Development of a Pressure Sensitive Paint (PSP) Measurement Technique for High-Speed Turbine Testing

In the recent years, aircraft engine manufacturers have set ambitious goals concerning the maximization of efficiency and the reduction of noise and fuel consumption. The design of the next-generation propulsion units plays a key role in addressing this challenge. The development of innovative and green engine architectures introduces challenging operating conditions for the low-pressure turbine such as transonic Mach and low-Reynolds numbers. In the frame of the EU-funded project SPLEEN commissioned by Safran Aircraft Engines, aimed at investigating the combined effect of secondary and leakage flows under modern engine-scaled flow conditions, the development of an advanced technique of surface pressure measurement applied in the linear cascade of the S-1/C wind tunnel at the von Karman Institute is of major importance for understanding the aerodynamic performance. Based on the oxygen quenching kinematics of luminescence, the optical measurement technique of Pressure Sensitive Paint aims at measuring the 2D surface pressure field on complex geometries, offering incredible advantages in terms of non-intrusiveness, high spatial resolution and low application costs compared to conventional measurement techniques. Nevertheless, the technique presents high complexity in the design and preparation of the setup, measurement testing and data-processing. The scope of the work is the development of the measurement chain for the implementation of PSP in the S-1/C facility. In particular, the main objective of the thesis is the optimization of the setup for the achievement of the final calibration curve which relates the acquired images by a photodetector to a 2D steady-state static pressure distribution over the model surface. The reduction of the final uncertainty in the calibration parameters, which is directly related to the measurement uncertainty, goes through a detailed attention of the setup design for the implementation in the turbine test rig, the realization of the calibration setup, the development of various experimental tests including data-processing and evaluation of results for each intermediate analysis.