Pressure Measurement on the Sidewall of a Supersonic Nozzle Using Pressure Sensitive Paints

Whilst pressure sensitive paints have become a mature method of pressure analysis their application with UNSW Canberra has been limited in exposure. This report aims to describe the analysis conducted in order to verify PSPs as an accurate, fast and costly method of data reduction to identify the pressure distribution for a specimen subjected to a flow field. Our chosen specimen was an over-expanded supersonic nozzle. The intensity ratio system of image processing showed agreeable results with the expected flow field resolved from CFD and schlieren image solution. A study on the 2D transverse assumption of the nozzle showed good agreement from the transverse pressure distribution. A comparative study of two forms of the chosen Stern-Volmer equation showed the linear solution to provide a more accurate solution to our Fourier series solution. The temperature dependency of the PSP was analysed and the degree of dependency shown to have an effect on time-step images taken from the same run-case. Whilst the intensity ratio system provided results with a good agreement, the analysis was conducted within a range of specific conditions which matched the chosen method. The requirement for a method of temperature correction, in the case the use of pressure taps, limits the application of this system. A decay-based system should be explored and the potential development of a binary paint investigated.