Image Measurements of Surface Pressure Distribution on a Model in a Unsteady Flow Using an Anodized Aluminum Pressure-Sensitive Coating

Quantitative measurement of unsteady surface pressure distribution on a wind tunnel model was conducted using a fast responding pressure-sensitive luminescent coating on porous anodized aluminum. The pressure sensitive dye was tris (4, 7-diphenylphenanthroline) ruthenium (II) ([Ru (dpp) 3] 2+). The coating has a short response time of O (10 μs), although it exhibits temperature and humid sensitivities. An effective data acquisition procedure as well as digital image processing algorithm was established to compensate the error from the temperature and humid senilities. A temperature sensitive paint was used to obtain the temperature distribution instantaneously with the pressure. The temperature data was used to correct the pressure-sensitive coating. The error from the humid sensitivity was eliminated with using two reference data acquired at dried and wet conditions. The present system was applied to measure the buffet phenomena on a delta wing at a high angle of attack in transonic flow, whose flow is unsteady due to the interaction between shock waves and leading edge vortices. The non-periodic unsteady pressure distribution on the delta wing was successfully measured with the sampling rate of 1 kHz and within a few percent error in absolute pressure level.