Pressure Sensitive Paint in Aeroelastic Experiments

The pressure sensitive paint technique (PSP) is an optical measurement technique for the determination of surface pressure distributions on objects. It is based on the photochemical excitation of dye molecules that are embedded in a oxygen-permeable paint, which is applied to the object’s surface. The fluorescent molecules are excited by light of a particular wave-length, whereas the surface light emission is typically found in a different spectral range. The emission intensity is hereby dependent of the partial oxygen pressure and temperature. Given a known temperature distribution (e.g. by infrared thermography) and a corresponding calibration, the surface pressure can be determined.

Despite the high technical complexity and multiple influencing parameters, the technique has been reliably established as a tool for visualization of complex three-dimensional pressure fields.

In the frame of the EU-funded project HOMER (Horizon 2020, No. 769237) the aeroelastic interaction of transonic buffeting was investigated in wind-tunnel experiments. The object of interest, a two-dimensional supercritical wing, executes hereby strong pitching motions, while it is in interaction with strong oscillating compression shock wave on the wing suction side.

Of particular interest during the experiments were the span-wise distribution of the shock front and its additional interaction with the wall boundary layer. Furthermore, the pressure distribution on the wing surface represents the actual aerodynamic force, which, in addition to elastic and inertial forces, determines the wing motion. For this reason, PSP measurements were conducted on the oscillating wing with particular attention to the mitigation of disturbing effects as: motion blur, motion-based correction of excitation light, Signal-to-noise maximization, and excitation alteration by high density gradients.

Person in charge:

  • Tim Korthäuer, M.Sc.
  • Alessandro Accorinti, M.Sc.