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DESIGN STUDY FOR A LOW COST ROTOR FOR A MEGAWATT RATED VERTICAL AXIS WIND TURBINE.

Objective

THE OBJECTIVES OF THIS DESIGN STUDY ARE TO INVESTIGATE PROMISING ROUTES TO ACHIEVING A MAJOR REDUCTION IN THE WEIGHT AND THE COST OF A MEGAWATT RATED VERTICAL AXIS WIND TURBINE AND TO PRODUCE REALISTIC COST ESTIMATE FOR BOTH A PROTOTYPE AND PRODUCTION UNITS.
A design study into a megawatt class vertical axis wind turbine (VAWT) was undertaken. Firstly, an intermediate technology stage between the 25 metre diameter research unit at Camarthen Bay and the offshore unit (which would have a minimum diameter of 100 metres) was provided and, secondly, the development of a machine for use in land based wind farms in the latter part of this century was developed.

Much experience was gained in the design and fabrication of the 25 metre research prototype and the 17 metre commercial prototype shortly to be erected on the Isles of Scilly. This, combined with concurrent studies leading to the design of a multimegawatt VAWT, has led to the development of a revised, second generation configuration for the wind turbine which shows considerable promise for reduction in weight and cost of the rotor for a variable geometry vertical axis wind turbine.


A RANGE OF VARIABLE GEOMETRY ROTOR ASPECT RATIOS AND CONFIGURATIONS WERE INVESTIGATED AND A NUMBER OF BLADE MATERIAL OPTIONS CONSIDERED INCLUDING GLASS REINFORCED, WOOD/EPOXY, AND ADVANCED COMPOSITES, HIGH STRENGTH STEEL, LOW STRENGTH STEEL, ALUMINIUM ALLOY AND HYBRID STRUCTURES. IN ADDITION DESIGN SCHEMES FOR THE SUPPORTING STRUTS, THE CROSSARM AND THE HUB HAVE BEEN PREPARED AS WELL AS FOR DIFFERENT AERODYNAMIC BRAKING AND REEFING SYSTEMS.
THE CONFIGURATION IDENTIFIED IN THIS STUDY HAS BEEN SHOWN TO OFFER SUBSTANTIALLY LOWER WEIGHT COMPARED TO THAT OF THE 25 METRE DIAMETER RESEARCH PROTOTYPE AT CARMARTHEN BAY POWER STATION. IT WAS CONCLUDED THAT THE 1.2 MW MACHINE SHOULD HAVE A ROTOR DIAMETER OF 67 METRES AND A BLADE LENGTH OF 35.8 METRES. COMPOSITE BLADE MATERIALS WERE SHOWN TO OFFER THE BEST COMBINATIONS OF LOW WEIGHT AND LOW COST.
AS A RESULT OF THIS AND OTHER DESIGN AND DEVELOPMENT STUDIES COMBINED WITH THE ANALYSIS OF DATA FROM OPERATIONAL MACHINES, IT HAS NOW BEEN CONCLUDED THAT STRAIGHT BLADED VERTICAL AXIS WIND TURBINES ARE ABLE TO OPERATE SATISFACTORILY IN THE FIXED GEOMETRY, STALL REGULATED CONFIGURATION. THIS LEADS TO REDUCTIONS IN CAPITAL COST AND TO SIGNIFICANT SIMPLIFICATIONS WHICH WILL RESULT IN IMPROVED RELIABILITY, REDUCED MAINTENANCE COSTS AND HENCE TO MINIMUM COST OF ENERGY. A FIXED GEOMETRY ROTOR ARRANGEMENT HAS THEREFORE BEEN ADOPTED FOR SUBSEQUENT DESIGN AND DEMONSTRATION PROJECTS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Sir Robert McAlpine
Address
40 Bernard Street
WC1N 1LG London
United Kingdom

Participants (1)

Northern Engineering Industries
United Kingdom
Address

Newcastle Upon Tyne