New Pressure Sensitive Paints (PSPs) for mapping pressure distributions on surfaces of building models under turbulent flow conditions in a wind tunnel

Abstract

A new Pressure Sensitive Paint (PSP) has been developed to map pressure distribution on surfaces of building models during aerodynamic tests in wind tunnel. The PSP consists of 2-hydroxyethyl acrylate (HEA) hydrogel matrix and ethyl eosin (EE) as a fluorescent pressure sensor. First, the spectroscopic properties and photostability of the PSP were investigated. The maximum coating thickness was determined to be 3 mm. The PSP system was studied in the Constant-Thickness-Mode (CTM) and Variable-Thickness-Mode (VTM). It was found that fluorescence intensity of the PSP decreased with increasing pressure. Under CTM conditions, the EE-based PSP system behaved like a classic Solvent-Quenched Pressure Sensitive Paint (SQ-PSP). Its sensitivity to changes of pressure was about 35 %/bar, which is comparable to the sensitivity of SQ-PSPs based on europium complexes and sensitivity of Oxygen Quenched Pressure Sensitive Paints (OQ-PSP). However, under VTM conditions, the sensitivity of the PSP studied turned out to be about 50 times higher than that in CTM mode, due to simultaneous solvent quenching of EE sensor and change of the paint thickness upon pressure, while the effect of thickness change on fluorescence intensity was dominating. Next, pressure distribution on the side wall surface of a building model at different angles of inclination to the wind direction was mapped using classic pressure taps (as a reference) and the new PSP system in VTM mode. It has been found that the pressure maps obtained using the new PSP system are consistent with those obtained using pressure taps in the overpressure area, but show some differences in the under-pressure area, which confirms that the new PSP system can be used for aerodynamic tests under certain conditions.