Anodized aluminium pressure sensitive paint: effect of paint application technique

The porous surface of the Anodized Aluminium Pressure Sensitive Paint (AA-PSP) is what differentiates it from conventional sol–gel based PSPs, leading to a faster response time of the paint. The objective of the current study is to examine the effect of the paint application technique, i.e., whether the AA substrate is dipped or sprayed, on the pressure and temperature sensitivity. A more practical procedure for preparing the AA samples is also presented. Scanning Electron Microscope (SEM) images are acquired together with the calibration of the AA-PSP at various temperatures and pressures to determine the effectiveness of each application technique. The results revealed that the AA sample which was dipped in the PSP solution shows a higher pressure sensitivity than the sprayed one. The SEMs show that spraying leads to the covering up of the micropores created on the surface and undermining the benefit of anodization

Application of AA-PSP to hypersonic flows: the double ramp model

Anodized Aluminium Pressure Sensitive Paint (AA-PSP) is known for its rapid response characteristics, making it a highly desirable technique when studying high-speed phenomenon on a global scale. The current study examines the efficacy of the AA-PSP technique, which is prepared with a more practical approach than that reported in literature, in analysing the flow characteristics of a double ramp model placed in hypersonic flow of M = 5. Three different flow angles of 0°, −2°, and −4° are studied. Two-dimensional colour schlieren visualisation, using a colour wheel, is employed alongside high sensitivity Kulite pressure tap data to corroborate the AA-PSP findings. The AA-PSP results show good correlation between the qualitative schlieren and ±8.9% discrepency with the quantitative pressure tap data. The more practical AA-PSP preparation proposed in the current study, which uses aluminium alloy 6-series rather than pure aluminium, is proved to have the response time and the accuracy to be applied to unsteady high-speed flows

Application of Fast Pressure Sensitive Paint in Hypervelocity Flow

The development of fast responding pressure sensitive paints for measurements in high-enthalpy, hypersonic flows is reported. Data are obtained for at plate boundary layers in an impulse facility with typical test gas times on the order of hundreds of microseconds. The fast pressure sensitive paint is found to have the required response time and sufficient signal level to visualize vortical boundary layer structures in a Mach 5.12 freestream. The flow behind protuberance strips with different geometries is evaluated with measurements of the vortex frequency and diameter, as well as breakdown distance. Comparisons with static pressure measurements made using pressure taps show differences of up to a factor of three, and calibration sources as well as an alternative lifetime measurement method remain to be investigated