ckelley2/nrt

National Rotor Testbed design documentation

NRT Design and Testing Documentation

• National Rotor Testbed design documentation is contained in this repository
• Field experiment is ongoing at Sandia/DOE SWiFT Facility, Lubbock, Texas
• Aerodynamic and instrumentation design by Sandia
• Final structural design and manufacturing drawings were provided by Wetzel Wind Energy Services
• Oakridge National Laboratory 3D printed the NRT blade mold
• TPI Composites manufactured 4 NRT Blades
• Structural testing conducted at NREL

Purpose

• To conduct wind turbine wake experiments relevant to megawatt scale turbines
• To be an open, well-documented, and highly instrumented wind turbine rotor design for model validation
• To demonstrate new blade technology

Aeroelastic Model

• Modelled in FAST version 7
• Blade aerodynamics including chord, twist, and airfoil locations in aerodyn file NRT_AD.ipt
• Blade structural properites including edge, flap, tension, and torsional stiffness, mass moments of inertia, and mass distribution in each blade file NRT_Blade1_as_built_balanced.dat, NRT_Blade2_as_built_balanced.dat, NRT_Blade3_as_built_balanced.dat
• Blade mass distribution updated to include ballast in balance boxes of each blade
• Airfoil lift, drag, and moment data from experimental wind tunnel testing by Somers
• Model will continue to be updated during ongoing NRT experiment
• Simple controller model, variable speed, variable pitch
• Please contact us for a detailed simulink model of the turbine controller
• Plotting scripts in matlab require txt2mat

Blade Instrumentation

• Strain gages:
  • Micron Optics Fiber Optic OS3200
  • Spaced 45 degrees at root, high/low pressure side outboard
  • calibrated to measure aerodynamic bending moment
• Accelerometers:
  • Silicon Designs 2470
• Blade Temperature:
  • Micron Optics Fiber Optic OS4300
  • to compensate for thermal strain
• All three blades have same sensors
  

Blade Properties

• Length: 13 m
• Blade Mass: 551 kg per blade, including balance box ballast
• Blade Center of Gravity: 4.04 m from root
• Construction: Fiberglass spar and skin
• Surface Roughness (Painted, clean): Ra = 0.45 𝜇m (17 𝜇in), Rz = 2.57 𝜇m (101 𝜇in)

Regions of Operation

• Region 2: 4-6.9 m/s, 25.9-43.6 rpm, TSR = 9
• Region 2.5: 6.9-11.4 m/s, 43.6-43.9 rpm
• Region 3: 11.4-20 m/s, 43.9 rpm

Aerodynamic Design

• Technical Report
• Create scaled wake of GE 1.5sle (GE37c blade) by having the same axial induction and dimensionless circulationacross the rotor normalized radius () in region 2
• NRT and GE rotor also have equal thrust coefficient and tip-speed-ratio in region 2
• S825 airfoil across outer 50% of rotor span
• S814 airfoil at maximum chord, c = 1.5 m
• Airfoils operate at a lift coefficient of 0.6 in region 2
• Overview of functional scaling (.pdf)

Structural Design

• Mass, Stiffness, and Modal Analysis Report (.pdf)
• Beam Properties (.xlsx)
• Material Properties and Standards (.xlsx)
• 3D CAD Models
• Manufacturing Drawings
• Note, the root plane was cut to add 0.5° of forward sweep to reduce nose down pitching moment about the blade pitch axis
• Initial structural design report at Sandia in 2015, superseded by Wetzel structural design

Static Blade Testing

• Conducted at NREL Structural Testing Lab

• Test Report (.pdf)

• Proof Tests:

  • maximum and minimum edge loads
  • maximum and minimum flap loads
  • fatigue test in flap direction
  • ultimate flap load to failure
  

Field Test

• Verify blade loading distribution creates scaled wake of GE 1.5 sle
• Fine tune pitch setting to create scaled wake
• Fine tune torque constant to achieve
• See technical report for description of tuning process
• Blade bending moment coefficients to achieve scaled wake (at reference air density of 1.225 kg/m3) are as follows for discreet strain gage locations in thrust and edge directions
• Wake Management demonstration showing a combination of yaw, induction, and dynamic induction control

SWiFT Site Documentation

• SWiFT Site Overview
• Wind Resource Assessment and Characterization

Point of Contact

Chris Kelley
[email protected]

References

C. Kelley, "Aerodynamic Design of the National Rotor Testbed," Sandia National Laboratories Technical Report, SAND2015-8989.

C. Kelley, B. Naughton, "NRT Design Verification Test Plan," Sandia National Laboratories Technical Report, SAND2018-14254.

C. Kelley, "National Rotor Testbed Overview for DOE Science Panel," Project Presentation, SAND2017-4446PE.

B. Ennis, J. Paquette, "NRT Rotor Structural/Aeroelastic Analysis for the Preliminary Design Review," Sandia National Laboratories Technical Report, SAND2015-9358

Copyright

Copyright 2020 National Technology & Engineering Solutions of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with NTESS, the U.S. Government retains certain rights.

NRT design documentation is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.