High-Speed Shadowgraphy Measurements of an Erosive Particle-Laden Jet Under High-Pressure Compressor Conditions

Abstract

Erosive damage done to jet engine compressor blading by solid particles has a negative influence on the compressor aerodynamic properties and hence decreases performance. The erosive change of shape has been investigated in a multitude of experiments ranging from eroding flat plates to eroding full engines. The basic challenge to transfer the results from very simple tests to real life erosion remains. Up to date measurement techniques today allow closing this gap. The necessary experimental and analytical steps are shown. The erosion resistance of Ti–6Al–4V at realistic flow conditions with fluid velocities ranging from 200 to 400 m/s is used. The erodent used was quartz sand with a size distribution corresponding to standardized Arizona Test Dust A3 (1–120 μm). Flat plates out of Ti–6Al–4V were eroded at different impingement angles. The particle velocities and sizes were investigated using a high-speed laser shadowgraphy technique. A dimensional analysis was carried out to obtain nondimensional parameters suitable for describing erosion. Different averaging methods of the particle velocity were examined in order to identify a representative particle velocity. Compared to the fluid velocity and the mean particle velocity, the energy averaged particle velocity is found to be the best representation of the erosiveness of a particle stream. The correlations derived from the dimensional analysis are capable of precisely predicting erosion rates for different rig operating points (OPs). The results can be applied to the methodology published by Schrade et al. (2015, “Experimental and Numerical Investigation of Erosive Change of Shape for High-Pressure Compressors,” ASME Paper No. GT2015-42061).