Property editor of the NZ Herald

Auckland University thinks big with wind tunnel testing

Huge wind tunnels and strong wall aid research on engineering campus.

How should cyclists best bend to reduce drag and how do new concrete or timber shear walls respond to severe earthquakes?

The answers are being revealed at Auckland University's Newmarket engineering campus, where two huge wind tunnels and Australasia's biggest strong wall are being used in experiments, research and tests.

Professor Richard Flay from the department of mechanical engineering and a specialist in the effects of wind and Professor Pierre Quenneville from the department of civil and environmental engineering revealed the gigantic testing equipment, now housed in two separate ex-Lion Breweries' warehouses.

The university buildings off Khyber Pass Rd have now been refitted for post-graduate studies and sophisticated research, as well as put to commercial use to generate income.

A 25m long twisted flow wind tunnel with two 45kW fans was built in 1994 to do tests for New Zealand's successful America's Cup campaign.

It was originally at two Tamaki sites before the university bought about 5ha of Newmarket, where it is now situated. Tunnel walls in the wooden structure can be contracted to give higher speed air flows.

A second, newer closed-circuit duct wind tunnel was built in-house and Flay said it was completed last year. That tunnel's two 90kW fans came from consultants supplying glass to the new eastern glazed wall at the Britomart Transport Terminal.

Testing was done at the university to examine whether rain would enter the terminal via the two-level bank of louvres above the station, Flay said.

Inside that steel tunnel is a 1:400 scale model of Auckland CBD buildings. That allows for testing of the effects of new towers on pedestrians, the streetscape and area. Flay had that built of galvanised steel.

Bran flakes - like those used in breakfast cereals - are placed in certain areas of the city model where measurements are being taken.

"These are the only two wind tunnels in Auckland. We are international standard and nowhere else in New Zealand has anything like this capability," Flay said of the structures where two full-time staff are employed - wind tunnel engineer Yin Fai Li, who has international specialist wind-tunnel testing and research experience, and assistant Ben Goodwin.

"The duct model is used to investigate pedestrian-level wind environment for resource consents. We measure the flow and write a report to say whether this complies with the District Plan," Flay said of one of its uses.

"We also measure wind pressures on models to help architects select glazing. Furthermore, we can measure forces on buildings to help structural engineers."

A model of New Zealand's most expensive office block - Shortland St's Vero Centre - is in the test lab. Research was conducted into wind loadings on its unusual roof detail, sometimes referred to as a halo but also as a toilet seat.

The tunnels are also used to test the effects of wind on yachts, cyclists, high-performance bikes and historical sailing vessels used in Pacific voyages to assist university anthropologists.

Flay said New Zealand's Olympic cycle team had used the duct tunnel leading up to Rio.

The university collaborated with the French Naval Academy, Edinburgh University and Newcastle University, he said.

A few buildings away, teams of engineers are working at the impressive three-level strong wall and a huge strong floor in the test hall. Testing of large-scale structural components and assemblies is done in this area.

The four-storey, concrete-and-steel structure is home to the largest seismic testing facility in Australasia. The strong wall can simulate earthquake forces by applying both static and dynamic loading.

Quenneville said one giant piston in the hall could lift the equivalent of 100 cars, while another could lift 180 cars.

Facilities included a 20m by 10m strong floor, the 9m by 10m strong wall, a 20-tonne overhead gantry crane and a 4.5m by 4.5m 20kN capacity single-axis earthquake shake table.

Quenneville said components were bolted on to that strong wall to test many effects, including loadings and strength.

"This serves as a tester for concrete, steel and timber to recommend design for engineers. It's a world-class facility and was commissioned early last year," Quenneville said.

Data from experiments conducted there is captured on specialised instrumentation capable of measuring displacements, accelerations, strains, temperature and other variables.

All information is then electronically logged on computers for real-time display of test results.

Quenneville said the test hall and its equipment was unique in New Zealand and the facilities were a huge step forward from the original university premises on the city campus site where post-graduate engineers were previously based.

Scarbro Construction built the new strong wall using Firth materials and creating a two-cell, four-cell and 1m-thick structure.

Top gear

• Large-scale Auckland engineering testing equipment:
• Wooden wind tunnel 25m long x 7m wide x 3.5m high.
• Galvanised steel/timber wind tunnel, 20m long x 3.6m high x 2.5m wide test section.
• Strong wall 9m high x 10m wide.
• Strong floor 20m x 10m.

[Source: University of Auckland]

- NZ Herald

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