Typical Specifications

A generic specification text is provided below.

Jet fans with shaped silencers, whose discharge flow is directed away from surrounding tunnel surfaces, in order to reduce the Coanda effect and to limit the thrust lost due to friction on tunnel surfaces. The direction of the discharged jet shall be capable of setting to an optimal value, by fixing the rotation angle of the silencer about the centreline of the jet fan, within the constraints of the bolt hole pitch on the silencer flanges.

For space-proofing and aerodynamic reasons, both the lower and upper edges of the jet fan silencers shall be straight, and parallel to the fan axis. The intake of the efficient jetfan shall be directed away from the tunnel surfaces, in order to reduce the choking effect at the inlet.

In comparison with an equivalent conventional jet fan with the same diameter, blade pitch angle and motor speed, the jet fan with shaped silencers shall:

1. 1. Not require any additional power consumption, within the measurement uncertainties defined in BS EN ISO 13350:2015
2. 2. Deliver the same or greater bench thrust, within the measurement uncertainties defined in BS EN ISO 13350:2015
3. 3. Not generate a higher sound power level, within the measurement uncertainties defined in BS EN ISO 13350:2015 or BS EN ISO 3744:2010

No parts shall be installed upstream or downstream of the silencers which may vibrate or flutter, in order to avoid issues with metal fatigue.