Visualization of Flow Field over Rotating Blades using Pressure Sensitive Foil Technique

A new pressure measurement technique for measuring the pressure over rotating blades of industrial axial flow fan is described in this paper. The new technique is called pressure sensitive foil (PS-Foil) technique. In this technique a very thin aluminum foil is coated with pressure sensitive paint using anodization method. The resulting PS-Foil can be stick over any existing blade using a very thin layer of silicon. The PS-Foil technique shows very fast time response as conventional porous anodized aluminum and can be applied to any existing rotor blade without the need to fabricate the blade from aluminum. The total thickness of the aluminum foil and silicon layer is as small as 200 µm. Intensity based method and prior calibration procedures are used to obtain the calibrated PSP image. The unsteady experimental setup presented in this paper showed that the PS-Foil time response is of the order 30 µ seconds which is very close to the conventional porous anodized aluminum. Two applications are considered in this paper to assess the applicability of this technique, which are subsonic jet-plate impingement and rotating blade of industrial fan. The pressure distribution over the impingement plate at different plate angles and over the rotating blade at varies rotating speeds could be obtained with sufficient spatial resolution. Nomenclatur