall performs better in terms of energy requirement than the Type I actuators. The evolution of the recirculation bubble between the jet and the lower Coanda surface shape in the mixing chamber was studied in terms of its area with respect to a certain phase of the oscillation and the corresponding deflection angle of the jet at the inlet. A correlation between the frequency of oscillation and recirculation bubble was found out. The results show that the actuators having the highest recirculation bubble area has the lowest frequency and vice versa. Type II actuators have higher frequency than Type I actuators due to presence of curved walls which does not delay the fueling of the recirculation bubble due to the absence of vortex formation and separation in the feedback channels.

Date of Award	Apr 2023
Original language	American English
Supervisor	Vladimir Parezanovic (Supervisor)