**Author details**

### N. A. Ahmed

**8. Safety net design**

450

**9. Conclusion**

is exercised in the aerodynamic design of the safety net.

44 Wind Tunnel Designs and Their Diverse Engineering Applications

in this case was relatively coarse, interlocked and 'cylcone' wire mesh.

other end is supported on an energy absorbing spring support.

and screen configurations have received special attention.

ranges of 0-25 ft/sec, 0-100 ft/sec and 0 -200 ft /sec.

control problems in this application.

**Acknowledgements**

For safe operation, a wind tunnel fan must have a suitable safety net located immediately upstream of it to prevent models, or tools, passing through the fan blades. The location of the fan in the University of new South Wales tunnel requires that the safety net be located in the relatively high speed portion of the tunnel circuit. This in turn, requires that considerable care

It is not unusual to find the safety net located before the first cascade corner even in tunnels with conventional fan layout. It is also known that such safety nets can result in considerable tunnel power expenditure. It was found during experiments on the pressure losses in the ARL 9 ft x 7 ft tunnel that the safety screen which was located before the first corner, contributed 28 % to the total losses. This was the largest of any component. However, the safety net used

The University of New South Wales tunnel safety screen is conical in shape and inclined at

A general purpose return circuit low speed wind tunnel has been designed for the Aerody‐ namics Laboratory of the University of New South Wales. A contraction ratio of 7:1 and four turbulence reduction screens are used. Low turbulence level is achieved with the assistance of some innovative design features. The fan is located upstream of the first corner. Corner cascade

Other unusual aspects of the design are three sizes of interchangeable test sections in the speed

The fan is driven by a hydraulic motor which considerably simplifies power transmission and

The Author wishes to gratefully acknowledge the hard works and dedication of Barry Motson

and the late Associate Professor Archer in the Design of this Wind Tunnel

 to the free stream direction in order to reduce the velocity component normal to the screen. This configuration also ensures that any object stopped by the screen will be forced to the outside against the tunnel walls. The screen is constructed specially from fine gauge stainless steel wire so as to ensure a low pressure loss. One end of the screen is rigidly held whilst the

School Of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW, Australia
