Digital tools to simulate in-flight icing Icing is a major hazard to aircrafts, particularly at high altitudes. A series of new software tools will help the aeronautical sector evaluate engines and improve flight safety. Transport and Mobility Security © truba71/stock.adobe.com Ice Crystal Icing (ICI) occurs when ice forms on aircraft during flight. Ice can affect the function of a range of aircraft parts, including wings, propellers, windscreens, and communication systems. In recent decades, engineers have identified an additional risk of ice collecting on warm parts of the engine core. Yet physical engine tests require the use of icing wind tunnels, making them difficult and costly. In the EU-funded MUSIC-haic project, researchers developed new ICI simulation tools to help the European aerospace industry progress with the development of next-generation engines. “During the design of a new aircraft or engine, the engineer can use the simulation tools to scan a large number of flight conditions and identify areas at risk in terms of ice crystal accumulation,” explains Phillipe Villedieu, energy research engineer at ONERA and MUSIC-haic project coordinator. Engineers can use the tool during certification too, minimising the need for icing wind tunnel or flight tests. “More generally, a validated numerical icing tool could be used as a means of compliance during the icing certification process,” Villedieu adds. Assisting with next generation engines Newer generation engines are expected to be more sensitive to the threat of ICI than current systems. These engines have very high bypass rations, meaning more air bypasses the engine core to reduce fuel consumption. The fans on these engines have fewer blades, and these spin more slowly. As the centrifugal forces on ice particles will be smaller, this will lead to a higher entry rate of ice particles into the engine core in comparison with today’s turbofans. “Comparative analysis methods to evaluate the ICI threat for current generation engines are not applicable to breakthrough architecture engines,” says Villedieu. “In addition, ICI is very difficult to address through ground-testing because of icing facility physical limitations, their low availability worldwide, and very high costs.” Generating data in icing tunnels and the lab To generate the new ICI simulation tools, the MUSIC-haic team carried out a range of experiments, either in a laboratory or an icing wind tunnel. Most of the experiments used small-scale models—representative of a blade or part of an engine, for example—which were placed in an artificial icing cloud in the wind tunnel. Using video cameras positioned at different angles, the researchers observed and recorded ice accretion phenomena to gather quantitative data for numerical models. “Most of the planned experiments were carried out, providing a wealth of new quantitative experimental data for understanding accretion on heated walls, shedding of ice blocks, or the impact of crystals on walls.” “All these data are now available to the international community and constitute an invaluable asset for further model improvement and validation,” says Villedieu. Incorporating ICI into industry tools The most important result was the successful integration of ICI capability into the 3D numerical tools used by project partners—Rolls Royce, General Electric, Safran, Airbus, and Dassault. “An important validation work was also carried out that gave very promising results on the ability of the new tools to predict ice crystal accretion zones in engines,” says Villedieu. Beyond MUSIC-haic, the models and tools that have been developed will continue to be used and tested intensively by the European aerospace industry and research centres. Keywords MUSIC-haic, icing, crystal, ice, airplane, aerospace, industry, tools, simulation, model, data
