Control of self-sustained jet oscillations in 3D thin rectangular cavity

- Control of oscillatory round jet submerged in a thin rectangular cavity, by two lateral jets.
- 3D - URANS second order modeling.
- Oscillations of the main jet have been highlighted for several momentum ratios (β).
- Particular flow pattern for the case of jets of same velocities (main jet and lateral jets.
- Jet deflection and is correlated according to jets momentum ratio.

The aim of this work is the control of an oscillatory jet submerged in a 3D thin rectangular cavity, with two opposite injections added on its thinnest sidewalls at the same height, perpendicular and above the jet exit. This type of control is required when the characteristics of the main jet (Reynolds number, nozzle size) are not modifiable. Due to Coanda effect, the oscillations of the main jet occur in the widest plane of the cavity, and depend on the mass flow of two injections. Unsteady, 3D problem is solved by finite volume method using URANS modeling. The validation confirms that second order models predict more accurately this flow configuration than first order models. Two behaviors of time average of flow fields corresponding for two ranges of β are detected. When 0 ≤ β <25.51%, the main jet effect decreases to reach the case without lateral injections (β = 0). Similarly for 25.51 ≤ β≤ 50.67%, the main jet effect diminishes for higher value of β. Thus, β = 25.51% is a threshold value for this type of flow configuration. Moreover, for β = 25.51% the minimum values for the kinetic energy, main jet deflection angle and oscillations frequency are reached. Furthermore, the deflection angle reaches its maximum value for β = 12.90% and the best deflections are recommended for β < 25.51%.