New and Improved formulations of Pressure Sensitive Paints for Aerodynamics

Pressure-Sensitive Paint (PSP) is an aerodynamic investigation technique that allows for the measurement of pressure over an entire aerodynamic surface allowing for integration of loads over surfaces. In addition to this, the technique allows for pressure measurement in areas where traditional sensors cannot be located. When applied correctly to a surface, unsteady pressure measurements can be made allowing for investigations of phenomena such as buffet, cavity oscillations, and even transient aerodynamic flow. This added capability has represented a step change in the ability of engineers to investigate aerodynamic flows and vehicles. The PSP method relies on the luminescence quenching of oxygen to deactivate a photoactive molecule known as a luminophore. Luminophores currently under use have remained unchanged since the early 00s. The most common methodology of applying the luminophore to a surface involves the use of an oxygen permeable binder material. This binder material again has remained unchanged for almost 20 years. The only PSP formulation currently available from commercial suppliers are based on heavily fluorinated molecules (platinium pentafluoro-tetraphenyl porphyrin, Pt(TFPP) and fluorinated binding agents (polymers), are therefore extremely expensive and the oxygen quenching properties remain unoptimised.
This project will investigate alternatives to the traditional PSP formulation (Pt(TFPP)) with the aim of developing new PSP formulations that are more sensitive, efficient and cheaper than current commercially available formulations. This will be achieved by synthesising a range of porphyrin luminophores that contain either a significantly reduced degree of fluorination, no fluorinated groups at all and that do not contain the heavy metal platinum. The triplet oxygen quenching properties of these new molecules will be determined by luminescence spectroscopy and the singlet oxygen quantum yields determined. The most promising candidates will then be taken forward for binder testing with a range of common polymers that possess a high oxygen permeability, and then the best performing combinations assessed for coating formulations and PSP performances in model wind tunnel conditions.