Results and achievements

Expected results

MUSIC-haic aimed to provide the aeronautic industry with an Ice Crystal Icing (ICI) numerical capability usable for both design and certification purposes and will bring the following main results:

• A better understanding of ICI physics
• Several new experimental databases to provide data for model development
• A comprehensive set of models to simulate ICI phenomena
• Updated 2D and 3D numerical tools with a validated ICI capability
• Clear conclusions on tools’ validation level and remaining limitations at the end of the project
• A set of best numerical practices to be followed to obtain exploitable results.

Work performed

The project was divided into 6 work-packages (WP), 4 technical ones (WP1 to WP4) and 2 other ones dedicated to management and dissemination. WP1 aimed to provide missing experimental data for model development and validation. The objective of WP2 was to complete the development of a comprehensive set of models for ice crystal icing (IC), building on previous projects outcomes and using WP1 experimental data. The aim of WP3 was to implement the new ICI models into the partners’ existing 3D multidisciplinary tools and to provide ready-to-run tools for WP4 final validation tests.

In WP1, numerous laboratory-scale experiments have been designed and completed:

• to measure some rheological properties of an ice layer (apparent yield stress, liquid water volume fraction, characteristic time scale of water imbibition),
• to investigate ice particle impact phenomena of ice crystals, in particular to characterize the size and velocity distributions of the reemitted fragments,
• to study the accretion of the ice crystals and shedding phenomena on heated and unheated walls,

Several new large experimental databases has been created and made available to the modelers involved in WP2. The corresponding test setups and results were described in deliverables D1.1, D1.2, D1.3 and D1.4 which will be publicly released.

In the scope of WP2, new models have been developed for:

• ice crystal impact onto a dry wall,
• the erosion rate of an ice layer due ice particle impacts,
• the sticking efficiency of ice crystals impinging a heated wall,
• ice crystal accretion and its coupling with heat conduction in the substrate.

These models have been implemented in the existing 2D numerical tools and numerical tests performed to assess the ability of the models to reproduce WP1 experimental results. The optimal calibration of the adjustable parameters has been completed as well. All Models and validation test results were described in deliverable D2.1, D2.2, D2.3, D2.4 and D2.5 which will be publicly released.

As far as WP3 is concerned, ONERA, CIRA and the industrial partners have completed the implementation of most of the HAIC and MUSIC-haic models in their in-house 3D numerical tools and have performed preliminary validation and cross comparisons tests.

Finally, in the scope of WP4, the final assessment of the updated 3D tools was completed. Relevant test cases for design and certification (based on existing industrial databases) were defined and run by the industrial partners with the support of tool developers. The level of technological readiness of most of the 3D tools was assessed at 5 at the end of the project.

Progress beyond the state of the art and impact

To develop the new 3D ICI numerical capability, MUSIC-haic did not start from scratch, but benefited from many important existing building blocks:

• Physical models: HAIC sub-project 6, which was devoted to models and tools development, made significant progress in the understanding of physical phenomena controlling ice crystal icing and led to the creation of a first generation of ICI models.
• ICI physics experimental database: To support the development of ICI models, extensive experimental activities were performed within the HAIC project and in parallel, in the scope of North American projects, by the CNRC and NASA. These complementary experimental investigations allowed a large database to be created.
• ICI industrial database: HAIC-HIWC flight tests permitted the characterization of high altitude ice crystals properties and the collection of data for quantifying probe installation effects. In parallel, full engine tests (with a Honeywell ALF 502 turbofan engine) were performed in NASA’s large IWT (Propulsion Systems Laboratory - PSL).

In MUSIC-haic significant progress beyond the state of the art has been made. First of all, the new experimental databases concerning accretion, shedding and impact phenomena constitute major advances compared to the state of the art. Moreover, the experiments concerning the initiation of the accretion phenomenon and the coupling between ice accretion and thermal conduction in the wall in the presence of a heat source have allowed important progress in the understanding of these phenomena. Regarding the development of new models, the most important achievements are the development of new fragmentation and erosion models with a less empirical basis than the HAIC models, the development of a new sticking model that is adapted to the case of heated walls, as well as the development of an extension of the classical Messinger model that takes into account both unsteady effects and the coupling with heat conduction in the wall and inside the ice layer. Finally yet importantly, all the industrial partners are now equipped with a 3D ice crystal icing numerical capability, which was not the case at the beginning of the project. The validation work carried out in WP4 gave very promising results on the ability of the new tools to predict accretion zones in engines (and the associated risk level) and to calculate probe installation factors. The level of technological readiness of most of the 3D tools was assessed at 5 at the end of the project.

In terms of potential impact of the project, the new ICI numerical capability will provide the European aeronautical industry with a tool to de-risk and optimize the design of new engines with breakthrough architecture, to optimize the efficiency of probes and their location on the nose and fuselage of aircraft, and to reduce the cost and duration of certification.

Heated flat plate accretion experiment performed in WP1. Left: Temperature field in the substrate and ice thickness on the flat plate at time t =100 s after the onset of the icing cloud. Right: Experimental data.

Influence of the air flow velocity on the wall temperature drop after the onset of the icing cloud

Ice Shedding on a heatable NACA0012 airfoil in TU Braunschweig IWT

Heated NACA0012 accretion experiment. Comparison between experimental and numerical results. On the left: Ice accretion shape at time t = 50s. On the right: time evolution of the ice thickness at the stagnation point

Simulation with Rolls-Royce’s 3D tool (top) and ONERA’s 3D tool (middle) of ice crystal accretion inside the CNRC’s ICE-MACR single stage module  (bottom)

Simulation of ice particle trajectories around an aircraft nose and fuselage configuration (Airbus XRF1 model). Left: with particle full deposition upon impact. Right: with particle fragmentation and fragment reemission.