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Innovative Systems to Prevent Ice on Regional Aircraft

Periodic Reporting for period 1 - InSPIRe (Innovative Systems to Prevent Ice on Regional Aircraft)

Reporting period: 2018-03-01 to 2019-08-31

In the current development of the More-Electric Aircraft technological portfolio, a full electric wing ice protection system plays the key role to eliminate bleed air and pneumatic devices. In this framework, the adoption of an electrothermal ice protection system instead of an electromechanical one allows easy integration with laminar wings and/or morphing leading edges, thus resulting in it being more suitable for implementation in the future regional aircraft.

The EU CleanSky2 funded research project InSPIRe focusses on designing, developing and manufacturing a demonstrator for the wing ice protection system (WIPS) of the Leonardo regional aircraft concept.

To meet the design and energy constraints, the solution proposed by InSPIRe is geared towards:
i. optimizing the areas that are ice protected and their power distribution in the morphing leading-edge;
ii. optimizing the heater scheduling and the control logic;
iii. exploring the potential for removing the energy intense parting strip to minimize power consumption for a thermal de-ice system to be suitable for a Regional platform;
iv. applying an innovative, light weight, highly reliable and durable electrothermal technology integrated into the LE composite structure.

Performance verification will be pursued by means of an Icing Wind Tunnel (IWT) test campaign to contribute to reaching TRL5 for the selected IPS technologies.
In WP1 initially the flight conditions and wing geometry of the regional aircraft were defined. The first step of analysis was to study which part of the aircraft wing needs to be protected during an icing encounter.The beneficiaries ATX and AIT analyzed the impingement of supercooled water droplets on the main wing with respect to an extensive set of aircraft flight conditions and the related icing conditions (as specified in CS-25 Appendix C for atmospheric icing conditions and in Appendix O for Supercooled Large Drop icing conditions) by means of numerical simulation applying in-house and commercial flow solvers. Some hundred simulations needed to be performed to identify the impingement limits on the upper and lower wing surfaces. From them, a first estimate of the wing extension that needs to be protected from icing was deduced.

Thermal analysis at the coldest and warmest conditions was performed by ATX for an initial leading-edge composite structure and material layup to obtain first estimates of the maximum total power demand of the WIPS, the maximum internal structural temperature and water runback. The feasibility of a pure de-icing system with low power demand by removing the always powered parting strip was studied. The first system concept was developed, including the distribution and maximum electrical power density of the heater elements, a basic structure of the WIPS control laws (developed by ATX) and power electronics (developed by AIT).

In WP2, a concept for a morphing leading-edge structure was introduced and InSPIRe adapted its initial IPS concept to integrate its main characteristics, specifically by considering a LE (Leading edge) skin with non-uniform thickness distribution.

A concept to integrate the heater layer into a composite LE structure that is compatible with the requirements of the morphing leading edge was developed by the beneficiaries PEAK and VILL and a first prototype has been built to test its manufacturing. The VILL heater layer technology is a carbon based (non-CNT), lightweight, elastic, thin, polymer coating with high power density, up to 120 kW/m², that can be integrated into composite structures and is easily applicable to 3D surfaces. It is tested according to DO-160G, is REACH compliant and has been already tested in the icing wind tunnel (IWT) and in-flight conditions for wing and rotor configurations.
In the second period of the project, the InSPIRe WIPS system concept will be finalized, environmental testing of the LE IPS structure will be performed, the test article for the Icing Wind Tunnel (consisting of a representative wing section with IPS installed in the LE and power electronics for control and power supply) will be designed, manufactured and delivered for the IWT test campaign at CIRA where ultimately the performance of the WIPS will be validated to reach TRL5.

Approximately 20% of the global regional aviation market is concentrated in the EU-27, i.e. short-to-medium haul flights within the EU, characterized by an average flight distance of 600 km and approximately 200 million passengers per year (25% of all passengers flown in the EU in 2016). The targeted low-power WIPS is a key technology for the development of the future more-electric regional aircraft. Adopting such a low-power technology can double the energy efficiency of the aircraft IPS and reduce the total fuel consumption of the aircraft by 0.5%. Thus 5 million tonnes of CO2 per year could be saved by InSPIRe WIPS technology.

Furthermore, the CS2 regional aircraft programme, with InSPIRe as a partner, aims at strengthening the European aviation industry.
Conceptual sketch of InSPIRe technology development and TRL step-up