Fast-Responding Cryogenic Pressure-Sensitive Paint with Porous PTMSP-Based Binder

Abstract

Fast-responding pressure-sensitive paint (PSP) is required for measuring unsteady surface pressure in cryogenic wind tunnels. However, the temporal response of conventional cryogenic PSP (cryoPSP) is limited by oxygen diffusion in the polymer binder. This study presents a fast-responding cryoPSP based on a porous poly[1-(trimethylsilyl)-1-propyne] (PTMSP) binder containing hydrophobically treated colloidal silica nanoparticles. The affinity between the trimethylsilyl-modified silica particles and PTMSP enables the formation of a porous coating with improved adhesion to model surfaces, even at high particle loadings. The response under cryogenic conditions was estimated using a model that accounts for oxygen diffusion in the binder and the luminescence lifetime of Pt(II) meso-tetra(pentafluorophenyl)porphine. For a formulation containing 400 nm colloidal silica particles at 95 wt%, the model-estimated cutoff frequency was 2833 Hz at 150 K and an oxygen partial pressure of 100 Pa. A sensitivity analysis showed that the cutoff frequency remained above 1 kHz even when the diffusion time constant was increased by a factor of 2.8. Pressure and temperature sensitivities remained stable for up to 119 h after coating. These results suggest that the proposed porous cryoPSP extends the measurable frequency range for unsteady pressure measurements in cryogenic wind tunnels, although direct response-time validation under cryogenic conditions remains necessary.

The authors' abstract, as published at the source. AIAA Journal, 2026 · DOI ↗