aerofoil design optimisation aero 20

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    Problem Definition Aero acoustic tests of seven airfoils were performed in

    an open wind tunnel . Out of which six of the airfoilsare used on small wind turbines at low Reynoldsnumber.

    Comparison is made for different airfoil sections and

    airfoil producing less noise is determined.

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    Introduction

    With reference to many aerofoil profiles, a method todesign new aerofoil shapes has been undertaken inthis research work by altering the position of

    maximum thickness along the aerofoil chord.

    The 4-digit NACA aerofoil series has been chosen asreference to start with.

    Experimental investigations have been carried out onthe standard NACA 0012 symmetrical aerofoil and theresponses to the changes in the aerofoil shapes havebeen noted.

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    Starting from the pressure variations to the aerodynamic

    characteristics and structural strength, different shapesgive various comparative results.

    For varying Mach number and Angle of Attack, theresults are compared and charted.

    Shape is an important factor in deciding the aerofoil

    performance and control.

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    The aerodynamic characteristics cause changes to the

    aerodynamic forces and pressures on the upper andlower surfaces of the aerofoil.

    The works done so far in the history of aerofoil haveled to the usage of many aerofoil families and shapes.

    By analyzing the air flow over and around the aerofoilfor different flow conditions, the shape can be changedas desired to yield a better output in the form of a

    smoother flow.

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    Balanced approach to aircraft noise managementconsists of identifying the noise problem at an

    airport and then analysing the various measuresavailable to reduce noise through the exploration offour principle elements.. Namely-

    Reduction at source

    Land use planning and management.

    Noise abatement operational procedures

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    Wind tunnel is a research tool used in aerodynamic

    research.

    It is used to study the effects of air moving pastsolid objects.

    Types:1)Open continuity and Bernoulli's

    2)Closed- Continuity law and used for isentropicflow

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    There is no evidence that audible sounds

    emitted by wind turbines have direct physiological

    effects.The sound produce by wind turbines are not

    unique.

    Mechanical noise is usually minimum-

    aerodynamic blade noise is often less than noise of

    wind.

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    Source of turbine blade noise Inflow turbulence

    Turbulent boundary layer trailing edge interaction.

    Separated flowVortex shedding

    Trailing edge bluntness

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    NACA 0012 Symmetric aerofoil

    The reason to choose the NACA 0012 symmeticaerofoil.

    It reduces the complexity in design and imparts

    easiness in the design modification of the aerofoil& reduces problem of Cp with varying angles ofattack.

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    Eight modified aerofoil profiles

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    Design specifications:Tests were conducted on seven airfoil models, eachhaving a 22.86 cm chord and a 0.51m span six ofthe airfoils are either being used or considered foruse on small wind turbine blades. These are the

    FX 63-137,

    S822, S834,

    (Selig-Donovan) SD2030,

    (Selig-Giguere) SG6043, and

    (Selig-hanley) SH3055.

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    FX 63-137

    x/c y/c

    1.000000 .000000

    .987490 .006299

    .967924 .013921

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    SAMPLE AIRFOIL DESIGN OF S822:

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    Future work Calculation of turbulence grid for different airfoil

    sections.

    Comparison of camber Cl and Cd, L/D, angle of attackrange for the airfoil sections.

    using the source plots noise originating from themodel is estimated.

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