DEFINITION:

In air intakes the kinetic energy is partially transformed into pressure. The distortion of the flow in front of the engine is due to the non uniformity of the flow in front of the lips, the shape of the diffusor, the development of boundary layer on the walls and sometimes the shock-boundary layer interaction. This distortion has to be reduced to keep a good efficiency of the turbojet. The mass flow needed by the engine has to be provided by the air intake for the overall flight envelope. Thus additional inlets or variable geometry are used for supersonic aircraft and fighter. For supersonic vehicles (aircraft and missile) external flow compression induces a penalty for the cowl drag, so mixed compression air intakes are interesting for high cruise Mach numbers. However in this case, some small perturbations can cause the buzz phenomenon by dynamic effect of the shock displacement near the throat. Some devices have to be developed to prevent this risk (internal diverter, porous wall,…). For turboprops, air intakes are located behind the propeller or under the rotor and these strong interactions have to be taken in account in air intake design. At the take-off the presence of the propeller reduce locally the leading edge slat efficiency. The rotative movement of the airflow issued from the propeller is at the origin of a rolling moment to be controlled. The design of air intake and its installation on the vehicle have to respect some constraints like noise reduction and minimisation of radar signature. Others problems are the icing of the lips and the ingestion of sand, dust or birds.

(Source: ACARE Domain 304)

SUBDOMAINS:

1. Computational Fluid Dynamics
2. Intakes
3. Propeller, propfans, turbojets, turbofan
4. Wind Tunnel Testing
5. Noise reduction
6. Radar signature
7. Buzz
8. Icing
9. Ingestion