Uncertainties in the aerodynamics and structural dynamics of rotors suitable for reliable and long life operation of small HAWTS
This study was undertaken to identify theoretical and experimental knowledge available and required to achieve reliable and long life operation of small horizontal axis wind turbine systems (SHAWTS) in utility applications. This class of HAWTS has been taken to range from 8 to 280 kW at the present time, with corresponding rotor diameters ranging from about 30 to 125 ft. There is a trend toward higher power machines, achieved with smaller diameter rotors operated at higher RPM and rated wind velocity, compared to the DOE/NASA MOD-0 and MOD-0A units. Because of the smaller diameter of SHAWTS relative to LHAWTS rotors, the former tend to operate with smaller unsteady loads from non-uniform inflow velocity profiles and from atmospheric gusts and turbulence. But because of the higher RPM of SHAWTS, the frequencies of the unsteady loads are higher. Finally because of their smaller blades, they are relatively stiffer, and on balance it appears that unsteady loads may more often be of less consequence than limit loads in blade structural design for SHAWTS. There are indications, however, that yaw dynamics in gusty and/or high velocity winds may be a critical fatigue design factor for free yaw SHAWTS rotor blades. There is a plethora of SHAWTS design concepts; however, many utilize downwind, stall controlled, free yaw rotors.
- Research Organization:
- RANN, Inc., Palo Alto, CA (USA)
- DOE Contract Number:
- AC04-82AL21362
- OSTI ID:
- 5481750
- Report Number(s):
- DOE/AL/21362-T1; ON: DE86010592
- Country of Publication:
- United States
- Language:
- English
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