National Renewable Energy Lab Testing Impact of Edge Wind’s Conformal Vortex Generator Tape on Wind Turbine Blade Performance
Edge Wind has contracted with the U.S. National Renewable Energy Lab (NREL) to conduct and independent field testing program to evaluate the performance. This research project, TSA-16-853 began in June 2016 and is expected to be completed in May 2017 before the AWEA Wind Power show. 7 of the research objectives have been completed as of mid-February, two are in progress, and four remaining ones remain to be completed.
Edge Wind Objectives
· Offer the wind industry a blade leading edge protection/repair treatment which, at a minimum, does not degrade turbine performance
· Mitigate adverse impacts to blade aerodynamic performance and rotor power production inherent to existing blade leading edge protection/repair treatments
· Attenuate unsteady separated aerodynamic interactions and structural fatigue loads caused by blade passage through inflow shear or turbulence
Hierarchy of Field Test Measurements
· Power performance – generator electrical power and rotor mechanical power
· Aerostructural loads – source of rotor torque and fatigue loads
· Blade flow field – source of blade aerodynamic loads and direct indication of CVG effects
Summary of Field Testing Program
Passive aerodynamic flow control technologies invented by Edge Wind, consisting of leading edge repair tapes augmented with conformal vortex generators (CVG’s) and trailing edge tabs, will be field tested at NREL’s National Wind Technology Center (NWTC) on the two-bladed Controls Advanced Research Turbine (CART2). This will be accomplished through CART2 power performance testing of these devices across a range of inflow and turbine operating conditions. Power performance testing will be accompanied by measurement of time varying aerostructural loads at the blade roots and on the low speed shaft. Device effectiveness will be assessed against a reference datum acquired through CART2 power performance and aerostructural loads testing with baseline unmodified blades. For select inflow conditions, turbine operating states, and flow control configurations, power performance and aerostructural loads data may be augmented with visualizations of the blade surface flow field. Testing will be structured in an incremental manner as described below.
Field Testing Tasks
1. The NWTC will convert the CART2 turbine controller from variable speed operation to constant speed operation. This conversion will eliminate rotor speed as a variable in these tests, which will serve to isolate rotor power performance and blade aerodynamic response as the measured quantities of interest. Focusing on these quantities will provide the most direct indication regarding effectiveness of the Edge Wind CVG’s and trailing edge tabs. PROJECT STATUS: COMPLETED
2. The NWTC will extract and post process power performance and aerostructural loads data acquired with the CART2 blades in the baseline unmodified state, around 2004. These data will be analyzed to extract relevant statistics regarding power performance and aerostructural loads, to serve as an initial reference datum for subsequent testing in this project. Raw data in CSV or similar format, and processed data will be delivered promptly to Edge Wind, with sufficient documentation to enable understanding of the data. PROJECT STATUS: COMPLETED
3. Edge Wind will apply 3M leading edge tapes to the blade with support from the NWTC, based on surveys of the blade surfaces. Then, the NWTC will operate the CART2 in constant speed mode with the 3M leading edge tapes applied, to characterize turbine power performance and time varying aerostructural loads. Edge Wind and the NWTC will cooperatively define the wind speeds to be targeted for testing, number and duration of individual data sets, and overall length of the data acquisition period, with reference to IEC 61400 in conjunction with NWTC historical inflow statistics. PROJECT STATUS: COMPLETED
4. The NWTC will extract and post process power performance and aerostructural loads data acquired with the CART2 blades having 3M leading edge tapes applied. These data will be analyzed to extract relevant statistics regarding power performance and aerostructural loads, and will be compared to the reference datum previously established using the baseline unmodified blade data. Raw data in CSV or similar format, and processed data will be delivered promptly to Edge Wind, with sufficient documentation to enable understanding of the data. PROJECT STATUS: COMPLETED
5. Once testing with 3M leading edge tapes is complete, Edge Wind will remove the 3M leading edge tapes and will apply Edge Wind CVG’s to the blade with support from the NWTC, based on surveys of the blade surfaces. Then, the NWTC will operate the CART2 in constant speed mode with the Edge Wind CVG’s applied, to characterize turbine power performance and time varying aerostructural loads. Edge Wind and the NWTC will cooperatively define the wind speeds to be targeted for testing, number and duration of individual data sets, and overall length of the data acquisition period, with reference to IEC 61400 in conjunction with NWTC historical inflow statistics. PROJECT STATUS: COMPLETED
6. The NWTC will extract and post process power performance and aerostructural loads data acquired with the CART2 blades having Edge Wind CVG’s applied. These data will be analyzed to extract relevant statistics regarding power performance and aerostructural loads, and will be compared to the reference datum previously established using the baseline unmodified blade data. Raw data in CSV or similar format, and processed data will be delivered promptly to Edge Wind, with sufficient document to enable understanding of the data. PROJECT STATUS: COMPLETED
7. After testing with the first configuration of Edge Wind CVG’s is complete, Edge Wind will remove the first configuration CVG’s and will apply a second configuration of CVG’s to the blade with support from the NWTC. Then, the NWTC will operate the CART2 in constant speed mode with the Edge Wind CVG’s applied, to characterize turbine power performance and time varying aerostructural loads. Edge Wind and the NWTC will cooperatively define the wind speeds to be targeted for testing, number and duration of individual data sets, and overall length of the data acquisition period, with reference to IEC 61400 in conjunction with NWTC historical inflow statistics. PROJECT STATUS: IN PROGRESS
8. The NWTC will extract and post process power performance and aerostructural loads data acquired with the CART2 blades having Edge Wind second configuration of CVG’s applied. These data will be analyzed to extract relevant statistics regarding power performance and aerostructural loads, and will be compared to the reference datum previously established using the baseline unmodified blade data. Raw data in CSV or similar format, and processed data will be delivered promptly to Edge Wind, with sufficient document to enable understanding of the data. Completion of Tasks 1.7 through 1.10 will take place during 1 February – 31 May 2017. PROJECT STATUS: IN PROGRESS
9. After testing with the Edge Wind CVG’s alone, Edge Wind will leave the Edge Wind CVG’s in place and will add trailing edge tabs to the blade, with support from the NWTC. Then, the NWTC will operate the CART2 in constant speed mode with the Edge Wind CVG’s and trailing edge tabs applied, to characterize turbine power performance and time varying aerostructural loads with blades modified only with leading edge tapes. Edge Wind and the NWTC will cooperatively define the wind speeds to be targeted for testing, number and duration of individual data sets, and overall length of the data acquisition period, with reference to IEC 61400 in conjunction with NWTC historical inflow statistics. PROJECT STATUS: TO BE COMPLETED
10. The NWTC will extract and post process power performance and aerostructural loads data acquired with the CART2 blades with both Edge Wind CVG’s and trailing edge tabs applied together. These data will be analyzed to extract relevant statistics regarding power performance and aerostructural loads, and will be compared to the reference datum previously established using the baseline unmodified blade data. Raw data in CSV or similar format, and processed data will be delivered promptly to Edge Wind, with sufficient documentation to enable understanding of the data. PROJECT STATUS: TO BE COMPLETED
11. Test measurements acquired with 3M leading edge tapes, Edge Wind CVG’s, trailing edge tabs, and combinations thereof as described above, will be compared with test measurements for the baseline unmodified blade. Based on the differential between these data sets and the unmodified baseline data sets, Edge Wind will decide whether or not to proceed with further testing, and will provide direction to the NWTC accordingly. PROJECT STATUS: TO BE COMPLETED
12. To support decision making by Edge Wind regarding future testing on the GE 1.5 MW turbine at the NWTC, the NWTC will do the following. Historical wind resource raw data will be extracted from NREL/NWTC archives, post processed, and used to calibrate wind resource distributions. These calibrated wind resource distributions then will be used in connection with standardized uncertainty analyses to project test durations needed to achieve statistically significant results for Edge Wind purposes. To enable access to the GE 1.5 MW blades for device installation and removal, the NWTC will obtain estimates for subcontracting a suitably sized crane, a Spider platform, and a rope crew. In addition, the NWTC also will project technician personnel needed to support subcontractor assets and personnel for these three access options. The NWTC will survey instrumentation currently available on the GE 1.5 MW turbine and on the associated meteorological tower, to determine whether existing instrumentation and data acquisition will meet Edge Wind needs, and will develop alternatives or plan for upgrades in case existing assets are deemed insufficient. Finally, the external geometry of the GE 1.5 MW blade will be extracted for selected radial locations, and contours for the leading and trailing edge vicinities will be isolated to avoid compromising GE intellectual property. The resulting “sanitized” geometry files will be provided to Edge Wind to enable them to design CVG’s and trailing edge tabs to be used in connection with testing on the GE 1.5 MW turbine at the NWTC. PROJECT STATUS: COMPLETED
13. At the conclusion of Phase 1 of this field testing project, the NWTC will prepare a report, documenting test objectives and planning; NWTC inflow environment and measurements; turbine geometry, operation, and instrumentation; data acquisition and processing; and power performance and aerostructural loads. The report will be delivered to Edge Wind in draft form for their review, and revision instructions will be returned to the NWTC for their action, with a final revised version submitted to Edge Aerodynamics by the NWTC. PROJECT STATUS: TO BE COMPLETED