1 / 25

Motivations Vortex Structure and Treatment of Yaw Equation for the Circulation

VALIDATION OF A HELICOIDAL VORTEX MODEL WITH THE NREL UNSTEADY AERODYNAMIC EXPERIMENT James M. Hallissy and Jean-Jacques Chattot University of California Davis OUTLINE. Motivations Vortex Structure and Treatment of Yaw Equation for the Circulation Convection in the Wake Results Conclusion.

colvinm
Download Presentation

Motivations Vortex Structure and Treatment of Yaw Equation for the Circulation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. VALIDATION OF A HELICOIDAL VORTEX MODEL WITH THE NREL UNSTEADY AERODYNAMIC EXPERIMENTJames M. Hallissy and Jean-Jacques ChattotUniversity of California DavisOUTLINE • Motivations • Vortex Structure and Treatment of Yaw • Equation for the Circulation • Convection in the Wake • Results • Conclusion 43rd AIAA Aerospace Sciences Meeting and Exhibit 24th ASME Wind Energy Symposium, Reno, NV, Jan.10-13, 2005

  2. MOTIVATIONS • Assess the Prediction Capabilities of Model in “Stand-alone” Mode • Analyze the Effect of Yaw as Source of Unsteadiness • Validate the Model as Far-Field Boundary Condition for Navier-Stokes Simulation

  3. VORTEX STRUCTURE AND TREATMENT OF YAW • Vortex Structure • Small Disturbance Treatment of Wake • Application of Biot-Savart Law • Blade Element Flow Conditions

  4. VORTEX STRUCTURE Vortex sheet constructed as perfect helix with variable pitch from average power:

  5. SMALL DISTURBANCE TREATMENT OF WAKE Vorticity is convected along the base helix, not the displaced helix, a first-order approximation

  6. APPLICATION OF BIOT-SAVART LAW

  7. BLADE ELEMENT FLOW CONDITIONS

  8. EQUATION FOR THE CIRCULATION • 2-D Viscous Polar • Kutta-Joukowski Lift Theorem

  9. 2-D VISCOUS POLAR S809 profile at Re=500,000 using XFOIL + linear extrapolation to

  10. KUTTA-JOUKOWSKI LIFT THEOREM

  11. NONLINEAR TREATMENT • Discrete equations: • If Where

  12. NONLINEAR TREATMENT (continued) • If • is the coefficient of artificial viscosity • Solved using Newton’s method

  13. CONVECTION IN THE WAKE • Mesh system: stretched mesh from blade To x=1 where Then constant steps to • Convection equation along vortex filament j: Boundary condition

  14. CONVECTION IN THE WAKE (continued)

  15. RESULTS Flow velocities and yaw angles analyzed at 30, 47, 63, 80 and 95% span

  16. STEADY FLOW Blade working conditions: attached/stalled

  17. STEADY FLOW Power output comparison

  18. STEADY FLOW Comparison of dynamic pressures at specified spanwise locations

  19. STEADY FLOW Normal forces comparison y=30% y=47% y=63% y=80% y=95%

  20. STEADY FLOW Tangential forces comparison y=30% y=47% y=63% y=95% y=80%

  21. YAWED FLOW Blade working conditions for V=10 m/s, =20 deg

  22. YAWED FLOW Torque versus azimuth angle for V=10 m/s, =10 deg

  23. YAWED FLOW Time-averaged power versus velocity at different yaw angles =10 deg =5 deg =20 deg =30 deg

  24. YAWED FLOW Force coefficients versus azimuth at 63% span, V=10 m/s, =10 deg

  25. CONCLUSIONS • The helicoidal vortex model is accurate in steady flow when flow attached (V 8 m/s) and for partially separated flow (V 10 m/s) • The effect of yaw is well accounted for in the range V 10 m/s, 0 20 deg • The vortex model will be used as far field condition with a near field Navier-Stokes simulation.

More Related