Numerical Comparison Between Steady and Sweeping Jets for Active Flow Control Applications

Abstract

A computational study is conducted to compare the performance of an array of steady jets and sweeping jets (generated by fluidic oscillator) interacting with an attached turbulent cross flow. Both jets operate at the same supply rate and with the jet-to-freestream velocity ratio of three. Two array spacings are considered in this study; one is chosen based on the minimum possible distance between the adjacent fluidic oscillators, and the other spacing represents an actuator’s configuration with the least interaction between jets. The improved delayed detached eddy simulation model is employed as a high fidelity turbulence modeling approach to resolve accurately the flow structures. Formation of strong vortex pairs is observed in both actuation techniques with the opposite sense of rotation between them. As expected, the sweeping jet affects a wider region of incoming turbulent flow along the spanwise direction compared to the steady jet. Examining the turbulence properties of the flow downstream of the jets indicates that the sweeping jet is a better candidate for enhancing the mixing mechanism used to control separation. Comparing both the instantaneous and time-averaged flow fields generated by the sweeping jets and steady jets reveals that the interaction between the adjacent sweeping jets at the minimum spacing arrangement is significantly stronger than that of the steady jets.