IN-FLIGHT LASER ANEMOMETRY FOR AERODYNAMIC INVESTIGATIONS ON AN AIRCRAFT

A differential laser Doppler anemometer (LDA) of NLR and a laser-two-f ocus (L2F) anemometer of DLR were selected to be installed in a resear ch aircraft to demonstrate their capabilities for in-flight flow inves tigations. A ground test with the anemometers was performed before the Fight tests. Experience with parallel operation of the anemometers wa s gained in a free jet and properties of both systems were investigate d. During the flight rests the aircraft was flown in different atmosph eric conditions to investigate whether the atmospheric seeding conditi ons ave sufficient for measurements. Measurement volumes were traverse d through the flow perpendicular to the fuselage. In this manner, the anemometers measured mean velocities, turbulence levels and the flow d irection. The experiment showed that laser anemometry can be applied s uccessfully for in-flight flow measurements. (C) 1997 Elsevier Science Ltd.