Ice Crystal Icing & Particle Impact
Ice crystal icing (ICI) is a complex and still not fully understood icing phenomenon occurring in high-altitude environments and mixed-phase conditions.
We perform experimental investigations of ice crystal icing in a modified icing wind tunnel testing facility, combining controlled generation of ice crystal clouds with advanced measurement techniques to study particle impact, accretion, and shedding processes.
Why Ice Crystal Icing Matters
Unlike classical icing from supercooled droplets, ice crystal icing involves solid particles interacting with surfaces and flow fields in a highly dynamic way.
Under certain conditions, ice crystals:
- Impact and fragment upon contact
- Partially melt and re-freeze
- Form complex, porous ice layers
- Lead to accretion even on heated surfaces
These processes can result in severe performance degradation or system failure, particularly in aerospace applications.
Despite significant research efforts, many underlying mechanisms remain insufficiently understood, making experimental investigation essential.
Experimental Ice Crystal Generation
We generate controlled ice crystal clouds by adapting wind tunnel operation and particle injection methods.
This enables:
- Reproducible particle impact conditions
- Control over particle size distributions
- Investigation of different icing regimes
Typical particle sizes range from microscopic to millimeter-scale crystals, covering the relevant range observed in natural icing environments.
Particle Impact Physics
A key aspect of ice crystal icing is the behavior of individual particles upon impact.
We investigate:
- Impact and fragmentation of ice crystals
- Rebound, sticking, and erosion mechanisms
- Influence of particle size, velocity, and temperature
Ice particles can exhibit a wide range of behaviors—from elastic rebound to catastrophic fragmentation—depending on impact conditions .
These microscopic processes govern the onset of ice accretion.
Accretion & Shedding Processes
Ice crystal icing involves the formation and evolution of complex ice layers.
We study:
- Accretion of ice layers from particle clouds
- Formation of mixed ice-water structures
- Shedding, erosion, and re-accretion mechanisms
Experiments show that accretion and shedding are governed by threshold-like behavior, where conditions lead either to continuous growth or periodic removal of ice .
On heated surfaces, additional effects such as melt-film formation and capillary-driven processes play a critical role.
Influence of Thermal Effects
Temperature and heat flux strongly influence ice crystal icing behavior.
We investigate:
- Accretion on heated and unheated surfaces
- Influence of heat flux on ice growth and stability
- Transition between accretion-dominated and erosion-dominated regimes
Experimental studies show that even fully glaciated ice crystal clouds can lead to significant accretion on heated surfaces, depending on thermal conditions.
Measurement & Analysis
We combine advanced experimental methods with custom data analysis tools:
- High-speed imaging of particle impacts and fragmentation
- Time-resolved observation of accretion and shedding
- Quantification of ice shapes, mass, and growth dynamics
- Automated image-based analysis of large datasets
This enables both detailed physical understanding and generation of high-quality experimental datasets.
Applications
Ice crystal icing investigations support:
- Development and validation of numerical icing models
- Fundamental research on particle-based icing processes
- Design and optimization of ice protection systems
- Evaluation of components exposed to ice crystal environments
Relevant Industries
Ice crystal icing is particularly relevant for:
- Aerospace and aviation
(e.g. jet engines, air data systems, high-altitude flight systems) - Research institutions and simulation developers
(e.g. model development and validation) - Advanced system development in icing environments
(e.g. components exposed to mixed-phase or particle-based icing)