Investigation of Factors Causing Nonuniformity in Luminescence Lifetime of Fast-Responding Pressure-Sensitive Paints

Abstract

Factors that cause nonuniformity in the luminescence lifetime of pressure-sensitive paints (PSPs) were investigated. The lifetime imaging method of PSP does not theoretically require wind-off reference images. Therefore, it can improve measurement accuracy because it can eliminate errors caused by the deformation or movement of the model during the measurement. However, it is reported that the luminescence lifetime of PSP is not uniform on the model, even under uniform conditions of pressure and temperature. Therefore, reference images are used to compensate for the nonuniformity of the luminescence lifetime, which significantly diminishes the advantages of the lifetime imaging method. In particular, fast-responding PSPs show considerable variation in luminescence lifetime compared to conventional polymer-based PSPs. Therefore, this study investigated and discussed the factors causing the nonuniformity of the luminescence lifetime, such as the luminophore solvent, luminophore concentrations, binder thickness, and spraying conditions. The results obtained suggest that the nonuniformity of the luminophore distribution in the binder caused by the various factors mentioned above during the coating process is closely related to the nonuniformity of the luminescence lifetime. For example, when the thickness of the binder became thinner than 8 μm, the fast-responding PSPs showed a tendency to vary significantly in the luminescence lifetime. In addition, it was found that the luminescence lifetime of fast-responding PSP could be changed in the depth direction of the binder depending on the coating conditions. Therefore, it is important to distribute the luminophore uniformly in the binder layer to create PSPs with a more uniform luminescence lifetime distribution.

Indexes for evaluation of dynamic characteristics of pressure-sensitive paint based on pressure sensitivity and frequency response

“…Table 1 describes the prepared PC-PSP samples based on the previous literature [42]. The following polymers, poly(isobutyl methacrylate) (poly(IBM)) [45,46] (Sigma Aldrich, USA), and RTV silicone [21] (Shin-Etsu Chemical, Japan), poly(TMSP) (Gelest, inc., USA) [42] were employed as the polymer for a binder. Hydrophobic TiO 2 particles with a diameter d of 15 nm and hydrophilic TiO 2 particles with d = 35 nm (Tayca Corporation, Japan) were used as particles.…”

The Art of Fluorescence Imaging with Chemical Sensors: The Next Decade 2012–2022

“…PC-PSP is a sprayable form of an unsteady (time-resolved) PSP that can be applied on an aerodynamic model before testing. It consists of a polymer/ceramic basecoat (SiO 2 , TiO 2 ), which is first applied on the model as a thin layer and subsequently used to host the luminophore molecules [159][160][161][162][163][164][165][166][167][168][169][170]. Since PC-PSPs usually consist of TiO 2 particles which show photocatalytic activity, the luminescent intensity will decrease over time.…”