CBL - Campus del Baix Llobregat

Projecte llegit

Títol: Active Flow Control of flow past an airfoil with Synthetic Jet Actuation

Estudiants que han llegit aquest projecte:

Director/a: MELLIBOVSKY ELSTEIN, FERNANDO PABLO

Departament: FIS

Títol: Active Flow Control of flow past an airfoil with Synthetic Jet Actuation

Data inici oferta: 11-07-2022     Data finalització oferta: 11-03-2023


Estudis d'assignació del projecte:
    GR ENG SIST AEROESP
Tipus: Individual
 
Lloc de realització: EETAC
 
Paraules clau:
Active Flow Control, Synthetic Jets, Airfoil, Computational Fluid Dynamics, Turbulence Models, Aerodynamics
 
Descripció del contingut i pla d'activitats:
Optimisation of Synthetic Jet (SJ) Fluidic Active Flow Control (AFC) parameters to maximise aerodynamic efficiency or lift and minimise drag of an airfoil is very demanding in terms of computational resources and time. This project aims at assessing the most convenient turbulence model which, in combination with the Reynolds-Averaged Navier-Stokes (RANS) equations, allows for accurate predictions of the aerodynamic performances of SJ-actuated post-stall airfoils at high values of the Reynolds number.

The work plan is as follows:

0) Literature review on typical airfoils for incompressible flow at moderately high values of the Reynolds number and on fluidic actuation with synthetic jets.

1) Test the spalart-allmaras, k-epsilon and k-omega turbulence models for a chosen airfoil in stall conditions, and compare against available literature results.

2) Test the turbulent models for AFC setups that have been tested in the literature.

3) Set up an optimisation procedure based on the best performing turbulence model, both using genetic algorithms (GA) and more classic methods such as Newton or steepes gradient.

4) Design strategies to reduce as much as possible the computational requirements for the optimisation process.
 
Overview (resum en anglès):
This work focuses on a parametric study of the implementation of Active Flow Control (AFC) on the Selig-Donovan 7003 (SD7003) airfoil at $Re=60,000$ and $\alpha=13^{\circ}$, employing the Reynolds-Averaged Navier-Stokes (RANS) resolution method through the open-source computational fluid dynamics (CFD) software OpenFOAM. The Spalart-Allmaras model has been applied for turbulence modeling. Active Flow Control involves the implementation of a synthetic jet aiming to increase the kinetic energy of the boundary layer, preventing or delaying its separation, and thereby improving the aerodynamic performance of the airfoil.

In the initial phase of the investigation, an analysis was conducted to verify the effects of implementing an inactive synthetic jet on aerodynamic performance. It has been confirmed that the presence of the jet slot on the airfoil does not entail serious losses in aerodynamic efficiency during flight phases for which it remains off, such as cruise. Specifically, the maximum loss resulted in a $\Delta \eta = -1.65$ at $\alpha=8^{\circ}$.

The two geometric parameters were determined based on conclusions drawn from previous studies. Regarding the angle $\theta_j$, its selection was based on the better aerodynamic efficiency observed with tangential angles rather than normal to the wall. As for the location of the jet, $x_j = 0.0082C$ was chosen, with $C$ being the airfoil chord.

The most relevant dynamic parameter of the study, subjected to a parametric study, is the dimensionless frequency $F^+$, which was varied within the interval $F^+ = [1.0, 4.0]$ with increments of $\Delta F^+ = 0.2$. Among all simulated configurations, particularly promising results were obtained for $F^+ = 3.0$, with aerodynamic efficiency improving by $233.67\%$ compared to the base case, with an increase in lift coefficient of $\Delta C_l = 60.3\%$ and a reduction in drag coefficient of $\Delta C_d = -51.9\%$.

In the baseline case with the inactive jet, the formation of a recirculation bubble near the leading edge was observed. In contrast, in the actuated case with the optimal configuration, a significant reduction in the recirculation bubble on the upper surface of the airfoil was evident, reducing the associated drag and delaying flow detachment, thereby expanding the area of the airfoil that generated lift.

© CBLTIC Campus del Baix Llobregat - UPC