Effect of geometric parameters and flow conditions on the frequency of fluidic oscillators for active flow control

A parametric study was performed to understand the frequency scaling produced by fluidic oscillators across a variety of geometric parameters and flow conditions. These oscillators are of interest for active flow control applications, where they can be used to re-energize the boundary layer to prevent trailing edge separation and promote more efficient pressure recovery. Matching the oscillator frequency to the natural instabilities in the flow can create a more efficient and effective approach to performing this unsteady actuation. Thirty-nine slightly different fluidic oscillators were designed for each of two common geometries to study the sensitivity of the oscillator frequency to slight variations in key geometric parameters. Testing was carried out on an isolated oscillator across a range of supply conditions from 6.9kPa to 33 kPa (~150 SLPM to ~400 SLPM) in increments of 172 kPa (~13 SLPM). A model was developed that allows for the prediction of oscillation frequency based on variations in these key geometric parameters and mass flow, which was demonstrated on an example application for sizing the oscillators within an airfoil to target specific F⁺ and Cμ requirements.