Two Capacitive Micro-Machined Ultrasonic Transducers for Wind Speed Measurement

Area of Science:

• Sensor Technology
• Acoustics
• Fluid Dynamics

Background:

• Conventional ultrasonic anemometers face limitations in size, weight, cost, and power consumption.
• Capacitive micro-machined ultrasonic transducers (CMUTs) offer potential for miniaturized sensor applications.

Purpose of the Study:

• To develop and evaluate novel CMUT designs for accurate wind speed measurement.
• To compare the performance of amplitude-based versus time-of-flight (TOF) measurement methods using CMUTs.
• To reduce the size, weight, cost, and power consumption of ultrasonic anemometers.

Main Methods:

• Two distinct CMUT designs with double array elements were developed.
• CMUTs were configured perpendicular to wind flow with a reflector.
• Wind speed was measured using both signal amplitude and time-of-flight (TOF) in five operation modes.
• Experimental validation was conducted for wind speeds ranging from 1 m/s to 10 m/s.

Main Results:

• CMUT designs utilizing the time-of-flight (TOF) method demonstrated superior performance compared to amplitude-based methods.
• The TOF method achieved a measurement error of less than 0.2 m/s for wind speeds between 1 m/s and 10 m/s.
• The sensitivity of the TOF method was found to be independent of the five tested operation modes.

Conclusions:

• CMUT-based ultrasonic anemometry, particularly using the TOF method, is a viable and accurate alternative to conventional systems.
• The developed CMUT designs offer a pathway to smaller, lighter, and more power-efficient wind speed measurement devices.
• The TOF measurement principle provides robust and consistent performance across different operational configurations.