Measurement of an Oscillating Shock Wave in a Transonic Flow Using Two Different Pressure Sensitive Paints* (*Ru-based on anodized aluminum vs. Pt-based with screen layer)

The performance of two different PSP used at DLR and ONERA is compared by carrying out bench mark testing using the oft-studied configuration of an oscillating shock wave (up to 100 Hz) on a bump in the Mach 1.4 flow of the ONERA S8Ch wind tunnel. The shock is made to oscillate by rotating a cam with elliptical cross section, placed at a further downstream position, at frequencies of 15, 30 and 50 Hz. Both paint types are well known and much has been published on their use: the ONERA PSP is a Ruthenium complex Ru(dpp)_3Cl_2 placed as a thin layer on an anodized aluminum substrate, while the DLR PSP is a Platinum complex PtTFPP on a base coating containing TiO_2 particles. S8 run conditions were held constant, and separate test run series were carried out with each paint. Instationary calibration was also carried out using a special test rig. Fourier analyses of the PSP results in S8 enabled a semi-quantitative comparison of the time response of both paints. This is the first published attempt (to the authors’ knowledge) of carrying out a side-by-side comparison of the characteristics of these two paints on such a flow configuration in a wind tunnel. Particular emphasis is placed on their handling properties and, above all, their time responses.