Can flying transducers be used to map the turbulence field behind wind tubines? This feasibility study shows the instrumentation pod
attached to the tethered balloon.
And what does it measure?
- 3D Windspeed, sonic temperature, and speed of sound (sampled 20 times per second) using ultrasonic Doppler shift technology
- 4-channel pitot tube air flow measurements (1000 samples/second)
- Temperature and Atmospheric presssure (sampled 2 times per second)
- Differential dual-frequency GPS data sampled at 20 times per second
- Triaxial digital gyroscope (1000 samples/s)
- Triaxial digital accelerometer (1000 samples/s)
- Triaxial digital magnetometer. (1000 samples/s)
All data (most with 24-bit resolution) is precision time-stamped with 100 ns accuracy referenced to international atom clocks used in GPS systems. This makes it possible for multiple sensors to have perfectly time-aligned data, essential for mapping of turbulence fields, and for any experiment that is used to validate CFD or FEM models.
A ground based reference receiver (yes, it is a prototype!) logs ground based data in parallel, making precision (1 cm accuracy) differential position determination of the Aerial Sensor possible
This feasibility study sponsored by energinet.dk points the way to future projects where smaller, less expensive devices are deployed to measure at multiple points simultaneously.
Mother Nature celebrated the maiden flight of the Aerial Sensor by demonstrating hundreds of autonomous, self powered, self-reproducing units flying in precision synchronization, somethings that helps keep us engineers humble.