Experimental Studies of Ice Crystal Accretion on Axisymmetric Bodies at Aeroengine Conditions

Abstract

It has been recognized in recent years that high-altitude atmospheric ice crystals pose a threat to aircraft engines in flight. It is believed that ice can accrete inside the core compressor, although the mechanism by which this occurs remains poorly understood. To model ice crystal accretion, an estimate of the proportion of the impinging ice and water that sticks to a surface (the sticking efficiency) is required. This Paper presents data from experiments undertaken using an axisymmetric test article in an altitude ice crystal wind tunnel. A 35 deg half-angle nose was used for a parametric study of Mach number, total water content, wet bulb temperature, and particle size distribution. An assessment of the response of a multiwire probe used for measuring liquid water content is also presented. A shadowgraphy technique was used to measure the ice accretion growth rate on the nose. The results show that sticking efficiency has a strong dependency on particle melt ratio. Erosion is shown to be correlated with particle size, Mach number, and surface angle. New semi-empirical models are presented for sticking probability and erosion.