Seminar: Seeing Turbulence with Sound, 8th December, 1pm

When: Thursday 8th of December, 1pm AEDT

Where: This seminar will be partially presented at the Rose Street Seminar area (J04) and partially online via Zoom, RSVP here.

Speaker: Graham Brooker and Samantha Gordon

Title: Seeing Turbulence with Sound

Abstract: Imagine a small non-contact sensor that can probe the air in front of a flying aircraft and “see” clear air turbulence. Impossible, you say!

The Sensor: Our Radar Acoustic Sounding System (RASS) sends out a narrow diameter ultrasound pulse and tracks its propagation through the air using a Bragg matched Doppler radar in the usual fashion.
Gross disturbances to the Doppler spectrogram are indicative of laminar air flow across the beam and we think micro-Doppler signatures would be indicative of turbulence.

Figure 1: The Doppler spectrum and spectrogram in still air

But how can we see the air turbulence to confirm this hypothesis? We use a novel form of Schlieren Imaging in combination with the RASS to see disturbances to the ultrasound pulse caused by turbulence.

Figure 2: Schematic showing the combined RASS and Schlieren Imager

Preliminary Results: Air disturbance produced by a vortex generating fan is clearly shown in one of these acoustic modulated Schlieren images, and there may be indications of its presence in the RASS time domain and spectral signatures.

Figure 3: preliminary results showing both Schlieren and RASS with and without turbulence

Come to our talk to find out more.


Samantha is a final year student at the University of Sydney studying a B. Engineering (Mechatronics) and a B. Science (Physics). She recently completed her engineering honours thesis with Dr Graham Brooker where they constructed a system capable of simultaneously detecting turbulence with a radio acoustic sounding system (RASS) and Schlieren imaging system. Samantha’s other research involves working with CSIRO to characterise radio frequency interference at Murriyang, the Parkes radio telescope.

Graham spent 20 years building radars for industry and defence projects in South Africa before being invited to join the ACFR by Hugh in 1999. For the first decade or so, he worked on radar mostly for mining applications while simultaneously developing and teaching a number of courses and writing up a PhD based on the radar work he did in South Africa. He has since published quite a lot, including two textbooks, one of which has just been revised as a 2nd edition. After a decade of focusing primarily on biomedical R&D, mostly related to childbirth, sensory substitution and balance disorders, his focus is again turning to radar, where a new generation of radar-on-a-chip sensors is revolutionising the field.


Australian Centre for Robotics