COMPARATIVE STUDY ON HAWT BLADE USING COMPOSITE MATERIAL FOR LOW WINDGagan sahu1, Sameer Sahu21Department of Mechanical Engineering, Christian College of Engineering And Technology Bhilai, India2Department of Mechanical Engineering, School of Engineering and IT MATS University Raipur, India

Abstract- Wind turbines are the one of the solutions for the todays energy crisis in the world. In India plays a significant role in renewable energy generation as it covers more than 70% of the energy generated by the renewable energy sources. Still we have wind turbine with comparative less efficiency. Selection of material such as composites for construction of wind turbine blades leads to optimum performance. For the purpose we are taking most basic blade profile for wind turbine blade i.e. NACA0012. 2-D analysis by ANSYS Fluent is performed on the same for local wind speed (Durg, Chhattisgarh, India) for obtaining shape factor for wind load calculation. Later on 3-D model of profile we have performed structural analysis using ANSYS Mechanical using different material and composite material for comparative study which will show the optimum material for the manufacturing of wind turbine blade. Keywords - Composite material, E glass fiber, E glass fiber UD, HAWT (horizontal axis wind turbine), NACA 0012, Std CF fabric, structural analysis, equivalent stress, stress xx, Total deformation.I. Brief about compositeA composite material is made by mixing two or more materials often ones that have very dissimilar properties. The two materials work jointly to give the composite exclusive properties. However, within the composite you can simply tell the dissimilar materials apart as they do not disband or blend into each other. [Composite materials page 1 of 3, Index 4.3.1] The first modern composite material was fibreglass. It is still widely used today for sports equipment, boat hulls, building panels and numerous car bodies. The surrounding substance is a plastic and the underpinning is glass that has been made into fine threads and often woven into a sort of fabric. On its own the glass is extremely sturdy but brittle and it will fracture if bent roughly. The plastic surrounding substance holds the glass fibres jointly and also protects them from smash up by sharing out the forces acting on them. Some highly developed composites are now prepared by using carbon fibres as an alternative of glass. These materials are lighter and stronger than fibreglass but more costly to produce. They are used to produce aircraft structures and expensive sports equipment such as golf clubs.I. Composite Material, general material and their propertyTABLE Iproperty of composite materialsPropertyUnitsStd CF FabricE Glass FibreE Glass Fibre UD

DensityKg/m3160026001900

Coefficient of thermal expansionK-12.1E-065.1E-051E-05

Youngs modulesPa7E+108.5E+104E+10

Poisons Ratio-0.10.230.25

Bulk ModulusPa2.2916E+105.2469E+102.6667E+10

Shear ModulusPa3.1818E+103.4553E+101.6E+10

Tensile Yield StrengthPa1.1E+081.95E+091.2E+08

Compressive Yield StrengthPa1.1E+084E+091.2E+08

Tensile Ultimate StrengthPa6E+082.05E+091E+09

Compressive Ultimate StrengthPa5.7E+085E+096E+08

TABLE IIIproperty of general materialsPropertyUnitsAluminium AlloyStructural Steel

DensityKg/m327707850

Coefficient of thermal expansionK-12.3E-051.2E-05

Youngs modulesPa7.1E+102E+11

Poisons Ratio-0.330.30

Bulk ModulusPa6.9608E+101.6667E+11

Shear ModulusPa2.6692E+107.6923E+10

Tensile Yield StrengthPa2.8E+082.5E+08

Compressive Yield StrengthPa2.8E+082.5E+08

Tensile Ultimate StrengthPa3.1E+084.6E+08

Compressive Ultimate StrengthPa00

II. MethodologyFor structural analysis we need value of load generated by the moving wind on the blade. For that we need to know the pressure generated by the wind which after multiplying with surface area will gives the load generated by wind. For calculation of that following method is adopted.The wind pressure can be approximated by: Pressure = x (density of air) x (wind speed)2x (shape factor) The density of air is about 1.25 kg/m3. The shape factor (drag coefficient) depends on the shape of the body. The wind speed must be expressed in m/s. In that case the pressure has units kg/m/s2, i.e. N/m2. Local average wind speed is found to be 3.9 m/s. For calculation of shape factor we need to do 2D analysis on our aerofoil which is generation the blade i.e. NACA0012III. Analysis of NACA0012figure 1messing of NACA0012 aerofoil

With the help of C Mesh we analysis the aerofoil and we got following results and plotsfigure IICp of NACA0012 aerofoil

Figure IIIVelocity and pressure contour of NACA0012 aerofoil

We have calculated the value of Cd (drag coefficient) for 3.9 m/s wind speed for 10 angle of attack. Obtained result is Cd= 0.609 IV. Calculation Of wind LoadPressure = x (density of air) x (wind speed)2x (shape factor)Pressure = 0.5 x 1.25 x (3.9)2 x 0.609 = 0.475 N/m2Geometry of our blade is 10 x 1 m approximate (because of varying sections) thus Wind Load = 0.475 x 10 NTaking approximate value of 50 N by considering upper tolerances.V. Structural AnalysisOn ANSYS mechanical, structure analysis of 3D blade of same profile is done for above mentioned materials results are as follows:-a. Structural Steel

b. Aluminum Alloy

c. E Glass Fiber

d. E Glass Fiber UD

e. Std CF Fabric

In tabular for we can conclude these as followsTABLE IIIIIresults of composite materialsParameterStd CF FabricE glass fiberE glass fiber UD

Total deformation (m)12.8E-511.46E-524.6E-5

Equivalent stress (pa)481364986450139

Stress xx (pa)284193155632040

TABLE IVVRESULTS OF general materialsParameterAluminum alloyStructural steel

Total deformation (m)14.5E-55.0721E-5

Equivalent stress (pa)5126650838 pa

Stress xx (pa)3399333257

VI. Result And DiscussionFrom above results it is clear that Std CF Fabric which is a composite material gives improved performance then the general structural material listed in table no. 4 in terms of reduced stress which will certain improve life span and aerodynamic performance of the wind turbine. Further optimization can be done by using more appropriate profile NACA4412; structural analysis of 3D generated blade will show promising results for low wind speed regime.References

[1] Ashwill, Thomas D., and Joshua A. Paquette. "Composite materials for innovative wind turbine blades."Wind Energy Technology Department, Sandia National Laboratories, Albuquerque, NM87185 (2008).[2] ASCE. "Minimum design loads for buildings and other structures."ASCE/SEI 7-05-2006(2006).[3] Mallick, Pankaj K., ed.Composites engineering handbook. CRC Press, 1997.[4] Ashby, Michael F., and D. Cebon. "Materials selection in mechanical design."Le Journal de Physique IV3.C7 (1993): C7-1.[5] Madhu, Singh, and Singh Payal. "A Review of Wind Energy Scenario in India."Int. Res J. of Env. Sc3.4 (2014): 87-92.[6] Guide, ANSYS Fluent UserS. "Ansys."Inc. Release15 (2013).[7] ANSYS, CFX. "ANSYS CFX."Reference Guide. Release13.0 (2010).[8] Guide, Ansys Mechanical Application UserS. "Release 14.5."Ansys Inc., Canonsburg(2012).