Pressure Sensitive Paint

Pressure distribution on the upper surface of maneuverable aircraft win

The method of Pressure Sensitive Paint (PSP) is based on attenuating the organic luminophores luminescence by air oxygen.This method is the only one that provides non-contact measuring the pressure distribution on the model surface under tests. To implement this technique the model surface is coated with a special paint that is a thin polymer layer that is permeable for oxygen and contains luminophor molecules. The luminophor is excited by appropriate wavelength light and digital cameras measure the luminescence intensity, which is reversely proportional to the pressure.

Digital technologies allow obtaining the pressure fields referred to the geometry of the studied model and the determination of loads and moments affecting some of aircraft structure components by the pressure forces vector integration. The accuracy of the obtained integral characteristics sometimes exceeds the accuracy of integrating the drainage measurement of pressure distribution, especially for complex 3D flows.

Key Features

Pressure Sensitive Paint is a sensor for absolute pressure measuring. Therefore it is difficult to use this method in subsonic flows where the pressure variation is low in respect to the absolute pressure. The coating thickness is 2…20 μm.
The wind tunnel conditions affect the pressure measuring accuracy. Even the insignificant condensation of water or nitrogen in the flow or the model surface contamination during the wind tunnel test can reduce the accuracy of pressure measurement significantly.
The pressure measurement accuracy of 5% can be provided in wind tunnels of TsAGI.

Application

Transonic, supersonic and hypersonic flows (M > 0.3). Temperature limit for the model surface is 100 °C.
Steady and unsteady flows (with frequency up to 100 Hz) flows.
Moving and rotating models.