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Analysis of Low-Speed Viscous Flow Past an Airfoil as a Wind Turbine Blade

This study explores the effects of boundary layer on the overall flow past a wind turbine blade. The difference in performance between lift and drag machines is discussed, emphasizing the higher relative wind velocities achievable with lift machines. The aerodynamic forces, speed ratios, and the impact of viscous boundary layer on lift and drag magnitudes are examined in detail. Understanding these aspects is crucial for accurate design and innovation in airfoil geometry and performance. Methods for tuning airfoil design for acceptable performance under viscous flow conditions are also explored.

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Analysis of Low-Speed Viscous Flow Past an Airfoil as a Wind Turbine Blade

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  1. Analysis of Low Speed Viscous Flow Past an Airfoil as A Wind Turbine Blade P M V Subbarao Professor Mechanical Engineering Department Analysis of BL Effects……

  2. An Overall Flow Past an WT Blade • A significant difference in the performance between lift and drag machines is that much higher relative wind velocities can be achieved with lift machines. • Relative velocities are always greater than the free stream wind speed, sometimes by an order of magnitude. • The relative wind velocity at the airfoil of a lift machine is:

  3. Airfoil : The Lift Machine in A WT • An airfoil as wind turbine blade can experience: • Speed ratios of up to 10. • Aerodynamic forces proportional to the square of the relative speed. • These conditions make the a lift machine to generate significantly greater force than a drag machine with the same surface area. • The larger forces allow for much greater power coefficients. • Viscous boundary layer modifies the relative magnitudes of lift and drag. • A thorough study of BL flow past an wind turbine blade is essential for accurate design.

  4. Essential Macro Steps in Innovation Airfoil geometry

  5. Surface Pressure Distributions • The aerodynamic performance of airfoil sections can be studied most easily by reference to the distribution of pressure over the airfoil. • This distribution is usually expressed in terms of the pressure coefficient: • Cp is the difference between local static pressure and freestream static pressure, non-dimensionalized by the freestream dynamic pressure. • Invoke Bernoulli's equation:

  6. Local Edge Velocity & Static Pressure over an Airfoil For incompressible flow, The corresponding pressure coefficient can then be found using V

  7. Airfoil Pressure Distributions

  8. Airfoil Pressures and Performance

  9. Angle of Attack Vs Pressure distribution : Ideal Flow Increasing Angle of Attack

  10. Angle of Attack Vs Pressure distribution : Real Flow

  11. Front Loaded Vs Aft Loaded Blades

  12. Essential Macro Steps in Innovation Airfoil geometry

  13. Essential Macro Steps in Tuning for Acceptable Performance Airfoil geometry

  14. Design Methods for Viscous Flow Past An Airfoil • Direct design methods • Inverse Methods • Inverse Method via velocity distributions • Inverse viscous design • Design for performance

  15. Direct Design Methods

  16. Inverse Method via Velocity Distributions

  17. Inverse Viscous Design

  18. Design for performance

  19. Wind Speed Distribution vs Performance Acquisition of more skills for development of the most eligible airfoil !?!??!

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