Aircraft de-icing system delivers energy efficiencies
In-flight icing occurs when water droplets in clouds or drizzle freeze on impact with an aircraft. This is why it is critically important that the airframe – and especially the wings and engine inlets – are protected from ice build-up. “This is usually achieved in two ways,” explains InSPIRe project coordinator Helmut Kuehnelt from the AIT Austrian Institute of Technology. “Either by anti-icing, where ice is prevented from building up, or by de-icing, where ice is removed after it has formed.” Large passenger aircraft usually employ anti-icing thermal systems that use bleed hot air from the engines to prevent ice from forming. Such systems however have to be continuously powered, and are thus highly energy-intensive.
Challenges of applying anti-icing technology
Indeed, for smaller regional aircraft, the limited electrical power available on board means that thermal anti-icing technology is not feasible. “We recognised the need for a de-icing system with minimum power demand, specifically tailored for regional aircraft, that also doesn’t require too much maintenance,” says Kuehnelt. The InSPIRe project therefore set out to design and develop a low-power, integrated electrothermal wing ice protection system (EWIPS). The aim was to then demonstrate this at full scale in an iwt (icing wind tunnel) (IWT). “We wanted to show that an electrothermal de-icing system could effectively provide ice protection, by repeatedly heating multiple zones without the need for continuously powered ones,” explains Kuehnelt.
Demonstrating low-power de-icing concept
To achieve this, the new EWIPS concept was designed from scratch. This first involved in-depth numerical analyses of airflow, ice accretion and a de-icing concept. Next, the wing leading edge – the part of the wing that first contacts the air – was developed specifically for the application of a prototype heater layer technology. This enabled the team to place heater zones as closely as possible next to each other, to minimise any unheated gaps. Heater integration was validated with numerous tests. Electronics hardware for EWIPS power supply and control was also developed. “However, the manufacture of the prototype leading edge, with integrated power supply and miniature thermal sensors, posed a real challenge,” notes Kuehnelt. “After a failed first trial, new manufacturing tools and processes needed to be developed.” Nonetheless, the project team persevered, and InSPIRe’s low-power EWIPS approach was successfully demonstrated at CIRA’s IWT towards the end of 2022. “Results demonstrated a 25 % power saving using the InSPIRe concept compared to a traditional de-icing system, and an estimated 70 % power saving when compared to a traditional anti-ice system,” adds Kuehnelt. “This will also have an impact on an aircraft’s overall fuel burn and emissions.”
Achieving operational fuel savings
The eventual commercial application of this low-power de-icing technology could help regional aircraft carriers to achieve significant fuel savings. The prototype leading wing edge was shown to be highly robust, and the team capable of overcoming initial setbacks to achieve their objectives. “Our hope is that these results will contribute to more energy-efficient and thus cleaner aircraft in the future,” says Kuehnelt. “Some aspects of the project will of course need to be revisited in order to mature the technology further and optimise the system for aircraft.” The low-power EWIPS technology pioneered by InSPIRe could also be attractive for other aeronautic applications, such as other commuter aircraft and larger drones. “There could be broader opportunities to exploit these results,” adds Kuehnelt.
Keywords
InSPIRe, aircraft, de-icing, thermal, EWIPS, aeronautic, airflow, electrothermal
