An optical-chemical sensor using pyrene-sulfonic acid for unsteady surface pressure measurements

Abstract

Optical measurement techniques are being employed more frequently in unsteady aerodynamic testing. One of these techniques is unsteady pressure-sensitive paint (PSP), used to capture global surface pressure measurements at sampling rates on the order of kilohertz or faster. Polymer ceramic PSP (PC-PSP) is often used for these applications due to its porous structure and increased oxygen diffusivity. A limiting drawback of current luminescent markers used in unsteady PSP is that they have non-negligible temperature dependency, which is a major source of measurement uncertainty. Chemical sensor development is needed to create a sensor with reduced or negligible temperature dependency. This study investigates the development and characterization of a PC-PSP with reduced temperature dependency due to the use of pyrene sulfonic acid as the luminophore, a novel application for this luminescent marker. This study examines the influence of particles and the solvent used to apply the luminescent chemical and particles onto a model in the dipping deposition method on sensor performance. The chemical interaction between these sensor elements, as well as the luminophore and binder material, largely determines the performance of the sensor. Static calibrations were performed from 10 to 120 kPa and 20–80 °C, with a resulting peak pressure sensitivity of 0.4 %/kPa and minimum temperature dependency of 0.3 %/°C using silica gel porous particles. This resulted in an uncertainty in pressure due to change in temperature of 0.75 kPa/°C, an almost 40 % reduction compared to the closest comparison sensor. Dynamic characterization also showed response times on the order of 40-80 μs, which compares well with current PC-PSP sensors.