Services
Wind Tunnel Testing
Test services performed at Otech are primarily anemometer or wind sensor calibrations. The Otech wind tunnels were designed so that flow quality in the test section is also uniformly maintained to within +/- 0.1% with turbulence levels less than 0.1% for the range of controlled wind speeds available. Such conditions are extremely critical in isolating the performance of an anemometer under test.
Otech wind tunnel facilities are identical in size with test section dimensions of 0.61 m x 0.61 m x 1.22 m (2′ x 2′ x 4′). Two of the wind tunnels are driven by a 15 hp fan motor capable of generating speeds up to 36 m/s in the test section. The newest wind tunnel is driven by a 30 hp fan motor with maximum wind speeds reaching up to 45 m/s in the test section.
Wind tunnel speed is determined using a Pitot-static tube system with four equally-positioned Pitot-static tubes located at the leading edge of the test section. The local wind speed is also calculated so that it accounts for the corresponding test section atmospheric conditions such as ambient pressure, temperature, and humidity. All measurements are simultaneously acquired using a National Instruments LabVIEW data acquisition system, which also allows for easy adaptation to any test protocol.
Otech opperates on specified terms and conditions. An accepted quote or contract combined with these terms and conditions define the entire agreement for service between Otech and its customers. Here is a PDF version of Otech Terms and Conditions.
Anemometer Calibration
Click through the gallery above for pictures of some of the models of rotating anemometers tested at Otech, which include:
- NRG #40
- NRG IceFree 3
- NRG Hybrid
- Windsensor (Riso) P2546A
- R.M. Young Propeller
- R.M. Young Wind Monitor 05103
- Thies First Class
- Thies First Class Advanced
- Met One 010C
- Met One 014A
- Met One 014 Mini
- Vaisala WAA252
- Vector A100LK
- Vector A100L2
- Ornytion 107A
- Richards C5
- Richards C5C
Sonic anemometers tested at Otech include:
- Gill WindObserver
- FT702LT
- Climatronics 102751
Quality Standards
Otech is accredited to ISO/IEC 17025:2005, “General Requirements for the Competence of Testing and Calibration Laboratories”. This accreditation was awarded by International Accreditation Service (IAS). Instruments used for wind speed measurements in the Otech wind tunnels are traceable to National Institute of Standards and Technology (NIST). If requested, traceability and conformity documents can be provided.
Anemometer testing and calibration procedures at Otech are designed and performed according to the following published guidelines and standards:
ASTM D 5096-02, Standard Test Method for Determining the Performance of a Cup Anemometer or Propeller Anemometer
ASTM D 6011-96, Standard Test Method for Determining the Performance of a Sonic Anemometer/Thermometer
IEC 61400-12-1, Power Performance Measurements of Electricity Producing Wind Turbines
ISO 16622, Meteorology – Sonic anemometers/thermometers – Acceptance Test Methods for Mean Wind Measurements
ISO 17713-1, Meteorology – Wind Measurements – Part 1: Wind Tunnel Test Methods for Rotating Anemometer Performance
As part of test reporting procedures, uncertainties are defined for the measured reference wind speed for each calibration test point. Uncertainties are calculated using procedures and guidelines given in the following published standards and textbook:
ECN-C-05-66, Uncertainties in Cup Anemometer Calibrations: Type A and Type B Uncertainties
ISO/IEC Guide 98-3, Uncertainty of Measurement – Part 3: Guide to the Expression of Uncertainty in Measurement (GUM:1995)
NIST TN 1297, Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results
Coleman, H.W. and W.G. Steele (1999), Experimentation and Uncertainty Analysis for Engineers 2nd ed, John Wiley and Sons, 275 pp.
