Study Of High-precision Airflow Sensor

Accurate measurement of wind speed and direction plays an important role in many aspects of social production and life.In order to meet the needs of various fields,researchers have developed a wide variety of unique airflow sensors.The traditional mechanical wind speed sensor(wind cup anemometer)is widely used in the field of meteorological monitoring,but the volume is large,and the starting wind speed is usually above 0.3 m/s,which is not conducive to low wind speed measurement.The measurement accuracy of the ultrasonic wind speed sensor can reach 0.01 m/s,but its price is relatively expensive.The thermal wind speed sensor has higher measurement sensitivity in low and medium speed airflow,but its power consumption is higher and it is susceptible to electromagnetic interference.In response to the above problems,owing to the advantages of high sensitivity,strong resistance to electromagnetic interference,simple structure and low price,this paper proposes two highprecision airflow sensors based on the optical method: wind speed sensors based on cantilever silicon waveguides and wind speed and direction sensor based on overhang tapered fiber.The two sensors proposed in this paper are mainly based on the waveguide energy coupling theory.The sensor device is used to convert the airflow velocity,airflow direction and other parameter information into the change of the output light energy.By collecting this change,the airflow velocity and direction are obtained.Using cantilever beam or overhang fiber tip as the sensing unit of airflow,these two sensors convert the airflow signal into the deformation of cantilever beam or overhang fiber tip,and use optical method to measure the deformation of cantilever beam or overhang fiber tip at the same time,avoiding the poor antiinterference ability of electrical system,and the problem of low sensitivity.Opti BPM and COMSOL Multiphysics simulation software are used to simulate the optical and mechanical properties of the sensor.Based on the simulation results,the device structure of the sensor is rationally designed to further improve the measurement accuracy of the device.In this paper,the experimental verification of the two designed airflow sensors is carried out.The experimental results show that: within the wind speed range of 0?60 mm/s,the measurement accuracy of the wind speed sensor based on the cantilever silicon waveguide can reach 0.094 mm/s.Within the wind speed range of 90 mm/s,the wind speed and direction sensor using overhang tapered fiber can achieve all-round and high-precision measurement.The measurement error of the wind speed does not exceed 1%,and the measurement error of the wind direction does not exceed ± 3°.