Authorized by Mittarfeqarfi it, the Greenland Airport Authorities, FORCE Technology has again performed an extensive investigation of terrain-induced wind shear and turbulence for an airport.

Nuuk is the main city of Greenland and may be reached by air only via the present airport for international fl ights, Kangerlusuaq. Several projects have been considered for a new or expanded Nuuk Airport for handling the Airbus A20 and similar class aircraft.

FORCE Technology has performed numerical experiments to investigate the wind conditions for the different alternatives. The overall most feasible solution appears to be an extension of the existing 800m runway to 1,800m which is required to handle the larger aircraft, and this solution was subjected to a detailed wind tunnel investigation to quantify the effect of terrain-induced wind shear and turbulence on the regularity of the airport.

Larger aircraft are far less manoeuvrable than the smaller propeller aircraft (DASH 8 and similar) presently serving Nuuk. Therefore, these large aircraft are more exposed to the terrain-induced wind shear and turbulence which is known to occur for certain wind directions. This may to some extent be avoided by the smaller aircraft by choosing a different visual approach.

Scale 1:2000

A very large terrain model covering an area of approximately 20 by 30 km2 was constructed in scale 1:2000 and installed in FORCE Technology’s wide boundary-layer wind tunnel where other similar investigations have been performed in the past. The model was exposed to wind from the known critical wind directions, and the variation of the wind speed “seen” by the landing aircraft in the approach route was measured by means of a 3D probe traversed along the approach route at the correctly scaled speed for a number of wind speeds.

By applying the generally recognized rules, the measured wind speed gradients were converted to the level of turbulent response of the aircraft, and the limiting wind speeds for the occurrence of severe turbulence were established for the different wind directions. By combining these limiting wind speeds with the wind statistics for the airport, the impact of terrain-induced turbulence on the regularity was determined.

Turbulence warning system

When the expansion of the airport is possibly decided, it may also be an option to install the FORCE Technology operative turbulence warning system. With this objective in mind, wind speed and direction measurements were performed at a number of potential sites for reference wind measurements for the turbulence warning system.