Experimental and numerical investigations on aircraft icing at mixed phase conditions.

Since the beginning of civil aviation, icing is a severe weather hazard for aircraft operation. In this context, the phenomenon of ice crystal icing has been identified as a risk for flight safety in the recent past. Ice crystals can accrete on warm components such as heated stagnation pressure probes and engine compressor blades. Liquid melt water or additional liquid droplets in the icing cloud enable the ice particles to stick to the component surface and to form a cohesive ice accretion layer. In this paper, we present results of comprehensive icing wind tunnel tests on ice crystal ice accretion together with results of complementary simulations by means of the ONERA icing code IGLOO2D. The experiments show a strong influence of ambient temperature on the icing process. In agreement with literature findings, ice particle sticking ability can be correlated with the ice cloud composition. Correlations between accretion shape and growth rate have been identified. IGLOO2D separates accretion abrasion by particle impact from the efficiency with which those particles stick to the deposit. Comparisons of computational and experimental results indicate that this sticking efficiency has the greatest effect on ice shapes at low Mach numbers, at least for the particle sizes and conditions used in the experiments. The experimental and numerical findings of this study can be considered as complementary to existing knowledge on ice crystal icing. Therefore, the experimental results are provided to an international benchmark of test cases for icing code validation. [ABSTRACT FROM AUTHOR]