Aerodynamics of Helicopters Experimental Activities
Many models are used for carrying out the experimental studies of helicopters in ONERA's different wind tunnels.
By preference, the different rotor geometries are tested at large scale (rotor diameter = 4.20m) in the S1MA wind tunnel in Modane up to high speed flight conditions. Generally, the blades are heavily equipped with unsteady pressure sensors.
Complete models of helicopters are used in the F1 wind tunnel in Le Fauga to study aerodynamic interactions. The measurements taken include the steady and unsteady pressures and an exploration of the wake by PIV.
The studies concerning the dynamic separation of profiles are carried out in the F2 wind tunnel in Le Fauga, which is equipped with a glass wall that allows great optical accessibility. The 3 component laser velocimeter installed in the wind tunnel and a PIV system are used for extensive exploration of the velocity field and the turbulence. Measurements of the steady and unsteady pressures and friction (by hot wires and hot films) are also taken.
H2T has participated, with DSNA, (in collaboration with the US Army, Nasa, the DLR and the DNW) in the Hart and HartII test campaigns, which provided a very well documented database, particularly in 3 component PIV data, and a better understanding of the blade-vortex interaction phenomenon, responsible for the BVI noise.
PIV Picture from the HART II project:
temporal average of the vorticity
PIV Picture from the HART II project:
centered average of the vorticity,
calculated starting from the rotational component speed
PIV Picture from the HART II project:
velocity distribution across the vortex center along the trajectory y/R=0.7, advancing blade
In-flight tests have also been carried out on the Dauphin 6075 of the In-Flight Test Center, with the DCSD department as prime contractor. Their objective is the acquisition of data about the complete machine (rotor downwash on the ground, tail rotor noise) in order to validate the calculation methods.
In Salon-de-Provence,
a "comb" makes it possible
to define the profile speed
generated by the rotor downwash.
