A gap correction for HAWT blades
Partial-span ''tip'' controls are used to start, stop, and regulate power on a number of horizontal-axis wind turbines (HAWT) including the MOD-2. There exists a physical gap in blade chord between the pitchable outer portion of the rotor blade and the inner, fixed portion of the blade. On the MOD-2, the gap is 0.28 m (11 inches) wide and the gap is situated at 70 percent of the rotor radius or 32.0 m (105 fet) from the rotor centerline. The chord at the gap is over 2.3 m (90 inches). A gap in the chord of the blade of a wind turbine causes the circulation to drop to zero at the opening. As a result of the drop in circulation, vorticity is shed in the wake with vorticity of opposite signs being present; the vorticity shed outboard of the gap is of the opposite sign of the vorticity shed inboard of the gap. Let us model the effect of this shed vorticity as a semi-infinite vortex doublet extending downwind of the gap. The vortex shed at the gap due to the difference in circulation between the inner and outer portions of the blade is neglected. Since the influence of a doublet falls off inversely as the square of the distance, the extent of the velocity field of a doublet is small enough to employ a straight vortex double.
- Research Organization:
- Mechanical Engineering Dept., Oregon State Univ., Corvallis, OR 97331
- OSTI ID:
- 6800966
- Journal Information:
- J. Sol. Energy Eng.; (United States), Vol. 109:1
- Country of Publication:
- United States
- Language:
- English
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