View Video Presentation: https://doi.org/10.2514/6.2022-3698.vid In the present study, a series of experimental investigations were conducted to elucidate the underlying physics of the dynamic ice accretion process pertinent to crystal icing phenomena. A novel ice crystal icing test rig with the capacity of generating a controllable amount of ice crystals and flying speed up to 100 m/s was developed in a temperature-controllable environment chamber for the ice crystal icing studies. A flat aluminum plate with constant heat flux at the back side was tested under various icing conditions with varying angles of attack (AOA). During the experiments, while cameras were used to record overall the ice accretion process over the heated aluminum surfaces, an infrared (IR) thermal imaging system as well as thermocouples were also utilized to map the corresponding temperature distributions over the flat surfaces to quantify the unsteady heat transfer processes under different test conditions. The results clearly reveal that the ice accretion occurs upon impacting ice crystals on a heated plate when the surface temperature is above the freezing point at significant ice water content (IWC) value. Under the test temperature range, the ice thickness increasing rate was found to be higher for the higher substrate temperature. On the other hand, with the decrease of the impingement angle of attack, the ice was found to be more challenging to accumulate on the substrate since fewer crystals are able to impinge onto the surface, and impacting ice crystals were found to have more effortless bouncing off and driving away by the boundary layer flow.

A numerical study of shock wave propagation through multiple raindrops is presented using a density-based compressible two-phase flow solver coupled with a sharp-interface volume-of-fluid (VoF) method. The piecewise linear interface calculation (PLIC) approach is employed to reconstruct gas–liquid interfaces and capture droplet deformation during shock interaction. The numerical framework is first validated using a one-dimensional gas–liquid shock tube problem and a shock–helium bubble interaction benchmark. The method is then applied to investigate shock interactions with single, double, and multiple raindrops under compressible flow conditions. Numerical results show that complex wave structures, including shock reflection, diffraction, and wave interference, develop during shock propagation through raindrop fields. Interactions between neighboring droplets lead to local pressure amplification and non-uniform flow structures.