The ejector system from the Free Stream Rig can be adapted for testing novel anti-icing systems and nacelle structures in flight conditions.

The twin ejector system can be attached to an annular settling chamber, which has a semispherical plug at the exhaust with a slightly smaller diameter than the chamber. The plug utilises the Coanda effect to accelerate and turn the flow into an axial exit. The flow therefore leaves in a "doughnut" shape and this can be sized to match the leading edge of an engine nacelle.

The technique was demonstrated using a Trent 700 nacelle in 2015 and hence the total diameter of the free stream was almost 3m. The compressor flow from two Gnome turboshaft rigs provided a flight stream of Mach 0.1 across the surface of the lipskin. The rig was developed as part of the SANTANA project, led by Bombardier Aerospace and co-funded by Innovate UK. In this instance the nacelle was equipped with novel anti-icing systems which were evaluated for efficiency in simulated flight conditions. Click here for full details of the work.

Now the test concept has been proven, it is hoped that the experimental capability will be exploited for a wider range of future novel nacelle systems. The plenum and Coanda plug could be resized for different nacelles, and a smaller diameter would result in higher Mach numbers.