ACCs & Crosswinds

The Effect of Crosswinds on an Unprotected ACC

If an ACC is subject to crosswinds and steps are not taken to protect the installation from those winds the result can be loss of MW output, increases in mechanical stress on the fans and overall performance loss.

As crosswinds hit the side of the ACC they are deflected and cause a jet stream beneath the fans. Strong winds can cause severe air disturbance, changes in static pressure, an increase in back pressure (vacuum) and significant reduction in fan airflow.

The impact on the fans
  • High wind load on the fan blades
  • Changes in fan static pressure
  • Disturbed airflow through the fans
  • Mechanical stresses
  • Fan and motor damage
The impact on the ACC
  • Wind shear
  • Increases in back pressure
  • Increased fouling
  • Drop in vacuum performance
  • Decline in power output

How Crosswinds Affect ACC Performance

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How Galebreaker Windscreens Reduce Back Pressure (vacuum) beneath the fans

Back pressure with screens


Correct specification of the Windscreen system is essential if the maximum performance of ACC and fan equipment is to be achieved.

Our experience in delivering numerous successful systems in often challenging environments combined with valuable monitoring and feedback from plant managers puts Galebreaker in the valuable position of being experts in this field.

Screen Positioning

The flexibility of the Galebreaker system allows the Windscreens to be positioned to gain the best performance. Perimeter, cruciform or one-bay-in configurations can be adopted either individually or in combination.

Fixed or Retractable

Systems can be fixed or retractable to maximise performance.

Fabric Selection

Windscreen fabrics can be specified in a range of solidities.

Following CFD modelling and a site survey our experienced team can specify the best possible Windscreen installation for each individual ACC.

The Galebreaker Solutions

To mitigate the effect of crosswinds on the ACC Galebreaker offer two basic types of Windscreens; fixed and retractable. Fixed Windscreens can be positioned around the perimeter of the ACC and/or beneath the ACC in a cross or ‘cruciform’ configuration. Each uses high quality mesh material (solidity dependant upon specific application). The screens are positioned and fixed so that they slow the passage of air beneath the fans during windy conditions. This allows the fan systems to work efficiently which in turn improves the overall performance of the ACC.

Fixed Windscreen Systems

Afton Fixed System

Above: A 225MW ACC at Afton, USA fitted with a Galebreaker fixed Perimeter Windscreen system.
Below: A 360MW ACC at Kings Lynn, UK fitted with both Cruciform and Perimeter fixed Windscreen systems.
The mesh fabric panels are fixed to the steel uprights and tensioned with high quality ratchet clamps.

Kings Lynn Cruciform

Retractable Windscreen System

Rolling System

Above: A 350MW ACC at Caithness, Long Island, USA fitted with a Galebreaker Windscreen retractable system.