Effectinevess of Naca

International Journal of Engineering and Technology Volume 3 No. 5, May, 2013

Analysis of Effectiveness an Airfoil with Bicamber Surface Md.Shamim Mahmud Department of Naval Architecture and Marine Engineering Bangladesh University of Engineering and Technology

ABSTRACT The research provide a stable, high-efficiency, high angle of attack, airfoil. The means for accomplishing these improvements is a novel,bicamberd surface profile with two or more raised ridges placed laterally to fluid flow and generally running parallel to the leading and trailing edge.A primary objective of this research is to improve the efficiency of airfoil to obtain higher ratio of useful work output to energy input, thereby saving significant energy resources. This is achieved because bicambered surface airfoil produce greater lift and reduced drag at normal operating angle of attack. A bicamber surface airfoil improved ability to retain an attached boundary layer allows a lower thickness to chord profile to give performance comparable to thicker ,single cambered surface airfoil. The above capabilities provide extensive possibilities in design of high altitude aircraft where lift coefficient is low due to thin air. Flow over a short radius object must be at a greater velocity than flow over a long radius object. There for bicambered surface airfoil effectively lower local Reynolds number is respect to boundary layer development. This stable high angle of attack airfoil is improving aviation safety. Private aircraft accident involve wing stall. Higher attack angles combined with higher lift/drag ratios would enhance glide capabilities. A secondary objective of this research is to reduce mechanical force input requires pitch airfoils such as rotary wings, propeller, rotors and impeller, saving weight in the construction. The more central aerodynamic center and low or negative pitches moment of bicambered surface airfoils allows this objective to be fulfilled. For helicopter high vehicle velocities, where high maneuverability is desired, different lift and stall properties from one side of the aircraft to the other cause problems. The anti stall characteristics to the bicambered surface airfoil can prevent much of these problems and greatly enhance the maneuverability of rotary wing vehicles.

BACKGROUND In the past century extensive research with single cambered aerofoil has provided numerous airfoil designs that optimize aerodynamic performance under given condition. For instance reduced drag can be achieved while stall performance is sacrificed, higher lift is possible, but usually at the expenses of increased darg.Stall performance can be improved, but lift or drag performance suffers. Overall performance can be improved at some angle of attack or at some Reynolds number while accepting reduced performance at others.In many cases aerofoil efficiency depends on the presence of camber line. The relation between lift and drag coefficient for non camber and camber airfoil is stated here. And for the improvement of the efficiency of airfoil Author introduces with a bicamber airfoil where the bicamber airfoil is most effective than camber and non camber airfoil. Generally the efficiency of airfoil depends on the turbulent effect which is created on trailing edge of the airfoil. The lift coefficient is high where the vorticity is lower and due to increase of vortecity the lift coefficient is reduced as well as drag coefficient is increased. Here (NACA 4412),(NACA 0012),( NACA 2412) and a bicamber model are used as a test case. This research exposes that bicamber profile is most effective from naca camber and non camber profile. Keywords: Airfoil, Mach number, STAR CCM+, ANSYS13, NACA, Lift coefficient, Drag coefficient, Bicamber, FVM, FEM

1. METHOD OF APPROACH Here is used the finite volume method (FVM) to solve this problem..The airfoil mesh is developed by using commercial CFD software ANSYS ICEM CFD (version 13.0). The numerical solutions of the governing equations have been found using commercial CFD software package STAR CCM+(version 4.04.011) for analyzing airfoil.

Two-dimensional Finite Volume Method (FVM) has been applied, turbulent flow at 60 m/s free stream velocities at different angle of attacks are simulated. Free stream boundary conditions applied in this research. The numerical results in terms of pressure coefficient, drag coefficient and lift coefficient for different meshing and conditions have been shown either graphically or in the tabular form. Contour of pressure distribution have also

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013 been displayed graphically. And finally calculate the structural effect of camber and bicamber airfoil by using FEM analysis. FD = L=

∑ ∫

Nface = number of faces enclosing cell

v2 Cd A

= value of

v2 CL A

convected through face f

= mass flux through the face

Cp = The transport of a scalar quantity represented by the integral equation: ∫

∑

∮

⃗

⃗

∮

in a continuum is

= area of face f =gradient of

⃗

∫

at face f

V = cell volume Bicamber’s maximum thickness is 0.12m and maximum thickness position is 0.16m from leading edge

⃗= velocity vector ⃗= surface area vector = diffusion coefficient for = gradient of = source of per unit volume

Author has taken free stream boundary condition. Temperature 291k Dynamic viscosity 4.61×10^-5

The terms in this equation are, from left to right, the transient term, the convective flux, the diffusive flux and the volumetric source term. Discrete Form:-

Turbulent model, Spalart-Allmaras Turbulence Velocity 60 m/s Density of air 1.2126 kg/m^3

Applying the above equation to a cell-centered control volume for cell-0, the following is obtained:

Mach Number 0.1807

2. RESULT

Fig: Mesh of NACA 2412 profile

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013

Fig: Mesh of Bicamber profile

Fig: Trailing edge vortecity of NACA 2412 profile

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013

Fig: clips edge vortecity of Bicamber profile

Fig: Velocity distribution of Bicamber profile

Fig: Mach Number distribution of NACA 2412 profile

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013

Fig: Mach Number distribution of Bicamber profile

Fig: Drag Coefficient Vs Angle of Attack

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013

Fig: Lift coefficient Vs Angle of Attack

Validation of the result by wind tunnel test data

The two graphs, red line shows the wind tunnel test result and blue line shows FVM simulation result for bicamber profile. ISSN: 2049-3444 © 2013 – IJET Publications UK. All rights reserved.

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013

3. Model Analysis: Now for structural effect analysis the author is considered 3d NACA and Bicamber profile. Cord Length of the NACA and Bicamber Profile 1m and Wideth also 1 m. Material Name: Model type: Default failure criterion: Yield strength: Tensile strength: Elastic modulus: Poisson's ratio: Mass density: Shear modulus: Thermal expansion:

Aluminum Alloy 6063T4 Linear Elastic Isotropic Max von Mises Stress 9e+007 N/m^2 1.7e+008 N/m^2 6.9e+010 N/m^2 0.33 2700 kg/m^3 2.58e+010 N/m^2 2.34e-005 /Kelvin

Fig: Stress distribution of Bicamber Profile

Fig: Displacement of Bicamber Profile ISSN: 2049-3444 © 2013 – IJET Publications UK. All rights reserved.

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013

Fig: Stress distribution of NACA 4412 Profile

Fig: Stress Displacement of Bicamber Profile

Profile name

velocit y

Lift Force

Stress (max)

Stress (min)

Strain (max)

Strain (min)

Displacement (max)

Bicambe r

60m/s

4908.6 3N

953787 N/m^2

1189.09 N/m^2

1.03523e-005

2.87658e-008

0.0694524 mm

Naca 4412

60m/s

4908.6 3N

1.07106e+006 N/m^2

1708.52 N/m^2

1.18481e-005

3.7737e-008

0.085971 mm

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International Journal of Engineering and Technology (IJET) – Volume 3 No. 5, May, 2013

4. COMMENTS This research shows how the bicamber profile acts perfectly in vortex condition. As angle of attack increases the vorticity in upper surface also increases, so the lift force reduces and drag force increases. In turbulent flow, vortex is created in the clips between the two camber of a bicambered foil. The lifting effect reduced by the vorticity is recovered by generating the lift force in 2 nd camber. Thus, the lesser vortex effect in bicamber profile results in higher lift force and lower drag force, hence increases the lift by drag ratio. In this research the Author finds that lift-drag ratio of the bicamber airfoil is higher than NACA profile.On the other hand, the angle of attack increases lift-drag ratio is inversely proportional to the angle of attack. And findings suggest that for same lift force, both maximum displacement and stress are lower for a bicambered foil when compared with NACA profile. Thus, airfoil with bicamber profile is more effective than NACA profile.

ACKNOWLEDGEMENT The author is grateful to the University of Illinois for providing airfoil coordinate data .

REFERENCES [1] Badran O (2008). Formulation of Two-Equation Turbulence Models for Turbulent Flow over a NACA

4412 Airfoil at Angle of Attack 15 Degree, 6th International Colloquium on Bluff Bodies Aerodynamics and Applications, Milano, 20-24 July. [2] Douvi C. Eleni*, Tsavalos I. Athanasios and Margaris P. Dionissios,( 2012) “Evaluation of the Turbulence Models for the Simulation of the Flow Over a National Advisory Committee for Aeronautics (NACA) 0012 Airfoil”, Journal of Mechanical Engineering Research Vol. 4(3), pp. 100-11. [3] Frederick.L.Felix.(March,7,1995) “Airfoil with Bicamber Surface”, United State Patent Number 5395071 [4] S.Kandwal1 and, Dr. S. Singh(2012) "Computational Fluid Dynamics Study Of Fluid Flow And Aerodynamic Forces On An Airfoil". International Journal Of Engineering Research & Technology (IJERT) Vol. 1 Issue 7, September – 2012 .ISSN: 2278-0181 [5] McCroskey WJ (1987). A Critical Assessment of Wind Tunnel Results for the NACA 0012 Airfoil. U.S. Army Aviation Research and Technology Activity, Nasa Technical Memorandum, 42: 285-330. [6] Menter FR (1994). Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications. AIAA J., 32: 1598-1605

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