Fiber Bragg grating anemometer and temperature compensation technology

To better address the temperature interference problem of fiber Bragg grating (FBG) strain-based anemometer sensors, based on the FBG sensor theory, the cross-sensitivity mechanism of the fiber grating during wind speed and temperature measurement is analyzed, and the relations between the central wavelength variation of dual Bragg gratings and that of the temperature and wind speed are derived. Two Bragg gratings with different periods are created in the same fiber for wind speed and temperature measurements. The temperature detection grating is encapsulated in a stainless-steel capillary tube single-end fixed support structure to shield the device from wind pressure, achieve a rapid thermal response, and improve the real-time performance of wind speed compensation. To further improve the wind speed temperature compensation results, modification of the surface of the temperature detection grating is proposed via an aluminium coating with a high linear thermal expansion coefficient to improve the temperature detection resolution and thus improve the compensation precision. Additionally, to improve the stability of the anemometer sensor in a wind field, a concave windward baffle structure is proposed. Flow field simulation via the ANSYS software FLUENT shows that this structure is superior to the existing plate structure. The anemometer sensor is evaluated using temperature detection and wind pressure simulation experiments, and the results are as follows: the wind speed detection range is 0 to 35 m / s, the linear sensitivity is 2.4261 × 10 − 1 pm / v2, the temperature detection range is 0°C to 50°C, and the linear sensitivity of the temperature detection grating with aluminium coating modification is increased to 33.9 pm / ° C. In the wind speed range of 0 to 25.4 m / s, the maximum error after temperature compensation is 0.39 m / s.