Abstract

We present the development and capabilities of unsteady pressure-sensitive paint (PSP) technique for the investigation of transonic buffeting. PSP provides an optical measurement technique based on oxygen quenching of luminescence. The intensity or lifetime of light emitted by the PSP layer depends on oxygen partial pressure; thus, acquired luminescence images provide a way to calculate air pressure. In recent years, fast-response PSP with a highly diffusive porous binder is employed to measure time-resolved pressure distributions. However, there are several issues on existing fast-response PSPs, such as applicability, sensitivity characteristics, and surface roughness. In order to solve these issues, we have developed a sprayable polymer/ceramic PSP (PC-PSP) with reduced surface roughness, which has an arithmetic surface roughness of 0.5 microns and a frequency response of 3 kHz. The PC-PSP was applied to transonic wind tunnel tests, and transonic buffeting phenomena on a three-dimensional swept wing were analysed in detail.