Blown Lift - Cal Poly`s AMELIA STOL-liner
Baku, March 28 (AZERTAC). One of the unconventional aircraft configurations NASA is researching is a cruise-efficient short take-off and landing (CESTOL) airliner that would be able to make steep approaches to and departures from short, underused runways, increasing airport capacity while keeping more of the noise within the boundary fence.
CESTOL is a powered-lift configuration, with a circulation-control wing that uses leading- and trailing-edge blowing to increase lift for take-off and landing. Most STOL aircraft are slow, but CESTOL is intended to cruise at jet speeds by also using wing blowing to reduce drag.
Not much experimental data exists to help design a circulation-control aircraft, so California Polytechnic State University San Louis Obispo built a large windtunnel model for NASA to collect both aerodynamic and acoustic data with which to validate the computational tools.
Preliminary results from the tests were presented in Cleveland last week, at NASA`s Fundamental Aeronautics program annual meeting, by Cal Poly assistant professor Tina Jameson (aerodynamics) and NASA Ames engineer Clif Horne (acoustics).
First of all, the idea of circulation control is to use blowing from thin slots in the leading and trailing edges to increase the velocity of air flowing over the wing and keep the airflow attached, increasing lift and allowing slower, steeper approaches and departures.
AMELIA is equipped with a pair of turbine propulsion simulators mounted over the wing so that their jet noise is shielded from the ground, and so that their jet exhaust blowing over the flaps helps increase lift at low speed. The model was tested with a clean wing, with and without blowing, and with the engine simulators mounted on low and high pylons.
The model is instrumented to measure aerodynamic forces and moments, wing surface pressure and skin friction, and flow visualization. The sequence of smoke-wand photos below shows air flowing over the wing at 30kt as blowing is increased - Cµ is the momentum coefficient. The higher the blowing, the greater the angle through which the airflow is turned.
Overall, says Jameson, the AMELIA windtunnel tests show leading-edge blowing is critical to the performance of a circulation-control wing. On the acoustic side, Horne says the tests show the noise and aerodynamic trends are consistent for a circulation-control wing. The acronym AMELIA was chosen to commemorate Amelia Erhart`s stop-over at the Cal Poly Aeronautical Engineering Department campus in 1935 for structural repairs to her aircraft.
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