On the day I telephoned Mr. Jesper Nielsen, a coastal and riverine engineer and a PhD candidate at the University of Queensland, he was standing on the muddy bank of a river in south east Queensland. ` I am looking at the tower right now’.
The fully fledged turbulence tower stood securely on the floor of the river bed, the tip of its fifteen metre mast poking just above the fast flowing river’s surface. The mast supports a three metre horizontal arm. This arm, fitted with sensors, travels up and down the mast measuring the variety of currents, eddies and turbulence, at different depths, just as it was designed to do.
Earlier in the design process, Mr Nielsen determined the mast required the assistance of aerodynamic foils attached to the mast so the tower did not fall foul (fall over) of the same currents and turbulence it was trying to measure. The foils needed to move in synchronicity with the currents and counter-intuitively with the mast they are attached to.
Also the horizontal arm, armed with sensors, needed free passage up and down the mast throughout the water column. The problem: how to attach the foils within these requirements?
“Magnets were the only solution”, he stated with deadpan authority.
Initially Mr Nielsen had dismissed magnets, concerned they would not be powerful enough and probably too expensive. Other fixing systems were examined, then discarded. He returned to magnets and tested his misgivings by googling, Magnets, Australia.
In an email to AMF Magnets soon after, Mr Nielsen wrote, ‘….thank you for your service…AMF have easily been the most efficient supplier I have worked with on this project…’, before asking, wait for it, before asking for a magnetic recommendation to his turbulence tower foil fixing issue. (Phew!)
Contrary to his initial concerns about magnets, Mr Nielsen’s thesis abstract for his turbulence tower to the university’s PhD selection committee stated in section 2.3, ` …rare earth magnets are both powerful and affordable and provide the means to attach the foils to the mast whilst permitting the horizontal arm to pass during profiling’ (measuring turbulence).