Examination, evaluation, and repair of laminated wood blades after service on the Mod-OA wind turbine
As a result of about 7 years of effort at the NASA Lewis Research Center, laminated wood blades were designed, fabricated, and installed on a 200-kW wind turbine (Mod-OA). The machine uses a two-blade rotor with a diameter of 38.1 m (125 ft). Each blade weighs less than 1361 kg (3000 lb). After operating in the field, two blade sets were returned for inspection. One set had been in Hawaii for 17 months (7844 h of operation) and the other had been at Block Island, Rhode Island, for 26 months (22 months operating - 7564 h). The Hawaii set was returned because one of the studs that holds the blade to the hub had failed. This was found to be caused by a combination of improper installation and inadequate corrosion protection. No other problems were found. The broken stud (along with four others that were badly corroded) was replaced and the blades are now in storage. The Block Island set of blades was returned at the completion of the test program, but one blade was found to have developed a crack in the leading edge along the entire span. This crack was found to be the result of a manufacturing process problem but was not structurally critical. When a load-deflection test was conducted on the cracked blade, the response was identical to that measured before installation. In general, the laminate quality of both blade sets was excellent. No significant internal delamination or structural defects were found in any blade. The stud bonding process requires close tolerance control and adequate corrosion protection, but studs can be removed and replaced without major problems. Moisture content stabilization does not appear to be a problem, and laminated wood blades are satisfactory for long-term operation on Mod-OA wind turbines.
- Research Organization:
- NASA Lewis Research Center, Cleveland, OH (United States)
- DOE Contract Number:
- AI01-76ET20320
- OSTI ID:
- 5612396
- Report Number(s):
- DOE/NASA/20320-53; NASA-TM-83483; CONF-831093-1; ON: DE84001931
- Resource Relation:
- Conference: Wind expo '83 and AWEA national conference, San Francisco, CA, USA, 16 Oct 1983
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
TURBINE BLADES
INSPECTION
WOOD-PLASTIC COMPOSITES
WIND TURBINES
CORROSION
CRACKS
INSTALLATION
MANUFACTURING
MOISTURE
REPAIR
CHEMICAL REACTIONS
COMPOSITE MATERIALS
MACHINERY
MATERIALS
TURBINES
TURBOMACHINERY
170602* - Wind Energy Engineering- Turbine Design & Operation
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