Skip to main content

AN EXPERIMENTAL INVESTIGATION OF HORIZONTAL- AXIS WIND TURBINE AERODYNAMICS IN NATURAL CONDITIONS.

Objective

THE AIM OF THIS THREE-PRONGED COLLABORATIVE PROGRAMME IS TO PROVIDE A COHERENT SET OF MEASURED AERODYNAMIC DATA ACCOUNTING FOR AXIAL AND NON-AXIAL FLOW, FREE-STREAM TURBULENCE AND STALL IN HIGH WINDS ON THREE SIMILAR HAWT ROTORS WITH DIAMETERS 3M, 19M AND 26M. THESE MEASUREMENTS ARE DESIGNED TO QUANTIFY THE RELATIVE IMPORTANCE OF THREE-DIMENSIONAL, UNSTEADY AND SCALE EFFECTS. THE 3M DIAMETER ROTOR, FITTED WITH FAST-RESPONSE PRESSURE TRANSDUCERS, IS BEING OPERATED AT CRANFIELD IN BOTH CONVENTIONAL FIELD TESTS AND CONTROLLED VELOCITY TESTS.

THE PROJECT DEVELOPMENT HAS PROCEEDED IN FOUR DISTINCT STAGES. FIRSTLY A SET OF 1KW MARLEC BLADES WAS FITTED ON THE CRANFIELD TEST-BED TURBINE, AND THE ROTOR PERFORMANCE ESTABLISHED IN FIELD TESTS. NEXT A PARTIALLY INSTRUMENTED BLADE, WITH JUST EIGHT PRESSURE TRANSDUCERS OVER THE ROOT AND MID SECTION, WAS TESTED ON THE FIELD SITE; THIS DATA IS CURRENTLY BEING ANALYSED FOR THE SPANWISE EXTENT OF STALL, ''TOWER BLOCKAGE'' EFFECT, AND INCIDENT FLOW VARIATION IN TURBULENT WIND. THE THIRD PROJECT STAGE WAS TO DEVELOP A MOBILE FACILITY TO CARRY THE TURBINE ALONG THE CRANFIELD RUNWAY AT SPEEDS UP TO 25 M/S. THE TRAILER UNIT HAS BEEN BUILT AND RIGOROUSLY TESTED, BOTH STATICALLY IN THE WORKSHOP AND DYNAMICALLY ON THE RUNWAY, LOADED TO SIMULATE BOTH THE MASS AND DRAG (AXIAL AND YAWED) OF THE TURBINE. THE FINAL STAGE HAS BEEN TO INSTALL FORTY PRESSURE TRANSDUCERS, CONCENTRATED AT THE 35%R AND 75%R STATIONS, SUFFICIENT TO PROVIDE A PRESSURE DISTRIBUTION AND INTEGRATED FORCE MEASUREMENT. THIS ROTOR HAS BEEN MOUNTED ON THE TRAILER AND THE INSTRUMENTATION RE-COMMISSIONED AS AN AUTONOMOUS SYSTEM. CONTROLLED VELOCITY TESTS ON THIS FULLY INSTRUMENTED BLADE ARE IN PROGRESS; THE DATA WILL BE ANALYSED TO SHOW THE ROTOR'S AERODYNAMIC RESPONSE IN RELATION TO TIP SPEED RATIO, DISC LOADING, CHORD REYNOLDS NUMBER AND YAW ANGLE, UNDER CONDITIONS OF LOW FREE-STREAM TURBULENCE.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Cranfield University
Address
Silsoe Campus Wharley End
MK45 4DT Cranfield
United Kingdom

Participants (2)

Central Electricity Generating Board (CEGB)
United Kingdom
Address

London
Risø National Laboratory
Denmark
Address

4000 Roskilde