1Faculty of Engineering Technology, Al-Balqa` Applied University, Jordon
2Faculty of Engineering Technology, University of Baghdad, Iraq
*Corresponding author: Najdat Nashat Abdull, Faculty of Engineering Technology, Al-Balqa` Applied University, Jordon
Submission: August 8, 2017; Published: February 16, 2018
ISSN: 2576-8840Volume3 Issue4
The present study explores the effect of the gap between the airfoil and the rotating cylinder embedded on leading edge of the airfoil on its aerodynamic performance theoretically and experimentally. Numerically, two-dimensional turbulent flows with Reynolds number of (700,000) based on the chord length over conventional airfoil (NACA 0012) and unconventional airfoil (NACA0012 airfoil with embedded rotating cylinder) have been investigated by solving continuity, Navier-Stokes equations and turbulent model (SST,−W) equations. The gap with (1,2,3,4 and 5 mm) between rotated cylinder and airfoil have been studied for different cylinder speed to main free velocity ratios of (Uc/U∞= 1, 2, and 3) and for different angles of attack, (α), (0°, 5°, 8°, 10°, 12° and 15°).
Based on the numerical results, the best aerodynamic performance for the unconventional airfoil was found and adopted for construction. The pressure distributions on the manufactured NACA 0012 airfoil and the unconventional airfoil in a subsonic wind tunnel were measured experimentally with cylinder rotated at (8000rpm) and free stream velocity of (20m/s). These velocities represent the velocity ratio (Uc/U∞=1), with angles of attack ranged from (0° to 15°) with gaps sizes from (1mm to 5mm).
Numerically, the optimum configuration for the unconventional airfoil was found to be at velocities ratio of (Uc/U∞= 3) with a space gap of (3mm) for best airfoil performance. Lift to drag coefficients values of (58.9, 60.6, and 62) were obtained for velocity ratios of (Uc/U∞=1, 2, and 3) respectively at gap space (3mm) compared with value of 18 for normal airfoil. For optimum configuration, an increase of (35%) in lift coefficient and a reduction of (21%) in drag coefficient were obtained compared with normal airfoil.
Comparisons between the numerical and experimental results for both airfoils showed acceptable agreement. Furthermore, similar trends observed between the results of the present work and some other available previous works.
Keywords: Boundary layer control; Rotating cylinder; Computational fluid dynamics; Airfoil; Gap space
Abbreviations: C: Chord Length, m; Cd: Drag Coefficient, Dimensionless; Ci: Lift Coefficient, Dimensionless; Dw: Cross-Diffusion Term, Dimensionless; K: Turbulent Kinetic Energy, m2/s2; L: Turbulent Length, m;p: Local Pressure, N⁄m2; P∞: Atmospheric Pressure, N⁄m2; Re: Reynolds Number, Re=pul/m; sϕ: Linearized Source Term For f, Dimensionless; U∞: free stream velocity, m/S; Uc: Cylinder Surface Velocity, m/S; UV: Mean Velocity Components in (x,y)Directions, m/S; uv: Reynolds Shear Stress Components, m/S; ui uj: Velocity in Tensor Notation, M.S; Γ: Diffusion Coefficient, Dimensionless; mt: Turbulent or Eddy Viscosity, Kg/M.S; vt: Kinematic Turbulence Viscosity, m2/S