Abstract

Due to the long service life of modern aeroplanes, operators often want to modify the basic airframe in order that it can undertake different tasks.

In many cases these tasks require the addition of new avionic capabilities, such as RADAR , mounted on the outside of the original airframe in “blister” structures. The shapes of these structures are normally restricted by their contents, rather than by their aerodynamic considerations. Therefore, investigations have to be undertaken to identify any potential unstable flow phenomena that could cause unwanted effects to the performance or handling of the aeroplane.

This presentation details such an investigation where blister fairings will be added to an existing aircraft in order to extend its operational capabilities. By using the results from specific wind tunnel experiments in the Cambridge University Engineering Department (CUED), critical flow characteristics identified through computational fluid dynamics (CFD) from the sponsoring company, could be corroborated.