Skip to main content

Development and demonstration of materials and manufacturing process for ultra high reliability electric Anti-ice/De-ice thermal layers for high strain rotor blades and helicopter airframe sections

Periodic Reporting for period 2 - NO-ICE-ROTOR (Development and demonstration of materials and manufacturing process for ultra high reliability electric Anti-ice/De-ice thermal layers for high strain rotor blades and helicopter airframe sections)

Reporting period: 2018-07-01 to 2019-12-31

Every icing incident of airplane components may have serious consequences for aircraft flying performance and can even lead to fatal accidents. The statistics on ice- related accidents, reporting of more than 10.000 accidents between 1982 and 2001, make it very clear that ice prevention measures are of great importance.

Ice shapes on aircraft components can have substantial effects on lift, drag, and pitching moment. Even very little surface roughness caused by a thin ice layer generates significant aerodynamic effects, such as a precipitous drop in lift caused by flow separation. Ice accretion can be especially dangerous and fatal on propellers and rotors, significantly reducing propeller or rotor performance.

For tilt rotor aircraft, in-flight icing is an even greater issue - as a balanced and even power output between the two rotors is essential in all phases of flight. Uneven ice accretion between the two rotors, which may be caused by uncontrolled, uneven ice shed, will result in different efficiency and performance output between the two rotors on either side of the centre of gravity, resulting in a severe unbalance of the aircraft.
Furthermore, ballistic shedding of larger ice pieces may cause severe damage on the aircraft fuselage.

Taking all these factors into account, ice protection systems for tilt-rotor aircraft must be designed in a smart way in order to ensure sufficient safety in all weather conditions. Despite a large number of conventional approaches, anti-icing and the removal of existing ice on tilt-rotors are still not completely and satisfactorily solved.

The expected outcome of project NO-ICE-ROTOR is the development, manufacture and environmental test validation of ultra high reliability heater layers for future platforms.

The overall objectives of the project are:
o Design and development of electrically operated heater layers, to be embedded in the rotor blade structure up to a certain TRL
o Definition of test criteria and test matrix
o Manufacturing of suitable test specimens for structural-, and environmental coupon testing and ice wind tunnel testing
o Environmental testing at coupon level
o Structural testing at coupon level
o Ice wind tunnel, in both static-, and rotating configuration at full-scale level with fully functional prop rotor blade section
o Synthesis of testing results
Management including risk management, coordination, and communication within the project team as well as with the TM, is done by Villinger. In order to ensure proper management and coordination of the project, weekly telecons are being held between the TM and the consortium.

Under the framework of WP2, the design and development of the heater layer-based IPS to be incorporated into a prop rotor or panel composite structure will be delivered. AIT has performed CFD simulations in order to determine the requirements for the heater layer in terms of location and arrangement of heating zones on the rotor blade and power density for anti- icing and de-icing strategies. A number of anti-icing and de-icing zones along the rotor blade have been defined to ensure proper ice protection properties.

The first step was the aerodynamic characterisation of several iso-radial blade sections of the Proprotor in different operating conditions. Based on these flow fields, the particle tracking has been computed for the worst case scenarios and the impingement limits have been identified.

To guarantee a fair comparison between the current technology and the one employing the Villinger heater layer, the design will proceed by adopting the chord extension of the current heater layer.
Another action conducted in WP2 was the estimation of the parting strip power density requirements.
The parting strip baseline design has been analysed and, based on the constraints provided by the TM, a design for the Villinger heater layer has been proposed.
The anti-icing and de-icing system baseline designs were analysed and a design with the Villinger heater layer will be presented. The IPS developed was numerically simulated and it was verified that the maximum internal temperature of the PropRotor section at R=3175 mm in the most critical condition is below the maximum value indicated by the TM.

In order to secure that the basis for a future certification of the heater layer is sound, partner CEST has performed extensive material characterisation and qualification tests of coupons combined with the evaluation of materials safety and compatibility in accordance to the DO160 specification. For this testing campaign, rectangular-shaped flat coupons provided by the TM to Villinger and equipped with different heater layer configurations have been used.

Various techniques were employed to characterize the quality of adhesion and functionality of the heater layer applied on these two different types of substrates. Their reliability, heating uniformity and structural integrity after exposure to harsh environmental conditions as in the case of corrosion and humidity was evaluated. Laboratory heating results were obtained using a self-made set-up used to calculate resistance, and an infrared camera used to monitor and record images and heat changes during the investigated time.

The results were very promising and make it clear that the heater layer can withstand the applicable environmental and mechanical hazards.

In WP4, structural element test specimen, representative of the actual system design later applied to a blade specimen, will be manufactured for structural testing at Aviatest's facility. 5 coupons, consisting only of the structural laminate base material, without electrical elements included, will be tested to establish the laminate strength and failure modes.
Furthermore, several coupons (exact number TBD) with functioning electrical elements, including the heater layer, busbars and cables will be tested to establish the elements strength and failure modes of the heater layer.
The heater layers developed in NO-ICE-ROTOR will not only be characterized by high energy efficiency and cost efficiency, but also by increased reliability and lower weight compared to conventional technologies.

The NextGenCTR, capable of generating lift and propulsion with two powered rotating rotors mounted at the ends of a fixed wing, will cover the market need of a civil aircraft that combines the VTOL capabilities of a rotorcraft with the speed and range of a conventional fixed-wing aircraft. The vehicle will expand the EU industry's existing portfolio of heavy multi-engine rotorcraft, providing high-speed, long-range and versatile operation.

Besides the Aviation industry, heater layer- based ice protection measures are of great importance also for all other means of transportation (cars, trains, and vessels), cooling and refrigeration units, for wind energy plants, for bridges, for antennas, and for transmission lines as well. Beyond numerous aeronautical applications, the heater layer technology proposed by NO-ICE-ROTOR has also been successfully applied in the wind energy domain. The further development of this technology pushed by NO-ICE-ROTOR will allow a cross-fertilization between aviation and other technological areas.
Next Generation Civil Tilt Rotor