Super-hydrophobic porous pressure-sensitive paint for global unsteady flow measurements

Super-hydrophobic porous pressure-sensitive paint (hydrophobic PSP) is developed based on polytetrafluorethylene (PTFE) particle and platinum (II) meso-tetra(pentafluorophenyl) porphine. The former functions as the water repellent surface, and the latter gives luminescent output related to the pressures. From the luminescent image, global pressure measurements can be achieved in aerodynamic applications. The developed PSP is resistant to the change in the humidity of the test gas, which is one of the major issues for a PSP application in a practical use. The developed PSP shows contact angle more than 150° by the PTFE particle and a porous structure, which describes that the PSP surface is super-hydrophobic. It can be sprayed onto a testing object to open its applications for aerodynamic measurements. The change in the luminescent intensity by the relative humidity of 80% is 6%, and the change by the relative humidity of 60% is only 2% above the pressure at 40 kPa. The pressure sensitivity as well as the response time is independent of the humidity.