Effectinevess of Naca

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

ISSN: 2049-3444 © 2013 – IJET Publications UK. All rights reserved. 569

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

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 =

v2 Cd A

L =

v2 CL A

Cp =

The transport of a scalar quantity in a continuum is

represented by the integral equation:

∫

∮

∮ ∫

= velocity vector

= surface area vector

= diffusion coefficient for

= gradient of

= source of per unit volume

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:-

Applying the above equation to a cell-centered control

volume for cell-0, the following is obtained:

∑

∑

∫

Nface = number of faces enclosing cell

= value of convected through face f

= mass flux through the face

= 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

Author has taken free stream boundary condition.

Temperature 291k

Dynamic viscosity 4.61×10^-5

Turbulent model, Spalart-Allmaras Turbulence

Velocity 60 m/s

Density of air 1.2126 kg/m^3

Mach Number 0.1807

2. RESULT

Fig: Mesh of NACA 2412 profile



Fig: Mesh of Bicamber profile

Fig: Trailing edge vortecity of NACA 2412 profile



Fig: clips edge vortecity of Bicamber profile

Fig: Velocity distribution of Bicamber profile

Fig: Mach Number distribution of NACA 2412 profile



Fig: Mach Number distribution of Bicamber profile

Fig: Drag Coefficient Vs Angle of Attack



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.



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: Aluminum Alloy 6063T4

Model type: Linear Elastic Isotropic

Default failure criterion: Max von Mises Stress

Yield strength: 9e+007 N/m^2

Tensile strength: 1.7e+008 N/m^2

Elastic modulus: 6.9e+010 N/m^2

Poisson's ratio: 0.33

Mass density: 2700 kg/m^3

Shear modulus: 2.58e+010 N/m^2

Thermal expansion: 2.34e-005 /Kelvin

Fig: Stress distribution of Bicamber Profile

Fig: Displacement of Bicamber Profile



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

3 N

953787

N/m^2

1189.09

N/m^2

1.03523e-005

2.87658e-008

0.0694524

mm

Naca

4412

60m/s 4908.6

3 N

1.07106e+006

N/m^2

1708.52

N/m^2

1.18481e-005

3.7737e-008

0.085971 mm



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 2nd 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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Effectinevess of Naca