, 44:220 | Cite as

Comparative study of flow separation control using suction and blowing over an airfoil with/without flap

  • Esmaeel Fatahian
  • Ali Lohrasbi NichkoohiEmail author
  • Hesamoddin Salarian
  • Jahanfar Khaleghinia


This study mainly focused on the comparison of the effect of single and simultaneous suction and blowing jets on the aerodynamic performance of an airfoil with/without flap to evaluate the most effective flow control configuration using computational fluid dynamics (CFD) method. Moreover, the effect of applying single and simultaneous jets have been conducted on delaying and controlling the flow separation. The results were obtained using two-dimensional incompressible Unsteady Reynolds-Averaged Navier–Stokes (URANS), and the turbulence was simulated with SST k-ω turbulence model. Also, different parameters including two jet locations (Ljet), three jet velocity ratios (Rjet), three jet angles (θjet) and three flap deflections (δf) were analyzed to find the most effective case of applying flow control jets to delay the boundary layer separation. It was concluded that applying a single suction jet and simultaneous suction and blowing jets on the flapped airfoil was more effective to improve the lift-to-drag ratio (CL/CD) than applying these jets to the without flap case. The maximum value of CL/CD was achieved by single suction jet for the without flap case which was equal to 73.7. The maximum increment of stall angle over the without flap airfoil and flapped airfoil was obtained by applying single suction jet, which increased the stall angle from 14° to 20° and 14° to 16° for the suction angle of −90° and suction velocity ratio of 0.15, respectively.


Flow separation suction blowing lift coefficient drag coefficient flapped airfoil 

List of symbols


Angle of attack


The angle between the freestream velocity direction and the local jet surface


Airfoil chord length


Pressure coefficient


Lift coefficient


Drag coefficient


Turbulent dissipation rate


Turbulent kinetic energy




Turbulent viscosity




Shear stress


Flap deflection




Reynolds number


Free stream velocity


Dimensionless wall distance

\( \delta_{ij} \)

Kronecker Delta


Jet angle


Jet location


Jet velocity


Jet velocity ratio


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Copyright information

© Indian Academy of Sciences 2019

Authors and Affiliations

  • Esmaeel Fatahian
    • 1
  • Ali Lohrasbi Nichkoohi
    • 2
    Email author
  • Hesamoddin Salarian
    • 1
  • Jahanfar Khaleghinia
    • 1
  1. 1.Department of Mechanical Engineering, Nour BranchIslamic Azad UniversityNourIran
  2. 2.Department of Mechanical Engineering, Nowshahr BranchIslamic Azad UniversityNowshahrIran

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